Json message loader clean up

* Rename JsonMessageLoader to ULSJsonMessageLoader
* Correct the return type of mw.uls.loadLocalization

Follow up: Ic39dec1c484982fb07edd167e83794c0b5f470ee

Change-Id: I13c64a5e89ac75be8a95d951658018a78534f466

includes/ULSJsonMessageLoader.php

@@ -0,0 +1,79 @@
+<?php
+/**
+ * Json formatted MessageLoader for ULS
+ *
+ * Copyright (C) 2013 Alolita Sharma, Amir Aharoni, Arun Ganesh, Brandon Harris,
+ * Niklas Laxström, Pau Giner, Santhosh Thottingal, Siebrand Mazeland and other
+ * contributors. See CREDITS for a list.
+ *
+ * UniversalLanguageSelector is dual licensed GPLv2 or later and MIT. You don't
+ * have to do anything special to choose one license or the other and you don't
+ * have to notify anyone which license you are using. You are free to use
+ * UniversalLanguageSelector in commercial projects as long as the copyright
+ * header is left intact. See files GPL-LICENSE and MIT-LICENSE for details.
+ *
+ * @file
+ * @ingroup Extensions
+ * @licence GNU General Public Licence 2.0 or later
+ * @licence MIT License
+ * @since 2013.11
+ */
+
+class ULSJsonMessageLoader {
+	/**
+	 * Returns all message files that are used to load messages for the given
+	 * language.
+	 * @param string $language Language code.
+	 * @return string[]
+	 */
+	public static function getFilenames( $language ) {
+		$filenames = array();
+
+		$languages = Language::getFallbacksFor( $language );
+		// Prepend the requested language code
+		// to load them all in one loop
+		array_unshift( $languages, $language );
+
+		// jQuery.uls localization
+		foreach ( $languages as $language ) {
+			$filenames[] = __DIR__ . "/../lib/jquery.uls/i18n/$language.json";
+		}
+
+		// mediaWiki.uls localization
+		foreach ( $languages as $language ) {
+			$filenames[] = __DIR__ . "/../i18n/$language.json";
+		}
+
+		$filenames = array_filter( $filenames, function( $filename ) {
+			return file_exists( $filename );
+		} );
+
+		return $filenames;
+	}
+
+	/**
+	 * Get messages for the given language.
+	 * @param string $language Language code.
+	 * @return array
+	 */
+	public static function getMessages( $language ) {
+		$contents = array();
+
+		foreach ( self::getFilenames( $language ) as $filename ) {
+			$contents += self::loadI18nFile( $filename );
+		}
+
+		return $contents;
+	}
+
+	/**
+	 * Load messages from a json file.
+	 * @param string $filename Directory of the json file.
+	 * @return array
+	 */
+	protected static function loadI18nFile( $filename ) {
+		$contents = file_get_contents( $filename );
+
+		return json_decode( $contents, true );
+	}
+}