Bug.pm

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# This Source Code Form is "Incompatible With Secondary Licenses", as
# defined by the Mozilla Public License, v. 2.0.

package Bugzilla::Bug;

use 5.10.1;
use strict;
use warnings;

use Bugzilla::Attachment;
use Bugzilla::Constants;
use Bugzilla::Field;
use Bugzilla::Flag;
use Bugzilla::FlagType;
use Bugzilla::Hook;
use Bugzilla::Keyword;
use Bugzilla::Milestone;
use Bugzilla::User;
use Bugzilla::Util;
use Bugzilla::Version;
use Bugzilla::Error;
use Bugzilla::Product;
use Bugzilla::Component;
use Bugzilla::Group;
use Bugzilla::Status;
use Bugzilla::Comment;
use Bugzilla::BugUrl;
use Bugzilla::BugUserLastVisit;

use List::MoreUtils qw(firstidx uniq part);
use List::Util qw(min max first);
use Storable qw(dclone);
use Scalar::Util qw(blessed);

use parent qw(Bugzilla::Object Exporter);
@Bugzilla::Bug::EXPORT = qw(
    bug_alias_to_id
    LogActivityEntry
    editable_bug_fields
);

#####################################################################
# Constants
#####################################################################

use constant DB_TABLE   => 'bugs';
use constant ID_FIELD   => 'bug_id';
use constant NAME_FIELD => 'bug_id';
use constant LIST_ORDER => ID_FIELD;
# Bugs have their own auditing table, bugs_activity.
use constant AUDIT_CREATES => 0;
use constant AUDIT_UPDATES => 0;
# This will be enabled later
use constant USE_MEMCACHED => 0;

# This is a sub because it needs to call other subroutines.
sub DB_COLUMNS {
    my $dbh = Bugzilla->dbh;
    my @custom = grep {$_->type != FIELD_TYPE_MULTI_SELECT}
                      Bugzilla->active_custom_fields;
    my @custom_names = map {$_->name} @custom;

    my @columns = (qw(
        assigned_to
        bug_file_loc
        bug_id
        bug_severity
        bug_status
        cclist_accessible
        component_id
        creation_ts
        delta_ts
        estimated_time
        everconfirmed
        lastdiffed
        op_sys
        priority
        product_id
        qa_contact
        remaining_time
        rep_platform
        reporter_accessible
        resolution
        short_desc
        status_whiteboard
        target_milestone
        version
    ),
    'reporter    AS reporter_id',
    $dbh->sql_date_format('deadline', '%Y-%m-%d') . ' AS deadline',
    @custom_names);
    
    Bugzilla::Hook::process("bug_columns", { columns => \@columns });
    
    return @columns;
}

sub VALIDATORS {

    my $validators = {
        alias          => \&_check_alias,
        assigned_to    => \&_check_assigned_to,
        blocked        => \&_check_dependencies,
        bug_file_loc   => \&_check_bug_file_loc,
        bug_severity   => \&_check_select_field,
        bug_status     => \&_check_bug_status,
        cc             => \&_check_cc,
        comment        => \&_check_comment,
        component      => \&_check_component,
        creation_ts    => \&_check_creation_ts,
        deadline       => \&_check_deadline,
        dependson      => \&_check_dependencies,
        dup_id         => \&_check_dup_id,
        estimated_time => \&_check_time_field,
        everconfirmed  => \&Bugzilla::Object::check_boolean,
        groups         => \&_check_groups,
        keywords       => \&_check_keywords,
        op_sys         => \&_check_select_field,
        priority       => \&_check_priority,
        product        => \&_check_product,
        qa_contact     => \&_check_qa_contact,
        remaining_time => \&_check_time_field,
        rep_platform   => \&_check_select_field,
        resolution     => \&_check_resolution,
        short_desc     => \&_check_short_desc,
        status_whiteboard => \&_check_status_whiteboard,
        target_milestone  => \&_check_target_milestone,
        version           => \&_check_version,

        cclist_accessible   => \&Bugzilla::Object::check_boolean,
        reporter_accessible => \&Bugzilla::Object::check_boolean,
    };

    # Set up validators for custom fields.    
    foreach my $field (Bugzilla->active_custom_fields) {
        my $validator;
        if ($field->type == FIELD_TYPE_SINGLE_SELECT) {
            $validator = \&_check_select_field;
        }
        elsif ($field->type == FIELD_TYPE_MULTI_SELECT) {
            $validator = \&_check_multi_select_field;
        }
        elsif ($field->type == FIELD_TYPE_DATETIME) {
            $validator = \&_check_datetime_field;
        }
        elsif ($field->type == FIELD_TYPE_DATE) {
            $validator = \&_check_date_field;
        }
        elsif ($field->type == FIELD_TYPE_FREETEXT) {
            $validator = \&_check_freetext_field;
        }
        elsif ($field->type == FIELD_TYPE_BUG_ID) {
            $validator = \&_check_bugid_field;
        }
        elsif ($field->type == FIELD_TYPE_TEXTAREA) {
            $validator = \&_check_textarea_field;
        }
        elsif ($field->type == FIELD_TYPE_INTEGER) {
            $validator = \&_check_integer_field;
        }
        else {
            $validator = \&_check_default_field;
        }
        $validators->{$field->name} = $validator;
    }

    return $validators;
};

sub VALIDATOR_DEPENDENCIES {
    my $cache = Bugzilla->request_cache;
    return $cache->{bug_validator_dependencies} 
        if $cache->{bug_validator_dependencies};

    my %deps = (
        assigned_to      => ['component'],
        blocked          => ['product'],
        bug_status       => ['product', 'comment', 'target_milestone'],
        cc               => ['component'],
        comment          => ['creation_ts'],
        component        => ['product'],
        dependson        => ['product'],
        dup_id           => ['bug_status', 'resolution'],
        groups           => ['product'],
        keywords         => ['product'],
        resolution       => ['bug_status', 'dependson'],
        qa_contact       => ['component'],
        target_milestone => ['product'],
        version          => ['product'],
    );

    foreach my $field (@{ Bugzilla->fields }) {
        $deps{$field->name} = [ $field->visibility_field->name ]
            if $field->{visibility_field_id};
    }

    $cache->{bug_validator_dependencies} = \%deps;
    return \%deps;
};

sub UPDATE_COLUMNS {
    my @custom = grep {$_->type != FIELD_TYPE_MULTI_SELECT}
                      Bugzilla->active_custom_fields;
    my @custom_names = map {$_->name} @custom;
    my @columns = qw(
        assigned_to
        bug_file_loc
        bug_severity
        bug_status
        cclist_accessible
        component_id
        deadline
        estimated_time
        everconfirmed
        op_sys
        priority
        product_id
        qa_contact
        remaining_time
        rep_platform
        reporter_accessible
        resolution
        short_desc
        status_whiteboard
        target_milestone
        version
    );
    push(@columns, @custom_names);
    return @columns;
};

use constant NUMERIC_COLUMNS => qw(
    estimated_time
    remaining_time
);

sub DATE_COLUMNS {
    my @fields = (@{ Bugzilla->fields({ type => [FIELD_TYPE_DATETIME,
                                                 FIELD_TYPE_DATE] })
                   });
    return map { $_->name } @fields;
}

# Used in LogActivityEntry(). Gives the max length of lines in the
# activity table.
use constant MAX_LINE_LENGTH => 254;

# This maps the names of internal Bugzilla bug fields to things that would
# make sense to somebody who's not intimately familiar with the inner workings
# of Bugzilla. (These are the field names that the WebService and email_in.pl
# use.)
use constant FIELD_MAP => {
    blocks           => 'blocked',
    commentprivacy   => 'comment_is_private',
    creation_time    => 'creation_ts',
    creator          => 'reporter',
    description      => 'comment',
    depends_on       => 'dependson',
    dupe_of          => 'dup_id',
    id               => 'bug_id',
    is_confirmed     => 'everconfirmed',
    is_cc_accessible => 'cclist_accessible',
    is_creator_accessible => 'reporter_accessible',
    last_change_time => 'delta_ts',
    platform         => 'rep_platform',
    severity         => 'bug_severity',
    status           => 'bug_status',
    summary          => 'short_desc',
    url              => 'bug_file_loc',
    whiteboard       => 'status_whiteboard',
};

use constant REQUIRED_FIELD_MAP => {
    product_id   => 'product',
    component_id => 'component',
};

# Creation timestamp is here because it needs to be validated
# but it can be NULL in the database (see comments in create above)
#
# Target Milestone is here because it has a default that the validator
# creates (product.defaultmilestone) that is different from the database
# default.
#
# CC is here because it is a separate table, and has a validator-created
# default of the component initialcc.
#
# QA Contact is allowed to be NULL in the database, so it wouldn't normally
# be caught by _required_create_fields. However, it always has to be validated,
# because it has a default of the component.defaultqacontact.
#
# Groups are in a separate table, but must always be validated so that
# mandatory groups get set on bugs.
use constant EXTRA_REQUIRED_FIELDS => qw(creation_ts target_milestone cc qa_contact groups);

#####################################################################

sub new {
    my $invocant = shift;
    my $class = ref($invocant) || $invocant;
    my $param = shift;

    # Remove leading "#" mark if we've just been passed an id.
    if (!ref $param && $param =~ /^#(\d+)$/) {
        $param = $1;
    }

    # If we get something that looks like a word (not a number),
    # make it the "name" param.
    if (!defined $param
        || (!ref($param) && $param =~ /\D/)
        || (ref($param) && $param->{id} =~ /\D/))
    {
        if ($param) {
            my $alias = ref($param) ? $param->{id} : $param;
            my $bug_id = bug_alias_to_id($alias);
            if (! $bug_id) {
                my $error_self = {};
                bless $error_self, $class;
                $error_self->{'bug_id'} = $alias;
                $error_self->{'error'}  = 'InvalidBugId';
                return $error_self;
            }
            $param = { id => $bug_id,
                       cache => ref($param) ? $param->{cache} : 0 };
        }
        else {
            # We got something that's not a number.
            my $error_self = {};
            bless $error_self, $class;
            $error_self->{'bug_id'} = $param;
            $error_self->{'error'}  = 'InvalidBugId';
            return $error_self;
        }
    }

    unshift @_, $param;
    my $self = $class->SUPER::new(@_);

    # Bugzilla::Bug->new always returns something, but sets $self->{error}
    # if the bug wasn't found in the database.
    if (!$self) {
        my $error_self = {};
        if (ref $param) {
            $error_self->{bug_id} = $param->{name};
            $error_self->{error}  = 'InvalidBugId';
        }
        else {
            $error_self->{bug_id} = $param;
            $error_self->{error}  = 'NotFound';
        }
        bless $error_self, $class;
        return $error_self;
    }

    return $self;
}

sub initialize {
    $_[0]->_create_cf_accessors();
}

sub object_cache_key {
    my $class = shift;
    my $key = $class->SUPER::object_cache_key(@_)
      || return;
    return $key . ',' . Bugzilla->user->id;
}

sub check {
    my $class = shift;
    my ($param, $field) = @_;

    # Bugzilla::Bug throws lots of special errors, so we don't call
    # SUPER::check, we just call our new and do our own checks.
    my $id = ref($param)
        ? ($param->{id} = trim($param->{id}))
        : ($param = trim($param));
    ThrowUserError('improper_bug_id_field_value', { field => $field }) unless defined $id;

    my $self = $class->new($param);

    if ($self->{error}) {
        # For error messages, use the id that was returned by new(), because
        # it's cleaned up.
        $id = $self->id;

        if ($self->{error} eq 'NotFound') {
             ThrowUserError("bug_id_does_not_exist", { bug_id => $id });
        }
        if ($self->{error} eq 'InvalidBugId') {
            ThrowUserError("improper_bug_id_field_value",
                              { bug_id => $id,
                                field  => $field });
        }
    }

    unless ($field && $field =~ /^(dependson|blocked|dup_id)$/) {
        $self->check_is_visible($id);
    }
    return $self;
}

sub check_for_edit {
    my $class = shift;
    my $bug = $class->check(@_);

    Bugzilla->user->can_edit_product($bug->product_id)
        || ThrowUserError("product_edit_denied", { product => $bug->product });

    return $bug;
}

sub check_is_visible {
    my ($self, $input_id) = @_;
    $input_id ||= $self->id;
    my $user = Bugzilla->user;

    if (!$user->can_see_bug($self->id)) {
        # The error the user sees depends on whether or not they are
        # logged in (i.e. $user->id contains the user's positive integer ID).
        # If we are validating an alias, then use it in the error message
        # instead of its corresponding bug ID, to not disclose it.
        if ($user->id) {
            ThrowUserError("bug_access_denied", { bug_id => $input_id });
        } else {
            ThrowUserError("bug_access_query", { bug_id => $input_id });
        }
    }
}

sub match {
    my $class = shift;
    my ($params) = @_;

    # Allow matching certain fields by name (in addition to matching by ID).
    my %translate_fields = (
        assigned_to => 'Bugzilla::User',
        qa_contact  => 'Bugzilla::User',
        reporter    => 'Bugzilla::User',
        product     => 'Bugzilla::Product',
        component   => 'Bugzilla::Component',
    );
    my %translated;

    foreach my $field (keys %translate_fields) {
        my @ids;
        # Convert names to ids. We use "exists" everywhere since people can
        # legally specify "undef" to mean IS NULL (even though most of these
        # fields can't be NULL, people can still specify it...).
        if (exists $params->{$field}) {
            my $names = $params->{$field};
            my $type = $translate_fields{$field};
            my $param = $type eq 'Bugzilla::User' ? 'login_name' : 'name';
            # We call Bugzilla::Object::match directly to avoid the
            # Bugzilla::User::match implementation which is different.
            my $objects = Bugzilla::Object::match($type, { $param => $names });
            push(@ids, map { $_->id } @$objects);
        }
        # You can also specify ids directly as arguments to this function,
        # so include them in the list if they have been specified.
        if (exists $params->{"${field}_id"}) {
            my $current_ids = $params->{"${field}_id"};
            my @id_array = ref $current_ids ? @$current_ids : ($current_ids);
            push(@ids, @id_array);
        }
        # We do this "or" instead of a "scalar(@ids)" to handle the case
        # when people passed only invalid object names. Otherwise we'd
        # end up with a SUPER::match call with zero criteria (which dies).
        if (exists $params->{$field} or exists $params->{"${field}_id"}) {
            $translated{$field} = scalar(@ids) == 1 ? $ids[0] : \@ids;
        }
    }

    # The user fields don't have an _id on the end of them in the database,
    # but the product & component fields do, so we have to have separate
    # code to deal with the different sets of fields here.
    foreach my $field (qw(assigned_to qa_contact reporter)) {
        delete $params->{"${field}_id"};
        $params->{$field} = $translated{$field} 
            if exists $translated{$field};
    }
    foreach my $field (qw(product component)) {
        delete $params->{$field};
        $params->{"${field}_id"} = $translated{$field} 
            if exists $translated{$field};
    }

    return $class->SUPER::match(@_);
}

# Helps load up information for bugs for show_bug.cgi and other situations
# that will need to access info on lots of bugs.
sub preload {
    my ($class, $bugs) = @_;
    my $user = Bugzilla->user;

    # It would be faster but MUCH more complicated to select all the
    # deps for the entire list in one SQL statement. If we ever have
    # a profile that proves that that's necessary, we can switch over
    # to the more complex method.
    my @all_dep_ids;
    foreach my $bug (@$bugs) {
        push(@all_dep_ids, @{ $bug->blocked }, @{ $bug->dependson });
        push(@all_dep_ids, @{ $bug->duplicate_ids });
    }
    @all_dep_ids = uniq @all_dep_ids;
    # If we don't do this, can_see_bug will do one call per bug in
    # the dependency and duplicate lists, in Bugzilla::Template::get_bug_link.
    $user->visible_bugs(\@all_dep_ids);

    foreach my $bug (@$bugs) {
        $bug->_preload_referenced_bugs();
    }
}

# Helps load up bugs referenced in comments by retrieving them with a single
# query from the database and injecting bug objects into the object-cache.
sub _preload_referenced_bugs {
    my $self = shift;
    my @referenced_bug_ids;

    # inject current duplicates into the object-cache first
    foreach my $bug (@{ $self->duplicates }) {
        $bug->object_cache_set()
            unless Bugzilla::Bug->object_cache_get($bug->id);
    }

    # preload bugs from comments
    require Bugzilla::Template;
    foreach my $comment (@{ $self->comments }) {
        if ($comment->type == CMT_HAS_DUPE || $comment->type == CMT_DUPE_OF) {
            # duplicate bugs that aren't currently in $self->duplicates
            push @referenced_bug_ids, $comment->extra_data
                unless Bugzilla::Bug->object_cache_get($comment->extra_data);
        }
        else {
            # bugs referenced in comments
            Bugzilla::Template::quoteUrls($comment->body, undef, undef, undef,
                sub {
                    my $bug_id = $_[0];
                    push @referenced_bug_ids, $bug_id
                        unless Bugzilla::Bug->object_cache_get($bug_id);
                });
        }
    }

    # inject into object-cache
    my $referenced_bugs = Bugzilla::Bug->new_from_list(
        [ uniq @referenced_bug_ids ]);
    foreach my $bug (@$referenced_bugs) {
        $bug->object_cache_set();
    }

    # preload bug visibility
    Bugzilla->user->visible_bugs(\@referenced_bug_ids);
}

sub possible_duplicates {
    my ($class, $params) = @_;
    my $short_desc = $params->{summary};
    my $products = $params->{products} || [];
    my $limit = $params->{limit} || MAX_POSSIBLE_DUPLICATES;
    $limit = MAX_POSSIBLE_DUPLICATES if $limit > MAX_POSSIBLE_DUPLICATES;
    $products = [$products] if !ref($products) eq 'ARRAY';

    my $orig_limit = $limit;
    detaint_natural($limit) 
        || ThrowCodeError('param_must_be_numeric', 
                          { function => 'possible_duplicates',
                            param    => $orig_limit });

    my $dbh = Bugzilla->dbh;
    my $user = Bugzilla->user;
    my @words = split(/[\b\s]+/, $short_desc || '');
    # Remove leading/trailing punctuation from words
    foreach my $word (@words) {
        $word =~ s/(?:^\W+|\W+$)//g;
    }
    # And make sure that each word is longer than 2 characters.
    @words = grep { defined $_ and length($_) > 2 } @words;

    return [] if !@words;

    my ($where_sql, $relevance_sql);
    if ($dbh->FULLTEXT_OR) {
        my $joined_terms = join($dbh->FULLTEXT_OR, @words);
        ($where_sql, $relevance_sql) = 
            $dbh->sql_fulltext_search('bugs_fulltext.short_desc', $joined_terms);
        $relevance_sql ||= $where_sql;
    }
    else {
        my (@where, @relevance);
        foreach my $word (@words) {
            my ($term, $rel_term) = $dbh->sql_fulltext_search(
                'bugs_fulltext.short_desc', $word);
            push(@where, $term);
            push(@relevance, $rel_term || $term);
        }

        $where_sql = join(' OR ', @where);
        $relevance_sql = join(' + ', @relevance);
    }

    my $product_ids = join(',', map { $_->id } @$products);
    my $product_sql = $product_ids ? "AND product_id IN ($product_ids)" : "";

    # Because we collapse duplicates, we want to get slightly more bugs
    # than were actually asked for.
    my $sql_limit = $limit + 5;

    my $possible_dupes = $dbh->selectall_arrayref(
        "SELECT bugs.bug_id AS bug_id, bugs.resolution AS resolution,
                ($relevance_sql) AS relevance
           FROM bugs
                INNER JOIN bugs_fulltext ON bugs.bug_id = bugs_fulltext.bug_id
          WHERE ($where_sql) $product_sql
       ORDER BY relevance DESC, bug_id DESC " .
          $dbh->sql_limit($sql_limit), {Slice=>{}});

    my @actual_dupe_ids;
    # Resolve duplicates into their ultimate target duplicates.
    foreach my $bug (@$possible_dupes) {
        my $push_id = $bug->{bug_id};
        if ($bug->{resolution} && $bug->{resolution} eq 'DUPLICATE') {
            $push_id = _resolve_ultimate_dup_id($bug->{bug_id});
        }
        push(@actual_dupe_ids, $push_id);
    }
    @actual_dupe_ids = uniq @actual_dupe_ids;
    if (scalar @actual_dupe_ids > $limit) {
        @actual_dupe_ids = @actual_dupe_ids[0..($limit-1)];
    }

    my $visible = $user->visible_bugs(\@actual_dupe_ids);
    return $class->new_from_list($visible);
}

