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

namespace yii\i18n;

use Yii;

/**
 * PhpMessageSource represents a message source that stores translated messages in PHP scripts.
 *
 * PhpMessageSource uses PHP arrays to keep message translations.
 *
 * - Each PHP script contains one array which stores the message translations in one particular
 *   language and for a single message category;
 * - Each PHP script is saved as a file named as `[[basePath]]/LanguageID/CategoryName.php`;
 * - Within each PHP script, the message translations are returned as an array like the following:
 *
 * ~~~
 * return [
 *     'original message 1' => 'translated message 1',
 *     'original message 2' => 'translated message 2',
 * ];
 * ~~~
 *
 * You may use [[fileMap]] to customize the association between category names and the file names.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class PhpMessageSource extends MessageSource
{
	/**
	 * @var string the base path for all translated messages. Defaults to null, meaning
	 * the "messages" subdirectory of the application directory (e.g. "protected/messages").
	 */
	public $basePath = '@app/messages';
	/**
	 * @var array mapping between message categories and the corresponding message file paths.
	 * The file paths are relative to [[basePath]]. For example,
	 *
	 * ~~~
	 * [
	 *     'core' => 'core.php',
	 *     'ext' => 'extensions.php',
	 * ]
	 * ~~~
	 */
	public $fileMap;

	/**
	 * Loads the message translation for the specified language and category.
	 * If translation for specific locale code such as `en-US` isn't found it
	 * tries more generic `en`.
	 *
	 * @param string $category the message category
	 * @param string $language the target language
	 * @return array the loaded messages. The keys are original messages, and the values
	 * are translated messages.
	 */
	protected function loadMessages($category, $language)
	{
		$messageFile = $this->getMessageFilePath($category, $language);
		$messages = $this->loadMessagesFromFile($messageFile);

		$fallbackLanguage = substr($language, 0, 2);
		if ($fallbackLanguage != $language) {
			$fallbackMessageFile = $this->getMessageFilePath($category, $fallbackLanguage);
			$fallbackMessages = $this->loadMessagesFromFile($fallbackMessageFile);

			if ($messages === null && $fallbackMessages === null && $fallbackLanguage != $this->sourceLanguage) {
				Yii::error("The message file for category '$category' does not exist: $messageFile Fallback file does not exist as well: $fallbackMessageFile", __METHOD__);
			} elseif (empty($messages)) {
				return $fallbackMessages;
			} elseif (!empty($fallbackMessages)) {
				foreach ($fallbackMessages as $key => $value) {
					if (!empty($value) && empty($messages[$key])) {
						$messages[$key] = $fallbackMessages[$key];
					}
				}
			}
		} else {
			if ($messages === null) {
				Yii::error("The message file for category '$category' does not exist: $messageFile", __METHOD__);
			}
		}
		return (array)$messages;
	}

	/**
	 * Returns message file path for the specified language and category.
	 *
	 * @param string $category the message category
	 * @param string $language the target language
	 * @return string path to message file
	 */
	protected function getMessageFilePath($category, $language)
	{
		$messageFile = Yii::getAlias($this->basePath) . "/$language/";
		if (isset($this->fileMap[$category])) {
			$messageFile .= $this->fileMap[$category];
		} else {
			$messageFile .= str_replace('\\', '/', $category) . '.php';
		}
		return $messageFile;
	}

	/**
	 * Loads the message translation for the specified language and category or returns null if file doesn't exist.
	 *
	 * @param $messageFile string path to message file
	 * @return array|null array of messages or null if file not found
	 */
	protected function loadMessagesFromFile($messageFile)
	{
		if (is_file($messageFile)) {
			$messages = include($messageFile);
			if (!is_array($messages)) {
				$messages = [];
			}
			return $messages;
		} else {
			return null;
		}
	}
}
