ApiQueryBacklinks.php

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<?php
class ApiQueryBacklinks extends ApiQueryGeneratorBase {

    private $rootTitle;

    private $params;
    private $cont;
    private $redirect;
    private $bl_ns, $bl_from, $bl_from_ns, $bl_table, $bl_code, $bl_title, $bl_fields, $hasNS;

    private $helpUrl;

    private $pageMap = [];
    private $resultArr;

    private $redirTitles = [];
    private $continueStr = null;

    // output element name, database column field prefix, database table
    private $backlinksSettings = [
        'backlinks' => [
            'code' => 'bl',
            'prefix' => 'pl',
            'linktbl' => 'pagelinks',
            'helpurl' => 'https://www.mediawiki.org/wiki/Special:MyLanguage/API:Backlinks',
        ],
        'embeddedin' => [
            'code' => 'ei',
            'prefix' => 'tl',
            'linktbl' => 'templatelinks',
            'helpurl' => 'https://www.mediawiki.org/wiki/Special:MyLanguage/API:Embeddedin',
        ],
        'imageusage' => [
            'code' => 'iu',
            'prefix' => 'il',
            'linktbl' => 'imagelinks',
            'helpurl' => 'https://www.mediawiki.org/wiki/Special:MyLanguage/API:Imageusage',
        ]
    ];

    public function __construct( ApiQuery $query, $moduleName ) {
        $settings = $this->backlinksSettings[$moduleName];
        $prefix = $settings['prefix'];
        $code = $settings['code'];
        $this->resultArr = [];

        parent::__construct( $query, $moduleName, $code );
        $this->bl_ns = $prefix . '_namespace';
        $this->bl_from = $prefix . '_from';
        $this->bl_from_ns = $prefix . '_from_namespace';
        $this->bl_table = $settings['linktbl'];
        $this->bl_code = $code;
        $this->helpUrl = $settings['helpurl'];

        $this->hasNS = $moduleName !== 'imageusage';
        if ( $this->hasNS ) {
            $this->bl_title = $prefix . '_title';
            $this->bl_fields = [
                $this->bl_ns,
                $this->bl_title
            ];
        } else {
            $this->bl_title = $prefix . '_to';
            $this->bl_fields = [
                $this->bl_title
            ];
        }
    }

    public function execute() {
        $this->run();
    }

    public function getCacheMode( $params ) {
        return 'public';
    }

    public function executeGenerator( $resultPageSet ) {
        $this->run( $resultPageSet );
    }

    private function runFirstQuery( $resultPageSet = null ) {
        $this->addTables( [ $this->bl_table, 'page' ] );
        $this->addWhere( "{$this->bl_from}=page_id" );
        if ( is_null( $resultPageSet ) ) {
            $this->addFields( [ 'page_id', 'page_title', 'page_namespace' ] );
        } else {
            $this->addFields( $resultPageSet->getPageTableFields() );
        }
        $this->addFields( [ 'page_is_redirect', 'from_ns' => 'page_namespace' ] );

        $this->addWhereFld( $this->bl_title, $this->rootTitle->getDBkey() );
        if ( $this->hasNS ) {
            $this->addWhereFld( $this->bl_ns, $this->rootTitle->getNamespace() );
        }
        $this->addWhereFld( $this->bl_from_ns, $this->params['namespace'] );

        if ( count( $this->cont ) >= 2 ) {
            $op = $this->params['dir'] == 'descending' ? '<' : '>';
            if ( $this->params['namespace'] !== null && count( $this->params['namespace'] ) > 1 ) {
                $this->addWhere(
                    "{$this->bl_from_ns} $op {$this->cont[0]} OR " .
                    "({$this->bl_from_ns} = {$this->cont[0]} AND " .
                    "{$this->bl_from} $op= {$this->cont[1]})"
                );
            } else {
                $this->addWhere( "{$this->bl_from} $op= {$this->cont[1]}" );
            }
        }

        if ( $this->params['filterredir'] == 'redirects' ) {
            $this->addWhereFld( 'page_is_redirect', 1 );
        } elseif ( $this->params['filterredir'] == 'nonredirects' && !$this->redirect ) {
            // T24245 - Check for !redirect, as filtering nonredirects, when
            // getting what links to them is contradictory
            $this->addWhereFld( 'page_is_redirect', 0 );
        }

