# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2013 Matthieu Lucas <lucasmatthieu@gmail.com>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Low-level socket functionalities
module socket_c

in "C Header" `{
	#include <stdio.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <string.h>
	#include <sys/socket.h>
	#include <sys/types.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <netdb.h>
	#include <sys/poll.h>
	#include <errno.h>

	typedef int S_DESCRIPTOR;
	typedef struct sockaddr_in S_ADDR_IN;
	typedef struct sockaddr S_ADDR;
	typedef struct in_addr S_IN_ADDR;
	typedef struct hostent S_HOSTENT;
	typedef struct timeval S_TIMEVAL;
	typedef struct sockaccept_result { S_ADDR_IN addr_in; S_DESCRIPTOR s_desc; } S_ACCEPT_RESULT;
	typedef fd_set S_FD_SET;
	typedef socklen_t S_LEN;
`}

# Wrapper for the data structure PollFD used for polling on a socket
class PollFD

	# The PollFD object
	private var poll_struct: FFSocketPollFD

	# A collection of the events to be watched
	var events: Array[FFSocketPollValues]

	init(pid: Int, events: Array[FFSocketPollValues])
	do
		assert events.length >= 1
		self.events = events

		var events_in_one = events[0]

		for i in [1 .. events.length-1] do
			events_in_one += events[i]
		end

		self.poll_struct = new FFSocketPollFD(pid, events_in_one)
	end

	# Reads the response and returns an array with the type of events that have been found
	private fun check_response(response: Int): Array[FFSocketPollValues]
	do
		var resp_array = new Array[FFSocketPollValues]
		for i in events do
			if c_check_resp(response, i) != 0 then
				resp_array.push(i)
			end
		end
		return resp_array
	end

	# Checks if the poll call has returned true for a particular type of event
	private fun c_check_resp(response: Int, mask: FFSocketPollValues): Int
	`{
		return response & mask;
	`}

end

# Data structure used by the poll function
private extern FFSocketPollFD `{ struct pollfd `}
	# File descriptor id
	private fun fd: Int `{ return recv.fd; `}
	# List of events to be watched
	private fun events: Int `{ return recv.events; `}
	# List of events received by the last poll function
	private fun revents: Int `{  return recv.revents; `}

	new (pid: Int, events: FFSocketPollValues) `{
		struct pollfd poll;
		poll.fd = pid;
		poll.events = events;
		return poll;
	`}

end

extern FFSocket `{ S_DESCRIPTOR* `}
	new socket(domain: FFSocketAddressFamilies, socketType: FFSocketTypes, protocol: FFSocketProtocolFamilies) `{
		S_DESCRIPTOR *d = NULL; d = (S_DESCRIPTOR*) malloc( sizeof(S_DESCRIPTOR) );
		int ds = socket(domain, socketType, protocol);
		memcpy(d, &ds, sizeof(ds));
		return d;
	`}
	fun destroy `{ free(recv); `}
	fun close: Int `{ return close( *recv ); `}
	fun descriptor: Int `{ return *recv; `}
	fun errno: Int `{ return errno; `}

	fun gethostbyname(n: String): FFSocketHostent import String.to_cstring `{ return gethostbyname(String_to_cstring(n)); `}
	fun connect(addrIn: FFSocketAddrIn): Int `{ return connect( *recv, (S_ADDR*)addrIn, sizeof(*addrIn) ); `}
	fun write(buffer: String): Int import String.to_cstring, String.length `{ return write(*recv, (char*)String_to_cstring(buffer), String_length(buffer)); `}

	fun read: String import NativeString.to_s `{
		char *c = (char*)malloc(1024);
		int n = read(*recv, c, 1023);
		if(n < 0) exit(-1);
		c[n] = '\0';
		return NativeString_to_s(c);
	`}

	fun bind(addrIn: FFSocketAddrIn): Int `{ return bind(*recv, (S_ADDR*)addrIn, sizeof(*addrIn)); `}
	fun listen(size: Int): Int `{ return listen(*recv, size); `}

	# Checks if the buffer is ready for any event specified when creating the pollfd structure
	fun socket_poll(filedesc: PollFD, timeout: Int): Array[FFSocketPollValues]
	do
		var result = i_poll(filedesc.poll_struct, timeout)
		assert result != -1
		return filedesc.check_response(result)
	end

