module Fog
  module Storage
    class GoogleXML
      class Real
        # Get headers for an object from Google Storage
        #
        # ==== Parameters
        # * bucket_name<~String> - Name of bucket to read from
        # * object_name<~String> - Name of object to read
        # * options<~Hash>:
        #   * 'If-Match'<~String> - Returns object only if its etag matches this value, otherwise returns 412 (Precondition Failed).
        #   * 'If-Modified-Since'<~Time> - Returns object only if it has been modified since this time, otherwise returns 304 (Not Modified).
        #   * 'If-None-Match'<~String> - Returns object only if its etag differs from this value, otherwise returns 304 (Not Modified)
        #   * 'If-Unmodified-Since'<~Time> - Returns object only if it has not been modified since this time, otherwise returns 412 (Precodition Failed).
        #   * 'Range'<~String> - Range of object to download
        #   * 'versionId'<~String> - specify a particular version to retrieve
        #
        # ==== Returns
        # * response<~Excon::Response>:
        #   * body<~String> - Contents of object
        #   * headers<~Hash>:
        #     * 'Content-Length'<~String> - Size of object contents
        #     * 'Content-Type'<~String> - MIME type of object
        #     * 'ETag'<~String> - Etag of object
        #     * 'Last-Modified'<~String> - Last modified timestamp for object
        def head_object(bucket_name, object_name, options = {})
          raise ArgumentError.new("bucket_name is required") unless bucket_name
          raise ArgumentError.new("object_name is required") unless object_name
          if version_id = options.delete("versionId")
            query = { "versionId" => version_id }
          end
          headers = {}
          headers["If-Modified-Since"] = Fog::Time.at(options["If-Modified-Since"].to_i).to_date_header if options["If-Modified-Since"]
          headers["If-Unmodified-Since"] = Fog::Time.at(options["If-Unmodified-Since"].to_i).to_date_header if options["If-Modified-Since"]
          headers.merge!(options)
          request(:expects  => [200, 206],
                  :headers  => headers,
                  :host     => "#{bucket_name}.#{@host}",
                  :method   => "HEAD",
                  :path     => Fog::Google.escape(object_name),
                  :query    => query)
        end
      end

      class Mock
        def head_object(bucket_name, object_name, options = {})
          response = get_object(bucket_name, object_name, options)
          response.body = nil
          response
        end
      end
    end
  end
end