#include <sys/types.h>

#include <unistd.h>

#include <errno.h>

#include <stdbool.h>

#include <signal.h>

#include <stdio.h> // Per sprintf, fprintf

#include <string.h> // Per memset

#include <assert.h> // Pels assert

#include <stdlib.h> // Per l'abort

#include <fcntl.h> // Per l'open

#include <sys/stat.h> // Per l'open

#include <sys/select.h> // Pel select()

#include "rfc3164.h"

#include "syslog.h"

/* Program names */

static const char syslog_in_unix[] = "syslog_in_unix";

static const char syslog_in_npipe[] = "syslog_in_npipe";

static const char syslog_in_udp[] = "syslog_in_udp";

/* Global variables */

static bool reconfig = false;

/* Code */

static void term_handler(int parameter)

{

	term_childs();

}

static void reconfig_handler(int parameter)

{

	reconfig = true;

}

static int run_program(const char * restrict programname,

		const char * restrict parameter1, const int comm_pipe[])

{

	int pid;

	pid = child_fork();

	assert(pid != -1);

	if (pid == 0)

	{

		close(0);

		close(1);

		dup(comm_pipe[0]);

		dup(comm_pipe[1]);

		execl(programname, programname, parameter1, NULL);

		/* Unreachable if everything goes well */

		fprintf(stderr, "Child exec failed(%s %s): %s\n",

			programname, parameter1, strerror(errno));

		abort();

		return 0;

	}

	else

	{

		fprintf(stderr, "Child forked(%s %s): %i\n",

			programname, parameter1, pid);

		return pid;

	}

}

static int init_in_unix(const char * restrict socketname,

		const int input_pipe[2])

{

	return run_program(syslog_in_unix, socketname, input_pipe);

}

static int init_in_udp(const char * restrict port, const int input_pipe[2])

{

	return run_program(syslog_in_udp, port, input_pipe);

}

static int init_in_npipe(const char * restrict pipename,

		const int input_pipe[2])

{

	return run_program(syslog_in_npipe, pipename, input_pipe);

}

static void start_childs(const int input_pipe[2])

{

	char cvalue[MAX_STRING];

	/* The childs should not run */

	if (get_config(FROM_UNIX, cvalue, MAX_STRING) > 0)

	{

		init_in_unix(cvalue, input_pipe);

	}

	if (get_config(FROM_NPIPE, cvalue, MAX_STRING) > 0)

	{

		init_in_npipe(cvalue, input_pipe);

	}

	if (get_config(FROM_UDP, cvalue, MAX_STRING) > 0)

	{

		init_in_udp(cvalue, input_pipe);

	}

}

static int output_message(const char * restrict msg, const int len)

{

	int res1, res2, res;

	res = 0;

	res1 = write_out_udp(msg, len);

	res2 = write_out_file(msg, len);

	if (res1 == -1 || res2 == -1)

		res = -1;

	return res;

}

static void kernel_loop()

{

	int input_pipe[2];

	char missatge[MESSAGE_LENGTH+1];

	int res; /* resultat de la crida read */

	fd_set read_fd_set;

	struct timeval read_timeout;

	/* Pipe for the childs */

	pipe(input_pipe);

	start_childs(input_pipe);

	/* We don't want to write to the programs */

	close(input_pipe[1]);

	FD_ZERO(&read_fd_set);

	while(true)

	{

		/* pipe read handle */

		if (FD_ISSET(input_pipe[0], &read_fd_set))

		{

			res = read(input_pipe[0], missatge, MESSAGE_LENGTH);

			assert( res != -1 );

			if (res > 0)

			{

				/* Output to screen */

				/* Add a ZERO for displaying */

				missatge[res] = '\0';

				fprintf(stderr, "Received: %s\n",missatge);

				process_message(missatge);

				output_message(missatge, res);

			} else if (res == 0) /* EOF */

			{

				break;

			}

		}

		/* The select call may be interrupted by a signal */

		if (get_childs_alive() == 0)

			break;

		if (reconfig == true)

			break;

