Add service for posting statuses (normal and replies), mention regex to

fetch webfinger information of mentioned accounts

app/models/account.rb

@@ -14,6 +14,8 @@ class Account < ActiveRecord::Base
   has_many :following, through: :active_relationships,  source: :target_account
   has_many :followers, through: :passive_relationships, source: :account
 
+  MENTION_RE = /(?:^|\W)@([a-z0-9_]+(?:@[a-z0-9\.\-]+)?)/i
+
   def follow!(other_account)
     self.active_relationships.first_or_create!(target_account: other_account)
   end

app/models/status.rb

@@ -51,6 +51,17 @@ class Status < ActiveRecord::Base
     m << thread.account if reply?
     m << reblog.account if reblog?
 
+    unless reblog?
+      self.text.scan(Account::MENTION_RE).each do |match|
+        uri      = match.first
+        username = uri.split('@').first
+        domain   = uri.split('@').size == 2 ? uri.split('@').last : nil
+        account  = Account.find_by(username: username, domain: domain)
+
+        m << account unless account.nil?
+      end
+    end
+
     m
   end