Implement infinite scrolling

I't not perfect but it's a start.

index.html

@@ -36,6 +36,7 @@
     <script type="text/javascript" src="js/connection.js"></script>
     <script type="text/javascript" src="js/file-change.js"></script>
     <script type="text/javascript" src="js/imgur-drop-directive.js"></script>
+    <script type="text/javascript" src="js/whenscrolled-directive.js"></script>
     <script type="text/javascript" src="js/inputbar.js"></script>
     <script type="text/javascript" src="js/plugin-directive.js"></script>
     <script type="text/javascript" src="js/websockets.js"></script>
@@ -264,7 +265,7 @@ $ openssl req -nodes -newkey rsa:4096 -keyout relay.pem -x509 -days 365 -out rel
           </li>
         </ul>
       </div>
-      <div id="bufferlines" class="favorite-font" ng-swipe-right="showSidebar()" ng-swipe-left="hideSidebar()" ng-class="{'withnicklist': showNicklist}" imgur-drop>
+      <div id="bufferlines" class="favorite-font" ng-swipe-right="showSidebar()" ng-swipe-left="hideSidebar()" ng-class="{'withnicklist': showNicklist}" when-scrolled="infiniteScroll()" imgur-drop>
         <div id="nicklist" ng-if="showNicklist" ng-swipe-right="closeNick()" class="vertical-line-left">
           <ul class="nicklistgroup list-unstyled" ng-repeat="group in nicklist">
             <li ng-repeat="nick in group.nicks|orderBy:'name'">

js/glowingbear.js

@@ -539,6 +539,17 @@ weechat.controller('WeechatCtrl', ['$rootScope', '$scope', '$store', '$timeout',
         return connection.fetchMoreLines(numLines);
     };
 
+    $scope.infiniteScroll = function() {
+        // Check if we are already fetching
+        if ($rootScope.loadingLines) {
+            return;
+        }
+        var buffer = models.getActiveBuffer();
+        if (!buffer.allLinesFetched) {
+            $scope.fetchMoreLines();
+        }
+    };
+
     $rootScope.updateBufferBottom = function(bottom) {
             var eob = document.getElementById("end-of-buffer");
             var bl = document.getElementById('bufferlines');

js/whenscrolled-directive.js

@@ -0,0 +1,21 @@
+(function() {
+'use strict';
+
+var weechat = angular.module('weechat');
+weechat.directive('whenScrolled', function() {
+    return function(scope, elm, attr) {
+        var raw = elm[0];
+
+        var fun = function() {
+            if (raw.scrollTop === 0) {
+                scope.$apply(attr.whenScrolled);
+            }
+        };
+
+        elm.bind('scroll', function() {
+            _.debounce(fun, 200)();
+        });
+    };
+});
+
+})();