# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require_relative 'frame'

module HTTP
	module Protocol
		module HTTP2
			ACKNOWLEDGEMENT = 0x1
			
			module Acknowledgement
				def acknowledgement?
					flag_set?(ACKNOWLEDGEMENT)
				end
				
				def acknowledge
					frame = self.class.new
					
					frame.length = 0
					frame.set_flags(ACKNOWLEDGEMENT)
					
					return frame
				end
			end
			
			# The PING frame is a mechanism for measuring a minimal round-trip time from the sender, as well as determining whether an idle connection is still functional. PING frames can be sent from any endpoint.
			#
			# +---------------------------------------------------------------+
			# |                                                               |
			# |                      Opaque Data (64)                         |
			# |                                                               |
			# +---------------------------------------------------------------+
			#
			class PingFrame < Frame
				TYPE = 0x6
				
				include Acknowledgement
				
				def connection?
					true
				end
				
				def apply(connection)
					connection.receive_ping(self)
				end
				
				def acknowledge
					frame = super
					
					frame.pack self.unpack
					
					return frame
				end
				
				def read_payload(io)
					super
					
					if @length > 8
						raise FrameSizeError, "Invalid frame length"
					end
				end
			end
		end
	end
end