# Docs for create() (there's no POD in this file yet, but we very
# much need this documented right now):
#
# The same as Bugzilla::Object->create. Parameters are only required
# if they say so below.
#
# Params:
#
# C<product>     - B<Required> The name of the product this bug is being
#                  filed against.
# C<component>   - B<Required> The name of the component this bug is being
#                  filed against.
#
# C<bug_severity> - B<Required> The severity for the bug, a string.
# C<creation_ts>  - B<Required> A SQL timestamp for when the bug was created.
# C<short_desc>   - B<Required> A summary for the bug.
# C<op_sys>       - B<Required> The OS the bug was found against.
# C<priority>     - B<Required> The initial priority for the bug.
# C<rep_platform> - B<Required> The platform the bug was found against.
# C<version>      - B<Required> The version of the product the bug was found in.
#
# C<alias>        - An alias for this bug.
# C<target_milestone> - When this bug is expected to be fixed.
# C<status_whiteboard> - A string.
# C<bug_status>   - The initial status of the bug, a string.
# C<bug_file_loc> - The URL field.
#
# C<assigned_to> - The full login name of the user who the bug is
#                  initially assigned to.
# C<qa_contact>  - The full login name of the QA Contact for this bug. 
#                  Will be ignored if C<useqacontact> is off.
#
# C<estimated_time> - For time-tracking. Will be ignored if 
#                     C<timetrackinggroup> is not set, or if the current
#                     user is not a member of the timetrackinggroup.
# C<deadline>       - For time-tracking. Will be ignored for the same
#                     reasons as C<estimated_time>.
sub create {
    my ($class, $params) = @_;
    my $dbh = Bugzilla->dbh;

    $dbh->bz_start_transaction();

    # These fields have default values which we can use if they are undefined.
    $params->{bug_severity} = Bugzilla->params->{defaultseverity}
      unless defined $params->{bug_severity};
    $params->{priority} = Bugzilla->params->{defaultpriority}
      unless defined $params->{priority};
    $params->{op_sys} = Bugzilla->params->{defaultopsys}
      unless defined $params->{op_sys};
    $params->{rep_platform} = Bugzilla->params->{defaultplatform}
      unless defined $params->{rep_platform};
    # Make sure a comment is always defined.
    $params->{comment} = '' unless defined $params->{comment};
    $params->{is_markdown} = 0
      unless defined $params->{is_markdown} && $params->{is_markdown} eq '1';

    $class->check_required_create_fields($params);
    $params = $class->run_create_validators($params);

    # These are not a fields in the bugs table, so we don't pass them to
    # insert_create_data.
    my $bug_aliases      = delete $params->{alias};
    my $cc_ids           = delete $params->{cc};
    my $groups           = delete $params->{groups};
    my $depends_on       = delete $params->{dependson};
    my $blocked          = delete $params->{blocked};
    my $keywords         = delete $params->{keywords};
    my $creation_comment = delete $params->{comment};
    my $is_markdown      = delete $params->{is_markdown};
    my $see_also         = delete $params->{see_also};

    # We don't want the bug to appear in the system until it's correctly
    # protected by groups.
    my $timestamp = delete $params->{creation_ts}; 

    my $ms_values = $class->_extract_multi_selects($params);
    my $bug = $class->insert_create_data($params);

    # Add the group restrictions
    my $sth_group = $dbh->prepare(
        'INSERT INTO bug_group_map (bug_id, group_id) VALUES (?, ?)');
    foreach my $group (@$groups) {
        $sth_group->execute($bug->bug_id, $group->id);
    }

    $dbh->do('UPDATE bugs SET creation_ts = ? WHERE bug_id = ?', undef,
             $timestamp, $bug->bug_id);
    # Update the bug instance as well
    $bug->{creation_ts} = $timestamp;

    # Add the CCs
    my $sth_cc = $dbh->prepare('INSERT INTO cc (bug_id, who) VALUES (?,?)');
    foreach my $user_id (@$cc_ids) {
        $sth_cc->execute($bug->bug_id, $user_id);
    }

    # Add in keywords
    my $sth_keyword = $dbh->prepare(
        'INSERT INTO keywords (bug_id, keywordid) VALUES (?, ?)');
    foreach my $keyword_id (map($_->id, @$keywords)) {
        $sth_keyword->execute($bug->bug_id, $keyword_id);
    }

    # Set up dependencies (blocked/dependson)
    my $sth_deps = $dbh->prepare(
        'INSERT INTO dependencies (blocked, dependson) VALUES (?, ?)');
    my $sth_bug_time = $dbh->prepare('UPDATE bugs SET delta_ts = ? WHERE bug_id = ?');

    foreach my $depends_on_id (@$depends_on) {
        $sth_deps->execute($bug->bug_id, $depends_on_id);
        # Log the reverse action on the other bug.
        LogActivityEntry($depends_on_id, 'blocked', '', $bug->bug_id,
                         $bug->{reporter_id}, $timestamp);
        $sth_bug_time->execute($timestamp, $depends_on_id);
    }
    foreach my $blocked_id (@$blocked) {
        $sth_deps->execute($blocked_id, $bug->bug_id);
        # Log the reverse action on the other bug.
        LogActivityEntry($blocked_id, 'dependson', '', $bug->bug_id,
                         $bug->{reporter_id}, $timestamp);
        $sth_bug_time->execute($timestamp, $blocked_id);
    }

    # Insert the values into the multiselect value tables
    foreach my $field (keys %$ms_values) {
        $dbh->do("DELETE FROM bug_$field where bug_id = ?",
                undef, $bug->bug_id);
        foreach my $value ( @{$ms_values->{$field}} ) {
            $dbh->do("INSERT INTO bug_$field (bug_id, value) VALUES (?,?)",
                    undef, $bug->bug_id, $value);
        }
    }

    # Insert any see_also values
    if ($see_also) {
        my $see_also_array = $see_also;
        if (!ref $see_also_array) {
            $see_also = trim($see_also);
            $see_also_array = [ split(/[\s,]+/, $see_also) ];
        }
        foreach my $value (@$see_also_array) {
            $bug->add_see_also($value);
        }
        foreach my $see_also (@{ $bug->see_also }) {
            $see_also->insert_create_data($see_also);
        }
        foreach my $ref_bug (@{ $bug->{_update_ref_bugs} || [] }) {
            $ref_bug->update();
        }
        delete $bug->{_update_ref_bugs};
    }

    # Comment #0 handling...

    # We now have a bug id so we can fill this out
    $creation_comment->{'bug_id'} = $bug->id;
    $creation_comment->{'is_markdown'} = $is_markdown;

    # Insert the comment. We always insert a comment on bug creation,
    # but sometimes it's blank.
    Bugzilla::Comment->insert_create_data($creation_comment);

    # Set up aliases
    my $sth_aliases = $dbh->prepare('INSERT INTO bugs_aliases (alias, bug_id) VALUES (?, ?)');
    foreach my $alias (@$bug_aliases) {
        trick_taint($alias);
        $sth_aliases->execute($alias, $bug->bug_id);
    }

    Bugzilla::Hook::process('bug_end_of_create', { bug => $bug,
                                                   timestamp => $timestamp,
                                                 });

    $dbh->bz_commit_transaction();

    # Because MySQL doesn't support transactions on the fulltext table,
    # we do this after we've committed the transaction. That way we're
    # sure we're inserting a good Bug ID.
    $bug->_sync_fulltext( new_bug => 1 );

    return $bug;
}

sub run_create_validators {
    my $class  = shift;
    my $params = $class->SUPER::run_create_validators(@_);

    # Add classification for checking mandatory fields which depend on it
    $params->{classification} = $params->{product}->classification->name;

    my @mandatory_fields = @{ Bugzilla->fields({ is_mandatory => 1,
                                                 enter_bug    => 1,
                                                 obsolete     => 0 }) };
    foreach my $field (@mandatory_fields) {
        $class->_check_field_is_mandatory($params->{$field->name}, $field,
                                          $params);
    }

    my $product = delete $params->{product};
    $params->{product_id} = $product->id;
    my $component = delete $params->{component};
    $params->{component_id} = $component->id;

    # Callers cannot set reporter, creation_ts, or delta_ts.
    $params->{reporter} = $class->_check_reporter();
    $params->{delta_ts} = $params->{creation_ts};

    if ($params->{estimated_time}) {
        $params->{remaining_time} = $params->{estimated_time};
    }

    $class->_check_strict_isolation($params->{cc}, $params->{assigned_to},
                                    $params->{qa_contact}, $product);

    # You can't set these fields.
    delete $params->{lastdiffed};
    delete $params->{bug_id};
    delete $params->{classification};

    Bugzilla::Hook::process('bug_end_of_create_validators',
                            { params => $params });

    # And this is not a valid DB field, it's just used as part of 
    # _check_dependencies to avoid running it twice for both blocked 
    # and dependson.
    delete $params->{_dependencies_validated};

    return $params;
}

sub update {
    my $self = shift;
    my $dbh  = Bugzilla->dbh;
    my $user = Bugzilla->user;

    # XXX This is just a temporary hack until all updating happens
    # inside this function.
    my $delta_ts = shift || $dbh->selectrow_array('SELECT LOCALTIMESTAMP(0)');

    $dbh->bz_start_transaction();

    my ($changes, $old_bug) = $self->SUPER::update(@_);

    Bugzilla::Hook::process('bug_start_of_update',
        { timestamp => $delta_ts, bug => $self,
           old_bug => $old_bug, changes => $changes });

    # Certain items in $changes have to be fixed so that they hold
    # a name instead of an ID.
    foreach my $field (qw(product_id component_id)) {
        my $change = delete $changes->{$field};
        if ($change) {
            my $new_field = $field;
            $new_field =~ s/_id$//;
            $changes->{$new_field} = 
                [$self->{"_old_${new_field}_name"}, $self->$new_field];
        }
    }
    foreach my $field (qw(qa_contact assigned_to)) {
        if ($changes->{$field}) {
            my ($from, $to) = @{ $changes->{$field} };
            $from = $old_bug->$field->login if $from;
            $to   = $self->$field->login    if $to;
            $changes->{$field} = [$from, $to];
        }
    }

    # CC
    my @old_cc = map {$_->id} @{$old_bug->cc_users};
    my @new_cc = map {$_->id} @{$self->cc_users};
    my ($removed_cc, $added_cc) = diff_arrays(\@old_cc, \@new_cc);
    
    if (scalar @$removed_cc) {
        $dbh->do('DELETE FROM cc WHERE bug_id = ? AND ' 
                 . $dbh->sql_in('who', $removed_cc), undef, $self->id);
    }
    foreach my $user_id (@$added_cc) {
        $dbh->do('INSERT INTO cc (bug_id, who) VALUES (?,?)',
                 undef, $self->id, $user_id);
    }
    # If any changes were found, record it in the activity log
    if (scalar @$removed_cc || scalar @$added_cc) {
        my $removed_users = Bugzilla::User->new_from_list($removed_cc);
        my $added_users   = Bugzilla::User->new_from_list($added_cc);
        my $removed_names = join(', ', (map {$_->login} @$removed_users));
        my $added_names   = join(', ', (map {$_->login} @$added_users));
        $changes->{cc} = [$removed_names, $added_names];
    }

    # Aliases
    my $old_aliases = $old_bug->alias;
    my $new_aliases = $self->alias;
    my ($removed_aliases, $added_aliases) = diff_arrays($old_aliases, $new_aliases);

    foreach my $alias (@$removed_aliases) {
        $dbh->do('DELETE FROM bugs_aliases WHERE bug_id = ? AND alias = ?',
                 undef, $self->id, $alias);
    }
    foreach my $alias (@$added_aliases) {
        trick_taint($alias);
        $dbh->do('INSERT INTO bugs_aliases (bug_id, alias) VALUES (?,?)',
                 undef, $self->id, $alias);
    }
    # If any changes were found, record it in the activity log
    if (scalar @$removed_aliases || scalar @$added_aliases) {
        $changes->{alias} = [join(', ', @$removed_aliases), join(', ', @$added_aliases)];
    }

    # Keywords
    my @old_kw_ids = map { $_->id } @{$old_bug->keyword_objects};
    my @new_kw_ids = map { $_->id } @{$self->keyword_objects};

    my ($removed_kw, $added_kw) = diff_arrays(\@old_kw_ids, \@new_kw_ids);

    if (scalar @$removed_kw) {
        $dbh->do('DELETE FROM keywords WHERE bug_id = ? AND ' 
                 . $dbh->sql_in('keywordid', $removed_kw), undef, $self->id);
    }
    foreach my $keyword_id (@$added_kw) {
        $dbh->do('INSERT INTO keywords (bug_id, keywordid) VALUES (?,?)',
                 undef, $self->id, $keyword_id);
    }
    # If any changes were found, record it in the activity log
    if (scalar @$removed_kw || scalar @$added_kw) {
        my $removed_keywords = Bugzilla::Keyword->new_from_list($removed_kw);
        my $added_keywords   = Bugzilla::Keyword->new_from_list($added_kw);
        my $removed_names = join(', ', (map {$_->name} @$removed_keywords));
        my $added_names   = join(', ', (map {$_->name} @$added_keywords));
        $changes->{keywords} = [$removed_names, $added_names];
    }

    # Dependencies
    foreach my $pair ([qw(dependson blocked)], [qw(blocked dependson)]) {
        my ($type, $other) = @$pair;
        my $old = $old_bug->$type;
        my $new = $self->$type;
        
        my ($removed, $added) = diff_arrays($old, $new);
        foreach my $removed_id (@$removed) {
            $dbh->do("DELETE FROM dependencies WHERE $type = ? AND $other = ?",
                     undef, $removed_id, $self->id);
            
            # Add an activity entry for the other bug.
            LogActivityEntry($removed_id, $other, $self->id, '',
                             $user->id, $delta_ts);
            # Update delta_ts on the other bug so that we trigger mid-airs.
            $dbh->do('UPDATE bugs SET delta_ts = ? WHERE bug_id = ?',
                     undef, $delta_ts, $removed_id);
        }
        foreach my $added_id (@$added) {
            $dbh->do("INSERT INTO dependencies ($type, $other) VALUES (?,?)",
                     undef, $added_id, $self->id);
            
            # Add an activity entry for the other bug.
            LogActivityEntry($added_id, $other, '', $self->id,
                             $user->id, $delta_ts);
            # Update delta_ts on the other bug so that we trigger mid-airs.
            $dbh->do('UPDATE bugs SET delta_ts = ? WHERE bug_id = ?',
                     undef, $delta_ts, $added_id);
        }
        
        if (scalar(@$removed) || scalar(@$added)) {
            $changes->{$type} = [join(', ', @$removed), join(', ', @$added)];
        }
    }

    # Groups
    my %old_groups = map {$_->id => $_} @{$old_bug->groups_in};
    my %new_groups = map {$_->id => $_} @{$self->groups_in};
    my ($removed_gr, $added_gr) = diff_arrays([keys %old_groups],
                                              [keys %new_groups]);
    if (scalar @$removed_gr || scalar @$added_gr) {
        if (@$removed_gr) {
            my $qmarks = join(',', ('?') x @$removed_gr);
            $dbh->do("DELETE FROM bug_group_map
                       WHERE bug_id = ? AND group_id IN ($qmarks)", undef,
                     $self->id, @$removed_gr);
        }
        my $sth_insert = $dbh->prepare(
            'INSERT INTO bug_group_map (bug_id, group_id) VALUES (?,?)');
        foreach my $gid (@$added_gr) {
            $sth_insert->execute($self->id, $gid);
        }
        my @removed_names = map { $old_groups{$_}->name } @$removed_gr;
        my @added_names   = map { $new_groups{$_}->name } @$added_gr;
        $changes->{'bug_group'} = [join(', ', @removed_names),
                                   join(', ', @added_names)];
    }

    # Flags
    my ($removed, $added) = Bugzilla::Flag->update_flags($self, $old_bug, $delta_ts);
    if ($removed || $added) {
        $changes->{'flagtypes.name'} = [$removed, $added];
    }

    # Comments
    foreach my $comment (@{$self->{added_comments} || []}) {
        # Override the Comment's timestamp to be identical to the update
        # timestamp.
        $comment->{bug_when} = $delta_ts;
        $comment = Bugzilla::Comment->insert_create_data($comment);
        if ($comment->work_time) {
            LogActivityEntry($self->id, "work_time", "", $comment->work_time,
                             $user->id, $delta_ts);
        }
    }

    # Comment Privacy 
    foreach my $comment (@{$self->{comment_isprivate} || []}) {
        $comment->update();
        
        my ($from, $to) 
            = $comment->is_private ? (0, 1) : (1, 0);
        LogActivityEntry($self->id, "longdescs.isprivate", $from, $to, 
                         $user->id, $delta_ts, $comment->id);
    }

    # Insert the values into the multiselect value tables
    my @multi_selects = grep {$_->type == FIELD_TYPE_MULTI_SELECT}
                             Bugzilla->active_custom_fields;
    foreach my $field (@multi_selects) {
        my $name = $field->name;
        my ($removed, $added) = diff_arrays($old_bug->$name, $self->$name);
        if (scalar @$removed || scalar @$added) {
            $changes->{$name} = [join(', ', @$removed), join(', ', @$added)];

            $dbh->do("DELETE FROM bug_$name where bug_id = ?",
                     undef, $self->id);
            foreach my $value (@{$self->$name}) {
                $dbh->do("INSERT INTO bug_$name (bug_id, value) VALUES (?,?)",
                         undef, $self->id, $value);
            }
        }
    }

    # See Also

    my ($removed_see, $added_see) =
        diff_arrays($old_bug->see_also, $self->see_also, 'name');

    $_->remove_from_db foreach @$removed_see;
    $_->insert_create_data($_) foreach @$added_see;

    # If any changes were found, record it in the activity log
    if (scalar @$removed_see || scalar @$added_see) {
        $changes->{see_also} = [join(', ', map { $_->name } @$removed_see),
                                join(', ', map { $_->name } @$added_see)];
    }

    $_->update foreach @{ $self->{_update_ref_bugs} || [] };
    delete $self->{_update_ref_bugs};

    # Log bugs_activity items
    # XXX Eventually, when bugs_activity is able to track the dupe_id,
    # this code should go below the duplicates-table-updating code below.
    foreach my $field (keys %$changes) {
        my $change = $changes->{$field};
        my $from = defined $change->[0] ? $change->[0] : '';
        my $to   = defined $change->[1] ? $change->[1] : '';
        LogActivityEntry($self->id, $field, $from, $to,
                         $user->id, $delta_ts);
    }

    # Check if we have to update the duplicates table and the other bug.
    my ($old_dup, $cur_dup) = ($old_bug->dup_id || 0, $self->dup_id || 0);
    if ($old_dup != $cur_dup) {
        $dbh->do("DELETE FROM duplicates WHERE dupe = ?", undef, $self->id);
        if ($cur_dup) {
            $dbh->do('INSERT INTO duplicates (dupe, dupe_of) VALUES (?,?)',
                     undef, $self->id, $cur_dup);
            if (my $update_dup = delete $self->{_dup_for_update}) {
                $update_dup->update();
            }
        }

        $changes->{'dup_id'} = [$old_dup || undef, $cur_dup || undef];
    }

    Bugzilla::Hook::process('bug_end_of_update', 
        { bug => $self, timestamp => $delta_ts, changes => $changes,
          old_bug => $old_bug });

    # If any change occurred, refresh the timestamp of the bug.
    if (scalar(keys %$changes) || $self->{added_comments}
        || $self->{comment_isprivate})
    {
        $dbh->do('UPDATE bugs SET delta_ts = ? WHERE bug_id = ?',
                 undef, ($delta_ts, $self->id));
        $self->{delta_ts} = $delta_ts;
    }

    # Update last-visited
    if ($user->is_involved_in_bug($self)) {
        $self->update_user_last_visit($user, $delta_ts);
    }

