From 32bc0a30fc768528904aff9a4cf04a8afd057fa8 Mon Sep 17 00:00:00 2001
From: Dennis Kehrig <dkehrig@adobe.com>
Date: Fri, 30 Aug 2013 14:07:06 -0700
Subject: [PATCH 1/2] When saving a file at a different location, don't delete
 an existing assets folder there, but try to delete it. If 1000 attempts to do
 so are not enough, give up.

---
 main.js | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/main.js b/main.js
index 1f032d2a..50eb2afb 100644
--- a/main.js
+++ b/main.js
@@ -21,6 +21,8 @@
  * 
  */
 
+/*jshint unused: false */
+
 (function () {
     "use strict";
 
@@ -56,6 +58,7 @@
         FILES_TO_IGNORE = [".ds_store", "desktop.ini"],
         DELAY_TO_WAIT_UNTIL_USER_DONE = 300,
         MAX_SIMULTANEOUS_UPDATES = 50,
+        MAX_DIR_RENAME_ATTEMPTS = 1000,
         TIMEOUT_ERROR_MESSAGE = "timeout"; // must be in sync with Generator's timeout error
 
     // TODO: Once we get the layer change management/updating right, we should add a
@@ -793,12 +796,28 @@
                 return resolvedPromise();
             }
             else {
-                // Delete the assets of a previous file
-                // Photoshop will have asked the user to confirm overwriting the PSD file at this point,
-                // so "overwriting" its assets is fine, too
+                // Rename the assets folder of another document at this location
+                // Try foo-assets-old, then foo-assets-old-2, etc.
+                // Give up after MAX_DIR_RENAME_ATTEMPTS many unsuccessful attempts
                 if (fs.existsSync(newStorageDir)) {
-                    console.log("Deleting existing storage directory %j", newStorageDir);
-                    deleteDirectoryRecursively(newStorageDir);
+                    var attempts = 0,
+                        renamedNewStorageDir;
+                    do {
+                        attempts++;
+                        renamedNewStorageDir = newStorageDir + "-old";
+                        if (attempts > 1) {
+                            renamedNewStorageDir += "-" + attempts;
+                        }
+                    } while (fs.existsSync(renamedNewStorageDir) && attempts < MAX_DIR_RENAME_ATTEMPTS);
+                    
+                    // If the suggested path exists despite our efforts to find one that doesn't, give up
+                    if (fs.existsSync(renamedNewStorageDir)) {
+                        throw new Error("At least " + MAX_DIR_RENAME_ATTEMPTS + " other backups of " +
+                            newStorageDir + " already exist. Giving up.");
+                    }
+                    
+                    console.log("Renaming existing storage directory %j to %j", newStorageDir, renamedNewStorageDir);
+                    fs.renameSync(newStorageDir, renamedNewStorageDir);
                 }
 
                 // Move generated assets to the new directory and delete the old one if empty

From c61f19adeb39b4bedab47338df5313dec3b8d65d Mon Sep 17 00:00:00 2001
From: Dennis Kehrig <dkehrig@adobe.com>
Date: Fri, 30 Aug 2013 16:06:56 -0700
Subject: [PATCH 2/2] First check if we know the file at all before figuring
 out whether the changes are complex

---
 main.js | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/main.js b/main.js
index 50eb2afb..23f0a41e 100644
--- a/main.js
+++ b/main.js
@@ -418,8 +418,20 @@
             }
         }
 
-        var documentContext = _contextPerDocument[document.id],
-            unknownChange = false,
+        var documentContext = _contextPerDocument[document.id];
+        
+        // Possible reasons for an undefined context:
+        // - User created a new image
+        // - User opened an image
+        // - User switched to an image that was created/opened before Generator started
+        if (!documentContext) {
+            console.log("Unknown document, so getting all information");
+            requestEntireDocument(document.id);
+            return;
+        }
+
+        // We have seen this document before: information about the changes are enough
+        var unknownChange = false,
             layersMoved = false;
         
         traverseLayers(document, function (obj, isLayer) {
@@ -473,18 +485,6 @@
             return;
         }
 
-        // Possible reasons for an undefined context:
-        // - User created a new image
-        // - User opened an image
-        // - User switched to an image that was created/opened before Generator started
-        if (!documentContext) {
-            console.log("Unknown document, so getting all information");
-            requestEntireDocument(document.id);
-            return;
-        }
-            
-        // We have seen this document before: information about the changes are enough
-        
         // Resize event: regenerate everything
         if (!document.layers && document.bounds) {
             requestEntireDocument(document.id);