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User:AnomieBOT/source/tasks/BrokenRedirectDeleter.pm

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package tasks::BrokenRedirectDeleter;

=pod

=begin metadata

Bot:      AnomieBOT III
Task:     BrokenRedirectDeleter
BRFA:     Wikipedia:Bots/Requests for approval/AnomieBOT III
Status:   Approved 2014-02-26
+BRFA:    Wikipedia:Bots/Requests for approval/AnomieBOT III 4
+Status:  Approved 2017-05-22
Created:  2014-01-06

Cleans up broken redirects:
* Attempted interwiki redirects are replaced with {{tl|soft redirect}}
* Redirects broken due to a move of the target without leaving a redirect are
  updated, if possible.
* Other broken redirects are deleted if the following are true:
** The redirect has only 1 revision OR was created more than 4 days ago
** The redirect is not in the User or User talk namespaces
** The target page has no log entries less than 12 hours ago
** The redirect has 10 or fewer incoming links
** The bot is not excluded, e.g. with {{tl|nobots}}
* When a broken redirect is deleted, any subpages, and the talk page (if any)
  and its subpages will be deleted, unless:
** The page is a talk page with an existing subject page
** The page is tagged with {{tl|G8-exempt}}
** The page has more than 10 incoming links
** The bot is excluded, e.g. with {{tl|nobots}}
** The parent subpage wasn't deleted
* Skipped redirects will be reported to [[User:AnomieBOT III/Broken redirects]]

=end metadata

=cut

use utf8;
use strict;

use AnomieBOT::Task qw/ISO2timestamp/;
use Data::Dumper;
use Time::HiRes;
use URI::Escape;
use vars qw/@ISA/;
@ISA=qw/AnomieBOT::Task/;

my ($screwup, $ns_subpages, %ns, %rns);

my %ignore = (
    'Wikipedia:Example of a broken redirect' => 1,
);

sub new {
    my $class=shift;
    my $self=$class->SUPER::new();
    bless $self, $class;
    return $self;
}

=pod

=for info
BRFA approved 2014-02-26<br />[[Wikipedia:Bots/Requests for approval/AnomieBOT III]]

=for info
First supplemental BFRA approved 2017-05-22<br />[[Wikipedia:Bots/Requests for approval/AnomieBOT III 4]]

=cut

sub approved {
    return 500;
}

sub run {
    my ($self, $api)=@_;
    my $res;

    $screwup='If this bot is malfunctioning, please report it at [[User:'.$api->user.'/shutoff/BrokenRedirectDeleter]]';

    $api->task('BrokenRedirectDeleter', 0, 10, qw/d::IWNS d::Redirects/);

    %ns = $api->namespace_map();
    %rns = $api->namespace_reverse_map();

    $ns_subpages = $api->cache->get( 'BrokenRedirectDeleter:ns_subpages' );
    if ( !$ns_subpages ) {
        my $res = $api->query(
            meta => 'siteinfo',
            siprop => 'namespaces',
        );
        if ( $res->{'code'} ne 'success' ) {
            $api->warn( "Failed to fetch namespace info: " . $res->{'error'} . "\n" );
            return 60;
        }
        $ns_subpages = {};
        for my $ns (values %{$res->{'query'}{'namespaces'}}) {
            $ns_subpages->{$ns->{'id'}} = exists($ns->{'subpages'});
        }
        $api->cache->set( 'BrokenRedirectDeleter:ns_subpages', $ns_subpages, 86400 );
    }

    my ($dbh);
    eval {
        ($dbh) = $api->connectToReplica( 'enwiki', 'analytics' );
    };
    if ( $@ ) {
        $api->warn( "Error connecting to replica: $@\n" );
        return 300;
    }

    my $from = $self->{'dbfrom'} // 0;
    my $report = $self->{'report'} // {};

    if ( $from == 0 && %$report ) {
        $res = $self->do_report( $api, $report );
        return $res if $res;
        $self->{'report'} = $report = {};
    }

    # Ensure bot is logged in.
    $res = $api->login();
    if ( $res->{'code'} ne 'success' ) {
        $api->warn( "Not logged in (WTF?): " . $res->{'error'} . "\n" );
        return 300;
    }

    # Spend a max of 5 minutes on this task before restarting
    my $endtime=time()+300;

    my $dbmax = (@{ $dbh->selectcol_arrayref('SELECT MAX(rd_from) FROM redirect') })[0];

    while ( $from <= $dbmax ) {
        return 0 if $api->halting;

