# Socket over UDP, sends and receive data without the need for a connection
class UDPSocket
	super Socket

	# Last error raised by this socket
	var error: nullable Error = null

	init do native = new NativeSocket.socket(
			new NativeSocketAddressFamilies.af_inet,
			new NativeSocketTypes.sock_dgram,
			new NativeSocketProtocolFamilies.pf_unspec)

	# Bind this socket to an `address`, on `port` (to all addresses if `null`)
	#
	# On error, sets `error` appropriately.
	fun bind(address: nullable Text, port: Int)
	do
		var addr_in = new NativeSocketAddrIn
		addr_in.port = port
		if address != null then
			# FIXME replace all use of gethostbyname with something not obsolete
			var hostent = sys.gethostbyname(address.to_cstring)
			if hostent.address_is_null then
				error = new IOError.from_h_errno
				addr_in.free
				return
			end

			addr_in.fill_from_hostent hostent
		else
			addr_in.family = new NativeSocketAddressFamilies.af_inet
			addr_in.address_any
		end

		if native.bind(addr_in) != 0 then error = new IOError.from_errno

		addr_in.free
	end

	# Receive `length` bytes of data from any sender
	#
	# On error, returns an empty string and sets `error` appropriately.
	fun recv(length: Int): String
	do
		var buf = new CString(length)
		var len = native.recvfrom(buf, length, 0, new NativeSocketAddrIn.nul)
		if len == -1 then
			error = new IOError.from_errno
			return ""
		end
		return buf.to_s_unsafe(len, copy=false)
	end

	# Receive `length` bytes of data from any sender and store the sender info in `sender.item`
	#
	# On error, returns an empty string and sets `error` appropriately.
	fun recv_from(length: Int, sender: Ref[nullable SocketAddress]): String
	do
		var src = new NativeSocketAddrIn
		var buf = new CString(length)

		var len = native.recvfrom(buf, length, 0, src)
		if len == -1 then
			error = new IOError.from_errno
			src.free
			return ""
		end

		sender.item = new SocketAddress(src)
		return buf.to_s_unsafe(len, copy=false)
	end

	# Send `data` to `dest_address` on `port`
	#
	# On error, sets `error` appropriately.
	fun send_to(dest_address: Text, port: Int, data: Text)
	do
		var hostent = sys.gethostbyname(dest_address.to_cstring)
		if hostent.address_is_null then
			error = new IOError.from_h_errno
			return
		end

		var dest = new NativeSocketAddrIn
		dest.fill_from_hostent hostent
		dest.port = port
		native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.broadcast, 1)

		var buf = data.to_cstring
		if native.sendto(buf, data.length, 0, dest) == -1 then
			error = new IOError.from_errno
		end
		dest.free
	end

	# Enable broadcasting for this socket
	#
	# On error, sets `error` appropriately.
	fun enable_broadcast=(value: Bool) do
		var res = native.setsockopt(new NativeSocketOptLevels.socket, new NativeSocketOptNames.broadcast, value.to_i)
		if res == -1 then error = new IOError.from_errno
	end

	# Broadcast `data` on the network on `port`
	#
	# On error, sets `error` appropriately.
	#
	# Require: setting `enable_broadcast = true`
	fun broadcast(port: Int, data: Text)
	do
		var addr_in = new NativeSocketAddrIn
		addr_in.port = port
		addr_in.family = new NativeSocketAddressFamilies.af_inet
		addr_in.address_broadcast

		var buf = data.to_cstring
		if native.sendto(buf, data.length, 0, addr_in) == -1 then
			error = new IOError.from_errno
		end

		addr_in.free
	end
end