add post editing

util.lua

@@ -242,6 +242,27 @@ function util.create_post(thread_id, user_id, content, markup_language)
   return post
 end
 
+function util.update_post(post, new_content, markup_language)
+  markup_language = markup_language or "babycode"
+  db.query("BEGIN")
+  
+  local parsed_content = ""
+  if markup_language == "babycode" then
+    parsed_content = babycode.to_html(new_content, html_escape)
+  end
+  
+  local revision = PostHistory:create({
+    post_id = post.id,
+    content = parsed_content,
+    is_initial_revision = false,
+    original_markup = new_content,
+    markup_language = markup_language
+  })
+  
+  post:update({current_revision_id = revision.id})
+  db.query("COMMIT")
+end
+
 function util.transfer_and_delete_user(user)
   local deleted_user = Users:find({
     username = "DeletedUser",