    # If a user is no longer involved, remove their last visit entry
    my $last_visits =
      Bugzilla::BugUserLastVisit->match({ bug_id => $self->id });
    foreach my $lv (@$last_visits) {
        $lv->remove_from_db() unless $lv->user->is_involved_in_bug($self);
    }

    # Update bug ignore data if user wants to ignore mail for this bug
    if (exists $self->{'bug_ignored'}) {
        my $bug_ignored_changed;
        if ($self->{'bug_ignored'} && !$user->is_bug_ignored($self->id)) {
            $dbh->do('INSERT INTO email_bug_ignore
                      (user_id, bug_id) VALUES (?, ?)',
                     undef, $user->id, $self->id);
            $bug_ignored_changed = 1;

        }
        elsif (!$self->{'bug_ignored'} && $user->is_bug_ignored($self->id)) {
            $dbh->do('DELETE FROM email_bug_ignore
                      WHERE user_id = ? AND bug_id = ?',
                     undef, $user->id, $self->id);
            $bug_ignored_changed = 1;
        }
        delete $user->{bugs_ignored} if $bug_ignored_changed;
    }

    $dbh->bz_commit_transaction();

    # The only problem with this here is that update() is often called
    # in the middle of a transaction, and if that transaction is rolled
    # back, this change will *not* be rolled back. As we expect rollbacks
    # to be extremely rare, that is OK for us.
    $self->_sync_fulltext(
        update_short_desc => $changes->{short_desc},
        update_comments   => $self->{added_comments} || $self->{comment_isprivate}
    );

    # Remove obsolete internal variables.
    delete $self->{'_old_assigned_to'};
    delete $self->{'_old_qa_contact'};

    # Also flush the visible_bugs cache for this bug as the user's
    # relationship with this bug may have changed.
    delete $user->{_visible_bugs_cache}->{$self->id};

    return $changes;
}

# Used by create().
# We need to handle multi-select fields differently than normal fields,
# because they're arrays and don't go into the bugs table.
sub _extract_multi_selects {
    my ($invocant, $params) = @_;

    my @multi_selects = grep {$_->type == FIELD_TYPE_MULTI_SELECT}
                             Bugzilla->active_custom_fields;
    my %ms_values;
    foreach my $field (@multi_selects) {
        my $name = $field->name;
        if (exists $params->{$name}) {
            my $array = delete($params->{$name}) || [];
            $ms_values{$name} = $array;
        }
    }
    return \%ms_values;
}

# Should be called any time you update short_desc or change a comment.
sub _sync_fulltext {
    my ($self, %options) = @_;
    my $dbh = Bugzilla->dbh;

    my($all_comments, $public_comments);
    if ($options{new_bug} || $options{update_comments}) {
        my $comments = $dbh->selectall_arrayref(
            'SELECT thetext, isprivate FROM longdescs WHERE bug_id = ?',
            undef, $self->id);
        $all_comments = join("\n", map { $_->[0] } @$comments);
        my @no_private = grep { !$_->[1] } @$comments;
        $public_comments = join("\n", map { $_->[0] } @no_private);
    }

    if ($options{new_bug}) {
        $dbh->do('INSERT INTO bugs_fulltext (bug_id, short_desc, comments,
                                             comments_noprivate)
                 VALUES (?, ?, ?, ?)',
                 undef,
                 $self->id, $self->short_desc, $all_comments, $public_comments);
    } else {
        my(@names, @values);
        if ($options{update_short_desc}) {
            push @names, 'short_desc';
            push @values, $self->short_desc;
        }
        if ($options{update_comments}) {
            push @names, ('comments', 'comments_noprivate');
            push @values, ($all_comments, $public_comments);
        }
        if (@names) {
            $dbh->do('UPDATE bugs_fulltext SET ' .
                     join(', ', map { "$_ = ?" } @names) .
                     ' WHERE bug_id = ?',
                     undef,
                     @values, $self->id);
        }
    }
}

sub remove_from_db {
    my ($self) = @_;
    my $dbh = Bugzilla->dbh;

    ThrowCodeError("bug_error", { bug => $self }) if $self->{'error'};

    my $bug_id = $self->{'bug_id'};
    $self->SUPER::remove_from_db();
    # The bugs_fulltext table doesn't support foreign keys.
    $dbh->do("DELETE FROM bugs_fulltext WHERE bug_id = ?", undef, $bug_id);
}

#####################################################################
# Sending Email After Bug Update
#####################################################################

sub send_changes {
    my ($self, $changes, $vars) = @_;

    my $user = Bugzilla->user;

    my $old_qa  = $changes->{'qa_contact'}  
                  ? $changes->{'qa_contact'}->[0] : '';
    my $old_own = $changes->{'assigned_to'} 
                  ? $changes->{'assigned_to'}->[0] : '';
    my $old_cc  = $changes->{cc}
                  ? $changes->{cc}->[0] : '';

    my %forced = (
        cc        => [split(/[,;]+/, $old_cc)],
        owner     => $old_own,
        qacontact => $old_qa,
        changer   => $user,
    );

    _send_bugmail({ id => $self->id, type => 'bug', forced => \%forced }, 
                  $vars);

    # If the bug was marked as a duplicate, we need to notify users on the
    # other bug of any changes to that bug.
    my $new_dup_id = $changes->{'dup_id'} ? $changes->{'dup_id'}->[1] : undef;
    if ($new_dup_id) {
        _send_bugmail({ forced => { changer => $user }, type => "dupe",
                        id => $new_dup_id }, $vars);
    }

    # If there were changes in dependencies, we need to notify those
    # dependencies.
    if ($changes->{'bug_status'}) {
        my ($old_status, $new_status) = @{ $changes->{'bug_status'} };

        # If this bug has changed from opened to closed or vice-versa,
        # then all of the bugs we block need to be notified.
        if (is_open_state($old_status) ne is_open_state($new_status)) {
            my $params = { forced   => { changer => $user },
                           type     => 'dep',
                           dep_only => 1,
                           blocker  => $self,
                           changes  => $changes };

            foreach my $id (@{ $self->blocked }) {
                $params->{id} = $id;
                _send_bugmail($params, $vars);
            }
        }
    }

    # To get a list of all changed dependencies, convert the "changes" arrays
    # into a long string, then collapse that string into unique numbers in
    # a hash.
    my $all_changed_deps = join(', ', @{ $changes->{'dependson'} || [] });
    $all_changed_deps = join(', ', @{ $changes->{'blocked'} || [] },
                                   $all_changed_deps);
    my %changed_deps = map { $_ => 1 } split(', ', $all_changed_deps);
    # When clearning one field (say, blocks) and filling in the other
    # (say, dependson), an empty string can get into the hash and cause
    # an error later.
    delete $changed_deps{''};

    foreach my $id (sort { $a <=> $b } (keys %changed_deps)) {
        _send_bugmail({ forced => { changer => $user }, type => "dep",
                         id => $id }, $vars);
    }

    # Sending emails for the referenced bugs.
    foreach my $ref_bug_id (uniq @{ $self->{see_also_changes} || [] }) {
        _send_bugmail({ forced => { changer => $user },
                        id => $ref_bug_id }, $vars);
    }
}

sub _send_bugmail {
    my ($params, $vars) = @_;

    require Bugzilla::BugMail;

    my $results = 
        Bugzilla::BugMail::Send($params->{'id'}, $params->{'forced'}, $params);

    if (Bugzilla->usage_mode == USAGE_MODE_BROWSER) {
        my $template = Bugzilla->template;
        $vars->{$_} = $params->{$_} foreach keys %$params;
        $vars->{'sent_bugmail'} = $results;
        $template->process("bug/process/results.html.tmpl", $vars)
            || ThrowTemplateError($template->error());
        $vars->{'header_done'} = 1;
    }
}

#####################################################################
# Validators
#####################################################################

sub _check_alias {
    my ($invocant, $aliases) = @_;
    $aliases = ref $aliases ? $aliases : [split(/[\s,]+/, $aliases)];

    # Remove empty aliases
    @$aliases = grep { $_ } @$aliases;

    foreach my $alias (@$aliases) {
        $alias = trim($alias);

        # Make sure the alias isn't too long.
        if (length($alias) > 40) {
            ThrowUserError("alias_too_long");
        }
        # Make sure the alias isn't just a number.
        if ($alias =~ /^\d+$/) {
            ThrowUserError("alias_is_numeric", { alias => $alias });
        }
        # Make sure the alias has no commas or spaces.
        if ($alias =~ /[, ]/) {
            ThrowUserError("alias_has_comma_or_space", { alias => $alias });
        }
        # Make sure the alias is unique, or that it's already our alias.
        my $other_bug = new Bugzilla::Bug($alias);
        if (!$other_bug->{error}
            && (!ref $invocant || $other_bug->id != $invocant->id))
        {
            ThrowUserError("alias_in_use", { alias => $alias,
                                             bug_id => $other_bug->id });
        }
    }

    return $aliases;
}

sub _check_assigned_to {
    my ($invocant, $assignee, undef, $params) = @_;
    my $user = Bugzilla->user;
    my $component = blessed($invocant) ? $invocant->component_obj
                                       : $params->{component};

    # Default assignee is the component owner.
    my $id;
    # If this is a new bug, you can only set the assignee if you have editbugs.
    # If you didn't specify the assignee, we use the default assignee.
    if (!ref $invocant
        && (!$user->in_group('editbugs', $component->product_id) || !$assignee))
    {
        $id = $component->default_assignee->id;
    } else {
        if (!ref $assignee) {
            $assignee = trim($assignee);
            # When updating a bug, assigned_to can't be empty.
            ThrowUserError("reassign_to_empty") if ref $invocant && !$assignee;
            $assignee = Bugzilla::User->check($assignee);
        }
        $id = $assignee->id;
        # create() checks this another way, so we don't have to run this
        # check during create().
        $invocant->_check_strict_isolation_for_user($assignee) if ref $invocant;
    }
    return $id;
}

sub _check_bug_file_loc {
    my ($invocant, $url) = @_;
    $url = '' if !defined($url);
    $url = trim($url);
    # On bug entry, if bug_file_loc is "http://", the default, use an 
    # empty value instead. However, on bug editing people can set that
    # back if they *really* want to.
    if (!ref $invocant && $url eq 'http://') {
        $url = '';
    }
    return $url;
}

sub _check_bug_status {
    my ($invocant, $new_status, undef, $params) = @_;
    my $user = Bugzilla->user;
    my @valid_statuses;
    my $old_status; # Note that this is undef for new bugs.

    my ($product, $comment);
    if (ref $invocant) {
        @valid_statuses = @{$invocant->statuses_available};
        $product = $invocant->product_obj;
        $old_status = $invocant->status;
        my $comments = $invocant->{added_comments} || [];
        $comment = $comments->[-1];
    }
    else {
        $product = $params->{product};
        $comment = $params->{comment};
        @valid_statuses = @{ Bugzilla::Bug->statuses_available($product) };
    }

    # Check permissions for users filing new bugs.
    if (!ref $invocant) {
        if ($user->in_group('editbugs', $product->id)
            || $user->in_group('canconfirm', $product->id)) {
            # If the user with privs hasn't selected another status,
            # select the first one of the list.
            unless ($new_status) {
                if (scalar(@valid_statuses) == 1) {
                    $new_status = $valid_statuses[0];
                }
                else {
                    $new_status = ($valid_statuses[0]->name ne 'UNCONFIRMED') ?
                                  $valid_statuses[0] : $valid_statuses[1];
                }
            }
        }
        else {
            # A user with no privs cannot choose the initial status.
            # If UNCONFIRMED is valid for this product, use it; else
            # use the first bug status available.
            if (grep {$_->name eq 'UNCONFIRMED'} @valid_statuses) {
                $new_status = 'UNCONFIRMED';
            }
            else {
                $new_status = $valid_statuses[0];
            }
        }
    }

    # Time to validate the bug status.
    $new_status = Bugzilla::Status->check($new_status) unless ref($new_status);
    # We skip this check if we are changing from a status to itself.
    if ( (!$old_status || $old_status->id != $new_status->id)
          && !grep {$_->name eq $new_status->name} @valid_statuses) 
    {
        ThrowUserError('illegal_bug_status_transition',
                       { old => $old_status, new => $new_status });
    }

    # Check if a comment is required for this change.
    if ($new_status->comment_required_on_change_from($old_status)
        && !$comment->{'thetext'})
    {
        ThrowUserError('comment_required',
          { old => $old_status ? $old_status->name : undef,
            new => $new_status->name, field => 'bug_status' });
    }
    
    if (ref $invocant 
        && ($new_status->name eq 'IN_PROGRESS'
            # Backwards-compat for the old default workflow.
            or $new_status->name eq 'ASSIGNED')
        && Bugzilla->params->{"usetargetmilestone"}
        && Bugzilla->params->{"musthavemilestoneonaccept"}
        # musthavemilestoneonaccept applies only if at least two
        # target milestones are defined for the product.
        && scalar(@{ $product->milestones }) > 1
        && $invocant->target_milestone eq $product->default_milestone)
    {
        ThrowUserError("milestone_required", { bug => $invocant });
    }

    if (!blessed $invocant) {
        $params->{everconfirmed} = $new_status->name eq 'UNCONFIRMED' ? 0 : 1;
    }

    return $new_status->name;
}

sub _check_cc {
    my ($invocant, $ccs, undef, $params) = @_;
    my $component = blessed($invocant) ? $invocant->component_obj
                                       : $params->{component};
    return [map {$_->id} @{$component->initial_cc}] unless $ccs;

    # Allow comma-separated input as well as arrayrefs.
    $ccs = [split(/[,;]+/, $ccs)] if !ref $ccs;

    my %cc_ids;
    foreach my $person (@$ccs) {
        $person = trim($person);
        next unless $person;
        my $id = login_to_id($person, THROW_ERROR);
        $cc_ids{$id} = 1;
    }

    # Enforce Default CC
    $cc_ids{$_->id} = 1 foreach (@{$component->initial_cc});

    return [keys %cc_ids];
}

sub _check_comment {
    my ($invocant, $comment_txt, undef, $params) = @_;

    # Comment can be empty. We should force it to be empty if the text is undef
    if (!defined $comment_txt) {
        $comment_txt = '';
    }

    # Load up some data
    my $isprivate = delete $params->{comment_is_private};
    my $timestamp = $params->{creation_ts};

    # Create the new comment so we can check it
    my $comment = {
        thetext  => $comment_txt,
        bug_when => $timestamp,
    };

    # We don't include the "isprivate" column unless it was specified. 
    # This allows it to fall back to its database default.
    if (defined $isprivate) {
        $comment->{isprivate} = $isprivate;
    }

    # Validate comment. We have to do this special as a comment normally
    # requires a bug to be already created. For a new bug, the first comment
    # obviously can't get the bug if the bug is created after this
    # (see bug 590334)
    Bugzilla::Comment->check_required_create_fields($comment);
    $comment = Bugzilla::Comment->run_create_validators($comment,
                                                        { skip => ['bug_id'] }
    );

    return $comment; 
}

sub _check_commenton {
    my ($invocant, $new_value, $field, $params) = @_;

    my $has_comment =
        ref($invocant) ? $invocant->{added_comments}
                       : (defined $params->{comment}
                          and $params->{comment}->{thetext} ne '');

    my $is_changing = ref($invocant) ? $invocant->$field ne $new_value
                                     : $new_value ne '';

    if ($is_changing && !$has_comment) {
        my $old_value = ref($invocant) ? $invocant->$field : undef;
        ThrowUserError('comment_required',
            { field => $field, old => $old_value, new => $new_value });
    }
}

sub _check_component {
    my ($invocant, $name, undef, $params) = @_;
    $name = trim($name);
    $name || ThrowUserError("require_component");
    my $product = blessed($invocant) ? $invocant->product_obj 
                                     : $params->{product};
    my $old_comp = blessed($invocant) ? $invocant->component : '';
    my $object = Bugzilla::Component->check({ product => $product, name => $name });
    if ($object->name ne $old_comp && !$object->is_active) {
        ThrowUserError('value_inactive', { class => ref($object), value => $name });
    }
    return $object;
}

sub _check_creation_ts {
    return Bugzilla->dbh->selectrow_array('SELECT LOCALTIMESTAMP(0)');
}

sub _check_deadline {
    my ($invocant, $date) = @_;

    # When filing bugs, we're forgiving and just return undef if
    # the user isn't a timetracker. When updating bugs, check_can_change_field
    # controls permissions, so we don't want to check them here.
    if (!ref $invocant and !Bugzilla->user->is_timetracker) {
        return undef;
    }

    # Validate entered deadline
    $date = trim($date);
    return undef if !$date;
    validate_date($date)
        || ThrowUserError('illegal_date', { date   => $date,
                                            format => 'YYYY-MM-DD' });
    return $date;
}

# Takes two comma/space-separated strings and returns arrayrefs
# of valid bug IDs.
sub _check_dependencies {
    my ($invocant, $value, $field, $params) = @_;

    return $value if $params->{_dependencies_validated};

    if (!ref $invocant) {
        # Only editbugs users can set dependencies on bug entry.
        return ([], []) unless Bugzilla->user->in_group(
            'editbugs', $params->{product}->id);
    }

    # This is done this way so that dependson and blocked can be in
    # VALIDATORS, meaning that they can be in VALIDATOR_DEPENDENCIES,
    # which means that they can be checked in the right order during
    # bug creation.
    my $opposite = $field eq 'dependson' ? 'blocked' : 'dependson';
    my %deps_in = ($field => $value || '',
                   $opposite => $params->{$opposite} || '');

    foreach my $type (qw(dependson blocked)) {
        my @bug_ids = ref($deps_in{$type}) 
            ? @{$deps_in{$type}} 
            : split(/[\s,]+/, $deps_in{$type});
        # Eliminate nulls.
        @bug_ids = grep {$_} @bug_ids;

        my @check_access = @bug_ids;
        # When we're updating a bug, only added or removed bug_ids are 
        # checked for whether or not we can see/edit those bugs.
        if (ref $invocant) {
            my $old = $invocant->$type;
            my ($removed, $added) = diff_arrays($old, \@bug_ids);
            @check_access = (@$added, @$removed);
            
            # Check field permissions if we've changed anything.
            if (@check_access) {
                my $privs;
                if (!$invocant->check_can_change_field($type, 0, 1, \$privs)) {
                    ThrowUserError('illegal_change', { field => $type,
                                                       privs => $privs });
                }
            }
        }

        my $user = Bugzilla->user;
        foreach my $modified_id (@check_access) {
            my $delta_bug = $invocant->check($modified_id);
            # Under strict isolation, you can't modify a bug if you can't
            # edit it, even if you can see it.
            if (Bugzilla->params->{"strict_isolation"}) {
                if (!$user->can_edit_product($delta_bug->{'product_id'})) {
                    ThrowUserError("illegal_change_deps", {field => $type});
                }
            }
        }
        # Replace all aliases by their corresponding bug ID.
        @bug_ids = map { $_ =~ /^(\d+)$/ ? $1 : $invocant->check($_, $type)->id } @bug_ids;
        $deps_in{$type} = \@bug_ids;
    }

    # And finally, check for dependency loops.
    my $bug_id = ref($invocant) ? $invocant->id : 0;
    my %deps = ValidateDependencies($deps_in{dependson}, $deps_in{blocked},
                                    $bug_id);

    $params->{$opposite} = $deps{$opposite};
    $params->{_dependencies_validated} = 1;
    return $deps{$field};
}

sub _check_dup_id {
    my ($self, $dupe_of) = @_;
    my $dbh = Bugzilla->dbh;

    # Store the bug ID/alias passed by the user for visibility checks.
    my $orig_dupe_of = $dupe_of = trim($dupe_of);
    $dupe_of || ThrowCodeError('undefined_field', { field => 'dup_id' });
    # Validate the bug ID. The second argument will force check() to only
    # make sure that the bug exists, and convert the alias to the bug ID
    # if a string is passed. Group restrictions are checked below.
    my $dupe_of_bug = $self->check($dupe_of, 'dup_id');
    $dupe_of = $dupe_of_bug->id;

    # If the dupe is unchanged, we have nothing more to check.
    return $dupe_of if ($self->dup_id && $self->dup_id == $dupe_of);

    # If we come here, then the duplicate is new. We have to make sure
    # that we can view/change it (issue A on bug 96085).
    $dupe_of_bug->check_is_visible($orig_dupe_of);