		/* Prepare the fd_set */

		FD_ZERO(&read_fd_set);

		FD_SET(input_pipe[0], &read_fd_set);

		/* We set the timeout in order to save us easily from the race

		 * condition for signal receiving (select/pselect) */

		read_timeout.tv_sec = 5;

		read_timeout.tv_usec = 0;

		res = select(input_pipe[0]+1, &read_fd_set, NULL, NULL,

				&read_timeout);

		if (res == -1)

			FD_ZERO(&read_fd_set);

		assert( !(res == -1 && errno != EINTR) );

	}

	close(input_pipe[0]);

}

static void install_signal_handlers()

{

	program_child_handler(child_handler);

	program_handler(SIGTERM, term_handler);

	program_handler(SIGINT, term_handler);

	program_handler(SIGHUP, reconfig_handler);

}

static void check_pid()

{

	int fh;

	char name[MAX_STRING];

	char buffer[MAX_STRING];

	int buffer_size;

	int pid, res;

	assert (get_config(PID_FILE, name, MAX_STRING) > 0);

	fh = open(name, O_RDONLY);

	if (fh == -1)

	{

		/* If the file doesn't exist, it's normal. */

		return;

	}

	buffer_size = MAX_STRING;

	buffer_size = read(fh, buffer, buffer_size);

	if (buffer_size <= 0)

	{

		fprintf(stderr, "Error reading the pid file: %s\n",

				strerror(errno));

		close(fh);

		return;

	}

	buffer[buffer_size] = '\0';

	pid = atoi(buffer);

	if (pid > 0)

	{

		res = kill(pid, SIGHUP);

		if (res == 0)

		{

			/* The syslog_kernel seems to be running and restared */

			fprintf(stderr,"syslog_kernel running. Restarted.\n");

			close(fh);

			exit(0);

		} else if (res == -1)

		{

			fprintf(stderr,"An old pid file has been found. "

				"Ignoring it.\n");

		}

	}

	close(fh);

}

static void write_pid()

{

	int fh;

	char name[MAX_STRING];

	char buffer[MAX_STRING];

	int buffer_size;

	int res;

	assert (get_config(PID_FILE, name, MAX_STRING) > 0);

	fh = open(name, O_WRONLY | O_TRUNC | O_CREAT, 0644);

	if (fh == -1)

	{

		fprintf(stderr, "Error opening the pid file for write: %s\n",

				strerror(errno));

		return;

	}

	buffer_size = snprintf(buffer, MAX_STRING, "%i", getpid());

	if (buffer_size < MAX_STRING)

	{

		buffer[buffer_size++] = '\n';

	}

	res = write(fh, buffer, buffer_size);

	if (buffer_size <= 0)

		fprintf(stderr, "Error writting the pid file: %s\n",

				strerror(errno));

	close(fh);

}

static void remove_pid()

{

	int res;

	char name[MAX_STRING];

	assert (get_config(PID_FILE, name, MAX_STRING) > 0);

	res = unlink(name);

	if (res == -1)

		fprintf(stderr, "Error unlinking the pid file: %s\n",

				strerror(errno));

}

int main(int argn, char *argv[])

{

	int res;

	check_pid();

	write_pid();

	install_signal_handlers();

	do

	{

		reconfig = false;

		init_config();

		res = init_out_udp();

		if (res == -2)

			fprintf(stderr, "UDP output disabled.\n");

		else if (res == -1)

			fprintf(stderr, "error setting up the UDP output.\n");

		res = init_out_file();

		if (res == -2)

			fprintf(stderr, "File output disabled.\n");

		else if (res == -1)

			fprintf(stderr, "error setting up the File output.\n");

		init_tcp_server();

		kernel_loop();

		if (reconfig == true)

			fprintf(stderr, "reconfiguring...\n");

		close_out_tcp();

		term_childs();

		close_out_udp();

		close_out_file();

		wait_childs_die();

	}

	while(reconfig == true);

	remove_pid();

}