<?php
/**
 * This file is part of the POMO package.
 *
 * @copyright 2014 POMO
 * @license GPL
 */

namespace POMO;

use POMO\Streams\FileReader;
use POMO\Streams\NOOPReader;
use POMO\Translations\EntryTranslations;
use POMO\Translations\GettextTranslations;

/**
 * Class for working with MO files.
 */
class MO extends GettextTranslations
{
    public $_nplurals = 2;

    /**
     * Loaded MO file.
     *
     * @var string
     */
    private $filename = '';

    /**
     * Returns the loaded MO file.
     *
     * @return string The loaded MO file.
     */
    public function get_filename()
    {
        return $this->filename;
    }

    /**
     * Fills up with the entries from MO file $filename.
     *
     * @param string $filename MO file to load
     *
     * @return bool Success
     */
    public function import_from_file($filename)
    {
        $reader = new FileReader($filename);
        if (!$reader->is_resource()) {
            return false;
        }

        $this->filename = (string) $filename;

        return $this->import_from_reader($reader);
    }

    /**
     * @param string $filename
     *
     * @return bool
     */
    public function export_to_file($filename)
    {
        $fh = fopen($filename, 'wb');
        if (!$fh) {
            return false;
        }
        $res = $this->export_to_file_handle($fh);
        fclose($fh);

        return $res;
    }

    /**
     * @return string|false
     */
    public function export()
    {
        $tmp_fh = fopen('php://temp', 'r+');
        if (!$tmp_fh) {
            return false;
        }
        $this->export_to_file_handle($tmp_fh);
        rewind($tmp_fh);

        return stream_get_contents($tmp_fh);
    }

    /**
     * @param EntryTranslations $entry
     *
     * @return bool
     */
    public function is_entry_good_for_export(EntryTranslations $entry)
    {
        if (empty($entry->translations)) {
            return false;
        }

        if (!array_filter($entry->translations)) {
            return false;
        }

        return true;
    }

    /**
     * @param resource $fh
     *
     * @return true
     */
    public function export_to_file_handle($fh)
    {
        $entries = array_filter(
            $this->entries,
            array($this, 'is_entry_good_for_export')
        );
        ksort($entries);
        $magic = 0x950412de;
        $revision = 0;
        $total = count($entries) + 1; // all the headers are one entry
        $originals_lenghts_addr = 28;
        $translations_lenghts_addr = $originals_lenghts_addr + 8 * $total;
        $size_of_hash = 0;
        $hash_addr = $translations_lenghts_addr + 8 * $total;
        $current_addr = $hash_addr;
        fwrite($fh, pack(
            'V*',
            $magic,
            $revision,
            $total,
            $originals_lenghts_addr,
            $translations_lenghts_addr,
            $size_of_hash,
            $hash_addr
        ));
        fseek($fh, $originals_lenghts_addr);

        // headers' msgid is an empty string
        fwrite($fh, pack('VV', 0, $current_addr));
        $current_addr++;
        $originals_table = chr(0);

        $reader = new NOOPReader();

        foreach ($entries as $entry) {
            $originals_table .= $this->export_original($entry).chr(0);
            $length = $reader->strlen($this->export_original($entry));
            fwrite($fh, pack('VV', $length, $current_addr));
            $current_addr += $length + 1; // account for the NULL byte after
        }

        $exported_headers = $this->export_headers();
        fwrite($fh, pack(
            'VV',
            $reader->strlen($exported_headers),
            $current_addr
        ));
        $current_addr += strlen($exported_headers) + 1;
        $translations_table = $exported_headers.chr(0);

        foreach ($entries as $entry) {
            $translations_table .= $this->export_translations($entry).chr(0);
            $length = $reader->strlen($this->export_translations($entry));
            fwrite($fh, pack('VV', $length, $current_addr));
            $current_addr += $length + 1;
        }

        fwrite($fh, $originals_table);
        fwrite($fh, $translations_table);

        return true;
    }

    /**
     * @param EntryTranslations $entry
     *
     * @return string
     */
    public function export_original(EntryTranslations $entry)
    {
        //TODO: warnings for control characters
        $exported = $entry->singular;
        if ($entry->is_plural) {
            $exported .= chr(0).$entry->plural;
        }
        if (!is_null($entry->context)) {
            $exported = $entry->context.chr(4).$exported;
        }

        return $exported;
    }

    /**
     * @param EntryTranslations $entry
     *
     * @return string
     */
    public function export_translations(EntryTranslations $entry)
    {
        //TODO: warnings for control characters
        return $entry->is_plural ? implode(chr(0), $entry->translations) : $entry->translations[0];
    }

