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

fetch webfinger information of mentioned accounts

app/services/post_status_service.rb

@@ -0,0 +1,19 @@
+class PostStatusService < BaseService
+  def call(account, text, in_reply_to = nil)
+    status = account.statuses.create!(text: text, thread: in_reply_to)
+
+    status.text.scan(Account::MENTION_RE).each do |match|
+      next if match.first.split('@').size == 1
+      username, domain = match.first.split('@')
+      local_account = Account.find_by(username: username, domain: domain)
+      next unless local_account.nil?
+      follow_remote_account_service.("acct:#{match.first}")
+    end
+  end
+
+  private
+
+  def follow_remote_account_service
+    @follow_remote_account_service ||= FollowRemoteAccountService.new
+  end
+end