    # Make sure a loop isn't created when marking this bug
    # as duplicate.
   _resolve_ultimate_dup_id($self->id, $dupe_of, 1);

    my $cur_dup = $self->dup_id || 0;
    if ($cur_dup != $dupe_of && Bugzilla->params->{'commentonduplicate'}
        && !$self->{added_comments})
    {
        ThrowUserError('comment_required');
    }

    # Should we add the reporter to the CC list of the new bug?
    # If they can see the bug...
    if ($self->reporter->can_see_bug($dupe_of)) {
        # We only add them if they're not the reporter of the other bug.
        $self->{_add_dup_cc} = 1
            if $dupe_of_bug->reporter->id != $self->reporter->id;
    }
    # What if the reporter currently can't see the new bug? In the browser 
    # interface, we prompt the user. In other interfaces, we default to 
    # not adding the user, as the safest option.
    elsif (Bugzilla->usage_mode == USAGE_MODE_BROWSER) {
        # If we've already confirmed whether the user should be added...
        my $cgi = Bugzilla->cgi;
        my $add_confirmed = $cgi->param('confirm_add_duplicate');
        if (defined $add_confirmed) {
            $self->{_add_dup_cc} = $add_confirmed;
        }
        else {
            # Note that here we don't check if the user is already the reporter
            # of the dupe_of bug, since we already checked if they can *see*
            # the bug, above. People might have reporter_accessible turned
            # off, but cclist_accessible turned on, so they might want to
            # add the reporter even though they're already the reporter of the
            # dup_of bug.
            my $vars = {};
            my $template = Bugzilla->template;
            # Ask the user what they want to do about the reporter.
            $vars->{'cclist_accessible'} = $dupe_of_bug->cclist_accessible;
            $vars->{'original_bug_id'} = $dupe_of;
            $vars->{'duplicate_bug_id'} = $self->id;
            print $cgi->header();
            $template->process("bug/process/confirm-duplicate.html.tmpl", $vars)
              || ThrowTemplateError($template->error());
            exit;
        }
    }

    return $dupe_of;
}

sub _check_groups {
    my ($invocant, $group_names, undef, $params) = @_;

    my $bug_id = blessed($invocant) ? $invocant->id : undef;
    my $product = blessed($invocant) ? $invocant->product_obj 
                                     : $params->{product};
    my %add_groups;

    # In email or WebServices, when the "groups" item actually 
    # isn't specified, then just add the default groups.
    if (!defined $group_names) {
        my $available = $product->groups_available;
        foreach my $group (@$available) {
            $add_groups{$group->id} = $group if $group->{is_default};
        }
    }
    else {
        # Allow a comma-separated list, for email_in.pl.
        $group_names = [map { trim($_) } split(',', $group_names)]
            if !ref $group_names;

        # First check all the groups they chose to set.
        my %args = ( product => $product->name, bug_id => $bug_id, action => 'add' );
        foreach my $name (@$group_names) {
            my $group = Bugzilla::Group->check_no_disclose({ %args, name => $name });

            if (!$product->group_is_settable($group)) {
                ThrowUserError('group_restriction_not_allowed', { %args, name => $name });
            }
            $add_groups{$group->id} = $group;
        }
    }

    # Now enforce mandatory groups.
    $add_groups{$_->id} = $_ foreach @{ $product->groups_mandatory };

    my @add_groups = values %add_groups;
    return \@add_groups;
}

sub _check_keywords {
    my ($invocant, $keywords_in, undef, $params) = @_;

    return [] if !defined $keywords_in;

    my $keyword_array = $keywords_in;
    if (!ref $keyword_array) {
        $keywords_in = trim($keywords_in);
        $keyword_array = [split(/[\s,]+/, $keywords_in)];
    }
 
    my %keywords;
    foreach my $keyword (@$keyword_array) {
        next unless $keyword;
        my $obj = Bugzilla::Keyword->check($keyword);
        $keywords{$obj->id} = $obj;
    }
    return [values %keywords];
}

sub _check_product {
    my ($invocant, $name) = @_;
    $name = trim($name);
    # If we're updating the bug and they haven't changed the product,
    # always allow it.
    if (ref $invocant && lc($invocant->product_obj->name) eq lc($name)) {
        return $invocant->product_obj;
    }
    # Check that the product exists and that the user
    # is allowed to enter bugs into this product.
    my $product = Bugzilla->user->can_enter_product($name, THROW_ERROR);
    return $product;
}

sub _check_priority {
    my ($invocant, $priority) = @_;
    if (!ref $invocant && !Bugzilla->params->{'letsubmitterchoosepriority'}) {
        $priority = Bugzilla->params->{'defaultpriority'};
    }
    return $invocant->_check_select_field($priority, 'priority');
}

sub _check_qa_contact {
    my ($invocant, $qa_contact, undef, $params) = @_;
    $qa_contact = trim($qa_contact) if !ref $qa_contact;
    my $component = blessed($invocant) ? $invocant->component_obj
                                       : $params->{component};
    if (!ref $invocant) {
        # Bugs get no QA Contact on creation if useqacontact is off.
        return undef if !Bugzilla->params->{useqacontact};
        # Set the default QA Contact if one isn't specified or if the
        # user doesn't have editbugs.
        if (!Bugzilla->user->in_group('editbugs', $component->product_id)
            || !$qa_contact)
        {
            return $component->default_qa_contact ? $component->default_qa_contact->id : undef;
        }
    }

    # If a QA Contact was specified or if we're updating, check
    # the QA Contact for validity.
    my $id;
    if ($qa_contact) {
        $qa_contact = Bugzilla::User->check($qa_contact) if !ref $qa_contact;
        $id = $qa_contact->id;
        # create() checks this another way, so we don't have to run this
        # check during create().
        # If there is no QA contact, this check is not required.
        $invocant->_check_strict_isolation_for_user($qa_contact)
            if (ref $invocant && $id);
    }

    # "0" always means "undef", for QA Contact.
    return $id || undef;
}

sub _check_reporter {
    my $invocant = shift;
    my $reporter;
    if (ref $invocant) {
        # You cannot change the reporter of a bug.
        $reporter = $invocant->reporter->id;
    }
    else {
        # On bug creation, the reporter is the logged in user
        # (meaning that they must be logged in first!).
        Bugzilla->login(LOGIN_REQUIRED);
        $reporter = Bugzilla->user->id;
    }
    return $reporter;
}

sub _check_resolution {
    my ($invocant, $resolution, undef, $params) = @_;
    $resolution = trim($resolution);
    my $status = ref($invocant) ? $invocant->status->name 
                                : $params->{bug_status};
    my $is_open = ref($invocant) ? $invocant->status->is_open 
                                 : is_open_state($status);
    
    # Throw a special error for resolving bugs without a resolution
    # (or trying to change the resolution to '' on a closed bug without
    # using clear_resolution).
    ThrowUserError('missing_resolution', { status => $status })
        if !$resolution && !$is_open;
    
    # Make sure this is a valid resolution.
    $resolution = $invocant->_check_select_field($resolution, 'resolution');

    # Don't allow open bugs to have resolutions.
    ThrowUserError('resolution_not_allowed') if $is_open;
    
    # Check noresolveonopenblockers.
    my $dependson = ref($invocant) ? $invocant->dependson
                                   : ($params->{dependson} || []);
    if (Bugzilla->params->{"noresolveonopenblockers"}
        && $resolution eq 'FIXED'
        && (!ref $invocant or !$invocant->resolution 
            or $resolution ne $invocant->resolution)
        && scalar @$dependson)
    {
        my $dep_bugs = Bugzilla::Bug->new_from_list($dependson);
        my $count_open = grep { $_->isopened } @$dep_bugs;
        if ($count_open) {
            my $bug_id = ref($invocant) ? $invocant->id : undef;
            ThrowUserError("still_unresolved_bugs",
                           { bug_id => $bug_id, dep_count => $count_open });
        }
    }

    # Check if they're changing the resolution and need to comment.
    if (Bugzilla->params->{'commentonchange_resolution'}) {
        $invocant->_check_commenton($resolution, 'resolution', $params);
    }
    
    return $resolution;
}

sub _check_short_desc {
    my ($invocant, $short_desc) = @_;
    # Set the parameter to itself, but cleaned up
    $short_desc = clean_text($short_desc) if $short_desc;

    if (!defined $short_desc || $short_desc eq '') {
        ThrowUserError("require_summary");
    }
    if (length($short_desc) > MAX_FREETEXT_LENGTH) {
        ThrowUserError('freetext_too_long', 
                       { field => 'short_desc', text => $short_desc });
    }
    return $short_desc;
}

sub _check_status_whiteboard { return defined $_[1] ? $_[1] : ''; }

# Unlike other checkers, this one doesn't return anything.
sub _check_strict_isolation {
    my ($invocant, $ccs, $assignee, $qa_contact, $product) = @_;
    return unless Bugzilla->params->{'strict_isolation'};

    if (ref $invocant) {
        my $original = $invocant->new($invocant->id);

        # We only check people if they've been added. This way, if
        # strict_isolation is turned on when there are invalid users
        # on bugs, people can still add comments and so on.
        my @old_cc = map { $_->id } @{$original->cc_users};
        my @new_cc = map { $_->id } @{$invocant->cc_users};
        my ($removed, $added) = diff_arrays(\@old_cc, \@new_cc);
        $ccs = Bugzilla::User->new_from_list($added);

        $assignee = $invocant->assigned_to
            if $invocant->assigned_to->id != $original->assigned_to->id;
        if ($invocant->qa_contact
            && (!$original->qa_contact
                || $invocant->qa_contact->id != $original->qa_contact->id))
        {
            $qa_contact = $invocant->qa_contact;
        }
        $product = $invocant->product_obj;
    }

    my @related_users = @$ccs;
    push(@related_users, $assignee) if $assignee;

    if (Bugzilla->params->{'useqacontact'} && $qa_contact) {
        push(@related_users, $qa_contact);
    }

    @related_users = @{Bugzilla::User->new_from_list(\@related_users)}
        if !ref $invocant;

    # For each unique user in @related_users...(assignee and qa_contact
    # could be duplicates of users in the CC list)
    my %unique_users = map {$_->id => $_} @related_users;
    my @blocked_users;
    foreach my $id (keys %unique_users) {
        my $related_user = $unique_users{$id};
        if (!$related_user->can_edit_product($product->id) ||
            !$related_user->can_see_product($product->name)) {
            push (@blocked_users, $related_user->login);
        }
    }
    if (scalar(@blocked_users)) {
        my %vars = ( users   => \@blocked_users,
                     product => $product->name );
        if (ref $invocant) {
            $vars{'bug_id'} = $invocant->id;
        }
        else {
            $vars{'new'} = 1;
        }
        ThrowUserError("invalid_user_group", \%vars);
    }
}

# This is used by various set_ checkers, to make their code simpler.
sub _check_strict_isolation_for_user {
    my ($self, $user) = @_;
    return unless Bugzilla->params->{"strict_isolation"};
    if (!$user->can_edit_product($self->{product_id})) {
        ThrowUserError('invalid_user_group',
                       { users   => $user->login,
                         product => $self->product,
                         bug_id  => $self->id });
    }
}

sub _check_tag_name {
    my ($invocant, $tag) = @_;

    $tag = clean_text($tag);
    $tag || ThrowUserError('no_tag_to_edit');
    ThrowUserError('tag_name_too_long') if length($tag) > MAX_LEN_QUERY_NAME;
    trick_taint($tag);
    # Tags are all lowercase.
    return lc($tag);
}

sub _check_target_milestone {
    my ($invocant, $target, undef, $params) = @_;
    my $product = blessed($invocant) ? $invocant->product_obj 
                                     : $params->{product};
    my $old_target = blessed($invocant) ? $invocant->target_milestone : '';
    $target = trim($target);
    $target = $product->default_milestone if !defined $target;
    my $object = Bugzilla::Milestone->check(
        { product => $product, name => $target });
    if ($old_target && $object->name ne $old_target && !$object->is_active) {
        ThrowUserError('value_inactive', { class => ref($object),  value => $target });
    }
    return $object->name;
}

sub _check_time_field {
    my ($invocant, $value, $field, $params) = @_;

    # When filing bugs, we're forgiving and just return 0 if
    # the user isn't a timetracker. When updating bugs, check_can_change_field
    # controls permissions, so we don't want to check them here.
    if (!ref $invocant and !Bugzilla->user->is_timetracker) {
        return 0;
    }

    # check_time is in Bugzilla::Object.
    return $invocant->check_time($value, $field, $params);
}

sub _check_version {
    my ($invocant, $version, undef, $params) = @_;
    $version = trim($version);
    my $product = blessed($invocant) ? $invocant->product_obj 
                                     : $params->{product};
    my $old_vers = blessed($invocant) ? $invocant->version : '';
    my $object = Bugzilla::Version->check({ product => $product, name => $version });
    if ($object->name ne $old_vers && !$object->is_active) {
        ThrowUserError('value_inactive', { class => ref($object), value => $version });
    }
    return $object->name;
}

# Custom Field Validators

sub _check_field_is_mandatory {
    my ($invocant, $value, $field, $params) = @_;

    if (!blessed($field)) {
        $field = Bugzilla::Field->new({ name => $field });
        return if !$field;
    }

    return if !$field->is_mandatory;

    return if !$field->is_visible_on_bug($params || $invocant);

    return if ($field->type == FIELD_TYPE_SINGLE_SELECT
                 && scalar @{ get_legal_field_values($field->name) } == 1);

    return if ($field->type == FIELD_TYPE_MULTI_SELECT
                 && !scalar @{ get_legal_field_values($field->name) });

    if (ref($value) eq 'ARRAY') {
        $value = join('', @$value);
    }

    $value = trim($value);
    if (!defined($value)
        or $value eq ""
        or ($value eq '---' and $field->type == FIELD_TYPE_SINGLE_SELECT)
        or ($value =~ EMPTY_DATETIME_REGEX
            and $field->type == FIELD_TYPE_DATETIME))
    {
        ThrowUserError('required_field', { field => $field });
    }
}

sub _check_date_field {
    my ($invocant, $date) = @_;
    return $invocant->_check_datetime_field($date, undef, {date_only => 1});
}

sub _check_datetime_field {
    my ($invocant, $date_time, $field, $params) = @_;

    # Empty datetimes are empty strings or strings only containing
    # 0's, whitespace, and punctuation.
    if ($date_time =~ /^[\s0[:punct:]]*$/) {
        return undef;
    }

    $date_time = trim($date_time);
    my ($date, $time) = split(' ', $date_time);
    if ($date && !validate_date($date)) {
        ThrowUserError('illegal_date', { date   => $date,
                                         format => 'YYYY-MM-DD' });
    }
    if ($time && $params->{date_only}) {
        ThrowUserError('illegal_date', { date   => $date_time,
                                         format => 'YYYY-MM-DD' });
    }
    if ($time && !validate_time($time)) {
        ThrowUserError('illegal_time', { 'time' => $time,
                                         format => 'HH:MM:SS' });
    }
    return $date_time
}

sub _check_default_field { return defined $_[1] ? trim($_[1]) : ''; }

sub _check_freetext_field {
    my ($invocant, $text, $field) = @_;

    $text = (defined $text) ? trim($text) : '';
    if (length($text) > MAX_FREETEXT_LENGTH) {
        ThrowUserError('freetext_too_long', 
                       { field => $field, text => $text });
    }
    return $text;
}

sub _check_multi_select_field {
    my ($invocant, $values, $field) = @_;

    # Allow users (mostly email_in.pl) to specify multi-selects as
    # comma-separated values.
    if (defined $values and !ref $values) {
        # We don't split on spaces because multi-select values can and often
        # do have spaces in them. (Theoretically they can have commas in them
        # too, but that's much less common and people should be able to work
        # around it pretty cleanly, if they want to use email_in.pl.)
        $values = [split(',', $values)];
    }

    return [] if !$values;
    my @checked_values;
    foreach my $value (@$values) {
        push(@checked_values, $invocant->_check_select_field($value, $field));
    }
    return \@checked_values;
}

sub _check_select_field {
    my ($invocant, $value, $field) = @_;
    my $object = Bugzilla::Field::Choice->type($field)->check($value);
    return $object->name;
}

sub _check_bugid_field {
    my ($invocant, $value, $field) = @_;
    return undef if !$value;
    
    # check that the value is a valid, visible bug id
    my $checked_id = $invocant->check($value, $field)->id;
    
    # check for loop (can't have a loop if this is a new bug)
    if (ref $invocant) {
        _check_relationship_loop($field, $invocant->bug_id, $checked_id);
    }

    return $checked_id;
}

sub _check_textarea_field {
    my ($invocant, $text, $field) = @_;

    $text = (defined $text) ? trim($text) : '';

    # Web browsers submit newlines as \r\n.
    # Sanitize all input to match the web standard.
    # XMLRPC input could be either \n or \r\n
    $text =~ s/\r?\n/\r\n/g;

    return $text;
}

sub _check_integer_field {
    my ($invocant, $value, $field) = @_;
    $value = defined($value) ? trim($value) : '';

    if ($value eq '') {
        return 0;
    }

    my $orig_value = $value;
    if (!detaint_signed($value)) {
        ThrowUserError("number_not_integer",
                       {field => $field, num => $orig_value});
    }
    elsif ($value > MAX_INT_32) {
        ThrowUserError("number_too_large",
                       {field => $field, num => $orig_value, max_num => MAX_INT_32});
    }

    return $value;
}

sub _check_relationship_loop {
    # Generates a dependency tree for a given bug.  Calls itself recursively
    # to generate sub-trees for the bug's dependencies.
    my ($field, $bug_id, $dep_id, $ids) = @_;

    # Don't do anything if this bug doesn't have any dependencies.
    return unless defined($dep_id);

    # Check whether we have seen this bug yet
    $ids = {} unless defined $ids;
    $ids->{$bug_id} = 1;
    if ($ids->{$dep_id}) {
        ThrowUserError("relationship_loop_single", {
            'bug_id' => $bug_id,
            'dep_id' => $dep_id,
            'field_name' => $field});
    }
    
    # Get this dependency's record from the database
    my $dbh = Bugzilla->dbh;
    my $next_dep_id = $dbh->selectrow_array(
        "SELECT $field FROM bugs WHERE bug_id = ?", undef, $dep_id);

    _check_relationship_loop($field, $dep_id, $next_dep_id, $ids);
}

#####################################################################
# Class Accessors
#####################################################################

sub fields {
    my $class = shift;

   my @fields =
   (
        # Standard Fields
        # Keep this ordering in sync with bugzilla.dtd.
        qw(bug_id alias creation_ts short_desc delta_ts
           reporter_accessible cclist_accessible
           classification_id classification
           product component version rep_platform op_sys
           bug_status resolution dup_id see_also
           bug_file_loc status_whiteboard keywords
           priority bug_severity target_milestone
           dependson blocked everconfirmed
           reporter assigned_to cc estimated_time
           remaining_time actual_time deadline),

        # Conditional Fields
        Bugzilla->params->{'useqacontact'} ? "qa_contact" : (),
        # Custom Fields
        map { $_->name } Bugzilla->active_custom_fields
    );
    Bugzilla::Hook::process('bug_fields', {'fields' => \@fields} );
    
    return @fields;
}

#####################################################################
# Mutators 
#####################################################################

# To run check_can_change_field.
sub _set_global_validator {
    my ($self, $value, $field) = @_;
    my $current = $self->$field;
    my $privs;

    if (ref $current && ref($current) ne 'ARRAY'
        && $current->isa('Bugzilla::Object')) {
        $current = $current->id ;
    }
    if (ref $value && ref($value) ne 'ARRAY'
        && $value->isa('Bugzilla::Object')) {
        $value = $value->id ;
    }
    my $can = $self->check_can_change_field($field, $current, $value, \$privs);
    if (!$can) {
        if ($field eq 'assigned_to' || $field eq 'qa_contact') {
            $value   = Bugzilla::User->new($value)->login;
            $current = Bugzilla::User->new($current)->login;
        }
        ThrowUserError('illegal_change', { field    => $field,
                                           oldvalue => $current,
                                           newvalue => $value,
                                           privs    => $privs });
    }
    $self->_check_field_is_mandatory($value, $field);
}


