<?php
/**
 * I18N: WP_Translation_File_MO class.
 *
 * @package WordPress
 * @subpackage I18N
 * @since 6.5.0
 */

/**
 * Class WP_Translation_File_MO.
 *
 * @since 6.5.0
 */
class WP_Translation_File_MO extends WP_Translation_File {
    /**
     * Endian value.
     *
     * V for little endian, N for big endian, or false.
     *
     * Used for unpack().
     *
     * @since 6.5.0
     * @var false|'V'|'N'
     */
    protected $uint32 = false;

    /**
     * The magic number of the GNU message catalog format.
     *
     * @since 6.5.0
     * @var int
     */
    const MAGIC_MARKER = 0x950412de;

    /**
     * Detects endian and validates file.
     *
     * @since 6.5.0
     *
     * @param string $header File contents.
     * @return false|'V'|'N' V for little endian, N for big endian, or false on failure.
     */
    protected function detect_endian_and_validate_file( string $header ) {
        $big = unpack( 'N', $header );

        if ( false === $big ) {
            return false;
        }

        $big = reset( $big );

        if ( false === $big ) {
            return false;
        }

        $little = unpack( 'V', $header );

        if ( false === $little ) {
            return false;
        }

        $little = reset( $little );

        if ( false === $little ) {
            return false;
        }

        // Force cast to an integer as it can be a float on x86 systems. See https://core.trac.wordpress.org/ticket/60678.
        if ( (int) self::MAGIC_MARKER === $big ) {
            return 'N';
        }

        // Force cast to an integer as it can be a float on x86 systems. See https://core.trac.wordpress.org/ticket/60678.
        if ( (int) self::MAGIC_MARKER === $little ) {
            return 'V';
        }

        $this->error = 'Magic marker does not exist';
        return false;
    }

    /**
     * Parses the file.
     *
     * @since 6.5.0
     *
     * @return bool True on success, false otherwise.
     */
    protected function parse_file(): bool {
        $this->parsed = true;

        $file_contents = file_get_contents( $this->file );

        if ( false === $file_contents ) {
            return false;
        }

        $file_length = strlen( $file_contents );

        if ( $file_length < 24 ) {
            $this->error = 'Invalid data';
            return false;
        }

        $this->uint32 = $this->detect_endian_and_validate_file( substr( $file_contents, 0, 4 ) );

        if ( false === $this->uint32 ) {
            return false;
        }

        $offsets = substr( $file_contents, 4, 24 );

        if ( false === $offsets ) {
            return false;
        }

        $offsets = unpack( "{$this->uint32}rev/{$this->uint32}total/{$this->uint32}originals_addr/{$this->uint32}translations_addr/{$this->uint32}hash_length/{$this->uint32}hash_addr", $offsets );

        if ( false === $offsets ) {
            return false;
        }

        $offsets['originals_length']    = $offsets['translations_addr'] - $offsets['originals_addr'];
        $offsets['translations_length'] = $offsets['hash_addr'] - $offsets['translations_addr'];

        if ( $offsets['rev'] > 0 ) {
            $this->error = 'Unsupported revision';
            return false;
        }

        if ( $offsets['translations_addr'] > $file_length || $offsets['originals_addr'] > $file_length ) {
            $this->error = 'Invalid data';
            return false;
        }

        // Load the Originals.
        $original_data     = str_split( substr( $file_contents, $offsets['originals_addr'], $offsets['originals_length'] ), 8 );
        $translations_data = str_split( substr( $file_contents, $offsets['translations_addr'], $offsets['translations_length'] ), 8 );

        foreach ( array_keys( $original_data ) as $i ) {
            $o = unpack( "{$this->uint32}length/{$this->uint32}pos", $original_data[ $i ] );
            $t = unpack( "{$this->uint32}length/{$this->uint32}pos", $translations_data[ $i ] );

            if ( false === $o || false === $t ) {
                continue;
            }

            $original    = substr( $file_contents, $o['pos'], $o['length'] );
            $translation = substr( $file_contents, $t['pos'], $t['length'] );
            // GlotPress bug.
            $translation = rtrim( $translation, "\0" );

            // Metadata about the MO file is stored in the first translation entry.
            if ( '' === $original ) {
                foreach ( explode( "\n", $translation ) as $meta_line ) {
                    if ( '' === $meta_line || ! str_contains( $meta_line, ':' ) ) {
                        continue;
                    }

                    list( $name, $value ) = array_map( 'trim', explode( ':', $meta_line, 2 ) );

                    $this->headers[ strtolower( $name ) ] = $value;
                }
            } else {
                /*
                 * In MO files, the key normally contains both singular and plural versions.
                 * However, this just adds the singular string for lookup,
                 * which caters for cases where both __( 'Product' ) and _n( 'Product', 'Products' )
                 * are used and the translation is expected to be the same for both.
                 */
                $parts = explode( "\0", (string) $original );

                $this->entries[ $parts[0] ] = $translation;
            }
        }

        return true;
    }

    /**
     * Exports translation contents as a string.
     *
     * @since 6.5.0
     *
     * @return string Translation file contents.
     */
    public function export(): string {
        // Prefix the headers as the first key.
        $headers_string = '';
        foreach ( $this->headers as $header => $value ) {
            $headers_string .= "{$header}: $value\n";
        }
        $entries     = array_merge( array( '' => $headers_string ), $this->entries );
        $entry_count = count( $entries );

        if ( false === $this->uint32 ) {
            $this->uint32 = 'V';
        }

        $bytes_for_entries = $entry_count * 4 * 2;
        // Pair of 32bit ints per entry.
        $originals_addr    = 28; /* header */
        $translations_addr = $originals_addr + $bytes_for_entries;
        $hash_addr         = $translations_addr + $bytes_for_entries;
        $entry_offsets     = $hash_addr;

        $file_header = pack(
            $this->uint32 . '*',
            // Force cast to an integer as it can be a float on x86 systems. See https://core.trac.wordpress.org/ticket/60678.
            (int) self::MAGIC_MARKER,
            0, /* rev */
            $entry_count,
            $originals_addr,
            $translations_addr,
            0, /* hash_length */
            $hash_addr
        );

        $o_entries = '';
        $t_entries = '';
        $o_addr    = '';
        $t_addr    = '';

        foreach ( array_keys( $entries ) as $original ) {
            $o_addr        .= pack( $this->uint32 . '*', strlen( $original ), $entry_offsets );
            $entry_offsets += strlen( $original ) + 1;
            $o_entries     .= $original . "\0";
        }

        foreach ( $entries as $translations ) {
            $t_addr        .= pack( $this->uint32 . '*', strlen( $translations ), $entry_offsets );
            $entry_offsets += strlen( $translations ) + 1;
            $t_entries     .= $translations . "\0";
        }

        return $file_header . $o_addr . $t_addr . $o_entries . $t_entries;
    }
}