        # Load the list of redirects needing deletion
        my @rows;
        my $to = $from + 1e6;
        $api->debug(1, "Selecting broken redirects $from-$to");
        my $t0 = Time::HiRes::time();
        eval {
            @rows = @{ $dbh->selectall_arrayref( qq{
                SELECT rd_from, p1.page_namespace, p1.page_title, rd_interwiki, rd_namespace, rd_title, rd_fragment, last_updated
                FROM redirect
                    JOIN page AS p1 ON(rd_from = p1.page_id)
                    LEFT JOIN page AS p2 ON(rd_namespace=p2.page_namespace AND rd_title=p2.page_title)
                    JOIN heartbeat_p.heartbeat ON(shard = 's1')
                WHERE rd_namespace >= 0
                    AND (p2.page_id IS NULL OR rd_interwiki != '' AND rd_interwiki IS NOT NULL)
                    AND rd_from > $from AND rd_from <= $to
            }, { Slice => {} } ) };
        };
        if ( $@ ) {
            $api->warn( "Error fetching page list from replica: $@\n" );
            return 300;
        }
        my $t1 = Time::HiRes::time();
        $api->log( 'DB query took ' . ($t1-$t0) . ' seconds' );

        @rows = sort { $a->{'rd_from'} <=> $b->{'rd_from'} } @rows;
        for my $row (@rows) {
            return 0 if $api->halting;

            $row->{'rd_interwiki'} //= '';
            utf8::decode( $row->{'rd_interwiki'} ); # Data from database is binary

            utf8::decode( $row->{'page_title'} ); # Data from database is binary
            my $from = $row->{'page_title'};
            $from = $rns{$row->{'page_namespace'}} . ':' . $from if $row->{'page_namespace'} != 0;
            $from =~ s/_/ /g;

            utf8::decode( $row->{'rd_title'} ); # Data from database is binary
            my $to = $row->{'rd_title'};
            $to = $rns{$row->{'rd_namespace'}} . ':' . $to if $row->{'rd_namespace'} != 0;
            $to = $row->{'rd_interwiki'} . ':' . $to if $row->{'rd_interwiki'} ne '';
            $to =~ s/_/ /g;

            utf8::decode( $row->{'rd_fragment'} ); # Data from database is binary
            my $to_f = $row->{'rd_fragment'} ? "$to#$row->{rd_fragment}" : $to;

            if ( defined( $ignore{$from} ) ) {
                #$api->log( "Ignoring $from, it's on the ignore list." );
                goto done;
            }

            #$api->log( "Checking [[$from]] → [[$to_f]]" );

            if ( $row->{'page_namespace'} == $ns{'User'} || $row->{'page_namespace'} == $ns{'User talk'} ) {
                # Always skip User and User talk namespaces
                push @{$report->{'user'}}, "[[:$from]] → [[:$to_f]]";
                goto done;
            } elsif ( $row->{'rd_interwiki'} ne '' ) {
                my $tok = $api->edittoken( $from, EditRedir => 1 );
                if ( $tok->{'code'} eq 'shutoff' ) {
                    $api->warn( "Task disabled: " . $tok->{'content'} . "\n" );
                    return 300;
                }
                if ( $tok->{'code'} eq 'botexcluded' ) {
                    $api->warn( "Bot excluded from $from: " . $tok->{'error'} . "\n" );
                    push @{$report->{'skip'}}, "[[:$from]] → [[:$to_f]] (bot excluded)";
                    goto done;
                }
                if ( $tok->{'code'} ne 'success' ) {
                    $api->warn( "Failed to get edit token for $from: " . $tok->{'error'} . "\n" );
                    push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (couldn't fetch edit token)";
                    goto failed;
                }
                if ( exists( $tok->{'missing'} ) ) {
                    #$api->log("$from no longer exists, skipping");
                    goto done;
                }
                if ( $tok->{'revisions'}[0]{'timestamp'} gt $row->{'last_updated'} ) {
                    $api->log("Excessive replag for $from, skipping ($tok->{'revisions'}[0]{'timestamp'} > $row->{'last_updated'})");
                    goto done;
                }

                my $txt = $tok->{'revisions'}[0]{'slots'}{'main'}{'*'};
                $txt=~s/^\s*.*?\]\]/{{soft redirect|1=$to_f}}\n/;
                my $summary = "Changing interwiki redirect to [[:$to_f]] into a soft redirect";