#################
# "Set" Methods #
#################

# Note that if you are changing multiple bugs at once, you must pass
# other_bugs to set_all in order for it to behave properly.
sub set_all {
    my $self = shift;
    my ($input_params) = @_;
    
    # Clone the data as we are going to alter it, and this would affect
    # subsequent bugs when calling set_all() again, as some fields would
    # be modified or no longer defined.
    my $params = {};
    %$params = %$input_params;

    # You cannot mark bugs as duplicate when changing several bugs at once
    # (because currently there is no way to check for duplicate loops in that
    # situation). You also cannot set the alias of several bugs at once.
    if ($params->{other_bugs} and scalar @{ $params->{other_bugs} } > 1) {
        ThrowUserError('dupe_not_allowed') if exists $params->{dup_id};
        ThrowUserError('multiple_alias_not_allowed') 
            if defined $params->{alias};
    }

    # For security purposes, and because lots of other checks depend on it,
    # we set the product first before anything else.
    my $product_changed; # Used only for strict_isolation checks.
    if (exists $params->{'product'}) {
        $product_changed = $self->_set_product($params->{'product'}, $params);
    }

    # strict_isolation checks mean that we should set the groups
    # immediately after changing the product.
    $self->_add_remove($params, 'groups');

    if (exists $params->{'dependson'} or exists $params->{'blocked'}) {
        my %set_deps;
        foreach my $name (qw(dependson blocked)) {
            my @dep_ids = @{ $self->$name };
            # If only one of the two fields was passed in, then we need to
            # retain the current value for the other one.
            if (!exists $params->{$name}) {
                $set_deps{$name} = \@dep_ids;
                next;
            }

            # Explicitly setting them to a particular value overrides
            # add/remove.
            if (exists $params->{$name}->{set}) {
                $set_deps{$name} = $params->{$name}->{set};
                next;
            }

            foreach my $add (@{ $params->{$name}->{add} || [] }) {
                push(@dep_ids, $add) if !grep($_ == $add, @dep_ids);
            }
            foreach my $remove (@{ $params->{$name}->{remove} || [] }) {
                @dep_ids = grep($_ != $remove, @dep_ids);
            }
            $set_deps{$name} = \@dep_ids;
        }

        $self->set_dependencies($set_deps{'dependson'}, $set_deps{'blocked'});
    }

    if (exists $params->{'keywords'}) {
        # Sorting makes the order "add, remove, set", just like for other
        # fields.
        foreach my $action (sort keys %{ $params->{'keywords'} }) {
            $self->modify_keywords($params->{'keywords'}->{$action}, $action);
        }
    }

    if (exists $params->{'comment'} or exists $params->{'work_time'}) {
        # Add a comment as needed to each bug. This is done early because
        # there are lots of things that want to check if we added a comment.
        $self->add_comment($params->{'comment'}->{'body'},
            { isprivate => $params->{'comment'}->{'is_private'},
              work_time => $params->{'work_time'},
              is_markdown => $params->{'comment'}->{'is_markdown'} });
    }

    if (exists $params->{alias} && $params->{alias}{set}) {
        $params->{alias} = {
            add    => $params->{alias}{set},
            remove => $self->alias,
        };
    }

    my %normal_set_all;
    foreach my $name (keys %$params) {
        # These are handled separately below.
        if ($self->can("set_$name")) {
            $normal_set_all{$name} = $params->{$name};
        }
    }
    $self->SUPER::set_all(\%normal_set_all);

    $self->reset_assigned_to if $params->{'reset_assigned_to'};
    $self->reset_qa_contact  if $params->{'reset_qa_contact'};

    $self->_add_remove($params, 'see_also');

    # And set custom fields.
    my @custom_fields = Bugzilla->active_custom_fields;
    foreach my $field (@custom_fields) {
        my $fname = $field->name;
        if (exists $params->{$fname}) {
            $self->set_custom_field($field, $params->{$fname});
        }
    }

    $self->_add_remove($params, 'cc');
    $self->_add_remove($params, 'alias');

    # Theoretically you could move a product without ever specifying
    # a new assignee or qa_contact, or adding/removing any CCs. So,
    # we have to check that the current assignee, qa, and CCs are still
    # valid if we've switched products, under strict_isolation. We can only
    # do that here, because if they *did* change the assignee, qa, or CC,
    # then we don't want to check the original ones, only the new ones.
    $self->_check_strict_isolation() if $product_changed;
}

# Helper for set_all that helps with fields that have an "add/remove"
# pattern instead of a "set_" pattern.
sub _add_remove {
    my ($self, $params, $name) = @_;
    my @add    = @{ $params->{$name}->{add}    || [] };
    my @remove = @{ $params->{$name}->{remove} || [] };
    $name =~ s/s$// if $name ne 'alias';
    my $add_method = "add_$name";
    my $remove_method = "remove_$name";
    $self->$add_method($_) foreach @add;
    $self->$remove_method($_) foreach @remove;
}

sub set_assigned_to {
    my ($self, $value) = @_;
    $self->set('assigned_to', $value);
    # Store the old assignee. check_can_change_field() needs it.
    $self->{'_old_assigned_to'} = $self->{'assigned_to_obj'}->id;
    delete $self->{'assigned_to_obj'};
}
sub reset_assigned_to {
    my $self = shift;
    my $comp = $self->component_obj;
    $self->set_assigned_to($comp->default_assignee);
}
sub set_bug_ignored       { $_[0]->set('bug_ignored',       $_[1]); }
sub set_cclist_accessible { $_[0]->set('cclist_accessible', $_[1]); }
sub set_comment_is_private {
    my ($self, $comment_id, $isprivate) = @_;

    # We also allow people to pass in a hash of comment ids to update.
    if (ref $comment_id) {
        while (my ($id, $is) = each %$comment_id) {
            $self->set_comment_is_private($id, $is);
        }
        return;
    }

    my ($comment) = grep($comment_id == $_->id, @{ $self->comments });
    ThrowUserError('comment_invalid_isprivate', { id => $comment_id }) 
        if !$comment;

    $isprivate = $isprivate ? 1 : 0;
    if ($isprivate != $comment->is_private) {
        ThrowUserError('user_not_insider') if !Bugzilla->user->is_insider;
        $self->{comment_isprivate} ||= [];
        $comment->set_is_private($isprivate);
        push @{$self->{comment_isprivate}}, $comment;
    }
}
sub set_component  {
    my ($self, $name) = @_;
    my $old_comp  = $self->component_obj;
    my $component = $self->_check_component($name);
    if ($old_comp->id != $component->id) {
        $self->{component_id}  = $component->id;
        $self->{component}     = $component->name;
        $self->{component_obj} = $component;
        # For update()
        $self->{_old_component_name} = $old_comp->name;
        # Add in the Default CC of the new Component;
        foreach my $cc (@{$component->initial_cc}) {
            $self->add_cc($cc);
        }
    }
}
sub set_custom_field {
    my ($self, $field, $value) = @_;

    if (ref $value eq 'ARRAY' && $field->type != FIELD_TYPE_MULTI_SELECT) {
        $value = $value->[0];
    }
    ThrowCodeError('field_not_custom', { field => $field }) if !$field->custom;
    $self->set($field->name, $value);
}
sub set_deadline { $_[0]->set('deadline', $_[1]); }
sub set_dependencies {
    my ($self, $dependson, $blocked) = @_;
    my %extra = ( blocked => $blocked );
    $dependson = $self->_check_dependencies($dependson, 'dependson', \%extra);
    $blocked = $extra{blocked};
    # These may already be detainted, but all setters are supposed to
    # detaint their input if they've run a validator (just as though
    # we had used Bugzilla::Object::set), so we do that here.
    detaint_natural($_) foreach (@$dependson, @$blocked);
    $self->{'dependson'} = $dependson;
    $self->{'blocked'}   = $blocked;
    delete $self->{depends_on_obj};
    delete $self->{blocks_obj};
}
sub _clear_dup_id { $_[0]->{dup_id} = undef; }
sub set_dup_id {
    my ($self, $dup_id) = @_;
    my $old = $self->dup_id || 0;
    $self->set('dup_id', $dup_id);
    my $new = $self->dup_id;
    return if $old == $new;

    # Make sure that we have the DUPLICATE resolution. This is needed
    # if somebody calls set_dup_id without calling set_bug_status or
    # set_resolution.
    if ($self->resolution ne 'DUPLICATE') {
        # Even if the current status is VERIFIED, we change it back to
        # RESOLVED (or whatever the duplicate_or_move_bug_status is) here,
        # because that's the same thing the UI does when you click on the
        # "Mark as Duplicate" link. If people really want to retain their
        # current status, they can use set_bug_status and set the DUPLICATE
        # resolution before getting here.
        $self->set_bug_status(
            Bugzilla->params->{'duplicate_or_move_bug_status'},
            { resolution => 'DUPLICATE' });
    }
    
    # Update the other bug.
    my $dupe_of = new Bugzilla::Bug($self->dup_id);
    if (delete $self->{_add_dup_cc}) {
        $dupe_of->add_cc($self->reporter);
    }
    $dupe_of->add_comment("", { type       => CMT_HAS_DUPE,
                                extra_data => $self->id });
    $self->{_dup_for_update} = $dupe_of;
    
    # Now make sure that we add a duplicate comment on *this* bug.
    # (Change an existing comment into a dup comment, if there is one,
    # or add an empty dup comment.)
    if ($self->{added_comments}) {
        my @normal = grep { !defined $_->{type} || $_->{type} == CMT_NORMAL }
                          @{ $self->{added_comments} };
        # Turn the last one into a dup comment.
        $normal[-1]->{type} = CMT_DUPE_OF;
        $normal[-1]->{extra_data} = $self->dup_id;
    }
    else {
        $self->add_comment('', { type       => CMT_DUPE_OF,
                                 extra_data => $self->dup_id });
    }
}
sub set_estimated_time { $_[0]->set('estimated_time', $_[1]); }
sub _set_everconfirmed { $_[0]->set('everconfirmed', $_[1]); }
sub set_flags {
    my ($self, $flags, $new_flags) = @_;

    Bugzilla::Flag->set_flag($self, $_) foreach (@$flags, @$new_flags);
}
sub set_op_sys         { $_[0]->set('op_sys',        $_[1]); }
sub set_platform       { $_[0]->set('rep_platform',  $_[1]); }
sub set_priority       { $_[0]->set('priority',      $_[1]); }
# For security reasons, you have to use set_all to change the product.
# See the strict_isolation check in set_all for an explanation.
sub _set_product {
    my ($self, $name, $params) = @_;
    my $old_product = $self->product_obj;
    my $product = $self->_check_product($name);
    
    my $product_changed = 0;
    if ($old_product->id != $product->id) {
        $self->{product_id}  = $product->id;
        $self->{product}     = $product->name;
        $self->{product_obj} = $product;
        # For update()
        $self->{_old_product_name} = $old_product->name;
        # Delete fields that depend upon the old Product value.
        delete $self->{choices};
        $product_changed = 1;
    }

    $params ||= {};
    # We delete these so that they're not set again later in set_all.
    my $comp_name = delete $params->{component} || $self->component;
    my $vers_name = delete $params->{version}   || $self->version;
    my $tm_name   = delete $params->{target_milestone};
    # This way, if usetargetmilestone is off and we've changed products,
    # set_target_milestone will reset our target_milestone to
    # $product->default_milestone. But if we haven't changed products,
    # we don't reset anything.
    if (!defined $tm_name
        && (Bugzilla->params->{'usetargetmilestone'} || !$product_changed))
    {
        $tm_name = $self->target_milestone;
    }

    if ($product_changed && Bugzilla->usage_mode == USAGE_MODE_BROWSER) {
        # Try to set each value with the new product.
        # Have to set error_mode because Throw*Error calls exit() otherwise.
        my $old_error_mode = Bugzilla->error_mode;
        Bugzilla->error_mode(ERROR_MODE_DIE);
        my $component_ok = eval { $self->set_component($comp_name);      1; };
        my $version_ok   = eval { $self->set_version($vers_name);        1; };
        my $milestone_ok = 1;
        # Reporters can move bugs between products but not set the TM.
        if ($self->check_can_change_field('target_milestone', 0, 1)) {
            $milestone_ok = eval { $self->set_target_milestone($tm_name); 1; };
        }
        else {
            # Have to set this directly to bypass the validators.
            $self->{target_milestone} = $product->default_milestone;
        }
        # If there were any errors thrown, make sure we don't mess up any
        # other part of Bugzilla that checks $@.
        undef $@;
        Bugzilla->error_mode($old_error_mode);
        
        my $verified = $params->{product_change_confirmed};
        my %vars;
        if (!$verified || !$component_ok || !$version_ok || !$milestone_ok) {
            $vars{defaults} = {
                # Note that because of the eval { set } above, these are
                # already set correctly if they're valid, otherwise they're
                # set to some invalid value which the template will ignore.
                component => $self->component,
                version   => $self->version,
                milestone => $milestone_ok ? $self->target_milestone
                                           : $product->default_milestone
            };
            $vars{components} = [map { $_->name } grep($_->is_active, @{$product->components})];
            $vars{milestones} = [map { $_->name } grep($_->is_active, @{$product->milestones})];
            $vars{versions}   = [map { $_->name } grep($_->is_active, @{$product->versions})];
        }

        if (!$verified) {
            $vars{verify_bug_groups} = 1;
            my $dbh = Bugzilla->dbh;
            my @idlist = ($self->id);
            push(@idlist, map {$_->id} @{ $params->{other_bugs} })
                if $params->{other_bugs};
            @idlist = uniq @idlist;
            # Get the ID of groups which are no longer valid in the new product.
            my $gids = $dbh->selectcol_arrayref(
                'SELECT bgm.group_id
                   FROM bug_group_map AS bgm
                  WHERE bgm.bug_id IN (' . join(',', ('?') x @idlist) . ')
                    AND bgm.group_id NOT IN
                        (SELECT gcm.group_id
                           FROM group_control_map AS gcm
                           WHERE gcm.product_id = ?
                                 AND ( (gcm.membercontrol != ?
                                        AND gcm.group_id IN ('
                                        . Bugzilla->user->groups_as_string . '))
                                       OR gcm.othercontrol != ?) )',
                undef, (@idlist, $product->id, CONTROLMAPNA, CONTROLMAPNA));
            $vars{'old_groups'} = Bugzilla::Group->new_from_list($gids);

            # Did we come here from editing multiple bugs? (affects how we
            # show optional group changes)
            $vars{multiple_bugs} = (@idlist > 1) ? 1 : 0;
        }

        if (%vars) {
            $vars{product} = $product;
            $vars{bug} = $self;
            my $template = Bugzilla->template;
            $template->process("bug/process/verify-new-product.html.tmpl",
                \%vars) || ThrowTemplateError($template->error());
            exit;
        }
    }
    else {
        # When we're not in the browser (or we didn't change the product), we
        # just die if any of these are invalid.
        $self->set_component($comp_name);
        $self->set_version($vers_name);
        if ($product_changed 
            and !$self->check_can_change_field('target_milestone', 0, 1)) 
        {
            # Have to set this directly to bypass the validators.
            $self->{target_milestone} = $product->default_milestone;
        }
        else {
            $self->set_target_milestone($tm_name);
        }
    }

    if ($product_changed) {
        # Remove groups that can't be set in the new product.
        # We copy this array because the original array is modified while we're
        # working, and that confuses "foreach".
        my @current_groups = @{$self->groups_in};
        foreach my $group (@current_groups) {
            if (!$product->group_is_valid($group)) {
                $self->remove_group($group);
            }
        }

        # Make sure the bug is in all the mandatory groups for the new product.
        foreach my $group (@{$product->groups_mandatory}) {
            $self->add_group($group);
        }
    }
    
    return $product_changed;
}

sub set_qa_contact {
    my ($self, $value) = @_;
    $self->set('qa_contact', $value);
    # Store the old QA contact. check_can_change_field() needs it.
    if ($self->{'qa_contact_obj'}) {
        $self->{'_old_qa_contact'} = $self->{'qa_contact_obj'}->id;
    }
    delete $self->{'qa_contact_obj'};
}
sub reset_qa_contact {
    my $self = shift;
    my $comp = $self->component_obj;
    $self->set_qa_contact($comp->default_qa_contact);
}
sub set_remaining_time { $_[0]->set('remaining_time', $_[1]); }
# Used only when closing a bug or moving between closed states.
sub _zero_remaining_time { $_[0]->{'remaining_time'} = 0; }
sub set_reporter_accessible { $_[0]->set('reporter_accessible', $_[1]); }
sub set_resolution {
    my ($self, $value, $params) = @_;
    
    my $old_res = $self->resolution;
    $self->set('resolution', $value);
    delete $self->{choices};
    my $new_res = $self->resolution;

    if ($new_res ne $old_res) {
        # Clear the dup_id if we're leaving the dup resolution.
        if ($old_res eq 'DUPLICATE') {
            $self->_clear_dup_id();
        }
        # Duplicates should have no remaining time left.
        elsif ($new_res eq 'DUPLICATE' && $self->remaining_time != 0) {
            $self->_zero_remaining_time();
        }
    }
    
    # We don't check if we're entering or leaving the dup resolution here,
    # because we could be moving from being a dup of one bug to being a dup
    # of another, theoretically. Note that this code block will also run
    # when going between different closed states.
    if ($self->resolution eq 'DUPLICATE') {
        if (my $dup_id = $params->{dup_id}) {
            $self->set_dup_id($dup_id);
        }
        elsif (!$self->dup_id) {
            ThrowUserError('dupe_id_required');
        }
    }

    # This method has handled dup_id, so set_all doesn't have to worry
    # about it now.
    delete $params->{dup_id};
}
sub clear_resolution {
    my $self = shift;
    if (!$self->status->is_open) {
        ThrowUserError('resolution_cant_clear', { bug_id => $self->id });
    }
    $self->{'resolution'} = ''; 
    $self->_clear_dup_id; 
}
sub set_severity       { $_[0]->set('bug_severity',  $_[1]); }
sub set_bug_status {
    my ($self, $status, $params) = @_;
    my $old_status = $self->status;
    $self->set('bug_status', $status);
    delete $self->{'status'};
    delete $self->{'statuses_available'};
    delete $self->{'choices'};
    my $new_status = $self->status;
   
    if ($new_status->is_open) {
        # Check for the everconfirmed transition
        $self->_set_everconfirmed($new_status->name eq 'UNCONFIRMED' ? 0 : 1);
        $self->clear_resolution();
        # Calling clear_resolution handled the "resolution" and "dup_id"
        # setting, so set_all doesn't have to worry about them.
        delete $params->{resolution};
        delete $params->{dup_id};
    }
    else {
        # We do this here so that we can make sure closed statuses have
        # resolutions.
        my $resolution = $self->resolution;
        # We need to check "defined" to prevent people from passing
        # a blank resolution in the WebService, which would otherwise fail
        # silently.
        if (defined $params->{resolution}) {
            $resolution = delete $params->{resolution};
        }
        $self->set_resolution($resolution, $params);

        # Changing between closed statuses zeros the remaining time.
        if ($new_status->id != $old_status->id && $self->remaining_time != 0) {
            $self->_zero_remaining_time();
        }
    }
}
sub set_status_whiteboard { $_[0]->set('status_whiteboard', $_[1]); }
sub set_summary           { $_[0]->set('short_desc',        $_[1]); }
sub set_target_milestone  { $_[0]->set('target_milestone',  $_[1]); }
sub set_url               { $_[0]->set('bug_file_loc',      $_[1]); }
sub set_version           { $_[0]->set('version',           $_[1]); }

########################
# "Add/Remove" Methods #
########################

# These are in alphabetical order by field name.

# Accepts a User object or a username. Adds the user only if they
# don't already exist as a CC on the bug.
sub add_cc {
    my ($self, $user_or_name) = @_;
    return if !$user_or_name;
    my $user = ref $user_or_name ? $user_or_name
                                 : Bugzilla::User->check($user_or_name);
    $self->_check_strict_isolation_for_user($user);
    my $cc_users = $self->cc_users;
    push(@$cc_users, $user) if !grep($_->id == $user->id, @$cc_users);
}

