Fixed Version Handler obsolete files dialog on refresh.

In some cases an asset database refresh does not result in
a reload of the app domain (e.g non-DLL files are changed)
in which case the obsolete files dialog was not being displayed.
This changes the Version Handler to cache whether obsolete files
were found and an update should be performed when the asset
database refresh is complete, at which point the obsolete files
dialog is displayed prompting users to clean up old plugin
components.

Change-Id: I82796786615dbeb64d462dd5591c52c0b01e702f

Author: Stewart Miles

source/VersionHandlerImpl/src/VersionHandlerImpl.cs

@@ -2154,6 +2154,9 @@ private string LibraryPrefix {
     // Path of the file that indicates whether the asset database is currently being refreshed
     // due to this module.
     private const string REFRESH_PATH = "Temp/VersionHandlerImplRefresh";
+    // Path of the file that indicates whether files need to be cleaned up after an asset database
+    // refresh.
+    private const string CLEANUP_FILES_PENDING_PATH = "Temp/VersionHandlerImplCleanupFilesPending";
 
     // Whether compilation is currently occuring.
     private static bool compiling = false;
@@ -2231,6 +2234,26 @@ private static bool Refreshing {
         }
     }
 
+    /// <summary>
+    /// Whether files need to be cleaned up after an asset database refresh.
+    /// </summary>
+    private static bool CleanupFilesPending {
+        get {
+            return File.Exists(CLEANUP_FILES_PENDING_PATH);
+        }
+
+        set {
+            bool pending = CleanupFilesPending;
+            if (pending != value) {
+                if (value) {
+                    File.WriteAllText(CLEANUP_FILES_PENDING_PATH, "Cleanup files after refresh");
+                } else {
+                    File.Delete(CLEANUP_FILES_PENDING_PATH);
+                }
+            }
+        }
+    }
+
     /// <summary>
     /// Whether all editor DLLs have been loaded into the app domain.
     /// </summary>
@@ -2289,7 +2312,16 @@ private static void NotifyWhenCompliationComplete(bool forceNotification) {
                 // If a refresh was initiated by this module, clear the refresh flag.
                 var wasRefreshing = Refreshing;
                 Refreshing = false;
-                if (wasRefreshing || forceNotification) NotifyUpdateCompleteMethods();
+                if (wasRefreshing || forceNotification) {
+                    if (CleanupFilesPending) {
+                        CleanupFilesPending = false;
+                        RunOnMainThread.Run(() => {
+                                UpdateVersionedAssetsOnMainThread(false, () => {},
+                                                                  setCleanupFilesPending: false);
+                            }, runNow: false);
+                    }
+                    NotifyUpdateCompleteMethods();
+                }
                 return true;
             });
     }
@@ -2638,8 +2670,9 @@ public static void UpdateVersionedAssets(bool forceUpdate) {
     /// <param name="complete">Called when this is method is complete.</param>
     public static void UpdateVersionedAssets(bool forceUpdate, Action complete) {
         CancelUpdateVersionedAssets();
-        RunOnMainThread.Run(() => { UpdateVersionedAssetsOnMainThread(forceUpdate, complete); },
-                            runNow: false);
+        RunOnMainThread.Run(() => {
+                UpdateVersionedAssetsOnMainThread(forceUpdate, complete); },
+            runNow: false);
     }
 
     /// <summary>
@@ -2650,7 +2683,11 @@ public static void UpdateVersionedAssets(bool forceUpdate, Action complete) {
     /// </summary>
     /// <param name="forceUpdate">Whether to force an update.</param>
     /// <param name="complete">Called when this is method is complete.</param>
-    private static void UpdateVersionedAssetsOnMainThread(bool forceUpdate, Action complete) {
+    /// <param name="setCleanupFilesPending">Whether to set the CleanupFilesPending flag to run
+    /// this method again after an asset database refresh is complete.</param>
+    private static void UpdateVersionedAssetsOnMainThread(bool forceUpdate,
+                                                          Action complete,
+                                                          bool setCleanupFilesPending = true) {
         // If this module is disabled do nothing.
         if (!forceUpdate && !Enabled) {
             complete();
@@ -2709,7 +2746,8 @@ private static void UpdateVersionedAssetsOnMainThread(bool forceUpdate, Action c
             }
         }
 
-        if (cleanupFiles.Count > 0 && !Refreshing) {
+        bool cleanupFilesPending = cleanupFiles.Count > 0;
+        if (cleanupFilesPending && !Refreshing) {
             var window = MultiSelectWindow.CreateMultiSelectWindow(PLUGIN_NAME);
             Action<string> logObsoleteFile = (filename) => {
                 Log("Leaving obsolete file: " + filename, verbose: true);
@@ -2749,6 +2787,7 @@ private static void UpdateVersionedAssetsOnMainThread(bool forceUpdate, Action c
             window.OnCancel = leaveFiles;
             window.Show();
         } else {
+            if (cleanupFilesPending && setCleanupFilesPending) CleanupFilesPending = true;
             complete();
         }