CommentStore.php

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<?php
namespace MediaWiki\CommentStore;
 
use InvalidArgumentException;
use MediaWiki\Json\FormatJson;
use MediaWiki\Language\Language;
use MediaWiki\Language\RawMessage;
use MediaWiki\Message\Message;
use OverflowException;
use stdClass;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IReadableDatabase;
 
class CommentStore {
 
    public const COMMENT_CHARACTER_LIMIT = 500;
 
    public const MAX_DATA_LENGTH = 65535;
 
    private $joinCache = [];
 
    private $lang;
 
    public function __construct( Language $lang ) {
        $this->lang = $lang;
    }
 
    public function getJoin( $key ) {
        if ( !array_key_exists( $key, $this->joinCache ) ) {
            $tables = [];
            $fields = [];
            $joins = [];
 
            $alias = "comment_$key";
            $tables[$alias] = 'comment';
            $joins[$alias] = [ 'JOIN', "{$alias}.comment_id = {$key}_id" ];
 
            $fields["{$key}_text"] = "{$alias}.comment_text";
            $fields["{$key}_data"] = "{$alias}.comment_data";
            $fields["{$key}_cid"] = "{$alias}.comment_id";
 
            $this->joinCache[$key] = [
                'tables' => $tables,
                'fields' => $fields,
                'joins' => $joins,
            ];
        }
 
        return $this->joinCache[$key];
    }
 
    private function getCommentInternal( ?IReadableDatabase $db, $key, $row, $fallback = false ) {
        $row = (array)$row;
        if ( array_key_exists( "{$key}_text", $row ) && array_key_exists( "{$key}_data", $row ) ) {
            $cid = $row["{$key}_cid"] ?? null;
            $text = $row["{$key}_text"];
            $data = $row["{$key}_data"];
        } else {
            $row2 = null;
            if ( array_key_exists( "{$key}_id", $row ) ) {
                if ( !$db ) {
                    throw new InvalidArgumentException(
                        "\$row does not contain fields needed for comment $key and getComment(), but "
                        . "does have fields for getCommentLegacy()"
                    );
                }
                $id = $row["{$key}_id"];
                $row2 = $db->newSelectQueryBuilder()
                    ->select( [ 'comment_id', 'comment_text', 'comment_data' ] )
                    ->from( 'comment' )
                    ->where( [ 'comment_id' => $id ] )
                    ->caller( __METHOD__ )->fetchRow();
            }
            if ( $row2 === null && $fallback && isset( $row[$key] ) ) {
                wfLogWarning( "Using deprecated fallback handling for comment $key" );
                $row2 = (object)[ 'comment_text' => $row[$key], 'comment_data' => null ];
            }
            if ( $row2 === null ) {
                throw new InvalidArgumentException( "\$row does not contain fields needed for comment $key" );
            }
 
            if ( $row2 ) {
                $cid = $row2->comment_id;
                $text = $row2->comment_text;
                $data = $row2->comment_data;
            } else {
                // @codeCoverageIgnoreStart
                // @phan-suppress-next-line PhanPossiblyUndeclaredVariable $id is set when $row2 is okay
                wfLogWarning( "Missing comment row for $key, id=$id" );
                $cid = null;
                $text = '';
                $data = null;
                // @codeCoverageIgnoreEnd
            }
        }
 
        $msg = null;
        if ( $data !== null ) {
            $data = FormatJson::decode( $data, true );
            if ( !is_array( $data ) ) {
                // @codeCoverageIgnoreStart
                wfLogWarning( "Invalid JSON object in comment: $data" );
                $data = null;
                // @codeCoverageIgnoreEnd
            } else {
                if ( isset( $data['_message'] ) ) {
                    $msg = self::decodeMessage( $data['_message'] )
                        ->setInterfaceMessageFlag( true );
                }
                if ( !empty( $data['_null'] ) ) {
                    $data = null;
                } else {
                    foreach ( $data as $k => $v ) {
                        if ( substr( $k, 0, 1 ) === '_' ) {
                            unset( $data[$k] );
                        }
                    }
                }
            }
        }
 