                $api->log( "$summary in $from" );
                my $r = $api->edit( $tok, $txt, "$summary. $screwup", 0, 1 );
                if ( $r->{'code'} ne 'success' ) {
                    push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (edit failed)";
                    goto failed;
                }
                goto done;
            } else {
                # Make sure $to didn't get recreated
                my $pg2 = undef;
                if ( $to ne '' ) {
                    $res = $api->query( titles => $to, prop => 'imageinfo' );
                    if ( $res->{'code'} ne 'success' ) {
                        $api->warn( "Failed to get existence for $to: " . $res->{'error'} . "\n" );
                        push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (couldn't fetch target existence)";
                        goto failed;
                    }
                    $pg2 = (values %{$res->{'query'}{'pages'}})[0];
                    if ( exists( $pg2->{'pageid'} ) ) {
                        #$api->log("$to_f still exists, skipping");
                        goto done;
                    }

                    $res = $api->query( titles => $from, redirects => 1 );
                    if ( $res->{'code'} ne 'success' ) {
                        $api->warn( "Failed to resolve redirects $from: " . $res->{'error'} . "\n" );
                        push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (couldn't check redirect)";
                        goto failed;
                    }
                    my $pg3 = (values %{$res->{'query'}{'pages'}})[0];
                    if ( !exists( $pg3->{'missing'} ) && $pg3->{'title'} ne $to ) {
                        $api->log("$from is no longer a redirect to $to_f, skipping");
                        goto done;
                    }
                }

                my %q = (
                    titles => $from,
                    prop => 'info|revisions|imageinfo',
                    inprop => 'talkid',
                    rvprop => 'timestamp',
                    rvlimit => 2,
                    iiprop => 'canonicaltitle',
                );
                if ( $to ne '' ) {
                    %q = ( %q,
                        list => 'logevents',
                        letitle => $to,
                        lelimit => 1,
                    );
                }

                $res = $api->query( %q );
                if ( $res->{'code'} ne 'success' ) {
                    $api->warn( "Failed to get info for $from and $to: " . $res->{'error'} . "\n" );
                    push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (couldn't fetch page info)";
                    goto failed;
                }
                my @le = @{$res->{'query'}{'logevents'} // []};
                my $pg = (values %{$res->{'query'}{'pages'}})[0];
                if ( exists( $pg->{'missing'} ) ) {
                    #$api->log("$from no longer exists, skipping");
                    goto done;
                }
                if ( !exists( $pg->{'redirect'} ) ) {
                    $api->log("$from is no longer a redirect, skipping");
                    goto done;
                }
                if ( ($pg->{'imagerepository'}//'') eq 'local' && $pg->{'imageinfo'}[0]{'canonicaltitle'} eq $pg->{'title'} ) {
                    #$api->log("$from has a local file version");
                    push @{$report->{'skip'}}, "[[:$from]] → [[:$to_f]] (page is a redirect, but a local file exists at the title)";
                    goto done;
                }
                if ( $pg2 && ($pg2->{'imagerepository'}//'') eq 'local' ) {
                    #$api->log("$to has a file");
                    push @{$report->{'skip'}}, "[[:$from]] → [[:$to_f]] (a file exists at the target title)";
                    goto done;
                }
                if ( $pg2 && ($pg2->{'imagerepository'}//'') ne '' ) {
                    #$api->log("$to has a file");
                    push @{$report->{'skip'}}, "[[:$from]] → [[:$to_f]] (a non-local file exists at the target title; while this doesn't actually work, people would rather fix it manually)";
                    goto done;
                }
                if ( @{$pg->{'revisions'}} > 1 && ISO2timestamp( $pg->{'revisions'}[0]{'timestamp'} ) > time() - 4*86400 ) {
                    #$api->log("$from has more that one revision and was edited recently");
                    push @{$report->{'wait'}}, "[[:$from]] → [[:$to_f]] (redirect has more than 1 revision and was edited less than 4 days ago)";
                    goto done;
                }
                if ( @le ) {
                    my $le = $le[0];
                    my ( $err, $ts, $newTo ) = $self->checkLogEntry( $api, $le );
                    if ( $err ) {
                        push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] (couldn't check log entries)";
                        goto failed;
                    }
                    if ( ISO2timestamp( $ts ) > time() - 43200 ) {
                        #$api->log("$to (or something in the chain of moves after it) has recent log entries");
                        if ( $newTo && $newTo ne $to ) {
                            push @{$report->{'wait'}}, "[[:$from]] → [[:$to_f]] → [[:$newTo]] (intermediate or eventual target has recent log entries)";
                        } else {
                            push @{$report->{'wait'}}, "[[:$from]] → [[:$to_f]] (intermediate or eventual target has recent log entries)";
                        }
                        goto done;
                    }