	# Call to the poll function of the C socket
	#
	# Signature :
	# int poll(struct pollfd fds[], nfds_t nfds, int timeout);
	#
	# Official documentation of the poll function :
	#
	# The poll() function provides applications with a mechanism for multiplexing input/output over a set of file descriptors.
	# For each member of the array pointed to by fds, poll() shall examine the given file descriptor for the event(s) specified in events.
	# The number of pollfd structures in the fds array is specified by nfds.
	# The poll() function shall identify those file descriptors on which an application can read or write data, or on which certain events have occurred.
	# The fds argument specifies the file descriptors to be examined and the events of interest for each file descriptor.
	# It is a pointer to an array with one member for each open file descriptor of interest.
	# The array's members are pollfd structures within which fd specifies an open file descriptor and events and revents are bitmasks constructed by
	# OR'ing a combination of the pollfd flags.
	private fun i_poll(filedesc: FFSocketPollFD, timeout: Int): Int `{
		int poll_return = poll(&filedesc, 1, timeout);
		return poll_return;
	`}

	private fun i_accept(addrIn: FFSocketAddrIn): FFSocket `{
		S_LEN s = sizeof(S_ADDR);
		S_DESCRIPTOR *d = NULL;
		d = malloc(sizeof(S_DESCRIPTOR));
		*d = accept(*recv,(S_ADDR*)addrIn, &s);
		return d;
	`}
	fun accept: FFSocketAcceptResult
	do
		var addrIn = new FFSocketAddrIn
		var s = i_accept(addrIn)
		return new FFSocketAcceptResult(s, addrIn)
	end
end

extern FFSocketAcceptResult `{ S_ACCEPT_RESULT* `}
	new (socket: FFSocket, addrIn: FFSocketAddrIn) `{
		S_ACCEPT_RESULT *sar = NULL;
		sar = malloc( sizeof(S_ACCEPT_RESULT) );
		sar->s_desc = *socket;
		sar->addr_in = *addrIn;
		return sar;
	`}
	fun socket: FFSocket `{ return &recv->s_desc; `}
	fun addrIn: FFSocketAddrIn `{ return &recv->addr_in; `}
	fun destroy `{ free(recv); `}
end

extern FFSocketAddrIn `{ S_ADDR_IN* `}
	new `{
		S_ADDR_IN *sai = NULL;
		sai = malloc( sizeof(S_ADDR_IN) );
		return sai;
	`}
	new with(port: Int, family: FFSocketAddressFamilies) `{
		S_ADDR_IN *sai = NULL;
		sai = malloc( sizeof(S_ADDR_IN) );
		sai->sin_family = family;
		sai->sin_port = htons(port);
		sai->sin_addr.s_addr = INADDR_ANY;
		return sai;
	`}
	new with_hostent(hostent: FFSocketHostent, port: Int) `{
		S_ADDR_IN *sai = NULL;
		sai = malloc( sizeof(S_ADDR_IN) );
		sai->sin_family = hostent->h_addrtype;
		sai->sin_port = htons(port);
		memcpy( (char*)&sai->sin_addr.s_addr, (char*)hostent->h_addr, hostent->h_length );
		return sai;
	`}
	fun address: String import NativeString.to_s `{ return NativeString_to_s( (char*)inet_ntoa(recv->sin_addr) ); `}
	fun family: FFSocketAddressFamilies `{ return recv->sin_family; `}
	fun port: Int `{ return ntohs(recv->sin_port); `}
	fun destroy `{ free(recv); `}
end

extern FFSocketHostent `{ S_HOSTENT* `}
	private fun i_h_aliases(i: Int): String import NativeString.to_s `{ return NativeString_to_s(recv->h_aliases[i]); `}
	private fun i_h_aliases_reachable(i: Int): Bool `{ return (recv->h_aliases[i] != NULL); `}
	fun h_aliases: Array[String]
	do
		var i=0
		var d=new Array[String]
		loop
			d.add(i_h_aliases(i))
			if i_h_aliases_reachable(i+1) == false then break
			i += 1
		end
		return d
	end
	fun h_addr: String import NativeString.to_s `{ return NativeString_to_s( (char*)inet_ntoa(*(S_IN_ADDR*)recv->h_addr) ); `}
	fun h_addrtype: Int `{ return recv->h_addrtype; `}
	fun h_length: Int `{ return recv->h_length; `}
	fun h_name: String import NativeString.to_s `{ return NativeString_to_s(recv->h_name); `}
end

extern FFTimeval `{ S_TIMEVAL* `}
	new (seconds: Int, microseconds: Int) `{
		S_TIMEVAL* tv = NULL;
		tv = malloc( sizeof(S_TIMEVAL) );
		tv->tv_sec = seconds;
		tv->tv_usec = microseconds;
		return tv;
	`}
	fun seconds: Int `{ return recv->tv_sec; `}
	fun microseconds: Int `{ return recv->tv_usec; `}
	fun destroy `{ free( recv ); `}
end

