Adding common followers API, fixing fallback query again

app/models/account.rb

@@ -122,6 +122,15 @@ class Account < ApplicationRecord
     username
   end
 
+  def common_followers_with(other_account)
+    results  = Neography::Rest.new.execute_query('MATCH (a {account_id: {a_id}})-[:follows]->(b)-[:follows]->(c {account_id: {c_id}}) RETURN b.account_id', a_id: id, c_id: other_account.id)
+    ids      = results['data'].map(&:first)
+    accounts = self.where(id: ids).with_counters.map { |a| [a.id, a] }.to_h
+    ids.map { |id| accounts[id] }.compact
+  rescue Neography::NeographyError, Excon::Error::Socket
+    []
+  end
+
   def self.find_local!(username)
     find_remote!(username, nil)
   end