ArrayFlattener.php

<?php
declare( strict_types = 1 );
 
namespace MediaWiki\Extension\Translate\MessageProcessing;
 
use InvalidArgumentException;
use MediaWiki\Extension\Translate\Utilities\Utilities;
 
class ArrayFlattener {
    private const PLURAL_WORDS = [
        'zero' => 1,
        'one' => 1,
        'many' => 1,
        'few' => 1,
        'other' => 1,
        'two' => 1
    ];
 
    public function __construct(
        private readonly string $sep = '.',
        private readonly bool $parseCLDRPlurals = false,
    ) {
    }
 
    public function flatten( array $unflat ): array {
        $flat = [];
 
        foreach ( $unflat as $key => $value ) {
            if ( !is_array( $value ) ) {
                $flat[$key] = $value;
                continue;
            }
 
            $plurals = false;
            if ( $this->parseCLDRPlurals ) {
                $plurals = $this->flattenCLDRPlurals( $value );
            }
 
            if ( $this->parseCLDRPlurals && $plurals ) {
                $flat[$key] = $plurals;
            } else {
                $temp = [];
                foreach ( $value as $subKey => $subValue ) {
                    $newKey = "$key{$this->sep}$subKey";
                    $temp[$newKey] = $subValue;
                }
                $flat += $this->flatten( $temp );
            }
 
            // Can as well keep only one copy around.
            unset( $unflat[$key] );
        }
 
        return $flat;
    }
 
    public function flattenCLDRPlurals( array $messages ) {
        $hasNonPluralKeys = false;
        $pluralKeys = [];
        foreach ( $messages as $key => $value ) {
            if ( is_array( $value ) ) {
                // Plurals can only happen in the lowest level of the structure
                return false;
            }
 
            // Check if we find any reserved plural keyword
            if ( isset( self::PLURAL_WORDS[$key] ) ) {
                $pluralKeys[] = $key;
            } else {
                $hasNonPluralKeys = true;
            }
        }
 
        // No plural keys at all, we can skip
        if ( !$pluralKeys ) {
            return false;
        }
 
        // Mixed plural keys with other keys, should not happen
        if ( $hasNonPluralKeys ) {
            // Allow `other` with other keys, as long it is only one of the reserved ones
            if ( $pluralKeys === [ 'other' ] ) {
                return false;
            }
 
            $keys = implode( ', ', array_keys( $messages ) );
            throw new InvalidArgumentException( "Reserved plural keywords mixed with other keys: $keys." );
        }
 
        $pls = '{{PLURAL';
        foreach ( $messages as $key => $value ) {
            if ( $key === 'other' ) {
                continue;
            }
 
            $pls .= "|$key=$value";
        }
 
        // Put the "other" alternative last, without other= prefix.
        $other = isset( $messages['other'] ) ? '|' . $messages['other'] : '';
        $pls .= "$other}}";
 
        return $pls;
    }
 
    public function unflatten( array $flat ): array {
        $unflat = [];
 
        if ( $this->parseCLDRPlurals ) {
            $unflattenedPlurals = [];
            foreach ( $flat as $key => $value ) {
                $plurals = false;
                if ( !is_array( $value ) ) {
                    $plurals = $this->unflattenCLDRPlurals( $key, $value );
                }
                if ( is_array( $plurals ) ) {
                    $unflattenedPlurals += $plurals;
                } else {
                    $unflattenedPlurals[$key] = $value;
                }
            }
            $flat = $unflattenedPlurals;
        }
 
        foreach ( $flat as $key => $value ) {
            $path = explode( $this->sep, $key );
            if ( count( $path ) === 1 ) {
                $unflat[$key] = $value;
                continue;
            }
 
            $pointer = &$unflat;
            do {
                // Extract the level and make sure it exists.
                $level = array_shift( $path );
                if ( !isset( $pointer[$level] ) ) {
                    $pointer[$level] = [];
                }
 
                // Update the pointer to the new reference.
                $tmpPointer = &$pointer[$level];
                unset( $pointer );
                $pointer = &$tmpPointer;
                unset( $tmpPointer );
 
                // If next level is the last, add it into the array.
                if ( count( $path ) === 1 ) {
                    $lastKey = array_shift( $path );
                    $pointer[$lastKey] = $value;
                }
            } while ( count( $path ) );
        }
 
        return $unflat;
    }
 
    public function unflattenCLDRPlurals( string $key, string $message ) {
        // Quick escape.
        if ( !str_contains( $message, '{{PLURAL' ) ) {
            return false;
        }
 
        /*
         * Replace all variables with placeholders. Possible source of bugs
         * if other characters that given below are used.
         */
        $regex = '/\{[a-z_-]+}/i';
        $placeholders = [];
        $match = [];
 
        while ( preg_match( $regex, $message, $match ) ) {
            $uniqkey = Utilities::getPlaceholder();
            $placeholders[$uniqkey] = $match[0];
            $search = preg_quote( $match[0], '~' );
            $message = preg_replace( "~$search~", $uniqkey, $message );
        }
 
        // Then replace (possible multiple) plural instances into placeholders.
        $regex = '~\{\{PLURAL\|(.*?)}}~s';
        $matches = [];
        $match = [];
 
        while ( preg_match( $regex, $message, $match ) ) {
            $uniqkey = Utilities::getPlaceholder();
            $matches[$uniqkey] = $match;
            $message = preg_replace( $regex, $uniqkey, $message, 1 );
        }
 
        // No plurals, should not happen.
        if ( !count( $matches ) ) {
            return false;
        }
 
        // The final array of alternative plurals forms.
        $alts = [];
 
        /*
         * Then loop trough each plural block and replacing the placeholders
         * to construct the alternatives. Produces invalid output if there is
         * multiple plural bocks which don't have the same set of keys.
         */
        $pluralChoice = implode( '|', array_keys( self::PLURAL_WORDS ) );
        $regex = "~($pluralChoice)\s*=\s*(.*)~s";
        foreach ( $matches as $ph => $plu ) {
            $forms = explode( '|', $plu[1] );
 
            foreach ( $forms as $form ) {
                $match = [];
                if ( preg_match( $regex, $form, $match ) ) {
                    $formWord = "$key{$this->sep}{$match[1]}";
                    $value = $match[2];
                } else {
                    $formWord = "$key{$this->sep}other";
                    $value = $form;
                }
 
                if ( !isset( $alts[$formWord] ) ) {
                    $alts[$formWord] = $message;
                }
 
                $string = $alts[$formWord];
                $alts[$formWord] = str_replace( $ph, $value, $string );
            }
        }
 
        // Replace other variables.
        foreach ( $alts as &$value ) {
            $value = str_replace( array_keys( $placeholders ), array_values( $placeholders ), $value );
        }
 
        if ( !isset( $alts["$key{$this->sep}other"] ) ) {
            // Ensure other form is always present, even if missing from the translation
            $alts["$key{$this->sep}other"] = end( $alts );
        }
 
        return $alts;
    }
 
    public function compareContent( ?string $a, ?string $b ): bool {
        if ( !$this->parseCLDRPlurals || $a === null || $b === null ) {
            return $a === $b;
        }
 
        $a2 = $this->unflattenCLDRPlurals( 'prefix', $a );
        $b2 = $this->unflattenCLDRPlurals( 'prefix', $b );
 
        // Fall back to regular comparison if parsing fails.
        if ( $a2 === false || $b2 === false ) {
            return $a === $b;
        }
 
        // Require key-value pairs to match, but ignore order and types (all should be strings).
        return $a2 == $b2;
    }
}