create a hash format fcm response based on faraday response

Author: Roy-Mao

lib/fcm/response.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+require 'fcm/error'
+
+module Fcm
+  # Custome Fcm response
+  module Response
+    class << self
+      # Converts the faraday response into a custom fcm response
+      #
+      # @param response [Faraday::Response] a faraday response object
+      # @return [Hash] a custom fcm response hash
+      def build_fcm_response(response, registration_ids = [])
+        return success_response(response, registration_ids) if response.success?
+
+        failure_response(response)
+      end
+
+      private
+
+      def success_response(response, registration_ids)
+        body = response.body || {}
+        response_hash = {
+          body: body,
+          headers: response.headers,
+          status_code: response.status,
+          response: 'success'
+        }
+        return response_hash if registration_ids.empty?
+
+        body = JSON.parse(body) unless body.empty?
+        response_hash[:canonical_ids] = build_canonical_ids(
+          body, registration_ids
+        )
+        response_hash[:not_registered_ids] = build_not_registered_ids(
+          body, registration_ids
+        )
+        response_hash
+      end
+
+      def failure_response(response)
+        body = response.body || {}
+        response_hash = {
+          body: body,
+          headers: response.headers,
+          status_code: response.status
+        }
+
+        response_hash[:response] = case response.status.to_i
+                                   when 400
+                                     Fcm::Error::ERROR_RESPONSE_400
+                                   when 401
+                                     Fcm::Error::ERROR_RESPONSE_401
+                                   when 503
+                                     Fcm::Error::ERROR_RESPONSE_503
+                                   when 500..599
+                                     Fcm::Error::ERROR_RESPONSE_50X
+                                   end
+        response_hash
+      end
+
+      def build_canonical_ids(body, registration_ids)
+        canonical_ids = []
+        return canonical_ids if body.empty? || body['canonical_ids'] <= 0
+
+        body['results'].each_with_index do |result, index|
+          return canonical_ids unless canonical_id?(result)
+
+          canonical_ids << {
+            old: registration_ids[index], new: result['registration_id']
+          }
+        end
+        canonical_ids
+      end
+
+      def build_not_registered_ids(body, registration_id)
+        not_registered_ids = []
+        return not_registered_ids if body.empty?
+
+        if body['failure'].positive?
+          body['results'].each_with_index do |result, index|
+            not_registered_ids << registration_id[index] if not_registered?(result)
+          end
+        end
+        not_registered_ids
+      end
+
+      def canonical_id?(result)
+        !result['registration_id'].nil?
+      end
+
+      def not_registered?(result)
+        result['error'] == 'NotRegistered'
+      end
+    end
+  end
+end