# Copyright, 2019, 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 'address_endpoint'

module Async
	module IO
		# This class doesn't exert ownership over the specified unix socket and ensures exclusive access by using `flock` where possible.
		class UNIXEndpoint < AddressEndpoint
			def initialize(path, type, **options)
				# I wonder if we should implement chdir behaviour in here if path is longer than 104 characters.
				super(Address.unix(path, type), **options)
				
				@path = path
			end
			
			def to_s
				"\#<#{self.class} #{@path.inspect}>"
			end
			
			attr :path
			
			def bound?
				self.connect do
					return true
				end
			rescue Errno::ECONNREFUSED
				return false
			end
			
			def bind(&block)
				Socket.bind(@address, **@options, &block)
			rescue Errno::EADDRINUSE
				# If you encounter EADDRINUSE from `bind()`, you can check if the socket is actually accepting connections by attempting to `connect()` to it. If the socket is still bound by an active process, the connection will succeed. Otherwise, it should be safe to `unlink()` the path and try again.
				if !bound? && File.exist?(@path)
					File.unlink(@path)
					retry
				else
					raise
				end
			end
		end
		
		class Endpoint
			# @param path [String]
			# @param type Socket type
			# @param options keyword arguments passed through to {UNIXEndpoint#initialize}
			#
			# @return [UNIXEndpoint]
			def self.unix(path, type = ::Socket::SOCK_STREAM, **options)
				UNIXEndpoint.new(path, type, **options)
			end
		end
	end
end