        $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
        $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
        $orderBy = [];
        if ( $this->params['namespace'] !== null && count( $this->params['namespace'] ) > 1 ) {
            $orderBy[] = $this->bl_from_ns . $sort;
        }
        $orderBy[] = $this->bl_from . $sort;
        $this->addOption( 'ORDER BY', $orderBy );
        $this->addOption( 'STRAIGHT_JOIN' );

        $res = $this->select( __METHOD__ );
        $count = 0;
        foreach ( $res as $row ) {
            if ( ++$count > $this->params['limit'] ) {
                // We've reached the one extra which shows that there are
                // additional pages to be had. Stop here...
                // Continue string may be overridden at a later step
                $this->continueStr = "{$row->from_ns}|{$row->page_id}";
                break;
            }

            // Fill in continuation fields for later steps
            if ( count( $this->cont ) < 2 ) {
                $this->cont[] = $row->from_ns;
                $this->cont[] = $row->page_id;
            }

            $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
            $t = Title::makeTitle( $row->page_namespace, $row->page_title );
            if ( $row->page_is_redirect ) {
                $this->redirTitles[] = $t;
            }

            if ( is_null( $resultPageSet ) ) {
                $a = [ 'pageid' => (int)$row->page_id ];
                ApiQueryBase::addTitleInfo( $a, $t );
                if ( $row->page_is_redirect ) {
                    $a['redirect'] = true;
                }
                // Put all the results in an array first
                $this->resultArr[$a['pageid']] = $a;
            } else {
                $resultPageSet->processDbRow( $row );
            }
        }
    }

    private function runSecondQuery( $resultPageSet = null ) {
        $db = $this->getDB();
        $this->addTables( [ 'page', $this->bl_table ] );
        $this->addWhere( "{$this->bl_from}=page_id" );

        if ( is_null( $resultPageSet ) ) {
            $this->addFields( [ 'page_id', 'page_title', 'page_namespace', 'page_is_redirect' ] );
        } else {
            $this->addFields( $resultPageSet->getPageTableFields() );
        }

        $this->addFields( [ $this->bl_title, 'from_ns' => 'page_namespace' ] );
        if ( $this->hasNS ) {
            $this->addFields( $this->bl_ns );
        }

        // We can't use LinkBatch here because $this->hasNS may be false
        $titleWhere = [];
        $allRedirNs = [];
        $allRedirDBkey = [];
        foreach ( $this->redirTitles as $t ) {
            $redirNs = $t->getNamespace();
            $redirDBkey = $t->getDBkey();
            $titleWhere[] = "{$this->bl_title} = " . $db->addQuotes( $redirDBkey ) .
                ( $this->hasNS ? " AND {$this->bl_ns} = {$redirNs}" : '' );
            $allRedirNs[$redirNs] = true;
            $allRedirDBkey[$redirDBkey] = true;
        }
        $this->addWhere( $db->makeList( $titleWhere, LIST_OR ) );
        $this->addWhereFld( 'page_namespace', $this->params['namespace'] );

        if ( count( $this->cont ) >= 6 ) {
            $op = $this->params['dir'] == 'descending' ? '<' : '>';

