#include <unistd.h> // Per les crides a fitxer
#include <stdio.h>  // Per l'I/O de stdin/stdout
#include <errno.h>  // Pels errors de les crides a fitxer
#include <string.h> // Per strerror()
#include <stdlib.h> // Per abort()
#include <fcntl.h> // Per fcntl()
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <signal.h>
#include <assert.h> // Per assert()
#include <sys/select.h> // Pel select()

#include "syslog.h"

/* Prototypes */
static void listen_tcp(const int port, const bool ipv6enabled);
static int listen_tcp_ipv6(int port);
static int listen_tcp_ipv4(int port);
static int accept_connection(int socket);

/* Returns 0 on success. Returns -1 on error. */
int init_tcp_server()
{
	int pid;
	int port;
	char service[MAX_STRING];
	enum {
		SUCCESS=0,
		ERROR=-1,
		DISABLED=-2
	} ret;

	
	/* Get the configuration */
	get_config(TCP_MANAGER, service, MAX_STRING);
	if (strncmp(service, "disabled", MAX_STRING) == 0)
		return DISABLED;

	/* Check the configuration */
	port = atoi(service);
	if (port < -65535 || port > 65535)
		return ERROR;

	/* Create the server process */
	pid = child_fork();

	if (pid == 0)
	{
		program_child_handler(SIG_DFL);
		/* Child */
		close(0);
		close(1);
		//close(2);
		if(port < 0)
		{
			listen_tcp(-port, true);
		} else
		{
			listen_tcp(port, false);
		}
		/* Should be Not reachable */
		exit(0);
	} else if (pid > 0)
	{
		/* Parent */
		fprintf(stderr, "Child forked (tcp server on port %i): %i\n",
			port, pid);
		ret = SUCCESS;
	} else
	{
		ret = ERROR;
	}

	return ret;
}


static void listen_tcp(const int port, const bool ipv6enabled)
{
	int socket_ipv6, socket_ipv4;
	fd_set listen_sockets;
	int result;
	int high_socket;

	socket_ipv4 = listen_tcp_ipv4(port);

	if (ipv6enabled)
		socket_ipv6 = listen_tcp_ipv6(port);

	/* Mirem quin és el socket més alt pel select() */
	high_socket = socket_ipv4;
	if (ipv6enabled && (high_socket < socket_ipv6) )
		high_socket = socket_ipv6;
		
	high_socket += 1;

	result = 0;
	while (result >= 0)
	{
		/* Establim els FDs que volem esperar al select() */
		FD_ZERO(&listen_sockets);
		if (ipv6enabled)
			FD_SET(socket_ipv6, &listen_sockets);
		FD_SET(socket_ipv4, &listen_sockets);

		result = select(high_socket, &listen_sockets, NULL, NULL,
			NULL);
		if (result == 0)
		{
			/* Això no hauria de passar, no tenim timeout fixat. */
			continue;
		}
		else if (result == -1 && errno != EINTR)
		{
			fprintf(stderr, "Error in select(): %s\n",
				strerror(errno));
			abort();
		}

		/* Algun FD té dades... */
		if (FD_ISSET(socket_ipv4, &listen_sockets))
		{
			accept_connection(socket_ipv4);
		}

		if (ipv6enabled && FD_ISSET(socket_ipv6, &listen_sockets))
		{
			accept_connection(socket_ipv6);
		}
	}
}


static int listen_tcp_ipv6(int port)
{
	int socket_ipv6;
	struct sockaddr_in6 source_ipv6;
	int result;
	int on=1;


	socket_ipv6 = socket(PF_INET6, SOCK_STREAM, 0);
	if (socket_ipv6 == -1)
	{
		fprintf(stderr, "IPv6 socket failed.\n");
		abort();
	}

	/* Fem que poguem reutilitzar l'adreça encara que no s'hagi acabat
	   el timeout després de tancar-se la connexió */
	if (setsockopt(socket_ipv6, SOL_SOCKET, SO_REUSEADDR,
	                         (char *)&on,sizeof(on)) < 0)
	{
		fprintf(stderr, "IPv6 setsockopt() failed: %s.\n",
			strerror(errno));
		abort();
	}

	/* No volem que aquest socket bloquegi. */
	if (fcntl(socket_ipv6, F_SETFL, O_NONBLOCK) == -1)
	{
		fprintf(stderr, "IPv6 fcntl() failed: %s.\n",
			strerror(errno));
		abort();
	}

	/* IPv6 listen address */
	memset(&source_ipv6, 0, sizeof(source_ipv6));
	source_ipv6.sin6_family = AF_INET6;
	source_ipv6.sin6_flowinfo = 0;
	source_ipv6.sin6_port = htons(port);
	source_ipv6.sin6_addr = in6addr_any;
	result = bind(socket_ipv6, (struct sockaddr *) &source_ipv6,
		sizeof(source_ipv6));
	assert(result == 0);

	result = listen(socket_ipv6, TCP_LISTEN_QUEUE);
	if (result != 0)
	{
		fprintf(stderr,"Error in listen() ipv6: %s\n", strerror(errno));
		abort();
	}

	return socket_ipv6;
}

static int listen_tcp_ipv4(int port)
{
	int socket_ipv4;
	struct sockaddr_in source_ipv4;
	int result;
	int on=1;


	socket_ipv4 = socket(PF_INET, SOCK_STREAM, 0);
	if (socket_ipv4 == -1)
	{
		fprintf(stderr, "IPv4 socket not supported.\n");
		abort();
	}

	/* Fem que poguem reutilitzar l'adreça encara que no s'hagi acabat
	   el timeout després de tancar-se la connexió */
	if (setsockopt(socket_ipv4, SOL_SOCKET, SO_REUSEADDR,
	                         (char *)&on,sizeof(on)) < 0)
	{
		fprintf(stderr, "IPv4 setsockopt() failed: %s.\n",
			strerror(errno));
		abort();
	}

	/* No volem que aquest socket bloquegi. */
	if (fcntl(socket_ipv4, F_SETFL, O_NONBLOCK) == -1)
	{
		fprintf(stderr, "IPv6 fcntl() failed: %s.\n",
			strerror(errno));
		abort();
	}

	/* IPv4 listen address */
	memset(&source_ipv4, 0, sizeof(source_ipv4));
	source_ipv4.sin_family = AF_INET;
	source_ipv4.sin_port = htons(port);
	source_ipv4.sin_addr.s_addr = htonl(INADDR_ANY);
	result = bind(socket_ipv4, (struct sockaddr *) &source_ipv4,
		sizeof(source_ipv4));
	assert(result == 0);

	result = listen(socket_ipv4, TCP_LISTEN_QUEUE);
	if (result != 0)
	{
		fprintf(stderr,"Error in listen() ipv4: %s\n", strerror(errno));
		abort();
	}

	return socket_ipv4;
}


static int accept_connection(int socket)
{
	int newsock, pid;

	newsock = accept(socket, NULL, NULL);
	if (newsock == -1)
		return 0;

	/* We don't use child_fork(), as it's only for the _main parent_ */
	pid = fork();

	if (pid == 0)
	{
		/* Child */
		close(socket);
		send(newsock, "hola\n", 5, 0);
		close(newsock);
		exit(0);
		/* Unreachable */
	} else if (pid > 0)
	{
		/* Parent */
		close(newsock);
	}
	else
		return -1;

	return 0;
}