wikimedia/mediawiki-extensions-CirrusSearch

<?php

namespace CirrusSearch\Profile;

use Wikimedia\Assert\Assert;

/**
 * Transforms arrays based on replacement variable using a syntax
 * to lookup the entry to modify.
 *
 * Examples:
 *  [ 'elem1.elem2' => 'value' ]
 * will replace the following profile
 *  [ 'elem1' =>
 *      [
 *             'elem2' => 'placeholder'
 *      ]
 *  ]
 * with :
 *  [ 'elem1' =>
 *      [
 *             'elem2' => 'value'
 *      ]
 *  ]
 *
 * The syntax supports lookaheads on next array value:
 *  [ 'elem1.*[type=bar].element' => [ 'custom' => 'data' ] ]
 * will replace the following profile
 *  [ 'elem1' =>
 *      [
 *             [
 *                 'type' => 'foo'
 *                 'element' => []
 *             ],
 *             [
 *                 'type' => 'bar'
 *                 'element' => []
 *             ],
 *      ]
 *  ]
 * with :
 *  [ 'elem1' =>
 *      [
 *             [
 *                 'type' => 'foo'
 *                 'element' => []
 *             ],
 *             [
 *                 'type' => 'bar'
 *                 'element' => [ 'custom' => 'data' ]
 *             ],
 *      ]
 *  ]
 *
 * A single substition can occur, the first match wins.
 * The full path must always be matched.
 */
class ArrayPathSetter {
    private const PATTERN = '/\G(?:(?<!^)[.]|^)(?<keypath>[^.\[\]]+)(?:\[(?<lookaheadkey>[^.\[\]]+)=(?<lookaheadvalue>[^.\[\]]+)\])?/';
    /**
     * @var mixed[]
     */
    private $replacements;

    /**
     * Lazily initializaed after calling getCompiledReplacements
     * @var array|null list of replacements compiled after appyling preg_match_all
     */
    private $compiledReplacements;

    /**
     * @param mixed[] $replacements array of replacements indexed with a string in the syntax supported
     * by this class
     */
    public function __construct( array $replacements ) {
        $this->replacements = $replacements;
    }

    /**
     * Transform the profile
     * @param array|null $profile
     * @return array|null
     */
    public function transform( array $profile = null ) {
        if ( $profile === null ) {
            return null;
        }
        foreach ( $this->getCompiledReplacements() as $replacement ) {
            $profile = $this->replace( $profile, $replacement );
        }
        return $profile;
    }

    /**
     * @param array $profile
     * @param array $replacement
     * @return array transformed profile
     */
    private function replace( array $profile, array $replacement ) {
        $cur = &$profile;
        foreach ( $replacement['matches'] as $match ) {
            if ( !is_array( $cur ) ) {
                return $profile;
            }
            $keypath = $match['keypath'][0];
            $keys = [ $keypath ];
            if ( $keypath === '*' && isset( $match['lookaheadvalue'] ) && $match['lookaheadvalue'][0] !== '' ) {
                $keys = array_keys( $cur );
            }
            $found = false;
            foreach ( $keys as $key ) {
                if ( !array_key_exists( $key, $cur ) ) {
                    continue;
                }
                $maybeNext = $cur[$key];
                if ( is_array( $maybeNext ) && isset( $match['lookaheadvalue'] )
                     && $match['lookaheadvalue'][0] !== ''
                ) {
                    $lookaheadKey = $match['lookaheadkey'][0];
                    $lookaheadValue = $match['lookaheadvalue'][0];
                    if ( isset( $maybeNext[$lookaheadKey] ) ) {
                        $lookahead = $maybeNext[$lookaheadKey];
                        // Use == instead of === so that a pattern expression such as [boost=2]
                        // can match a profile declaring [ 'boost' => 2.0 ]
                        if ( !is_array( $lookahead ) && $lookahead == $lookaheadValue ) {
                            $cur = &$cur[$key];
                            $found = true;
                            break;
                        }
                    }
                } else {
                    $cur = &$cur[$key];
                    $found = true;
                    break;
                }
            }
            if ( !$found ) {
                return $profile;
            }
        }
        $cur = $replacement['value'];
        return $profile;
    }

    /**
     * Compile the replacement strings if needed
     * @return array
     */
    private function getCompiledReplacements() {
        if ( $this->compiledReplacements === null ) {
            $this->compiledReplacements = [];
            foreach ( $this->replacements as $repl => $value ) {
                if ( !is_string( $repl ) ) {
                    throw new SearchProfileException( "Replacement pattern must be string but is a " . get_debug_type( $repl ) );
                }
                $matches = [];
                $ret = preg_match_all( self::PATTERN, $repl, $matches, PREG_SET_ORDER | PREG_OFFSET_CAPTURE );
                Assert::postcondition( $ret !== false, 'preg_match_all should not fail' );
                if ( $matches !== [] ) {
                    $lastMatch = end( $matches )[0];
                    // Make sure that we matched the whole input if not it means we perhaps matched
                    // the beginning but some components at the end
                    $valid = ( strlen( $lastMatch[0] ) + $lastMatch[1] ) === strlen( $repl );
                    reset( $matches );
                } else {
                    $valid = false;
                }
                if ( !$valid ) {
                    throw new SearchProfileException( "Invalid replacement pattern provided: [$repl]." );
                }
                $this->compiledReplacements[] = [
                    'value' => $value,
                    'matches' => $matches
                ];
            }
        }
        return $this->compiledReplacements;
    }
}