            $where = "{$this->bl_from} $op= {$this->cont[5]}";
            // Don't bother with namespace, title, or from_namespace if it's
            // otherwise constant in the where clause.
            if ( $this->params['namespace'] !== null && count( $this->params['namespace'] ) > 1 ) {
                $where = "{$this->bl_from_ns} $op {$this->cont[4]} OR " .
                    "({$this->bl_from_ns} = {$this->cont[4]} AND ($where))";
            }
            if ( count( $allRedirDBkey ) > 1 ) {
                $title = $db->addQuotes( $this->cont[3] );
                $where = "{$this->bl_title} $op $title OR " .
                    "({$this->bl_title} = $title AND ($where))";
            }
            if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
                $where = "{$this->bl_ns} $op {$this->cont[2]} OR " .
                    "({$this->bl_ns} = {$this->cont[2]} AND ($where))";
            }

            $this->addWhere( $where );
        }
        if ( $this->params['filterredir'] == 'redirects' ) {
            $this->addWhereFld( 'page_is_redirect', 1 );
        } elseif ( $this->params['filterredir'] == 'nonredirects' ) {
            $this->addWhereFld( 'page_is_redirect', 0 );
        }

        $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
        $orderBy = [];
        $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
        // Don't order by namespace/title/from_namespace if it's constant in the WHERE clause
        if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
            $orderBy[] = $this->bl_ns . $sort;
        }
        if ( count( $allRedirDBkey ) > 1 ) {
            $orderBy[] = $this->bl_title . $sort;
        }
        if ( $this->params['namespace'] !== null && count( $this->params['namespace'] ) > 1 ) {
            $orderBy[] = $this->bl_from_ns . $sort;
        }
        $orderBy[] = $this->bl_from . $sort;
        $this->addOption( 'ORDER BY', $orderBy );
        $this->addOption( 'USE INDEX', [ 'page' => 'PRIMARY' ] );

        $res = $this->select( __METHOD__ );
        $count = 0;
        foreach ( $res as $row ) {
            $ns = $this->hasNS ? $row->{$this->bl_ns} : NS_FILE;

            if ( ++$count > $this->params['limit'] ) {
                // We've reached the one extra which shows that there are
                // additional pages to be had. Stop here...
                // Note we must keep the parameters for the first query constant
                // This may be overridden at a later step
                $title = $row->{$this->bl_title};
                $this->continueStr = implode( '|', array_slice( $this->cont, 0, 2 ) ) .
                    "|$ns|$title|{$row->from_ns}|{$row->page_id}";
                break;
            }

            // Fill in continuation fields for later steps
            if ( count( $this->cont ) < 6 ) {
                $this->cont[] = $ns;
                $this->cont[] = $row->{$this->bl_title};
                $this->cont[] = $row->from_ns;
                $this->cont[] = $row->page_id;
            }

            if ( is_null( $resultPageSet ) ) {
                $a = [ 'pageid' => (int)$row->page_id ];
                ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
                if ( $row->page_is_redirect ) {
                    $a['redirect'] = true;
                }
                $parentID = $this->pageMap[$ns][$row->{$this->bl_title}];
                // Put all the results in an array first
                $this->resultArr[$parentID]['redirlinks'][$row->page_id] = $a;
            } else {
                $resultPageSet->processDbRow( $row );
            }
        }
    }

    private function run( $resultPageSet = null ) {
        $this->params = $this->extractRequestParams( false );
        $this->redirect = isset( $this->params['redirect'] ) && $this->params['redirect'];
        $userMax = ( $this->redirect ? ApiBase::LIMIT_BIG1 / 2 : ApiBase::LIMIT_BIG1 );
        $botMax = ( $this->redirect ? ApiBase::LIMIT_BIG2 / 2 : ApiBase::LIMIT_BIG2 );

        $result = $this->getResult();

        if ( $this->params['limit'] == 'max' ) {
            $this->params['limit'] = $this->getMain()->canApiHighLimits() ? $botMax : $userMax;
            $result->addParsedLimit( $this->getModuleName(), $this->params['limit'] );
        } else {
            $this->params['limit'] = (int)$this->params['limit'];
            $this->validateLimit( 'limit', $this->params['limit'], 1, $userMax, $botMax );
        }

