Behave properly on non-tar-gz files

cms/templates/import.html

@@ -60,7 +60,6 @@ var submitBtn = $('.submit-button');
 
 $('#fileupload').fileupload({
 
-
     dataType: 'json',
     type: 'POST',
 
@@ -68,18 +67,35 @@ $('#fileupload').fileupload({
 
     autoUpload: false,
 
+    options: {
+        acceptFileTypes: /(\.|\/)tar\.gz$/i ,
+        processQueue: [{
+            action: 'validate',
+            acceptFileTypes: '@'
+        }]
+    },
+
     add: function(e, data) {
-        submitBtn.show().click(function(e){ 
-            e.preventDefault();
-            data.submit().complete(function(result, textStatus, xhr) {
-                if (result.status != 200) {
-                    alert('${_("Your import has failed.")}\n\n' + 
-                        JSON.parse(result.responseText)["ErrMsg"]);
-                    submitBtn.show();
-                    bar.hide();
-                }
+        var file = data.files[0];
+        if (file.type == "application/x-gzip") {
+            submitBtn.click(function(e){
+                e.preventDefault();
+                data.submit().complete(function(result, textStatus, xhr) {
+                    if (result.status != 200) {
+                        alert('${_("Your import has failed.")}\n\n' +
+                            JSON.parse(result.responseText)["ErrMsg"]);
+                        submitBtn.show();
+                        bar.hide();
+                    } else {
+                        bar.hide()
+                        alert('${_("Your import was successful.")}');
+                        window.location = '${successful_import_redirect_url}';
+                    }
+                });
             });
-        });
+        } else {
+            data.files = [];
+        }
     },
 
     progressall: function(e, data){
@@ -93,6 +109,20 @@ $('#fileupload').fileupload({
         alert('${_("Your import was successful.")}');
         window.location = '${successful_import_redirect_url}';
     },
+    processActions: {
+        validate: function(data, options) {
+            var dfdata = $.Deferred(),
+                file = data.files[data.index];
+            if (!options.acceptFileTypes.test(file.type)) {
+                file.error = 'Invalid file type: must be a tar.gz file!';
+                dfdata.rejectWith(this, [data]);
+            } else {
+                dfdata.resolveWith(this, [data]);
+            }
+            return dfdata.promise();
+        }
+    }
+
 
 
 });