# Accepts a User object or a username. Removes the User if they exist
# in the list, but doesn't throw an error if they don't exist.
sub remove_cc {
    my ($self, $user_or_name) = @_;
    my $user = ref $user_or_name ? $user_or_name
                                 : Bugzilla::User->check($user_or_name);
    my $currentUser = Bugzilla->user;
    if (!$self->user->{'canedit'} && $user->id != $currentUser->id) {
        ThrowUserError('cc_remove_denied');
    }
    my $cc_users = $self->cc_users;
    @$cc_users = grep { $_->id != $user->id } @$cc_users;
}

sub add_alias {
    my ($self, $alias) = @_;
    return if !$alias;
    my $aliases = $self->_check_alias($alias);
    $alias = $aliases->[0];
    my $bug_aliases = $self->alias;
    push(@$bug_aliases, $alias) if !grep($_ eq $alias, @$bug_aliases);
}

sub remove_alias {
    my ($self, $alias) = @_;
    my $bug_aliases = $self->alias;
    @$bug_aliases = grep { $_ ne $alias } @$bug_aliases;
}

# $bug->add_comment("comment", {isprivate => 1, work_time => 10.5,
#                               type => CMT_NORMAL, extra_data => $data});
sub add_comment {
    my ($self, $comment, $params) = @_;

    $params ||= {};

    # Fill out info that doesn't change and callers may not pass in
    $params->{'bug_id'}  = $self;
    $params->{'thetext'} = defined($comment) ? $comment : '';

    # Validate all the entered data
    Bugzilla::Comment->check_required_create_fields($params);
    $params = Bugzilla::Comment->run_create_validators($params);

    # This makes it so we won't create new comments when there is nothing
    # to add 
    if ($params->{'thetext'} eq ''
        && !($params->{type} || abs($params->{work_time} || 0)))
    {
        return;
    }

    # If the user has explicitly set remaining_time, this will be overridden
    # later in set_all. But if they haven't, this keeps remaining_time
    # up-to-date.
    if ($params->{work_time}) {
        $self->set_remaining_time(max($self->remaining_time - $params->{work_time}, 0));
    }

    $self->{added_comments} ||= [];

    push(@{$self->{added_comments}}, $params);
}

sub modify_keywords {
    my ($self, $keywords, $action) = @_;

    if (!$action || !grep { $action eq $_ } qw(add remove set)) {
        $action = 'set';
    }

    $keywords = $self->_check_keywords($keywords);
    my @old_keywords = @{ $self->keyword_objects };
    my @result;

    if ($action eq 'set') {
        @result = @$keywords;
    }
    else {
        # We're adding or deleting specific keywords.
        my %keys = map { $_->id => $_ } @old_keywords;
        if ($action eq 'add') {
            $keys{$_->id} = $_ foreach @$keywords;
        }
        else {
            delete $keys{$_->id} foreach @$keywords;
        }
        @result = values %keys;
    }

    # Check if anything was added or removed.
    my @old_ids = map { $_->id } @old_keywords;
    my @new_ids = map { $_->id } @result;
    my ($removed, $added) = diff_arrays(\@old_ids, \@new_ids);
    my $any_changes = scalar @$removed || scalar @$added;

    # Make sure we retain the sort order.
    @result = sort {lc($a->name) cmp lc($b->name)} @result;

    if ($any_changes) {
        my $privs;
        my $new = join(', ', (map {$_->name} @result));
        my $check = $self->check_can_change_field('keywords', 0, 1, \$privs)
            || ThrowUserError('illegal_change', { field    => 'keywords',
                                                  oldvalue => $self->keywords,
                                                  newvalue => $new,
                                                  privs    => $privs });
    }

    $self->{'keyword_objects'} = \@result;
}

sub add_group {
    my ($self, $group) = @_;

    # If the user enters "FoO" but the DB has "Foo", $group->name would
    # return "Foo" and thus revealing the existence of the group name.
    # So we have to store and pass the name as entered by the user to
    # the error message, if we have it.
    my $group_name = blessed($group) ? $group->name : $group;
    my $args = { name => $group_name, product => $self->product,
                 bug_id => $self->id, action => 'add' };

    $group = Bugzilla::Group->check_no_disclose($args) if !blessed $group;

    # If the bug is already in this group, then there is nothing to do.
    return if $self->in_group($group);


    # Make sure that bugs in this product can actually be restricted
    # to this group by the current user.
    $self->product_obj->group_is_settable($group)
         || ThrowUserError('group_restriction_not_allowed', $args);

    # OtherControl people can add groups only during a product change,
    # and only when the group is not NA for them.
    if (!Bugzilla->user->in_group($group->name)) {
        my $controls = $self->product_obj->group_controls->{$group->id};
        if (!$self->{_old_product_name}
            || $controls->{othercontrol} == CONTROLMAPNA)
        {
            ThrowUserError('group_restriction_not_allowed', $args);
        }
    }

    my $current_groups = $self->groups_in;
    push(@$current_groups, $group);
}

sub remove_group {
    my ($self, $group) = @_;

    # See add_group() for the reason why we store the user input.
    my $group_name = blessed($group) ? $group->name : $group;
    my $args = { name => $group_name, product => $self->product,
                 bug_id => $self->id, action => 'remove' };

    $group = Bugzilla::Group->check_no_disclose($args) if !blessed $group;

    # If the bug isn't in this group, then either the name is misspelled,
    # or the group really doesn't exist. Let the user know about this problem.
    $self->in_group($group) || ThrowUserError('group_invalid_removal', $args);

    # Check if this is a valid group for this product. You can *always*
    # remove a group that is not valid for this product (set_product does this).
    # This particularly happens when we're moving a bug to a new product.
    # You still have to be a member of an inactive group to remove it.
    if ($self->product_obj->group_is_valid($group)) {
        my $controls = $self->product_obj->group_controls->{$group->id};

        # Nobody can ever remove a Mandatory group, unless it became inactive.
        if ($controls->{membercontrol} == CONTROLMAPMANDATORY && $group->is_active) {
            ThrowUserError('group_invalid_removal', $args);
        }

        # OtherControl people can remove groups only during a product change,
        # and only when they are non-Mandatory and non-NA.
        if (!Bugzilla->user->in_group($group->name)) {
            if (!$self->{_old_product_name}
                || $controls->{othercontrol} == CONTROLMAPMANDATORY
                || $controls->{othercontrol} == CONTROLMAPNA)
            {
                ThrowUserError('group_invalid_removal', $args);
            }
        }
    }

    my $current_groups = $self->groups_in;
    @$current_groups = grep { $_->id != $group->id } @$current_groups;
}

sub add_see_also {
    my ($self, $input, $skip_recursion) = @_;

    # This is needed by xt/search.t.
    $input = $input->name if blessed($input);

    $input = trim($input);
    return if !$input;

    my ($class, $uri) = Bugzilla::BugUrl->class_for($input);

    my $params = { value => $uri, bug_id => $self, class => $class };
    $class->check_required_create_fields($params);

    my $field_values = $class->run_create_validators($params);
    my $value = $field_values->{value}->as_string;
    trick_taint($value);
    $field_values->{value} = $value;

    # We only add the new URI if it hasn't been added yet. URIs are
    # case-sensitive, but most of our DBs are case-insensitive, so we do
    # this check case-insensitively.
    if (!grep { lc($_->name) eq lc($value) } @{ $self->see_also }) {
        my $privs;
        my $can = $self->check_can_change_field('see_also', '', $value, \$privs);
        if (!$can) {
            ThrowUserError('illegal_change', { field    => 'see_also',
                                               newvalue => $value,
                                               privs    => $privs });
        }
        # If this is a link to a local bug then save the
        # ref bug id for sending changes email.
        my $ref_bug = delete $field_values->{ref_bug};
        if ($class->isa('Bugzilla::BugUrl::Bugzilla::Local')
            and !$skip_recursion
            and $ref_bug->check_can_change_field('see_also', '', $self->id, \$privs))
        {
            $ref_bug->add_see_also($self->id, 'skip_recursion');
            push @{ $self->{_update_ref_bugs} }, $ref_bug;
            push @{ $self->{see_also_changes} }, $ref_bug->id;
        }
        push @{ $self->{see_also} }, bless ($field_values, $class);
    }
}

sub remove_see_also {
    my ($self, $url, $skip_recursion) = @_;
    my $see_also = $self->see_also;

    # This is needed by xt/search.t.
    $url = $url->name if blessed($url);

    my ($removed_bug_url, $new_see_also) =
        part { lc($_->name) ne lc($url) } @$see_also;

    my $privs;
    my $can = $self->check_can_change_field('see_also', $see_also, $new_see_also, \$privs);
    if (!$can) {
        ThrowUserError('illegal_change', { field    => 'see_also',
                                           oldvalue => $url,
                                           privs    => $privs });
    }

    # Since we remove also the url from the referenced bug,
    # we need to notify changes for that bug too.
    $removed_bug_url = $removed_bug_url->[0];
    if (!$skip_recursion and $removed_bug_url
        and $removed_bug_url->isa('Bugzilla::BugUrl::Bugzilla::Local')
        and $removed_bug_url->ref_bug_url)
    {
        my $ref_bug
            = Bugzilla::Bug->check($removed_bug_url->ref_bug_url->bug_id);

        if (Bugzilla->user->can_edit_product($ref_bug->product_id)
            and $ref_bug->check_can_change_field('see_also', $self->id, '', \$privs))
        {
            my $self_url = $removed_bug_url->local_uri($self->id);
            $ref_bug->remove_see_also($self_url, 'skip_recursion');
            push @{ $self->{_update_ref_bugs} }, $ref_bug;
            push @{ $self->{see_also_changes} }, $ref_bug->id;
        }
    }

    $self->{see_also} = $new_see_also || [];
}

sub add_tag {
    my ($self, $tag) = @_;
    my $dbh = Bugzilla->dbh;
    my $user = Bugzilla->user;
    $tag = $self->_check_tag_name($tag);

    my $tag_id = $user->tags->{$tag}->{id};
    # If this tag doesn't exist for this user yet, create it.
    if (!$tag_id) {
        $dbh->do('INSERT INTO tag (user_id, name) VALUES (?, ?)',
                  undef, ($user->id, $tag));

        $tag_id = $dbh->selectrow_array('SELECT id FROM tag
                                         WHERE name = ? AND user_id = ?',
                                         undef, ($tag, $user->id));
        # The list has changed.
        delete $user->{tags};
    }
    # Do nothing if this tag is already set for this bug.
    return if grep { $_ eq $tag } @{$self->tags};

    # Increment the counter. Do it before the SQL call below,
    # to not count the tag twice.
    $user->tags->{$tag}->{bug_count}++;

    $dbh->do('INSERT INTO bug_tag (bug_id, tag_id) VALUES (?, ?)',
              undef, ($self->id, $tag_id));

    push(@{$self->{tags}}, $tag);
}

sub remove_tag {
    my ($self, $tag) = @_;
    my $dbh = Bugzilla->dbh;
    my $user = Bugzilla->user;
    $tag = $self->_check_tag_name($tag);

    my $tag_id = exists $user->tags->{$tag} ? $user->tags->{$tag}->{id} : undef;
    # Do nothing if the user doesn't use this tag, or didn't set it for this bug.
    return unless ($tag_id && grep { $_ eq $tag } @{$self->tags});

    $dbh->do('DELETE FROM bug_tag WHERE bug_id = ? AND tag_id = ?',
              undef, ($self->id, $tag_id));

    $self->{tags} = [grep { $_ ne $tag } @{$self->tags}];

    # Decrement the counter, and delete the tag if no bugs are using it anymore.
    if (!--$user->tags->{$tag}->{bug_count}) {
        $dbh->do('DELETE FROM tag WHERE name = ? AND user_id = ?',
                  undef, ($tag, $user->id));

        # The list has changed.
        delete $user->{tags};
    }
}

sub tags {
    my $self = shift;
    my $dbh = Bugzilla->dbh;
    my $user = Bugzilla->user;

    # This method doesn't support several users using the same bug object.
    if (!exists $self->{tags}) {
        $self->{tags} = $dbh->selectcol_arrayref(
            'SELECT name FROM bug_tag
             INNER JOIN tag ON tag.id = bug_tag.tag_id
             WHERE bug_id = ? AND user_id = ?',
             undef, ($self->id, $user->id));
    }
    return $self->{tags};
}

#####################################################################
# Simple Accessors
#####################################################################

# These are accessors that don't need to access the database.
# Keep them in alphabetical order.

sub bug_file_loc        { return $_[0]->{bug_file_loc}        }
sub bug_id              { return $_[0]->{bug_id}              }
sub bug_severity        { return $_[0]->{bug_severity}        }
sub bug_status          { return $_[0]->{bug_status}          }
sub cclist_accessible   { return $_[0]->{cclist_accessible}   }
sub component_id        { return $_[0]->{component_id}        }
sub creation_ts         { return $_[0]->{creation_ts}         }
sub estimated_time      { return $_[0]->{estimated_time}      }
sub deadline            { return $_[0]->{deadline}            }
sub delta_ts            { return $_[0]->{delta_ts}            }
sub error               { return $_[0]->{error}               }
sub everconfirmed       { return $_[0]->{everconfirmed}       }
sub lastdiffed          { return $_[0]->{lastdiffed}          }
sub op_sys              { return $_[0]->{op_sys}              }
sub priority            { return $_[0]->{priority}            }
sub product_id          { return $_[0]->{product_id}          }
sub remaining_time      { return $_[0]->{remaining_time}      }
sub reporter_accessible { return $_[0]->{reporter_accessible} }
sub rep_platform        { return $_[0]->{rep_platform}        }
sub resolution          { return $_[0]->{resolution}          }
sub short_desc          { return $_[0]->{short_desc}          }
sub status_whiteboard   { return $_[0]->{status_whiteboard}   }
sub target_milestone    { return $_[0]->{target_milestone}    }
sub version             { return $_[0]->{version}             }

#####################################################################
# Complex Accessors
#####################################################################

# These are accessors that have to access the database for additional
# information about a bug.

# These subs are in alphabetical order, as much as possible.
# If you add a new sub, please try to keep it in alphabetical order
# with the other ones.

# Note: If you add a new method, remember that you must check the error
# state of the bug before returning any data. If $self->{error} is
# defined, then return something empty. Otherwise you risk potential
# security holes.

sub dup_id {
    my ($self) = @_;
    return $self->{'dup_id'} if exists $self->{'dup_id'};

    $self->{'dup_id'} = undef;
    return if $self->{'error'};

    if ($self->{'resolution'} eq 'DUPLICATE') { 
        my $dbh = Bugzilla->dbh;
        $self->{'dup_id'} =
          $dbh->selectrow_array(q{SELECT dupe_of 
                                  FROM duplicates
                                  WHERE dupe = ?},
                                undef,
                                $self->{'bug_id'});
    }
    return $self->{'dup_id'};
}

sub _resolve_ultimate_dup_id {
    my ($bug_id, $dupe_of, $loops_are_an_error) = @_;
    my $dbh = Bugzilla->dbh;
    my $sth = $dbh->prepare('SELECT dupe_of FROM duplicates WHERE dupe = ?');

    my $this_dup = $dupe_of || $dbh->selectrow_array($sth, undef, $bug_id);
    my $last_dup = $bug_id;

    my %dupes;
    while ($this_dup) {
        if ($this_dup == $bug_id) {
            if ($loops_are_an_error) {
                ThrowUserError('dupe_loop_detected', { bug_id  => $bug_id,
                                                       dupe_of => $dupe_of });
            }
            else {
                return $last_dup;
            }
        }
        # If $dupes{$this_dup} is already set to 1, then a loop
        # already exists which does not involve this bug.
        # As the user is not responsible for this loop, do not
        # prevent them from marking this bug as a duplicate.
        return $last_dup if exists $dupes{$this_dup};
        $dupes{$this_dup} = 1;
        $last_dup = $this_dup;
        $this_dup = $dbh->selectrow_array($sth, undef, $this_dup);
    }

    return $last_dup;
}

sub actual_time {
    my ($self) = @_;
    return $self->{'actual_time'} if exists $self->{'actual_time'};

    if ( $self->{'error'} || !Bugzilla->user->is_timetracker ) {
        $self->{'actual_time'} = undef;
        return $self->{'actual_time'};
    }

    my $sth = Bugzilla->dbh->prepare("SELECT SUM(work_time)
                                      FROM longdescs 
                                      WHERE longdescs.bug_id=?");
    $sth->execute($self->{bug_id});
    $self->{'actual_time'} = $sth->fetchrow_array();
    return $self->{'actual_time'};
}

sub alias {
    my ($self) = @_;
    return $self->{'alias'} if exists $self->{'alias'};
    return [] if $self->{'error'};

    my $dbh = Bugzilla->dbh;
    $self->{'alias'} = $dbh->selectcol_arrayref(
        q{SELECT alias
            FROM bugs_aliases
           WHERE bug_id = ?
        ORDER BY alias},
      undef, $self->bug_id);

    $self->{'alias'} = [] if !scalar(@{$self->{'alias'}});

    return $self->{'alias'};
}

sub any_flags_requesteeble {
    my ($self) = @_;
    return $self->{'any_flags_requesteeble'} 
        if exists $self->{'any_flags_requesteeble'};
    return 0 if $self->{'error'};

    my $any_flags_requesteeble =
      grep { $_->is_requestable && $_->is_requesteeble } @{$self->flag_types};
    # Useful in case a flagtype is no longer requestable but a requestee
    # has been set before we turned off that bit.
    $any_flags_requesteeble ||= grep { $_->requestee_id } @{$self->flags};
    $self->{'any_flags_requesteeble'} = $any_flags_requesteeble;

    return $self->{'any_flags_requesteeble'};
}

sub attachments {
    my ($self) = @_;
    return $self->{'attachments'} if exists $self->{'attachments'};
    return [] if $self->{'error'};

    $self->{'attachments'} =
        Bugzilla::Attachment->get_attachments_by_bug($self, {preload => 1});
    return $self->{'attachments'};
}

sub assigned_to {
    my ($self) = @_;
    return $self->{'assigned_to_obj'} if exists $self->{'assigned_to_obj'};
    $self->{'assigned_to'} = 0 if $self->{'error'};
    $self->{'assigned_to_obj'} ||= new Bugzilla::User({ id => $self->{'assigned_to'}, cache => 1 });
    return $self->{'assigned_to_obj'};
}

sub blocked {
    my ($self) = @_;
    return $self->{'blocked'} if exists $self->{'blocked'};
    return [] if $self->{'error'};
    $self->{'blocked'} = EmitDependList("dependson", "blocked", $self->bug_id);
    return $self->{'blocked'};
}

sub blocks_obj {
    my ($self) = @_;
    $self->{blocks_obj} ||= $self->_bugs_in_order($self->blocked);
    return $self->{blocks_obj};
}

sub bug_group {
    my ($self) = @_;
    return join(', ', (map { $_->name } @{$self->groups_in}));
}

sub related_bugs {
    my ($self, $relationship) = @_;
    return [] if $self->{'error'};

    my $field_name = $relationship->name;
    $self->{'related_bugs'}->{$field_name} ||= $self->match({$field_name => $self->id});
    return $self->{'related_bugs'}->{$field_name}; 
}

sub cc {
    my ($self) = @_;
    return $self->{'cc'} if exists $self->{'cc'};
    return [] if $self->{'error'};

    my $dbh = Bugzilla->dbh;
    $self->{'cc'} = $dbh->selectcol_arrayref(
        q{SELECT profiles.login_name FROM cc, profiles
           WHERE bug_id = ?
             AND cc.who = profiles.userid
        ORDER BY profiles.login_name},
      undef, $self->bug_id);

    return $self->{'cc'};
}

# XXX Eventually this will become the standard "cc" method used everywhere.
sub cc_users {
    my $self = shift;
    return $self->{'cc_users'} if exists $self->{'cc_users'};
    return [] if $self->{'error'};
    
    my $dbh = Bugzilla->dbh;
    my $cc_ids = $dbh->selectcol_arrayref(
        'SELECT who FROM cc WHERE bug_id = ?', undef, $self->id);
    $self->{'cc_users'} = Bugzilla::User->new_from_list($cc_ids);
    return $self->{'cc_users'};
}

sub component {
    my ($self) = @_;
    return '' if $self->{error};
    $self->{component} //= $self->component_obj->name;
    return $self->{component};
}