        $this->rootTitle = $this->getTitleFromTitleOrPageId( $this->params );

        // only image titles are allowed for the root in imageinfo mode
        if ( !$this->hasNS && $this->rootTitle->getNamespace() !== NS_FILE ) {
            $this->dieWithError(
                [ 'apierror-imageusage-badtitle', $this->getModuleName() ],
                'bad_image_title'
            );
        }

        // Parse and validate continuation parameter
        $this->cont = [];
        if ( $this->params['continue'] !== null ) {
            $cont = explode( '|', $this->params['continue'] );

            switch ( count( $cont ) ) {
                case 8:
                    // redirect page ID for result adding
                    $this->cont[7] = (int)$cont[7];
                    $this->dieContinueUsageIf( $cont[7] !== (string)$this->cont[7] );

                    /* Fall through */

                case 7:
                    // top-level page ID for result adding
                    $this->cont[6] = (int)$cont[6];
                    $this->dieContinueUsageIf( $cont[6] !== (string)$this->cont[6] );

                    /* Fall through */

                case 6:
                    // ns for 2nd query (even for imageusage)
                    $this->cont[2] = (int)$cont[2];
                    $this->dieContinueUsageIf( $cont[2] !== (string)$this->cont[2] );

                    // title for 2nd query
                    $this->cont[3] = $cont[3];

                    // from_ns for 2nd query
                    $this->cont[4] = (int)$cont[4];
                    $this->dieContinueUsageIf( $cont[4] !== (string)$this->cont[4] );

                    // from_id for 1st query
                    $this->cont[5] = (int)$cont[5];
                    $this->dieContinueUsageIf( $cont[5] !== (string)$this->cont[5] );

                    /* Fall through */

                case 2:
                    // from_ns for 1st query
                    $this->cont[0] = (int)$cont[0];
                    $this->dieContinueUsageIf( $cont[0] !== (string)$this->cont[0] );

                    // from_id for 1st query
                    $this->cont[1] = (int)$cont[1];
                    $this->dieContinueUsageIf( $cont[1] !== (string)$this->cont[1] );

                    break;

                default:
                    $this->dieContinueUsageIf( true );
            }

            ksort( $this->cont );
        }

        $this->runFirstQuery( $resultPageSet );
        if ( $this->redirect && count( $this->redirTitles ) ) {
            $this->resetQueryParams();
            $this->runSecondQuery( $resultPageSet );
        }

        // Fill in any missing fields in case it's needed below
        $this->cont += [ 0, 0, 0, '', 0, 0, 0 ];

        if ( is_null( $resultPageSet ) ) {
            // Try to add the result data in one go and pray that it fits
            $code = $this->bl_code;
            $data = array_map( function ( $arr ) use ( $code ) {
                if ( isset( $arr['redirlinks'] ) ) {
                    $arr['redirlinks'] = array_values( $arr['redirlinks'] );
                    ApiResult::setIndexedTagName( $arr['redirlinks'], $code );
                }
                return $arr;
            }, array_values( $this->resultArr ) );
            $fit = $result->addValue( 'query', $this->getModuleName(), $data );
            if ( !$fit ) {
                // It didn't fit. Add elements one by one until the
                // result is full.
                ksort( $this->resultArr );
                if ( count( $this->cont ) >= 7 ) {
                    $startAt = $this->cont[6];
                } else {
                    reset( $this->resultArr );
                    $startAt = key( $this->resultArr );
                }
                $idx = 0;
                foreach ( $this->resultArr as $pageID => $arr ) {
                    if ( $pageID < $startAt ) {
                        continue;
                    }

                    // Add the basic entry without redirlinks first
                    $fit = $result->addValue(
                        [ 'query', $this->getModuleName() ],
                        $idx, array_diff_key( $arr, [ 'redirlinks' => '' ] ) );
                    if ( !$fit ) {
                        $this->continueStr = implode( '|', array_slice( $this->cont, 0, 6 ) ) .
                            "|$pageID";
                        break;
                    }

