From 31f5e27f60f3d9e5fcb3b6b9ab01b9d64a244b87 Mon Sep 17 00:00:00 2001
From: Steve Clay <steve@mrclay.org>
Date: Sun, 31 Mar 2013 18:18:33 -0400
Subject: Fixes #3754: Language JS views send cache headers and support
 conditional get

---
 js/lib/languages.js            |  3 +++
 views/default/js/languages.php | 24 +++++++++++++++++++++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/js/lib/languages.js b/js/lib/languages.js
index 44ea56d2b..d218cbc4f 100644
--- a/js/lib/languages.js
+++ b/js/lib/languages.js
@@ -30,6 +30,9 @@ elgg.reload_all_translations = function(language) {
 	var url, options;
 	url = 'ajax/view/js/languages';
 	options = {data: {language: lang}};
+    if (elgg.config.simplecache_enabled) {
+        options.data.lc = elgg.config.lastcache;
+    }
 
 	options['success'] = function(json) {
 		elgg.add_translation(lang, json);
diff --git a/views/default/js/languages.php b/views/default/js/languages.php
index c51d7bcb2..fcf903d4b 100644
--- a/views/default/js/languages.php
+++ b/views/default/js/languages.php
@@ -1,15 +1,33 @@
 <?php
 /**
  * @uses $vars['language']
+ * @uses $vars['lc'] if present, client will be sent long expires headers
  */
-global $CONFIG;
 
 $language = $vars['language'];
+$lastcache = elgg_extract('lc', $vars, 0);
 
-$translations = $CONFIG->translations['en'];
+// @todo add server-side caching
+if ($lastcache) {
+	// we're relying on lastcache changes to predict language changes
+	$etag = '"' . md5("$language|$lastcache") .  '"';
+
+	header('Expires: ' . gmdate('D, d M Y H:i:s \G\M\T', strtotime("+6 months")), true);
+	header("Pragma: public", true);
+	header("Cache-Control: public", true);
+	header("ETag: $etag");
+
+	if (isset($_SERVER['HTTP_IF_NONE_MATCH']) && trim($_SERVER['HTTP_IF_NONE_MATCH']) === $etag) {
+		header("HTTP/1.1 304 Not Modified");
+		exit;
+	}
+}
+
+$all_translations = elgg_get_config('translations');
+$translations = $all_translations['en'];
 
 if ($language != 'en') {
-	$translations = array_merge($translations, $CONFIG->translations[$language]);
+	$translations = array_merge($translations, $all_translations[$language]);
 }
 
 echo json_encode($translations);
\ No newline at end of file
-- 
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