# Copyright 2015, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

require 'googleauth/signet'
require 'googleauth/credentials_loader'
require 'multi_json'

module Google
  # Module Auth provides classes that provide Google-specific authorization
  # used to access Google APIs.
  module Auth
    # Authenticates requests using User Refresh credentials.
    #
    # This class allows authorizing requests from user refresh tokens.
    #
    # This the end of the result of a 3LO flow.  E.g, the end result of
    # 'gcloud auth login' saves a file with these contents in well known
    # location
    #
    # cf [Application Default Credentials](http://goo.gl/mkAHpZ)
    class UserRefreshCredentials < Signet::OAuth2::Client
      TOKEN_CRED_URI = 'https://www.googleapis.com/oauth2/v3/token'
      extend CredentialsLoader

      # Reads the client_id, client_secret and refresh_token fields from the
      # JSON key.
      def self.read_json_key(json_key_io)
        json_key = MultiJson.load(json_key_io.read)
        wanted = %w(client_id client_secret refresh_token)
        wanted.each do |key|
          fail "the json is missing the #{key} field" unless json_key.key?(key)
        end
        json_key
      end

      # Initializes a UserRefreshCredentials.
      #
      # @param scope [string|array] the scope(s) to access
      # @param json_key_io [IO] an IO from which the JSON key can be read
      def initialize(scope, json_key_io)
        user_creds = self.class.read_json_key(json_key_io)
        super(token_credential_uri: TOKEN_CRED_URI,
              client_id: user_creds['client_id'],
              client_secret: user_creds['client_secret'],
              refresh_token: user_creds['refresh_token'],
              scope: scope)
      end
    end
  end
end