# XXX Eventually this will replace component()
sub component_obj {
    my ($self) = @_;
    return $self->{component_obj} if defined $self->{component_obj};
    return {} if $self->{error};
    $self->{component_obj} =
        new Bugzilla::Component({ id => $self->{component_id}, cache => 1 });
    return $self->{component_obj};
}

sub classification_id {
    my ($self) = @_;
    return 0 if $self->{error};
    $self->{classification_id} //= $self->product_obj->classification_id;
    return $self->{classification_id};
}

sub classification {
    my ($self) = @_;
    return '' if $self->{error};
    $self->{classification} //= $self->product_obj->classification->name;
    return $self->{classification};
}

sub default_bug_status {
    my $class = shift;
    # XXX This should just call new_bug_statuses when the UI accepts closed
    # bug statuses instead of accepting them as a parameter.
    my @statuses = @_;

    my $status;
    if (scalar(@statuses) == 1) {
        $status = $statuses[0]->name;
    }
    else {
        $status = ($statuses[0]->name ne 'UNCONFIRMED')
                  ? $statuses[0]->name : $statuses[1]->name;
    }

    return $status;
}

sub dependson {
    my ($self) = @_;
    return $self->{'dependson'} if exists $self->{'dependson'};
    return [] if $self->{'error'};
    $self->{'dependson'} = 
        EmitDependList("blocked", "dependson", $self->bug_id);
    return $self->{'dependson'};
}

sub depends_on_obj {
    my ($self) = @_;
    $self->{depends_on_obj} ||= $self->_bugs_in_order($self->dependson);
    return $self->{depends_on_obj};
}

sub duplicates {
    my $self = shift;
    return $self->{duplicates} if exists $self->{duplicates};
    return [] if $self->{error};
    $self->{duplicates} = Bugzilla::Bug->new_from_list($self->duplicate_ids);
    return $self->{duplicates};
}

sub duplicate_ids {
    my $self = shift;
    return $self->{duplicate_ids} if exists $self->{duplicate_ids};
    return [] if $self->{error};

    my $dbh = Bugzilla->dbh;
    $self->{duplicate_ids} =
      $dbh->selectcol_arrayref('SELECT dupe FROM duplicates WHERE dupe_of = ?',
                               undef, $self->id);
    return $self->{duplicate_ids};
}

sub flag_types {
    my ($self) = @_;
    return $self->{'flag_types'} if exists $self->{'flag_types'};
    return [] if $self->{'error'};

    my $vars = { target_type  => 'bug',
                 product_id   => $self->{product_id},
                 component_id => $self->{component_id},
                 bug_id       => $self->bug_id };

    $self->{'flag_types'} = Bugzilla::Flag->_flag_types($vars);
    return $self->{'flag_types'};
}

sub flags {
    my $self = shift;

    # Don't cache it as it must be in sync with ->flag_types.
    $self->{flags} = [map { @{$_->{flags}} } @{$self->flag_types}];
    return $self->{flags};
}

sub isopened {
    my $self = shift;
    return is_open_state($self->{bug_status}) ? 1 : 0;
}

sub keywords {
    my ($self) = @_;
    return join(', ', (map { $_->name } @{$self->keyword_objects}));
}

# XXX At some point, this should probably replace the normal "keywords" sub.
sub keyword_objects {
    my $self = shift;
    return $self->{'keyword_objects'} if defined $self->{'keyword_objects'};
    return [] if $self->{'error'};

    my $dbh = Bugzilla->dbh;
    my $ids = $dbh->selectcol_arrayref(
         "SELECT keywordid FROM keywords WHERE bug_id = ?", undef, $self->id);
    $self->{'keyword_objects'} = Bugzilla::Keyword->new_from_list($ids);
    return $self->{'keyword_objects'};
}

sub comments {
    my ($self, $params) = @_;
    return [] if $self->{'error'};
    $params ||= {};

    if (!defined $self->{'comments'}) {
        $self->{'comments'} = Bugzilla::Comment->match({ bug_id => $self->id });
        my $count = 0;
        state $is_mysql = Bugzilla->dbh->isa('Bugzilla::DB::Mysql') ? 1 : 0;
        foreach my $comment (@{ $self->{'comments'} }) {
            $comment->{count} = $count++;
            $comment->{bug} = $self;
            # XXX - hack for MySQL. Convert [U+....] back into its Unicode
            # equivalent for characters above U+FFFF as MySQL older than 5.5.3
            # cannot store them, see Bugzilla::Comment::_check_thetext().
            if ($is_mysql) {
                # Perl 5.13.8 and older complain about non-characters.
                no warnings 'utf8';
                $comment->{thetext} =~ s/\x{FDD0}\[U\+((?:[1-9A-F]|10)[0-9A-F]{4})\]\x{FDD1}/chr(hex $1)/eg
            }
        }
        # Some bugs may have no comments when upgrading old installations.
        Bugzilla::Comment->preload($self->{'comments'}) if $count;
    }
    my @comments = @{ $self->{'comments'} };

    my $order = $params->{order} 
        || Bugzilla->user->setting('comment_sort_order');
    if ($order ne 'oldest_to_newest') {
        @comments = reverse @comments;
        if ($order eq 'newest_to_oldest_desc_first') {
            unshift(@comments, pop @comments);
        }
    }

    if ($params->{after}) {
        my $from = datetime_from($params->{after});
        @comments = grep { datetime_from($_->creation_ts) > $from } @comments;
    }
    if ($params->{to}) {
        my $to = datetime_from($params->{to});
        @comments = grep { datetime_from($_->creation_ts) <= $to } @comments;
    }
    return \@comments;
}

sub new_bug_statuses {
    my ($class, $product) = @_;
    my $user = Bugzilla->user;

    # Construct the list of allowable statuses.
    my @statuses = @{ Bugzilla::Bug->statuses_available($product) };

    # If the user has no privs...
    unless ($user->in_group('editbugs', $product->id)
            || $user->in_group('canconfirm', $product->id))
    {
        # ... use UNCONFIRMED if available, else use the first status of the list.
        my ($unconfirmed) = grep { $_->name eq 'UNCONFIRMED' } @statuses;
    
        # Because of an apparent Perl bug, "$unconfirmed || $statuses[0]" doesn't
        # work, so we're using an "?:" operator. See bug 603314 for details.
        @statuses = ($unconfirmed ? $unconfirmed : $statuses[0]);
    }

    return \@statuses;
}

# This is needed by xt/search.t.
sub percentage_complete {
    my $self = shift;
    return undef if $self->{'error'} || !Bugzilla->user->is_timetracker;
    my $remaining = $self->remaining_time;
    my $actual    = $self->actual_time;
    my $total = $remaining + $actual;
    return undef if $total == 0;
    # Search.pm truncates this value to an integer, so we want to as well,
    # since this is mostly used in a test where its value needs to be
    # identical to what the database will return.
    return int(100 * ($actual / $total));
}

sub product {
    my ($self) = @_;
    return '' if $self->{error};
    $self->{product} //= $self->product_obj->name;
    return $self->{product};
}

# XXX This should eventually replace the "product" subroutine.
sub product_obj {
    my $self = shift;
    return {} if $self->{error};
    $self->{product_obj} ||=
        new Bugzilla::Product({ id => $self->{product_id}, cache => 1 });
    return $self->{product_obj};
}

sub qa_contact {
    my ($self) = @_;
    return $self->{'qa_contact_obj'} if exists $self->{'qa_contact_obj'};
    return undef if $self->{'error'};

    if (Bugzilla->params->{'useqacontact'} && $self->{'qa_contact'}) {
        $self->{'qa_contact_obj'} = new Bugzilla::User({ id => $self->{'qa_contact'}, cache => 1 });
    } else {
        $self->{'qa_contact_obj'} = undef;
    }
    return $self->{'qa_contact_obj'};
}

sub reporter {
    my ($self) = @_;
    return $self->{'reporter'} if exists $self->{'reporter'};
    $self->{'reporter_id'} = 0 if $self->{'error'};
    $self->{'reporter'} = new Bugzilla::User({ id => $self->{'reporter_id'}, cache => 1 });
    return $self->{'reporter'};
}

sub see_also {
    my ($self) = @_;
    return [] if $self->{'error'};
    if (!exists $self->{see_also}) {
        my $ids = Bugzilla->dbh->selectcol_arrayref(
            'SELECT id FROM bug_see_also WHERE bug_id = ?',
            undef, $self->id);

        my $bug_urls = Bugzilla::BugUrl->new_from_list($ids);

        $self->{see_also} = $bug_urls;
    }
    return $self->{see_also};
}

sub status {
    my $self = shift;
    return undef if $self->{'error'};

    $self->{'status'} ||= new Bugzilla::Status({name => $self->{'bug_status'}});
    return $self->{'status'};
}

sub statuses_available {
    my ($invocant, $product) = @_;

    my @statuses;

    if (ref $invocant) {
      return [] if $invocant->{'error'};

      return $invocant->{'statuses_available'}
          if defined $invocant->{'statuses_available'};

        @statuses = @{ $invocant->status->can_change_to };
        $product = $invocant->product_obj;
    } else {
        @statuses = @{ Bugzilla::Status->can_change_to };
    }

    # UNCONFIRMED is only a valid status if it is enabled in this product.
    if (!$product->allows_unconfirmed) {
        @statuses = grep { $_->name ne 'UNCONFIRMED' } @statuses;
    }

    if (ref $invocant) {
        my $available = $invocant->_refine_available_statuses(@statuses);
        $invocant->{'statuses_available'} = $available;
        return $available;
    }

    return \@statuses;
}

sub _refine_available_statuses {
    my $self = shift;
    my @statuses = @_;

    my @available;
    foreach my $status (@statuses) {
        # Make sure this is a legal status transition
        next if !$self->check_can_change_field(
                     'bug_status', $self->status->name, $status->name);
        push(@available, $status);
    }

    # If this bug has an inactive status set, it should still be in the list.
    if (!grep($_->name eq $self->status->name, @available)) {
        unshift(@available, $self->status);
    }
    
    return \@available;
}

sub show_attachment_flags {
    my ($self) = @_;
    return $self->{'show_attachment_flags'} 
        if exists $self->{'show_attachment_flags'};
    return 0 if $self->{'error'};

    # The number of types of flags that can be set on attachments to this bug
    # and the number of flags on those attachments.  One of these counts must be
    # greater than zero in order for the "flags" column to appear in the table
    # of attachments.
    my $num_attachment_flag_types = Bugzilla::FlagType::count(
        { 'target_type'  => 'attachment',
          'product_id'   => $self->{'product_id'},
          'component_id' => $self->{'component_id'} });
    my $num_attachment_flags = Bugzilla::Flag->count(
        { 'target_type'  => 'attachment',
          'bug_id'       => $self->bug_id });

    $self->{'show_attachment_flags'} =
        ($num_attachment_flag_types || $num_attachment_flags);

    return $self->{'show_attachment_flags'};
}

sub groups {
    my $self = shift;
    return $self->{'groups'} if exists $self->{'groups'};
    return [] if $self->{'error'};

    my $dbh = Bugzilla->dbh;
    my @groups;

    # Some of this stuff needs to go into Bugzilla::User

    # For every group, we need to know if there is ANY bug_group_map
    # record putting the current bug in that group and if there is ANY
    # user_group_map record putting the user in that group.
    # The LEFT JOINs are checking for record existence.
    #
    my $grouplist = Bugzilla->user->groups_as_string;
    my $sth = $dbh->prepare(
             "SELECT DISTINCT groups.id, name, description," .
             " CASE WHEN bug_group_map.group_id IS NOT NULL" .
             " THEN 1 ELSE 0 END," .
             " CASE WHEN groups.id IN($grouplist) THEN 1 ELSE 0 END," .
             " isactive, membercontrol, othercontrol" .
             " FROM groups" . 
             " LEFT JOIN bug_group_map" .
             " ON bug_group_map.group_id = groups.id" .
             " AND bug_id = ?" .
             " LEFT JOIN group_control_map" .
             " ON group_control_map.group_id = groups.id" .
             " AND group_control_map.product_id = ? " .
             " WHERE isbuggroup = 1" .
             " ORDER BY description");
    $sth->execute($self->{'bug_id'},
                  $self->{'product_id'});

    while (my ($groupid, $name, $description, $ison, $ingroup, $isactive,
            $membercontrol, $othercontrol) = $sth->fetchrow_array()) {

        $membercontrol ||= 0;

        # For product groups, we only want to use the group if either
        # (1) The bit is set and not required, or
        # (2) The group is Shown or Default for members and
        #     the user is a member of the group.
        if ($ison ||
            ($isactive && $ingroup
                       && (($membercontrol == CONTROLMAPDEFAULT)
                           || ($membercontrol == CONTROLMAPSHOWN))
            ))
        {
            my $ismandatory = $isactive
              && ($membercontrol == CONTROLMAPMANDATORY);

            push (@groups, { "bit" => $groupid,
                             "name" => $name,
                             "ison" => $ison,
                             "ingroup" => $ingroup,
                             "mandatory" => $ismandatory,
                             "description" => $description });
        }
    }

    $self->{'groups'} = \@groups;

    return $self->{'groups'};
}

sub groups_in {
    my $self = shift;
    return $self->{'groups_in'} if exists $self->{'groups_in'};
    return [] if $self->{'error'};
    my $group_ids = Bugzilla->dbh->selectcol_arrayref(
        'SELECT group_id FROM bug_group_map WHERE bug_id = ?',
        undef, $self->id);
    $self->{'groups_in'} = Bugzilla::Group->new_from_list($group_ids);
    return $self->{'groups_in'};
}

sub in_group {
    my ($self, $group) = @_;
    return grep($_->id == $group->id, @{$self->groups_in}) ? 1 : 0;
}

sub user {
    my $self = shift;
    return $self->{'user'} if exists $self->{'user'};
    return {} if $self->{'error'};

    my $user = Bugzilla->user;
    my $prod_id = $self->{'product_id'};

    my $editbugs = $user->in_group('editbugs', $prod_id);
    my $is_reporter = $user->id == $self->{reporter_id} ? 1 : 0;
    my $is_assignee = $user->id == $self->{'assigned_to'} ? 1 : 0;
    my $is_qa_contact = Bugzilla->params->{'useqacontact'}
                        && $self->{'qa_contact'}
                        && $user->id == $self->{'qa_contact'} ? 1 : 0;

    my $canedit = $editbugs || $is_assignee || $is_qa_contact;
    my $canconfirm = $editbugs || $user->in_group('canconfirm', $prod_id);
    my $has_any_role = $is_reporter || $is_assignee || $is_qa_contact;

    $self->{'user'} = {canconfirm => $canconfirm,
                       canedit    => $canedit,
                       isreporter => $is_reporter,
                       has_any_role => $has_any_role};
    return $self->{'user'};
}

# This is intended to get values that can be selected by the user in the
# UI. It should not be used for security or validation purposes.
sub choices {
    my $self = shift;
    return $self->{'choices'} if exists $self->{'choices'};
    return {} if $self->{'error'};
    my $user = Bugzilla->user;

    my @products = @{ $user->get_enterable_products };
    # The current product is part of the popup, even if new bugs are no longer
    # allowed for that product
    if (!grep($_->name eq $self->product_obj->name, @products)) {
        unshift(@products, $self->product_obj);
    }
    my %class_ids = map { $_->classification_id => 1 } @products;
    my $classifications = 
        Bugzilla::Classification->new_from_list([keys %class_ids]);

    my %choices = (
        bug_status => $self->statuses_available,
        classification => $classifications,
        product    => \@products,
        component  => $self->product_obj->components,
        version    => $self->product_obj->versions,
        target_milestone => $self->product_obj->milestones,
    );

    my $resolution_field = new Bugzilla::Field({ name => 'resolution' });
    # Don't include the empty resolution in drop-downs.
    my @resolutions = grep($_->name, @{ $resolution_field->legal_values });
    $choices{'resolution'} = \@resolutions;

    $self->{'choices'} = \%choices;
    return $self->{'choices'};
}

# Convenience Function. If you need speed, use this. If you need
# other Bug fields in addition to this, just create a new Bug with
# the alias.
# Queries the database for the bug with a given alias, and returns
# the ID of the bug if it exists or the undefined value if it doesn't.
sub bug_alias_to_id {
    my ($alias) = @_;
    my $dbh = Bugzilla->dbh;
    trick_taint($alias);
    return $dbh->selectrow_array(
        "SELECT bug_id FROM bugs_aliases WHERE alias = ?", undef, $alias);
}

#####################################################################
# Subroutines
#####################################################################

# Returns a list of currently active and editable bug fields,
# including multi-select fields.
sub editable_bug_fields {
    my @fields = Bugzilla->dbh->bz_table_columns('bugs');
    # Add multi-select fields
    push(@fields, map { $_->name } @{Bugzilla->fields({obsolete => 0,
                                                       type => FIELD_TYPE_MULTI_SELECT})});
    # Obsolete custom fields are not editable.
    my @obsolete_fields = @{ Bugzilla->fields({obsolete => 1, custom => 1}) };
    @obsolete_fields = map { $_->name } @obsolete_fields;
    foreach my $remove ("bug_id", "reporter", "creation_ts", "delta_ts", 
                        "lastdiffed", @obsolete_fields) 
    {
        my $location = firstidx { $_ eq $remove } @fields;
        # Ensure field exists before attempting to remove it.
        splice(@fields, $location, 1) if ($location > -1);
    }
    return @fields;
}

# XXX - When Bug::update() will be implemented, we should make this routine
#       a private method.
# Join with bug_status and bugs tables to show bugs with open statuses first,
# and then the others
sub EmitDependList {
    my ($my_field, $target_field, $bug_id, $exclude_resolved) = @_;
    my $cache = Bugzilla->request_cache->{bug_dependency_list} ||= {};

    my $dbh = Bugzilla->dbh;
    $exclude_resolved = $exclude_resolved ? 1 : 0;
    my $is_open_clause = $exclude_resolved ? 'AND is_open = 1' : '';

    $cache->{"${target_field}_sth_$exclude_resolved"} ||= $dbh->prepare(
          "SELECT $target_field
             FROM dependencies
                  INNER JOIN bugs ON dependencies.$target_field = bugs.bug_id
                  INNER JOIN bug_status ON bugs.bug_status = bug_status.value
            WHERE $my_field = ? $is_open_clause
            ORDER BY is_open DESC, $target_field");

    return $dbh->selectcol_arrayref(
        $cache->{"${target_field}_sth_$exclude_resolved"},
        undef, $bug_id);
}

# Creates a lot of bug objects in the same order as the input array.
sub _bugs_in_order {
    my ($self, $bug_ids) = @_;
    my %bug_map;
    # there's no need to load bugs from the database if they are already in the
    # object-cache
    my @missing_ids;
    foreach my $bug_id (@$bug_ids) {
        if (my $bug = Bugzilla::Bug->object_cache_get($bug_id)) {
            $bug_map{$bug_id} = $bug;
        }
        else {
            push @missing_ids, $bug_id;
        }
    }
    my $bugs = $self->new_from_list(\@missing_ids);
    foreach my $bug (@$bugs) {
        $bug_map{$bug->id} = $bug;
    }
    return [ map { $bug_map{$_} } @$bug_ids ];
}

# Get the activity of a bug, starting from $starttime (if given).
# This routine assumes Bugzilla::Bug->check has been previously called.
sub get_activity {
    my ($self, $attach_id, $starttime, $include_comment_tags) = @_;
    my $dbh = Bugzilla->dbh;
    my $user = Bugzilla->user;

    # Arguments passed to the SQL query.
    my @args = ($self->id);

    # Only consider changes since $starttime, if given.
    my $datepart = "";
    if (defined $starttime) {
        trick_taint($starttime);
        push (@args, $starttime);
        $datepart = "AND bug_when > ?";
    }

    my $attachpart = "";
    if ($attach_id) {
        push(@args, $attach_id);
        $attachpart = "AND bugs_activity.attach_id = ?";
    }

