add dmail notices for mentions in forum posts

app/logical/d_text.rb

@@ -2,6 +2,8 @@ require 'cgi'
 require 'uri'
 
 class DText
+  MENTION_REGEXP = /(?:^| )@\S+/
+  
   def self.u(string)
     CGI.escape(string)
   end
@@ -36,7 +38,7 @@ class DText
     str.gsub!(/&/, "&")
     str.gsub!(/</, "&lt;")
     str.gsub!(/>/, "&gt;")
-    str.gsub!(/(?:^| )@\S+/) do |name| 
+    str.gsub!(MENTION_REGEXP) do |name| 
       if name =~ /([:;,.!?\)\]<>])$/
         name.chop!
         ch = $1

app/logical/mentionable.rb

@@ -0,0 +1,41 @@
+module Mentionable
+  extend ActiveSupport::Concern
+
+  module ClassMethods
+    # options:
+    # - message_field
+    # - user_field
+    def mentionable(options = {})
+      @mentionable_options = options
+
+      after_create :queue_mention_messages
+    end
+
+    def mentionable_option(key)
+      @mentionable_options[key]
+    end
+  end
+
+  def queue_mention_messages
+    title = self.class.mentionable_option(:title)
+    from_id = read_attribute(self.class.mentionable_option(:user_field))
+    text = read_attribute(self.class.mentionable_option(:message_field))
+
+    text.scan(DText::MENTION_REGEXP).each do |mention|
+      mention.gsub!(/(?:^\s*@)|(?:[:;,.!?\)\]<>]$)/, "")
+      user = User.find_by_name(mention)
+      body = self.class.mentionable_option(:body).call(self, user.name)
+
+      if user
+        dmail = Dmail.new(
+          from_id: from_id,
+          to_id: user.id,
+          title: title,
+          body: body
+        )
+        dmail.owner_id = user.id
+        dmail.save
+      end
+    end
+  end
+end