Merging for item descriptions

src/JS.hs

@@ -508,10 +508,24 @@ submitCategoryNotes =
 
 submitItemDescription :: JSFunction a => a
 submitItemDescription =
-  makeJSFunction "submitItemDescription" ["node", "itemId", "s"]
+  makeJSFunction "submitItemDescription"
+                 ["node", "itemId", "original", "ours"]
   [text|
-    $.post("/haskell/set/item/"+itemId+"/description", {content: s})
-     .done(replaceWithData(node));
+    $.post({
+      url: "/haskell/set/item/"+itemId+"/description",
+      data: {
+        original: original,
+        content: ours },
+      success: function (data) {
+        $.magnificPopup.close();
+        $(node).replaceWith(data); },
+      statusCode: {
+        409: function (xhr, st, err) {
+          modified = xhr.responseJSON["modified"];
+          merged   = xhr.responseJSON["merged"];
+          showDiffPopup(ours, modified, merged, function (x) {
+            submitItemDescription(node, itemId, modified, x) }); } }
+      });
   |]
 
 submitItemEcosystem :: JSFunction a => a

src/Main.hs

@@ -461,11 +461,20 @@ setMethods = Spock.subcomponent "set" $ do
     lucidIO $ renderItemInfo category item
   -- Item description
   Spock.post (itemVar <//> "description") $ \itemId -> do
+    original <- param' "original"
     content' <- param' "content"
-    invalidateCache' (CacheItemDescription itemId)
-    (edit, item) <- dbUpdate (SetItemDescription itemId content')
-    addEdit edit
-    lucidIO $ renderItemDescription item
+    modified <- view (description.mdText) <$> dbQuery (GetItem itemId)
+    if modified == original
+      then do
+        invalidateCache' (CacheItemDescription itemId)
+        (edit, item) <- dbUpdate (SetItemDescription itemId content')
+        addEdit edit
+        lucidIO $ renderItemDescription item
+      else do
+        setStatus HTTP.status409
+        json $ M.fromList [
+          ("modified" :: Text, modified),
+          ("merged" :: Text, merge original content' modified)]
   -- Item ecosystem
   Spock.post (itemVar <//> "ecosystem") $ \itemId -> do
     original <- param' "original"

src/View.hs

@@ -930,7 +930,8 @@ renderItemDescription item = cached (CacheItemDescription (item^.uid)) $ do
       markdownEditor
         [rows_ "10"]
         (item^.description)
-        (\val -> JS.submitItemDescription (this, item^.uid, val))
+        (\val -> JS.submitItemDescription
+                   (this, item^.uid, item^.description.mdText, val))
         (JS.switchSection (this, "normal" :: Text))
 
 renderItemEcosystem :: (MonadIO m, MonadRandom m) => Item -> HtmlT m ()