Added LRU (Least Recently Used) semantics to Group switch mode.

OnTopReplica/MessagePumpProcessors/GroupSwitchManager.cs

@@ -20,9 +20,16 @@ namespace OnTopReplica.MessagePumpProcessors {
 
         uint _hookMsgId;
         bool _active = false;
-        IList<WindowHandle> _handles;
+        List<WindowHandleWrapper> _lruHandles;
 
+        /// <summary>
+        /// Enables group switch mode.
+        /// </summary>
+        /// <param name="handles">List of window handles to track.</param>
         public void EnableGroupMode(IList<WindowHandle> handles) {
+            if (handles == null || handles.Count == 0)
+                return;
+
             //Enable new hook
             if (!_active) {
                 if (!HookMethods.RegisterShellHookWindow(Form.Handle)) {
@@ -32,10 +39,28 @@ namespace OnTopReplica.MessagePumpProcessors {
             }
 
             //Okey dokey, will now track handles
-            _handles = handles;
+            TrackHandles(handles);
             _active = true;
         }
 
+        /// <summary>
+        /// Initializes the LRU sorted list of window handles.
+        /// </summary>
+        private void TrackHandles(IList<WindowHandle> handles) {
+            _lruHandles = new List<WindowHandleWrapper>(handles.Count);
+            var now = DateTime.Now;
+
+            foreach(var h in handles){
+                _lruHandles.Add(new WindowHandleWrapper {
+                    WindowHandle = h,
+                    LastTimeUsed = now
+                });
+            }
+        }
+
+        /// <summary>
+        /// Disables group switch mode.
+        /// </summary>
         public void Disable() {
             if (!_active)
                 return;
@@ -43,9 +68,13 @@ namespace OnTopReplica.MessagePumpProcessors {
             if (!HookMethods.DeregisterShellHookWindow(Form.Handle))
                 Console.Error.WriteLine("Failed to deregister shell hook window.");
 
+            _lruHandles = null;
             _active = false;
         }
 
+        /// <summary>
+        /// Processes the message pump.
+        /// </summary>
         public override void Process(Message msg) {
             if (_active && msg.Msg == _hookMsgId) {
                 int hookCode = msg.WParam.ToInt32();
@@ -59,17 +88,18 @@ namespace OnTopReplica.MessagePumpProcessors {
         }
 
         private void HandleForegroundWindowChange(IntPtr activeWindow) {
-            int iActive = -1;
-            for (int i = 0; i < _handles.Count; ++i) {
-                if (_handles[i].Handle == activeWindow)
-                    iActive = i;
-            }
-
 #if DEBUG
             Console.Write("New active window (h {0}). ", activeWindow);
 #endif
 
-            if (iActive < 0) {
+            //Seek window in tracked handles
+            WindowHandleWrapper activated = null;
+            foreach (var i in _lruHandles) {
+                if (i.WindowHandle.Handle == activeWindow)
+                    activated = i;
+            }
+
+            if (activated == null) {
 #if DEBUG
                 //new foreground window is not tracked
                 Console.WriteLine("Active window is not tracked.");
@@ -77,16 +107,18 @@ namespace OnTopReplica.MessagePumpProcessors {
                 return;
             }
 
-            //Get new handle to clone
-            int iNewToClone = (iActive + 1) % _handles.Count;
+            //Update tracked handle
+            activated.LastTimeUsed = DateTime.Now;
+            _lruHandles.Sort(new LruDateTimeComparer());
+
+            //Get least recently used
+            var next = _lruHandles[0];
 
 #if DEBUG
-            Console.WriteLine("Tracked as {0}. Switching to {1}.", iActive, iNewToClone);
+            Console.WriteLine("Tracked. Switching to {0} (last use: {1}).", next.WindowHandle.Title, next.LastTimeUsed);
 #endif
 
-
-            //TODO: use real least-recently-used semantics
-            Form.SetThumbnail(_handles[iNewToClone], null);
+            Form.SetThumbnail(next.WindowHandle, null);
         }
 
         protected override void Shutdown() {
@@ -102,6 +134,26 @@ namespace OnTopReplica.MessagePumpProcessors {
             }
         }
 
+        #region List sorting stuff
+
+        class WindowHandleWrapper {
+            public WindowHandle WindowHandle { get; set; }
+            public DateTime LastTimeUsed { get; set; }
+        }
+
+        class LruDateTimeComparer : IComparer<WindowHandleWrapper> {
+
+            #region IComparer<WindowHandleWrapper> Members
+
+            public int Compare(WindowHandleWrapper x, WindowHandleWrapper y) {
+                return x.LastTimeUsed.CompareTo(y.LastTimeUsed);
+            }
+
+            #endregion
+        }
+
+        #endregion
+
     }
 
 }