SYWEB-12: More formatting and tweaking of state event JSON.

Use a proper elastic directive to make the <textarea> resize dynamically.
Use an 'asjson' directive to turn an ngModel of a JSON object into a
formatted JSON string so it can be displayed on the textarea. Also, deep
copy the state events being displayed, else it actually alters the underlying
data structures when playing around with the JSON in the textarea!

webclient/app-directive.js

@@ -41,18 +41,44 @@ angular.module('matrixWebClient')
         }
     };
 }])
-.directive('elastic', [ // http://stackoverflow.com/questions/17772260/textarea-auto-height
-    '$timeout',
-    function($timeout) {
-      return {
+.directive('asjson', function() {
+    return {
         restrict: 'A',
-        link: function($scope, element) {
-          var resize = function() {
-            return element[0].style.height = "" + element[0].scrollHeight + "px";
-          };
-          element.on("blur keyup change", resize);
-          $timeout(resize, 10);
+        require: 'ngModel',
+        link: function (scope, element, attrs, ngModelCtrl) {
+            function isValidJson(model) {
+                var flag = true;
+                try {
+                    angular.fromJson(model);
+                } catch (err) {
+                    flag = false;
+                }
+                return flag;
+            };
+
+            function string2JSON(text) {
+                try {
+                    var j = angular.fromJson(text);
+                    ngModelCtrl.$setValidity('json', true);
+                    return j;
+                } catch (err) {
+                    //returning undefined results in a parser error as of angular-1.3-rc.0, and will not go through $validators
+                    //return undefined
+                    ngModelCtrl.$setValidity('json', false);
+                    return text;
+                }
+            };
+
+            function JSON2String(object) {
+                return angular.toJson(object, true);
+            };
+
+            //$validators is an object, where key is the error
+            //ngModelCtrl.$validators.json = isValidJson;
+
+            //array pipelines
+            ngModelCtrl.$parsers.push(string2JSON);
+            ngModelCtrl.$formatters.push(JSON2String);
         }
-      };
     }
-]);;
+});