extern FFSocketSet `{ S_FD_SET* `}
	new `{
		S_FD_SET *f = NULL;
		f = malloc( sizeof(S_FD_SET) );
		return f;
	`}
	fun set(s: FFSocket) `{ FD_SET( *s, recv ); `}
	fun is_set(s: FFSocket): Bool `{ return FD_ISSET( *s, recv ); `}
	fun zero `{ FD_ZERO( recv ); `}
	fun clear(s: FFSocket) `{ FD_CLR( *s, recv ); `}
	fun destroy `{ free( recv ); `}
end

class FFSocketObserver
	fun select(max: FFSocket, reads: nullable FFSocketSet, write: nullable FFSocketSet,
             except: nullable FFSocketSet, timeout: FFTimeval): Int `{
		S_FD_SET *rds, *wts, *exs = NULL;
		S_TIMEVAL *tm = NULL;
		if(reads != NULL) rds = (S_FD_SET*)reads;
		if(write != NULL) wts = (S_FD_SET*)write;
		if(except != NULL) exs = (S_FD_SET*)except;
		if(timeout != NULL) tm = (S_TIMEVAL*)timeout;
		return select(*max, rds, wts, exs, tm);
	`}
end

extern FFSocketTypes `{ int `}
	new sock_stream `{ return SOCK_STREAM; `}
	new sock_dgram `{ return SOCK_DGRAM; `}
	new sock_raw `{ return SOCK_RAW; `}
	new sock_seqpacket `{ return SOCK_SEQPACKET; `}
end
extern FFSocketAddressFamilies `{ int `}
	new af_null `{ return 0; `}
	new af_unspec `{ return  AF_UNSPEC; `} 		# unspecified
	new af_unix `{ return  AF_UNIX; `} 		# local to host (pipes)
	new af_local `{ return  AF_LOCAL; `} 		# backward compatibility
	new af_inet `{ return  AF_INET; `}		# internetwork: UDP, TCP, etc.
	new af_sna `{ return  AF_SNA; `}		# IBM SNA
	new af_decnet `{ return  AF_DECnet; `}		# DECnet
	new af_route `{ return  AF_ROUTE; `}		# Internal Routing Protocol
	new af_ipx `{ return  AF_IPX; `}		# Novell Internet Protocol
	new af_isdn `{ return  AF_ISDN; `}		# Integrated Services Digital Network
	new af_inet6 `{ return  AF_INET6; `}		# IPv6
	new af_max `{ return  AF_MAX; `}
end
extern FFSocketProtocolFamilies `{ int `}
	new pf_null `{ return 0; `}
	new pf_unspec `{ return PF_UNSPEC; `}
	new pf_local `{ return PF_LOCAL; `}
	new pf_unix `{ return PF_UNIX; `}
	new pf_inet `{ return PF_INET; `}
	new pf_sna `{ return PF_SNA; `}
	new pf_decnet `{ return PF_DECnet; `}
	new pf_route `{ return PF_ROUTE; `}
	new pf_ipx `{ return PF_IPX; `}
	new pf_isdn `{ return PF_ISDN; `}
	new pf_key `{ return PF_KEY; `}
	new pf_inet6 `{ return PF_INET6; `}
	new pf_max `{ return PF_MAX; `}
end

# Used for the poll function of a socket, mix several Poll values to check for events on more than one type of event
extern FFSocketPollValues `{ int `}
	new pollin `{ return POLLIN; `}           # Data other than high-priority data may be read without blocking.
	new pollrdnorm `{ return POLLRDNORM; `}   # Normal data may be read without blocking.
	new pollrdband `{ return POLLRDBAND; `}   # Priority data may be read without blocking.
	new pollpri `{ return POLLPRI; `}         # High-priority data may be read without blocking.
	new pollout `{ return POLLOUT; `}         # Normal data may be written without blocking.
	new pollwrnorm `{ return POLLWRNORM; `}   # Equivalent to POLLOUT
	new pollwrband `{ return POLLWRBAND; `}   # Priority data may be written.
	new pollerr `{ return POLLERR; `}         # An error has occurred on the device or stream. This flag is only valid in the revents bitmask; it shall be ignored in the events member.
	new pollhup `{ return POLLHUP; `}         # The device has been disconnected. This event and POLLOUT are mutually-exclusive; a stream can never be writable if a hangup has occurred. However, this event and POLLIN, POLLRDNORM, POLLRDBAND, or POLLPRI are not mutually-exclusive. This flag is only valid in the revents bitmask; it shall be ignored in the events member.
	new pollnval `{ return POLLNVAL; `}       # The specified fd value is invalid. This flag is only valid in the revents member; it shall ignored in the events member.

	# Combines two FFSocketPollValues
	private fun +(other: FFSocketPollValues): FFSocketPollValues `{
		return recv | other;
	`}
end