    /**
     * @return string
     */
    public function export_headers()
    {
        $exported = '';
        foreach ($this->headers as $header => $value) {
            $exported .= "$header: $value\n";
        }

        return $exported;
    }

    /**
     * @param int $magic
     *
     * @return string|false
     */
    public function get_byteorder($magic)
    {
        // The magic is 0x950412de
        $magic_little = (int) -1794895138;
        $magic_little_64 = (int) 2500072158;
        // 0xde120495
        $magic_big = ((int) -569244523) & 0xFFFFFFFF;
        if ($magic_little == $magic || $magic_little_64 == $magic) {
            return 'little';
        } elseif ($magic_big == $magic) {
            return 'big';
        } else {
            return false;
        }
    }

    /**
     * @param FileReader $reader
     *
     * @return bool
     */
    public function import_from_reader(FileReader $reader)
    {
        $endian_string = $this->get_byteorder($reader->readint32());
        if (false === $endian_string) {
            return false;
        }
        $reader->setEndian($endian_string);

        $endian = ('big' == $endian_string) ? 'N' : 'V';

        $header = $reader->read(24);
        if ($reader->strlen($header) != 24) {
            return false;
        }

        // parse header
        $header = unpack("{$endian}revision/{$endian}total/{$endian}originals_lenghts_addr/{$endian}translations_lenghts_addr/{$endian}hash_length/{$endian}hash_addr", $header);
        if (!is_array($header)) {
            return false;
        }

        // support revision 0 of MO format specs, only
        if ($header['revision'] != 0) {
            return false;
        }

        // seek to data blocks
        $reader->seekto($header['originals_lenghts_addr']);

        // read originals' indices
        $originals_lengths_length = $header['translations_lenghts_addr'] - $header['originals_lenghts_addr'];
        if ($originals_lengths_length != $header['total'] * 8) {
            return false;
        }

        $originals = $reader->read($originals_lengths_length);
        if ($reader->strlen($originals) != $originals_lengths_length) {
            return false;
        }

        // read translations' indices
        $translations_lenghts_length = $header['hash_addr'] - $header['translations_lenghts_addr'];
        if ($translations_lenghts_length != $header['total'] * 8) {
            return false;
        }

        $translations = $reader->read($translations_lenghts_length);
        if ($reader->strlen($translations) != $translations_lenghts_length) {
            return false;
        }

        // transform raw data into set of indices
        $originals = $reader->str_split($originals, 8);
        $translations = $reader->str_split($translations, 8);

        // skip hash table
        $strings_addr = $header['hash_addr'] + $header['hash_length'] * 4;

        $reader->seekto($strings_addr);

        $strings = $reader->read_all();
        $reader->close();

        for ($i = 0; $i < $header['total']; $i++) {
            $o = unpack("{$endian}length/{$endian}pos", $originals[$i]);
            $t = unpack("{$endian}length/{$endian}pos", $translations[$i]);
            if (!$o || !$t) {
                return false;
            }

            // adjust offset due to reading strings to separate space before
            $o['pos'] -= $strings_addr;
            $t['pos'] -= $strings_addr;

            $original = $reader->substr($strings, $o['pos'], $o['length']);
            $translation = $reader->substr($strings, $t['pos'], $t['length']);

            if ('' === $original) {
                $this->set_headers($this->make_headers($translation));
            } else {
                $entry = &static::make_entry($original, $translation);
                $this->entries[$entry->key()] = &$entry;
            }
        }

        return true;
    }

    /**
     * Build a  from original string and translation strings,
     * found in a MO file.
     *
     * @param string $original    original string to translate from MO file.
     *                            Might contain 0x04 as context separator or
     *                            0x00 as singular/plural separator
     * @param string $translation translation string from MO file.Might contain
     *                            0x00 as a plural translations separator
     *
     * @return EntryTranslations New entry
     */
    public static function &make_entry($original, $translation)
    {
        $entry = new EntryTranslations();
        // look for context
        $parts = explode(chr(4), $original);
        if (isset($parts[1])) {
            $original = $parts[1];
            $entry->context = $parts[0];
        }
        // look for plural original
        $parts = explode(chr(0), $original);
        $entry->singular = $parts[0];
        if (isset($parts[1])) {
            $entry->is_plural = true;
            $entry->plural = $parts[1];
        }
        // plural translations are also separated by \0
        $entry->translations = explode(chr(0), $translation);

        return $entry;
    }

    /**
     * @param int $count
     *
     * @return string
     */
    public function select_plural_form($count)
    {
        return $this->gettext_select_plural_form($count);
    }

    /**
     * @return int
     */
    public function get_plural_forms_count()
    {
        return $this->_nplurals;
    }
}