                    if ( $newTo && $newTo ne $to ) {
                        my $newTo_f = $newTo;
                        $newTo_f .= $1 if $to_f =~ /(#.*)$/;
                        my $tok = $api->edittoken( $from, EditRedir => 1, NoExclusion => 1 );
                        if ( $tok->{'code'} eq 'shutoff' ) {
                            $api->warn( "Task disabled: " . $tok->{'content'} . "\n" );
                            return 300;
                        }
                        if ( $tok->{'code'} ne 'success' ) {
                            $api->warn( "Failed to get edit token for $from: " . $tok->{'error'} . "\n" );
                            push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] → [[:$newTo]] (couldn't fetch edit token)";
                            goto failed;
                        }

                        my $re = $api->redirect_regex();
                        my $txt = $tok->{'revisions'}[0]{'slots'}{'main'}{'*'} // '';
                        unless ( $txt=~s/($re)\[\[[^]]+\]\]/$1\[\[$newTo_f\]\]/ ) {
                            $api->warn( "Failed to replace #REDIRECT in $from\n" );
                            push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] → [[:$newTo]] (couldn't replace #REDIRECT)";
                            goto failed;
                        }
                        my $summary = "Redirecting [[:$from]] to [[:$newTo_f]] following a move-without-redirect of [[:$to]]";
                        $api->log( $summary );
                        my $r = $api->edit( $tok, $txt, "$summary. $screwup", 0, 1 );
                        if ( $r->{'code'} ne 'success' ) {
                            push @{$report->{'fail'}}, "[[:$from]] → [[:$to_f]] → [[:$newTo]] (edit failed)";
                            goto failed;
                        }
                        goto done;
                    }
                }

                my ($key, $reason);
                ($res, $key, $reason) = $self->do_delete( $api, $row->{'page_namespace'}, $row->{'page_title'}, "[[WP:CSD#G8|G8]]: Broken redirect to [[:$to_f]]", 1 );
                if ( $res ) {
                    return $res if $res > 0;
                    push @{$report->{$key}}, "[[:$from]] → [[:$to_f]] ($reason)";
                    goto failed if $key eq 'failed';
                    goto done;
                }

                $self->do_delete( $api, $row->{'page_namespace'}+1, $row->{'page_title'}, "[[WP:CSD#G8|G8]]: Talk page of deleted page", 1 ) if exists($pg->{'talkid'});
            }

            done:
            $self->{'dbfrom'} = $row->{'rd_from'};

            failed:
            $self->{'report'} = $report;

            # If we've been at it long enough, let another task have a go.
            return 0 if time()>=$endtime;
        }

        $self->{'dbfrom'} = $from = $to;
    }

    $self->{'dbfrom'} = 0;
    my $wait = exists($report->{'fail'}) ? 60 : 21600;

    $res = $self->do_report( $api, $report );
    return $res if $res;
    $self->{'report'} = {};

    return $wait;
}

sub do_delete {
    my ($self, $api, $ns, $title, $reason, $subpages) = @_;
    $title =~ s/_/ /g;
    my $page = $ns ? $rns{$ns} . ':' . $title : $title;

    my $tok=$api->gettoken('csrf', Title => $page, EditRedir => 1, templates => { templates => 'Template:G8-exempt' } );
    if ( $tok->{'code'} eq 'shutoff' ) {
        $api->warn( "Task disabled: " . $tok->{'content'} . "\n" );
        return (300, undef);
    }
    if ( $tok->{'code'} eq 'botexcluded' ) {
        $api->warn( "Bot excluded from $page: " . $tok->{'error'} . "\n" );
        return (-1, 'skip', 'bot excluded');
    }
    if ( $tok->{'code'} ne 'success' ) {
        $api->warn( "Failed to get delete token for $page: " . $tok->{'error'} . "\n" );
        return (-1, 'fail', "couldn't fetch delete token");
    }
    if ( exists( $tok->{'missing'} ) ) {
        #$api->log("$page no longer exists, skipping");
        return (0, 'ok', "no longer exists");
    }
    if ( @{$tok->{'templates'} // []} ) {
        #$api->log("$page is G8-exempt");
        return (-1, 'skip', "marked G8-exempt");
    }
    my $res = $api->query(
        list => 'backlinks',
        bltitle => $page,
        bllimit => 10,
    );
    if ( exists( $res->{'query-continue'}{'backlinks'} ) ) {
        #$api->log("$page has too many backlinks");
        return (-1, 'skip', "too many incoming links");
    }

