wikimedia/mediawiki-core

<?php

use MediaWiki\Shell\ShellboxClientFactory;

/**
 * An ICU collation that uses a remote server to compute sort keys. This can be
 * used in conjunction with $wgTempCategoryCollations to migrate to a different
 * version of ICU.
 */
class RemoteIcuCollation extends Collation {
    private $rpcClient;
    private $locale;

    /**
     * @param ShellboxClientFactory $shellboxClientFactory
     * @param string $locale
     */
    public function __construct( ShellboxClientFactory $shellboxClientFactory, $locale ) {
        $this->rpcClient = $shellboxClientFactory->getRpcClient(
            [ 'service' => 'icu-collation' ] );
        $this->locale = $locale;
    }

    public function getSortKey( $string ) {
        return $this->getSortKeys( [ $string ] )[0];
    }

    /**
     * Encode an array of binary strings as a string
     *
     * @param string[] $strings
     * @return string
     */
    private static function encode( $strings ) {
        $ret = '';
        foreach ( $strings as $s ) {
            $ret .= sprintf( "%08x", strlen( $s ) ) . $s;
        }
        return $ret;
    }

    /**
     * Decode the value returned by encode()
     *
     * @param string $blob
     * @return string[]
     */
    private static function decode( $blob ) {
        $p = 0;
        $ret = [];
        while ( $p < strlen( $blob ) ) {
            $len = intval( substr( $blob, $p, 8 ), 16 );
            $p += 8;
            $ret[] = substr( $blob, $p, $len );
            $p += $len;
        }
        return $ret;
    }

    public function getSortKeys( $strings ) {
        if ( !count( $strings ) ) {
            return [];
        }
        $blob = $this->rpcClient->call(
            'icu-collation',
            self::class . '::' . 'doGetSortKeys',
            [
                $this->locale,
                self::encode( array_values( $strings ) )
            ],
            [
                'classes' => [ parent::class, self::class ],
                'binary' => true
            ]
        );
        return array_combine(
            array_keys( $strings ),
            self::decode( $blob )
        );
    }

    public function getFirstLetter( $string ) {
        // @phan-suppress-previous-line PhanPluginNeverReturnMethod
        throw new RuntimeException( __METHOD__ . ': not implemented' );
    }

    /**
     * The remote entry point. Get sort keys for an encoded list of inputs.
     *
     * @param string $locale The ICU locale
     * @param string $blob The input array encoded with encode()
     * @return string The encoded result
     */
    public static function doGetSortKeys( $locale, $blob ) {
        $mainCollator = Collator::create( $locale );
        if ( !$mainCollator ) {
            throw new RuntimeException( "Invalid ICU locale specified for collation: $locale" );
        }

        // If the special suffix for numeric collation is present, turn on numeric collation.
        if ( str_ends_with( $locale, '-u-kn' ) ) {
            $mainCollator->setAttribute( Collator::NUMERIC_COLLATION, Collator::ON );
        }
        $ret = [];
        foreach ( self::decode( $blob ) as $string ) {
            $ret[] = $mainCollator->getSortKey( $string );
        }
        return self::encode( $ret );
    }
}