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require 'signet/oauth_2/client'

module Signet
  # OAuth2 supports OAuth2 authentication.
  module OAuth2
    AUTH_METADATA_KEY = :Authorization
    # Signet::OAuth2::Client creates an OAuth2 client
    #
    # This reopens Client to add #apply and #apply! methods which update a
    # hash with the fetched authentication token.
    class Client
      # Updates a_hash updated with the authentication token
      def apply!(a_hash, opts = {})
        # fetch the access token there is currently not one, or if the client
        # has expired
        fetch_access_token!(opts) if access_token.nil? || expired?
        a_hash[AUTH_METADATA_KEY] = "Bearer #{access_token}"
      end

      # Returns a clone of a_hash updated with the authentication token
      def apply(a_hash, opts = {})
        a_copy = a_hash.clone
        apply!(a_copy, opts)
        a_copy
      end

      # Returns a reference to the #apply method, suitable for passing as
      # a closure
      def updater_proc
        lambda(&method(:apply))
      end

      def on_refresh(&block)
        @refresh_listeners ||= []
        @refresh_listeners << block
      end

      alias_method :orig_fetch_access_token!, :fetch_access_token!
      def fetch_access_token!(options)
        info = orig_fetch_access_token!(options)
        notify_refresh_listeners
        info
      end

      def notify_refresh_listeners
        listeners = @refresh_listeners || []
        listeners.each do |block|
          block.call(self)
        end
      end
    end
  end
end