    $api->log( "Deleting $page: $reason" );
    $res = $api->action( $tok,
        action => 'delete',
        title => $page,
        reason => "$reason. $screwup",
    );
    if ( $res->{'code'} ne 'success' ) {
        $api->warn( "Failed to delete $page: " . $res->{'error'} . "\n" );
        return (-1, 'fail', 'delete failed');
    }

    if ( $subpages && $ns_subpages->{$ns} ) {
        # Delete subpages of deleted page
        my $iter = $api->iterator(
            generator => 'allpages',
            gapnamespace => $ns,
            gapprefix => "$title/",
            gaplimit => 'max',
            prop => 'info',
            inprop => 'subjectid',
        );
        my %skip = ();
        ITER: while( my $p = $iter->next ) {
            last unless $p->{'_ok_'};
            my @parts = split( m!/!, $p->{'title'} );
            for ( my $i = 0; $i < @parts; $i++ ) {
                my $t = join( '/', @parts[0..$i] );
                next ITER if exists( $skip{$t} );
            }
            if ( exists( $p->{'subjectid'} ) || @{$p->{'templates'} // []} ) {
                $skip{$p->{'title'}} = 1;
                next ITER;
            }
            $p->{'title'}=~s/^[^:]*:// if $ns;
            my ($res, $key, $reason) = $self->do_delete( $api, $ns, $p->{'title'}, "[[WP:CSD#G8|G8]]: Subpage of a deleted page", 0 );
            $skip{$p->{'title'}} = 1 if $res;
        }
    }
}

sub do_report {
    my ($self, $api, $report) = @_;
    my $txt;

    $txt = "<noinclude>This page reports on redirects that AnomieBOT\'s BrokenRedirectDeleter will not clean up because they are in the User or User talk namespace. This page was last updated {{#time:Y-m-d H:i:s|{{REVISIONTIMESTAMP}}}} (UTC).";
    if ( exists( $report->{'user'} ) ) {
        $txt .= "</noinclude>\n";
        $txt .= "== User space ==\nThese redirects are in the User or User talk namespaces, and will '''not''' be automatically cleaned up.\n<includeonly>{{collapse top|title=Userspace redirects}}</includeonly>\n";
        $txt .= "* " . join( "\n* ", @{$report->{'user'}} ) . "\n<includeonly>{{collapse bottom}}</includeonly>";
    } else {
        $txt .= "\n\nThere are no unhandled redirects at this time.</noinclude>";
    }
    $txt =~ s/(?<=^\* )\[\[:(.*?)\]\]/{{no redirect|1=$1}}/gm;
    $txt =~ s/\s*$/\n/;

    my $title = "User:" . $api->user . "/Broken redirects/Userspace";
    my $tok = $api->edittoken( $title, EditRedir => 1, NoExclusion => 1 );
    if ( $tok->{'code'} eq 'shutoff' ) {
        $api->warn( "Task disabled: " . $tok->{'content'} . "\n" );
        return 300;
    }
    if ( $tok->{'code'} ne 'success' ) {
        $api->warn( "Failed to get edit token for $title: " . $tok->{'error'} . "\n" );
        return 60;
    }

    my $intxt = $tok->{'revisions'}[0]{'slots'}{'main'}{'*'} // '';
    $intxt =~ s/\s*$/\n/;
    if ( $txt ne $intxt ) {
        $api->log( "Updating $title" );
        my $r = $api->edit( $tok, $txt, "Updating broken redirects list", 0, 1 );
        if ( $r->{'code'} ne 'success' ) {
            return 60;
        }
    }