    # Only includes attachments the user is allowed to see.
    my $suppjoins = "";
    my $suppwhere = "";
    if (!$user->is_insider) {
        $suppjoins = "LEFT JOIN attachments 
                   ON attachments.attach_id = bugs_activity.attach_id";
        $suppwhere = "AND COALESCE(attachments.isprivate, 0) = 0";
    }

    my $query = "SELECT fielddefs.name, bugs_activity.attach_id, " .
        $dbh->sql_date_format('bugs_activity.bug_when', '%Y.%m.%d %H:%i:%s') .
            " AS bug_when, bugs_activity.removed, bugs_activity.added, profiles.login_name,
               bugs_activity.comment_id
          FROM bugs_activity
               $suppjoins
    INNER JOIN fielddefs
            ON bugs_activity.fieldid = fielddefs.id
    INNER JOIN profiles
            ON profiles.userid = bugs_activity.who
         WHERE bugs_activity.bug_id = ?
               $datepart
               $attachpart
               $suppwhere ";

    if (Bugzilla->params->{'comment_taggers_group'}
        && $include_comment_tags
        && !$attach_id)
    {
        # Only includes comment tag activity for comments the user is allowed to see.
        $suppjoins = "";
        $suppwhere = "";
        if (!Bugzilla->user->is_insider) {
            $suppjoins = "INNER JOIN longdescs
                          ON longdescs.comment_id = longdescs_tags_activity.comment_id";
            $suppwhere = "AND longdescs.isprivate = 0";
        }

        $query .= "
            UNION ALL
            SELECT 'comment_tag' AS name,
                   NULL AS attach_id," .
                   $dbh->sql_date_format('longdescs_tags_activity.bug_when', '%Y.%m.%d %H:%i:%s') . " AS bug_when,
                   longdescs_tags_activity.removed,
                   longdescs_tags_activity.added,
                   profiles.login_name,
                   longdescs_tags_activity.comment_id as comment_id
              FROM longdescs_tags_activity
                   INNER JOIN profiles ON profiles.userid = longdescs_tags_activity.who
                   $suppjoins
             WHERE longdescs_tags_activity.bug_id = ?
                   $datepart
                   $suppwhere
        ";
        push @args, $self->id;
        push @args, $starttime if defined $starttime;
    }

    $query .= "ORDER BY bug_when, comment_id";

    my $list = $dbh->selectall_arrayref($query, undef, @args);

    my @operations;
    my $operation = {};
    my $changes = [];
    my $incomplete_data = 0;

    foreach my $entry (@$list) {
        my ($fieldname, $attachid, $when, $removed, $added, $who, $comment_id) = @$entry;
        my %change;
        my $activity_visible = 1;

        # check if the user should see this field's activity
        if (grep { $fieldname eq $_ } TIMETRACKING_FIELDS) {
            $activity_visible = $user->is_timetracker;
        }
        elsif ($fieldname eq 'longdescs.isprivate'
               && !$user->is_insider && $added)
        { 
            $activity_visible = 0;
        } 
        else {
            $activity_visible = 1;
        }

        if ($activity_visible) {
            # Check for the results of an old Bugzilla data corruption bug
            if (($added eq '?' && $removed eq '?')
                || ($added =~ /^\? / || $removed =~ /^\? /)) {
                $incomplete_data = 1;
            }

            # An operation, done by 'who' at time 'when', has a number of
            # 'changes' associated with it.
            # If this is the start of a new operation, store the data from the
            # previous one, and set up the new one.
            if ($operation->{'who'}
                && ($who ne $operation->{'who'}
                    || $when ne $operation->{'when'}))
            {
                $operation->{'changes'} = $changes;
                push (@operations, $operation);

                # Create new empty anonymous data structures.
                $operation = {};
                $changes = [];
            }

            # If this is the same field as the previous item, then concatenate
            # the data into the same change.
            if ($operation->{'who'} && $who eq $operation->{'who'}
                && $when eq $operation->{'when'}
                && $fieldname eq $operation->{'fieldname'}
                && ($comment_id || 0) == ($operation->{'comment_id'} || 0)
                && ($attachid || 0) == ($operation->{'attachid'} || 0))
            {
                my $old_change = pop @$changes;
                $removed = join_activity_entries($fieldname, $old_change->{'removed'}, $removed);
                $added = join_activity_entries($fieldname, $old_change->{'added'}, $added);
            }
            $operation->{'who'} = $who;
            $operation->{'when'} = $when;
            $operation->{'fieldname'} = $change{'fieldname'} = $fieldname;
            $operation->{'attachid'} = $change{'attachid'} = $attachid;
            $change{'removed'} = $removed;
            $change{'added'} = $added;

            if ($comment_id) {
                $operation->{comment_id} = $change{'comment'} = Bugzilla::Comment->new($comment_id);
            }

            push (@$changes, \%change);
        }
    }

    if ($operation->{'who'}) {
        $operation->{'changes'} = $changes;
        push (@operations, $operation);
    }

    return(\@operations, $incomplete_data);
}

# Update the bugs_activity table to reflect changes made in bugs.
sub LogActivityEntry {
    my ($bug_id, $field, $removed, $added, $user_id, $timestamp, $comment_id,
        $attach_id) = @_;
    my $sth = Bugzilla->dbh->prepare_cached(
        'INSERT INTO bugs_activity
        (bug_id, who, bug_when, fieldid, removed, added, comment_id, attach_id)
        VALUES (?, ?, ?, ?, ?, ?, ?, ?)');

    # in the case of CCs, deps, and keywords, there's a possibility that someone
    # might try to add or remove a lot of them at once, which might take more
    # space than the activity table allows.  We'll solve this by splitting it
    # into multiple entries if it's too long.
    while ($removed || $added) {
        my ($removestr, $addstr) = ($removed, $added);
        if (length($removestr) > MAX_LINE_LENGTH) {
            my $commaposition = find_wrap_point($removed, MAX_LINE_LENGTH);
            $removestr = substr($removed, 0, $commaposition);
            $removed = substr($removed, $commaposition);
        } else {
            $removed = ""; # no more entries
        }
        if (length($addstr) > MAX_LINE_LENGTH) {
            my $commaposition = find_wrap_point($added, MAX_LINE_LENGTH);
            $addstr = substr($added, 0, $commaposition);
            $added = substr($added, $commaposition);
        } else {
            $added = ""; # no more entries
        }
        trick_taint($addstr);
        trick_taint($removestr);
        my $fieldid = get_field_id($field);
        $sth->execute($bug_id, $user_id, $timestamp, $fieldid, $removestr,
            $addstr, $comment_id, $attach_id);
    }
}

# Update bug_user_last_visit table
sub update_user_last_visit {
    my ($self, $user, $last_visit_ts) = @_;
    my $lv = Bugzilla::BugUserLastVisit->match({ bug_id  => $self->id,
                                                 user_id => $user->id })->[0];

    if ($lv) {
        $lv->set(last_visit_ts => $last_visit_ts);
        $lv->update;
    }
    else {
        Bugzilla::BugUserLastVisit->create({ bug_id        => $self->id,
                                             user_id       => $user->id,
                                             last_visit_ts => $last_visit_ts });
    }
}

# Convert WebService API and email_in.pl field names to internal DB field
# names.
sub map_fields {
    my ($params, $except) = @_; 

    my %field_values;
    foreach my $field (keys %$params) {
        # Don't allow setting private fields via email_in or the WebService.
        next if $field =~ /^_/;
        my $field_name;
        if ($except->{$field}) {
           $field_name = $field;
        }
        else {
            $field_name = FIELD_MAP->{$field} || $field;
        }
        $field_values{$field_name} = $params->{$field};
    }
    return \%field_values;
}

################################################################################
# check_can_change_field() defines what users are allowed to change. You
# can add code here for site-specific policy changes, according to the
# instructions given in the Bugzilla Guide and below. Note that you may also
# have to update the Bugzilla::Bug::user() function to give people access to the
# options that they are permitted to change.
#
# check_can_change_field() returns true if the user is allowed to change this
# field, and false if they are not.
#
# The parameters to this method are as follows:
# $field    - name of the field in the bugs table the user is trying to change
# $oldvalue - what they are changing it from
# $newvalue - what they are changing it to
# $PrivilegesRequired - return the reason of the failure, if any
################################################################################
sub check_can_change_field {
    my $self = shift;
    my ($field, $oldvalue, $newvalue, $PrivilegesRequired) = (@_);
    my $user = Bugzilla->user;

    $oldvalue = defined($oldvalue) ? $oldvalue : '';
    $newvalue = defined($newvalue) ? $newvalue : '';

    # Return true if they haven't changed this field at all.
    if ($oldvalue eq $newvalue) {
        return 1;
    } elsif (ref($newvalue) eq 'ARRAY' && ref($oldvalue) eq 'ARRAY') {
        my ($removed, $added) = diff_arrays($oldvalue, $newvalue);
        return 1 if !scalar(@$removed) && !scalar(@$added);
    } elsif (trim($oldvalue) eq trim($newvalue)) {
        return 1;
    # numeric fields need to be compared using ==
    } elsif (($field eq 'estimated_time' || $field eq 'remaining_time' 
              || $field eq 'work_time')
             && $oldvalue == $newvalue)
    {
        return 1;
    }

    my @priv_results;
    Bugzilla::Hook::process('bug_check_can_change_field',
        { bug => $self, field => $field, 
          new_value => $newvalue, old_value => $oldvalue, 
          priv_results => \@priv_results });
    if (my $priv_required = first { $_ > 0 } @priv_results) {
        $$PrivilegesRequired = $priv_required;
        return 0;
    }
    my $allow_found = first { $_ == 0 } @priv_results;
    if (defined $allow_found) {
        return 1;
    }

    # Allow anyone to change comments, or set flags
    if ($field =~ /^longdesc/ || $field eq 'flagtypes.name') {
        return 1;
    }

    # If the user isn't allowed to change a field, we must tell them who can.
    # We store the required permission set into the $PrivilegesRequired
    # variable which gets passed to the error template.
    #
    # $PrivilegesRequired = PRIVILEGES_REQUIRED_NONE : no privileges required;
    # $PrivilegesRequired = PRIVILEGES_REQUIRED_REPORTER : the reporter, assignee or an empowered user;
    # $PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE : the assignee or an empowered user;
    # $PrivilegesRequired = PRIVILEGES_REQUIRED_EMPOWERED : an empowered user.

    # Only users in the time-tracking group can change time-tracking fields,
    # including the deadline.
    if (grep { $_ eq $field } (TIMETRACKING_FIELDS, 'deadline')) {
        if (!$user->is_timetracker) {
            $$PrivilegesRequired = PRIVILEGES_REQUIRED_EMPOWERED;
            return 0;
        }
    }

    # Allow anyone with (product-specific) "editbugs" privs to change anything.
    if ($user->in_group('editbugs', $self->{'product_id'})) {
        return 1;
    }

    # *Only* users with (product-specific) "canconfirm" privs can confirm bugs.
    if ($self->_changes_everconfirmed($field, $oldvalue, $newvalue)) {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_EMPOWERED;
        return $user->in_group('canconfirm', $self->{'product_id'});
    }

    # Make sure that a valid bug ID has been given.
    if (!$self->{'error'}) {
        # Allow the assignee to change anything else.
        if ($self->{'assigned_to'} == $user->id
            || $self->{'_old_assigned_to'} && $self->{'_old_assigned_to'} == $user->id)
        {
            return 1;
        }

        # Allow the QA contact to change anything else.
        if (Bugzilla->params->{'useqacontact'}
            && (($self->{'qa_contact'} && $self->{'qa_contact'} == $user->id)
                || ($self->{'_old_qa_contact'} && $self->{'_old_qa_contact'} == $user->id)))
        {
            return 1;
        }
    }

    # At this point, the user is either the reporter or an
    # unprivileged user. We first check for fields the reporter
    # is not allowed to change.

    # The reporter may not:
    # - reassign bugs, unless the bugs are assigned to them;
    #   in that case we will have already returned 1 above
    #   when checking for the assignee of the bug.
    if ($field eq 'assigned_to') {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
        return 0;
    }
    # - change the QA contact
    if ($field eq 'qa_contact') {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
        return 0;
    }
    # - change the target milestone
    if ($field eq 'target_milestone') {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
        return 0;
    }
    # - change the priority (unless they could have set it originally)
    if ($field eq 'priority'
        && !Bugzilla->params->{'letsubmitterchoosepriority'})
    {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
        return 0;
    }
    # - unconfirm bugs (confirming them is handled above)
    if ($field eq 'everconfirmed') {
        $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
        return 0;
    }
    # - change the status from one open state to another
    if ($field eq 'bug_status'
        && is_open_state($oldvalue) && is_open_state($newvalue)) 
    {
       $$PrivilegesRequired = PRIVILEGES_REQUIRED_ASSIGNEE;
       return 0;
    }

    # The reporter is allowed to change anything else.
    if (!$self->{'error'} && $self->{'reporter_id'} == $user->id) {
        return 1;
    }

    # If we haven't returned by this point, then the user doesn't
    # have the necessary permissions to change this field.
    $$PrivilegesRequired = PRIVILEGES_REQUIRED_REPORTER;
    return 0;
}

# A helper for check_can_change_field
sub _changes_everconfirmed {
    my ($self, $field, $old, $new) = @_;
    return 1 if $field eq 'everconfirmed';
    if ($field eq 'bug_status') {
        if ($self->everconfirmed) {
            # Moving a confirmed bug to UNCONFIRMED will change everconfirmed.
            return 1 if $new eq 'UNCONFIRMED';
        }
        else {
            # Moving an unconfirmed bug to an open state that isn't 
            # UNCONFIRMED will confirm the bug.
            return 1 if (is_open_state($new) and $new ne 'UNCONFIRMED');
        }
    }
    return 0;
}

#
# Field Validation
#

# Validate and return a hash of dependencies
sub ValidateDependencies {
    my $fields = {};
    # These can be arrayrefs or they can be strings.
    $fields->{'dependson'} = shift;
    $fields->{'blocked'} = shift;
    my $id = shift || 0;

    unless (defined($fields->{'dependson'})
            || defined($fields->{'blocked'}))
    {
        return;
    }

    my $dbh = Bugzilla->dbh;
    my %deps;
    my %deptree;
    foreach my $pair (["blocked", "dependson"], ["dependson", "blocked"]) {
        my ($me, $target) = @{$pair};
        $deptree{$target} = [];
        $deps{$target} = [];
        next unless $fields->{$target};

        my %seen;
        my $target_array = ref($fields->{$target}) ? $fields->{$target}
                           : [split(/[\s,]+/, $fields->{$target})];
        foreach my $i (@$target_array) {
            if ($id == $i) {
                ThrowUserError("dependency_loop_single");
            }
            if (!exists $seen{$i}) {
                push(@{$deptree{$target}}, $i);
                $seen{$i} = 1;
            }
        }
        # populate $deps{$target} as first-level deps only.
        # and find remainder of dependency tree in $deptree{$target}
        @{$deps{$target}} = @{$deptree{$target}};
        my @stack = @{$deps{$target}};
        while (@stack) {
            my $i = shift @stack;
            my $dep_list =
                $dbh->selectcol_arrayref("SELECT $target
                                          FROM dependencies
                                          WHERE $me = ?", undef, $i);
            foreach my $t (@$dep_list) {
                # ignore any _current_ dependencies involving this bug,
                # as they will be overwritten with data from the form.
                if ($t != $id && !exists $seen{$t}) {
                    push(@{$deptree{$target}}, $t);
                    push @stack, $t;
                    $seen{$t} = 1;
                }
            }
        }
    }

    my @deps   = @{$deptree{'dependson'}};
    my @blocks = @{$deptree{'blocked'}};
    my %union = ();
    my %isect = ();
    foreach my $b (@deps, @blocks) { $union{$b}++ && $isect{$b}++ }
    my @isect = keys %isect;
    if (scalar(@isect) > 0) {
        ThrowUserError("dependency_loop_multi", {'deps' => \@isect});
    }
    return %deps;
}


#####################################################################
# Custom Field Accessors
#####################################################################

sub _create_cf_accessors {
    my ($invocant) = @_;
    my $class = ref($invocant) || $invocant;
    return if Bugzilla->request_cache->{"${class}_cf_accessors_created"};

    my $fields = Bugzilla->fields({ custom => 1 });
    foreach my $field (@$fields) {
        my $accessor = $class->_accessor_for($field);
        my $name = "${class}::" . $field->name;
        {
            no strict 'refs';
            next if defined *{$name};
            *{$name} = $accessor;
        }
    }

    Bugzilla->request_cache->{"${class}_cf_accessors_created"} = 1;
}

sub _accessor_for {
    my ($class, $field) = @_;
    if ($field->type == FIELD_TYPE_MULTI_SELECT) {
        return $class->_multi_select_accessor($field->name);
    }
    return $class->_cf_accessor($field->name);
}

sub _cf_accessor {
    my ($class, $field) = @_;
    my $accessor = sub {
        my ($self) = @_;
        return $self->{$field};
    };
    return $accessor;
}

sub _multi_select_accessor {
    my ($class, $field) = @_;
    my $accessor = sub {
        my ($self) = @_;
        $self->{$field} ||= Bugzilla->dbh->selectcol_arrayref(
            "SELECT value FROM bug_$field WHERE bug_id = ? ORDER BY value",
            undef, $self->id);
        return $self->{$field};
    };
    return $accessor;
}

1;

__END__
=head1 B<Methods>

=over

=item C<initialize>

Ensures the accessors for custom fields are always created.

=item C<add_alias($alias)>

Adds an alias to the internal respresentation of the bug. You will need to
call L<update> to make the changes permanent.

=item C<remove_alias($alias)>

Removes an alias from the internal respresentation of the bug. You will need to
call L<update> to make the changes permanent.

=item C<update_user_last_visit($user, $last_visit)>

Creates or updates a L<Bugzilla::BugUserLastVisit> for this bug and the supplied
$user, the timestamp given as $last_visit.

=back

=head1 B<Methods in need of POD>

=over

=item remove_cc

=item add_see_also

=item choices

=item keywords

=item blocked

=item qa_contact

=item add_comment

=item bug_severity

=item dup_id

=item set_priority

=item any_flags_requesteeble

=item set_bug_status

=item estimated_time

=item set_platform

=item statuses_available

=item set_custom_field

=item remove_see_also

=item remove_from_db

=item product_obj

=item reporter_accessible

=item set_summary

=item LogActivityEntry

=item set_assigned_to

=item add_group

=item bug_file_loc

=item DATE_COLUMNS

=item set_component

=item delta_ts

=item set_resolution

=item version

=item deadline

=item fields

=item dependson

=item check_can_change_field

=item update

=item set_op_sys

=item object_cache_key

=item bug_group

=item comments

=item map_fields

=item assigned_to

=item user

=item ValidateDependencies

=item short_desc

=item duplicate_ids

=item isopened

=item remaining_time

=item set_deadline

=item preload

=item groups_in

=item clear_resolution

=item set_estimated_time

=item in_group

=item status

=item get_activity

=item reporter

=item rep_platform

=item DB_COLUMNS

=item flag_types

=item bug_status

=item attachments

=item flags

=item set_flags

=item actual_time

=item component

=item UPDATE_COLUMNS

=item set_cclist_accessible

=item set_bug_ignored

=item product

=item VALIDATORS

=item show_attachment_flags

=item set_comment_is_private

=item set_severity

=item send_changes

=item add_tag

=item bug_id

=item reset_qa_contact

=item remove_group

=item set_dup_id

=item set_target_milestone

=item cc_users

=item everconfirmed

=item check_is_visible

=item check_for_edit

=item match

=item VALIDATOR_DEPENDENCIES

=item possible_duplicates

=item set_url

=item add_cc

=item blocks_obj

=item set_status_whiteboard

=item product_id

=item error

=item reset_assigned_to

=item status_whiteboard

=item create

=item set_all

=item set_reporter_accessible

=item classification_id

=item tags

=item modify_keywords

=item priority

=item keyword_objects

=item set_dependencies

=item depends_on_obj

=item cclist_accessible

=item cc

=item duplicates

=item component_obj

=item see_also

=item groups

=item default_bug_status

=item related_bugs

=item editable_bug_fields

=item resolution

=item lastdiffed

=item classification

=item alias

=item op_sys

=item remove_tag

=item percentage_complete

=item EmitDependList

=item bug_alias_to_id

=item set_qa_contact

=item creation_ts

=item set_version

=item component_id

=item new_bug_statuses

=item set_remaining_time

=item target_milestone

=back