<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\i18n;

use Yii;

/**
 * GettextPoFile represents a PO Gettext message file.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class GettextPoFile extends GettextFile
{
	/**
	 * Loads messages from a PO file.
	 * @param string $filePath file path
	 * @param string $context message context
	 * @return array message translations. Array keys are source messages and array values are translated messages:
	 * source message => translated message.
	 */
	public function load($filePath, $context)
	{
		$pattern = '/(msgctxt\s+"(.*?(?<!\\\\))")?\s+' // context
			. 'msgid\s+((?:".*(?<!\\\\)"\s*)+)\s+' // message ID, i.e. original string
			. 'msgstr\s+((?:".*(?<!\\\\)"\s*)+)/'; // translated string
		$content = file_get_contents($filePath);
		$matches = [];
		$matchCount = preg_match_all($pattern, $content, $matches);

		$messages = [];
		for ($i = 0; $i < $matchCount; ++$i) {
			if ($matches[2][$i] == $context) {
				$id = $this->decode($matches[3][$i]);
				$message = $this->decode($matches[4][$i]);
				$messages[$id] = $message;
			}
		}
		return $messages;
	}

	/**
	 * Saves messages to a PO file.
	 * @param string $filePath file path
	 * @param array $messages message translations. Array keys are source messages and array values are
	 * translated messages: source message => translated message. Note if the message has a context,
	 * the message ID must be prefixed with the context with chr(4) as the separator.
	 */
	public function save($filePath, $messages)
	{
		$content = '';
		foreach ($messages as $id => $message) {
			$separatorPosition = strpos($id, chr(4));
			if ($separatorPosition !== false) {
				$content .= 'msgctxt "' . substr($id, 0, $separatorPosition) . "\"\n";
				$id = substr($id, $separatorPosition + 1);
			}
			$content .= 'msgid "' . $this->encode($id) . "\"\n";
			$content .= 'msgstr "' . $this->encode($message) . "\"\n\n";
		}
		file_put_contents($filePath, $content);
	}

	/**
	 * Encodes special characters in a message.
	 * @param string $string message to be encoded
	 * @return string the encoded message
	 */
	protected function encode($string)
	{
		return str_replace(
			['"', "\n", "\t", "\r"],
			['\\"', '\\n', '\\t', '\\r'],
			$string
		);
	}

	/**
	 * Decodes special characters in a message.
	 * @param string $string message to be decoded
	 * @return string the decoded message
	 */
	protected function decode($string)
	{
		$string = preg_replace(
			['/"\s+"/', '/\\\\n/', '/\\\\r/', '/\\\\t/', '/\\\\"/'],
			['', "\n", "\r", "\t", '"'],
			$string
		);
		return substr(rtrim($string), 1, -1);
	}
}