    $txt = "This page reports on redirects that AnomieBOT\'s BrokenRedirectDeleter cannot clean up. This page was last updated {{#time:Y-m-d H:i:s|{{REVISIONTIMESTAMP}}}} (UTC).\n\n";
    unless ( %$report ) {
        $txt .= "There are no unhandled redirects at this time.";
    }
    if ( exists( $report->{'skip'} ) ) {
        $txt .= "== Skipped ==\nThese redirects were skipped by the bot, and will '''not''' be automatically cleaned up as long as the indicated issues apply.\n";
        $txt .= "* " . join( "\n* ", @{$report->{'skip'}} ) . "\n\n";
    }
    if ( exists( $report->{'user'} ) ) {
        $txt =~ s/\s*$/\n/;
        $txt .= "{{ {{FULLPAGENAME}}/Userspace }}\n";
    }
    if ( exists( $report->{'wait'} ) ) {
        $txt .= "== Recently changed ==\nThese redirects were created recently, or their targets have recent log entries. The bot will process them after the appropriate waiting period.\n";
        $txt .= "* " . join( "\n* ", @{$report->{'wait'}} ) . "\n\n";
    }
    if ( exists( $report->{'fail'} ) ) {
        $txt .= "== Failed ==\nThe most recent attempt to edit or delete these redirects failed. The bot will retry on its next run.\n";
        $txt .= "* " . join( "\n* ", @{$report->{'fail'}} ) . "\n\n";
    }
    $txt =~ s/(?<=^\* )\[\[:(.*?)\]\]/{{no redirect|1=$1}}/gm;
    $txt =~ s/\s*$/\n/;

    $title = "User:" . $api->user . "/Broken redirects";
    $tok = $api->edittoken( $title, EditRedir => 1, NoExclusion => 1 );
    if ( $tok->{'code'} eq 'shutoff' ) {
        $api->warn( "Task disabled: " . $tok->{'content'} . "\n" );
        return 300;
    }
    if ( $tok->{'code'} ne 'success' ) {
        $api->warn( "Failed to get edit token for $title" . $tok->{'error'} . "\n" );
        return 60;
    }

    $intxt = $tok->{'revisions'}[0]{'slots'}{'main'}{'*'} // '';
    $intxt =~ s/\s*$/\n/;
    if ( $txt ne $intxt ) {
        $api->log( "Updating $title" );
        my $r = $api->edit( $tok, $txt, "Updating broken redirects list", 0, 1 );
        if ( $r->{'code'} ne 'success' ) {
            return 60;
        }
    }

    return 0;
}

sub checkLogEntry {
    my ( $self, $api, $le ) = @_;

    my $ts = $le->{'timestamp'};

    return ( undef, $ts, undef ) unless ( $le->{'type'} eq 'move' && exists( $le->{'params'}{'suppressredirect'} ) && $le->{'params'}{'target_ns'} == $le->{'ns'} );

    # Find the new target
    my $target = $le->{'params'}{'target_title'};

    # Bypass double redirects
    my $res = $api->query( titles => $target, redirects => 1 );
    if ( $res->{'code'} ne 'success' ) {
        $api->warn( "Failed to retrieve info for $target: " . $res->{'error'} . "\n" );
        return ( 'fail' );
    }
    my %map = ();
    if ( exists( $res->{'query'}{'normalized'} ) ) {
        $map{$_->{'from'}} = $_->{'to'} foreach @{$res->{'query'}{'normalized'}};
    }
    if ( exists($res->{'query'}{'redirects'} ) ) {
        $map{$_->{'from'}} = $_->{'to'} foreach @{$res->{'query'}{'redirects'}};
    }
    $target = $map{$target} if exists( $map{$target} );

    # Does the final target exist?
    my %exists = ();
    if ( exists( $res->{'query'}{'pages'} ) ) {
        for my $p (values %{$res->{'query'}{'pages'}}) {
            $exists{$p->{'title'}} = $p->{'ns'} if $p->{'pageid'}//0;
        }
    }
    if ( exists( $exists{$target} ) ) {
        return ( undef, $ts, ($exists{$target} == $le->{'ns'} ? $target : undef ) );
    }

    # No, check if it in turn was moved-without-redirect.
    $res = $api->query( list => 'logevents', letitle => $target, lelimit => 1 );
    if ( $res->{'code'} ne 'success' ) {
        $api->warn( "Failed to retrieve log events for $target: " . $res->{'error'} . "\n" );
        return ( 'fail' );
    }
    $target = undef; # If not, just return no target.
    my @le = @{$res->{'query'}{'logevents'} // []};
    if ( @le ) {
        my ( $err, $ts2 );
        ( $err, $ts2, $target ) = $self->checkLogEntry( $api, $le[0] );
        return ( $err ) if $err;
        $ts = $ts2 if defined( $ts2 ) && $ts2 lt $ts;
    }
    return ( undef, $ts, $target );
}

1;