/*
 * neocon.c - An interface for changing tty devices
 *
 * Copyright (C) 2007, 2008 by OpenMoko, Inc.
 * Copyright 2011, 2013 by Werner Almesberger
 * Written by Werner Almesberger <werner@almesberger.net>
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */


#include <stdlib.h>
#include <stdio.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <termios.h>
#include <fcntl.h>
#include <assert.h>
#include <sys/time.h>
#include <sys/select.h>


#define MAX_BUF 2048

static char *const *ttys;
static int num_ttys;
static int curr_tty = -1; /* start with first tty */
static speed_t speed = B115200;
static struct termios console, tty;
static FILE *log = NULL;
static int timestamp = 0;
static char escape = '~';


static struct bps {
	speed_t speed;
	int bps;
} bps_tab[] = {
	{ B300,       300 },
	{ B1200,     1200 },
	{ B2400,     2400 },
	{ B9600,     9600 },
	{ B19200,   19200 },
	{ B38400,   38400 },
	{ B57600,   57600 },
	{ B115200, 115200 },
	{ 0, 0 }
};


static speed_t bps_to_speed(int bps)
{
	const struct bps *p;

	for (p = bps_tab; p->bps; p++)
		if (p->bps == bps)
			return p->speed;
	fprintf(stderr, "no such speed: %d bps\n", bps);
	exit(1);
}


static void make_raw(int fd, struct termios *old, int cr)
{
	struct termios t;
	long flags;

	if (tcgetattr(fd, &t) < 0) {
		perror("tcgetattr");
		exit(1);
	}
	if (old)
		*old = t;
	cfmakeraw(&t);
	if (fd) {
		t.c_iflag &= ~(IXON | IXOFF);
		t.c_cflag |= CLOCAL;
		t.c_cflag &= ~CRTSCTS;
		if (cfsetispeed(&t, speed) < 0) {
			perror("cfsetispeed");
			exit(1);
		}
		if (cfsetospeed(&t, speed) < 0) {
			perror("cfsetospeed");
			exit(1);
		}
	}
	if (cr)
		t.c_oflag |= OPOST | ONLCR;
	if (tcsetattr(fd, TCSANOW, &t) < 0) {
		perror("tcsetattr");
		exit(1);
	}
	flags = fcntl(fd, F_GETFL);
	if (flags < 0) {
		perror("fcntl F_GETFL");
		exit(1);
	}
	if (fcntl(fd, F_SETFL, flags & ~O_NONBLOCK) < 0) {
		perror("fcntl F_GETFL");
		exit(1);
	}
}


static int open_next_tty(void)
{
	int i, fd = -1;

	for (i = 0; i != num_ttys; i++) {
		curr_tty = (curr_tty+1) % num_ttys;
		fd = open(ttys[curr_tty], O_RDWR | O_NDELAY);
		if (fd >= 0)
			break;
	}
	if (fd >= 0)
		make_raw(fd, &tty, 0);
    	return fd;
}


/*
 * Return 1 if the user manually forces a device change.
 */


static int scan(const char *s, size_t len)
{
	static int state = 0;
	const char *p;
	int res = 0;

	for (p = s; p != s+len; p++)
		switch (state) {
		case 0:
			if (*p == escape)
				state++;
			else
				state = 0;
			break;
		case 1:
			if (*p == '.')
				exit(0);
			if (*p == 'n')
				res = 1;
			state = 0;
			break;
		}
	return res;
}


static int write_log(const char *buf, ssize_t len)
{
	size_t wrote;

	wrote = fwrite(buf, 1, len, log);
	if (wrote == len)
		return 1;
	fprintf(stderr, "write failed. closing log file.\n");
	fclose(log);
	log = NULL;
	return 0;
}


static int add_timestamp(void)
{
	struct timeval tv;
	char buf[40]; /* be generous */
	int len;

	if (gettimeofday(&tv, NULL) < 0) {
		perror("gettimeofday");
		exit(1);
	}
	len = sprintf(buf, "%lu.%06lu ",
	    (unsigned long) tv.tv_sec, (unsigned long) tv.tv_usec);
	return write_log(buf, len);
}


static void do_log(const char *buf, ssize_t len)
{
	static int nl = 1; /* we're at the beginning of a new line */
	char tmp[MAX_BUF];
	const char *from;
	char *to;