        return new CommentStoreComment( $cid, $text, $msg, $data );
    }
 
    public function getComment( $key, $row = null, $fallback = false ) {
        if ( $row === null ) {
            // @codeCoverageIgnoreStart
            throw new InvalidArgumentException( '$row must not be null' );
            // @codeCoverageIgnoreEnd
        }
        return $this->getCommentInternal( null, $key, $row, $fallback );
    }
 
    public function getCommentLegacy( IReadableDatabase $db, $key, $row = null, $fallback = false ) {
        if ( $row === null ) {
            // @codeCoverageIgnoreStart
            throw new InvalidArgumentException( '$row must not be null' );
            // @codeCoverageIgnoreEnd
        }
        return $this->getCommentInternal( $db, $key, $row, $fallback );
    }
 
    public function createComment( IDatabase $dbw, $comment, ?array $data = null ) {
        $comment = CommentStoreComment::newUnsavedComment( $comment, $data );
 
        # Truncate comment in a Unicode-sensitive manner
        $comment->text = $this->lang->truncateForVisual( $comment->text, self::COMMENT_CHARACTER_LIMIT );
 
        if ( !$comment->id ) {
            $dbData = $comment->data;
            if ( !$comment->message instanceof RawMessage ) {
                $dbData ??= [ '_null' => true ];
                $dbData['_message'] = self::encodeMessage( $comment->message );
            }
            if ( $dbData !== null ) {
                $dbData = FormatJson::encode( (object)$dbData, false, FormatJson::ALL_OK );
                $len = strlen( $dbData );
                if ( $len > self::MAX_DATA_LENGTH ) {
                    $max = self::MAX_DATA_LENGTH;
                    throw new OverflowException( "Comment data is too long ($len bytes, maximum is $max)" );
                }
            }
 
            $hash = self::hash( $comment->text, $dbData );
            $commentId = $dbw->newSelectQueryBuilder()
                ->select( 'comment_id' )
                ->from( 'comment' )
                ->where( [
                    'comment_hash' => $hash,
                    'comment_text' => $comment->text,
                    'comment_data' => $dbData,
                ] )
                ->caller( __METHOD__ )->fetchField();
            if ( !$commentId ) {
                $dbw->newInsertQueryBuilder()
                    ->insertInto( 'comment' )
                    ->row( [ 'comment_hash' => $hash, 'comment_text' => $comment->text, 'comment_data' => $dbData ] )
                    ->caller( __METHOD__ )->execute();
                $commentId = $dbw->insertId();
            }
            $comment->id = (int)$commentId;
        }
 
        return $comment;
    }
 
    public function insert( IDatabase $dbw, $key, $comment = null, $data = null ) {
        if ( $comment === null ) {
            // @codeCoverageIgnoreStart
            throw new InvalidArgumentException( '$comment can not be null' );
            // @codeCoverageIgnoreEnd
        }
 
        $comment = $this->createComment( $dbw, $comment, $data );
        return [ "{$key}_id" => $comment->id ];
    }
 
    private static function encodeMessage( Message $msg ) {
        $key = count( $msg->getKeysToTry() ) > 1 ? $msg->getKeysToTry() : $msg->getKey();
        $params = $msg->getParams();
        foreach ( $params as &$param ) {
            if ( $param instanceof Message ) {
                $param = [
                    'message' => self::encodeMessage( $param )
                ];
            }
        }
        array_unshift( $params, $key );
        return $params;
    }
 
    private static function decodeMessage( $data ) {
        $key = array_shift( $data );
        foreach ( $data as &$param ) {
            if ( is_object( $param ) ) {
                $param = (array)$param;
            }
            if ( is_array( $param ) && count( $param ) === 1 && isset( $param['message'] ) ) {
                $param = self::decodeMessage( $param['message'] );
            }
        }
        return new Message( $key, $data );
    }
 
    private static function hash( $text, $data ) {
        $hash = crc32( $text ) ^ crc32( (string)$data );
 
        // 64-bit PHP returns an unsigned CRC, change it to signed for
        // insertion into the database.
        if ( $hash >= 0x80000000 ) {
            $hash |= -1 << 32;
        }
 
        return $hash;
    }
 
}