                    $hasRedirs = false;
                    $redirLinks = isset( $arr['redirlinks'] ) ? (array)$arr['redirlinks'] : [];
                    ksort( $redirLinks );
                    if ( count( $this->cont ) >= 8 && $pageID == $startAt ) {
                        $redirStartAt = $this->cont[7];
                    } else {
                        reset( $redirLinks );
                        $redirStartAt = key( $redirLinks );
                    }
                    foreach ( $redirLinks as $key => $redir ) {
                        if ( $key < $redirStartAt ) {
                            continue;
                        }

                        $fit = $result->addValue(
                            [ 'query', $this->getModuleName(), $idx, 'redirlinks' ],
                            null, $redir );
                        if ( !$fit ) {
                            $this->continueStr = implode( '|', array_slice( $this->cont, 0, 6 ) ) .
                                "|$pageID|$key";
                            break;
                        }
                        $hasRedirs = true;
                    }
                    if ( $hasRedirs ) {
                        $result->addIndexedTagName(
                            [ 'query', $this->getModuleName(), $idx, 'redirlinks' ],
                            $this->bl_code );
                    }
                    if ( !$fit ) {
                        break;
                    }

                    $idx++;
                }
            }

            $result->addIndexedTagName(
                [ 'query', $this->getModuleName() ],
                $this->bl_code
            );
        }
        if ( !is_null( $this->continueStr ) ) {
            $this->setContinueEnumParameter( 'continue', $this->continueStr );
        }
    }

    public function getAllowedParams() {
        $retval = [
            'title' => [
                ApiBase::PARAM_TYPE => 'string',
            ],
            'pageid' => [
                ApiBase::PARAM_TYPE => 'integer',
            ],
            'continue' => [
                ApiBase::PARAM_HELP_MSG => 'api-help-param-continue',
            ],
            'namespace' => [
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_TYPE => 'namespace'
            ],
            'dir' => [
                ApiBase::PARAM_DFLT => 'ascending',
                ApiBase::PARAM_TYPE => [
                    'ascending',
                    'descending'
                ]
            ],
            'filterredir' => [
                ApiBase::PARAM_DFLT => 'all',
                ApiBase::PARAM_TYPE => [
                    'all',
                    'redirects',
                    'nonredirects'
                ]
            ],
            'limit' => [
                ApiBase::PARAM_DFLT => 10,
                ApiBase::PARAM_TYPE => 'limit',
                ApiBase::PARAM_MIN => 1,
                ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
                ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
            ]
        ];
        if ( $this->getModuleName() == 'embeddedin' ) {
            return $retval;
        }
        $retval['redirect'] = false;

        return $retval;
    }

    protected function getExamplesMessages() {
        static $examples = [
            'backlinks' => [
                'action=query&list=backlinks&bltitle=Main%20Page'
                    => 'apihelp-query+backlinks-example-simple',
                'action=query&generator=backlinks&gbltitle=Main%20Page&prop=info'
                    => 'apihelp-query+backlinks-example-generator',
            ],
            'embeddedin' => [
                'action=query&list=embeddedin&eititle=Template:Stub'
                    => 'apihelp-query+embeddedin-example-simple',
                'action=query&generator=embeddedin&geititle=Template:Stub&prop=info'
                    => 'apihelp-query+embeddedin-example-generator',
            ],
            'imageusage' => [
                'action=query&list=imageusage&iutitle=File:Albert%20Einstein%20Head.jpg'
                    => 'apihelp-query+imageusage-example-simple',
                'action=query&generator=imageusage&giutitle=File:Albert%20Einstein%20Head.jpg&prop=info'
                    => 'apihelp-query+imageusage-example-generator',
            ]
        ];

        return $examples[$this->getModuleName()];
    }

    public function getHelpUrls() {
        return $this->helpUrl;
    }
}