	assert(len <= MAX_BUF);
	from = buf;
	to = tmp;
	while (from != buf+len) {
		if (*from == '\r') {
			from++;
			continue;
		}
		if (nl && timestamp)
			if (!add_timestamp())
				return;
		nl = 0;
		if (*from == '\n') {
			*to++ = *from++;
			if (!write_log(tmp, to-tmp))
				return;
			to = tmp;
			nl = 1;
			continue;
		}
		*to++ = *from < ' ' || *from > '~' ? '#' : *from;
		from++;
	}
	write_log(tmp, to-tmp);
}


static int copy(int in, int out, int from_user, int single)
{
	char buffer[MAX_BUF];
	ssize_t got, wrote, pos;

	got = read(in, buffer, single ? 1 : sizeof(buffer));
	if (got <= 0)
		return 0;
	if (from_user) {
		if (scan(buffer, got))
			return 0;
	} else {
		if (log)
			do_log(buffer, got);
	}
	for (pos = 0; pos != got; pos += wrote) {
		wrote = write(out, buffer+pos, got-pos);
		if (wrote < 0)
			return 0;
	}
	return 1;
}


static void write_string(const char *s)
{
	int len = strlen(s);

	while (len) {
		ssize_t wrote;

		wrote = write(1, s, len);
		if (wrote < 0) {
			perror("write");
			exit(1);
		}
		s += wrote;
		len -= wrote;
	}
}


static void cleanup(void)
{
	if (tcsetattr(0, TCSANOW, &console) < 0)
		perror("tcsetattr");
	write(1, "\n", 1);
}


static void usage(const char *name)
{
	fprintf(stderr,
"usage: %s [-b bps] [-c] [-e escape] [-l logfile [-a] [-T]] [-t delay_ms] "
    "tty ...\n\n"
"  -a           append to the log file if it already exists\n"
"  -b bps       set the TTY to the specified bit rate\n"
"  -c           add carriage return before newline (on console)\n"
"  -e escape    set the escape character (default: ~)\n"
"  -l logfile   log all output to the specified file\n"
"  -t delay_ms  wait the specified amount of time between input characters\n"
"  -T           add timestamps to the log file\n"
	    , name);
	exit(1);
}


int main(int argc, char *const *argv)
{
	char *end;
	int c, bps, cr = 0;
	int fd = -1;
	int append = 0;
	const char *logfile = NULL;
	int throttle_us = 0;
	int throttle = 0;

	while ((c = getopt(argc, argv, "ab:ce:l:t:T")) != EOF)
		switch (c) {
		case 'a':
			append = 1;
			break;
		case 'b':
			bps = strtoul(optarg, &end, 0);
			if (*end)
		    		usage(*argv);
			speed = bps_to_speed(bps);
			break;
		case 'c':
			cr = 1;
			break;
		case 'e':
			if (strlen(optarg) != 1)
				usage(*argv);
			escape = *optarg;
			break;
		case 'l':
			logfile = optarg;
			break;
		case 't':
			throttle_us = strtoul(optarg, &end, 0)*1000;
			if (*end)
				usage(*argv);
			break;
		case 'T':
			timestamp = 1;
			break;
		default:
			usage(*argv);
	}
	num_ttys = argc-optind;
	ttys = argv+optind;

	if (logfile) {
		log = fopen(logfile, append ? "a" : "w");
		if (!log) {
			perror(logfile);
			exit(1);
		}
		setlinebuf(log);
	}

	make_raw(0, &console, cr);
	atexit(cleanup);
	while (1) {
		struct timeval tv;
		fd_set set;
		int res;

		if (fd < 0) {
			fd = open_next_tty();
			if (fd > 0) {
				char buf[1024]; /* enough :-) */

				sprintf(buf, "\r\r[Open %s]\r\n",
				    ttys[curr_tty]);
				write_string(buf);
			}
		}
		FD_ZERO(&set);
		if (!throttle)
			FD_SET(0, &set);
		if (fd >= 0)
			FD_SET(fd, &set);
		tv.tv_sec = 0;
		tv.tv_usec = throttle ? throttle_us : 100000;
		res = select(fd < 0 ? 1 : fd+1, &set, NULL, NULL, &tv);
		if (res < 0) {
			perror("select");
			return 1;
		}
		if (!res)
			throttle = 0;
		if (FD_ISSET(0, &set)) {
			if (throttle_us)
				throttle = 1;
			if (!copy(0, fd, 1, throttle_us != 0))
				goto failed;
		}
		if (fd >= 0 && FD_ISSET(fd, &set))
			if (!copy(fd, 1, 0, 0))
				goto failed;
		continue;

failed:
		write_string("\r\n[Closed]\r\n");
		(void) close(fd);
		fd = -1;
	}
	return 0;
}