Use similar language as a fallback for plugin localization (#1488401)

Don't load en_US localization more than once

Conflicts:

	CHANGELOG
	program/include/rcube.php

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Use similar language as a fallback for plugin localization (#1488401)
 - Fix issue where signature wasn't re-added on draft compose (#1488322)
 - Update to TinyMCE 3.5 (#1488459)
 - Fixed multi-threaded autocompletion when number of threads > number of sources

program/include/rcmail.php

@@ -1167,7 +1167,7 @@ class rcmail
         $this->texts = array_merge($this->texts, $messages);
 
       // include user language files
-      if ($lang != 'en' && is_dir(INSTALL_PATH . 'program/localization/' . $lang)) {
+      if ($lang != 'en' && $lang != 'en_US' && is_dir(INSTALL_PATH . 'program/localization/' . $lang)) {
         include_once(INSTALL_PATH . 'program/localization/' . $lang . '/labels.inc');
         include_once(INSTALL_PATH . 'program/localization/' . $lang . '/messages.inc');
 

program/include/rcube_plugin.php

@@ -152,20 +152,48 @@ abstract class rcube_plugin
   public function add_texts($dir, $add2client = false)
   {
     $domain = $this->ID;
-
-    $lang = $_SESSION['language'];
+    $lang   = $_SESSION['language'];
+    $langs  = array_unique(array('en_US', $lang));
     $locdir = slashify(realpath(slashify($this->home) . $dir));
-    $texts = array();
+    $texts  = array();
+
+    // Language aliases used to find localization in similar lang, see below
+    $aliases = array(
+        'de_CH' => 'de_DE',
+        'es_AR' => 'es_ES',
+        'fa_AF' => 'fa_IR',
+        'nl_BE' => 'nl_NL',
+        'pt_BR' => 'pt_PT',
+        'zh_CN' => 'zh_TW',
+    );
 
     // use buffering to handle empty lines/spaces after closing PHP tag
     ob_start();
 
-    foreach (array('en_US', $lang) as $lng) {
+    foreach ($langs as $lng) {
       $fpath = $locdir . $lng . '.inc';
       if (is_file($fpath) && is_readable($fpath)) {
-        include($fpath);
+        include $fpath;
         $texts = (array)$labels + (array)$messages + (array)$texts;
       }
+      else if ($lng != 'en_US') {
+        // Find localization in similar language (#1488401)
+        $alias = null;
+        if (!empty($aliases[$lng])) {
+          $alias = $aliases[$lng];
+        }
+        else if ($key = array_search($lng, $aliases)) {
+          $alias = $key;
+        }
+
+        if (!empty($alias)) {
+          $fpath = $locdir . $alias . '.inc';
+          if (is_file($fpath) && is_readable($fpath)) {
+            include $fpath;
+            $texts = (array)$labels + (array)$messages + (array)$texts;
+          }
+        }
+      }
     }
 
     ob_end_clean();