Added Instagram login method

lib/auth/instagram_authenticator.rb

@@ -0,0 +1,49 @@
+class Auth::InstagramAuthenticator < Auth::Authenticator
+
+  def name
+    "instagram"
+  end
+
+  # TODO twitter provides all sorts of extra info, like website/bio etc.
+  #  it may be worth considering pulling some of it in.
+  def after_authenticate(auth_token)
+
+    result = Auth::Result.new
+
+    data = auth_token[:info]
+
+    result.username = screen_name = data["nickname"]
+    result.name = name = data["name"]
+    instagram_user_id = auth_token["uid"]
+
+    result.extra_data = {
+      instagram_user_id: instagram_user_id,
+      instagram_screen_name: screen_name
+    }
+
+    user_info = InstagramUserInfo.find_by(instagram_user_id: instagram_user_id)
+
+    result.user = user_info.try(:user)
+
+    result
+  end
+
+  def after_create_account(user, auth)
+    data = auth[:extra_data]
+    InstagramUserInfo.create(
+      user_id: user.id,
+      screen_name: data[:instagram_screen_name],
+      instagram_user_id: data[:instagram_user_id]
+    )
+  end
+
+  def register_middleware(omniauth)
+    omniauth.provider :instagram,
+           :setup => lambda { |env|
+              strategy = env["omniauth.strategy"]
+              strategy.options[:client_id] = SiteSetting.instagram_consumer_key
+              strategy.options[:client_secret] = SiteSetting.instagram_consumer_secret
+           }
+  end
+
+end