/*
 * Copyright (c) 2000 Satoru Takabayashi <satoru@namazu.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

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

#include "ttyrec.h"
#include "io.h"

typedef double	(*WaitFunc)	(struct timeval prev, 
				 struct timeval cur, 
				 double speed);
typedef int	(*ReadFunc)	(FILE *fp, Header *h, char **buf);
typedef void	(*WriteFunc)	(char *buf, int len);
typedef void	(*ProcessFunc)	(FILE *fp, double speed, 
				 ReadFunc read_func, WaitFunc wait_func);

struct timeval
timeval_diff (struct timeval tv1, struct timeval tv2)
{
    struct timeval diff;

    diff.tv_sec = tv2.tv_sec - tv1.tv_sec;
    diff.tv_usec = tv2.tv_usec - tv1.tv_usec;
    if (diff.tv_usec < 0) {
	diff.tv_sec--;
	diff.tv_usec += 1000000;
    }

    return diff;
}

struct timeval
timeval_div (struct timeval tv1, double n)
{
    double x = ((double)tv1.tv_sec  + (double)tv1.tv_usec / 1000000.0) / n;
    struct timeval div;
    
    div.tv_sec  = (int)x;
    div.tv_usec = (x - (int)x) * 1000000;

    return div;
}

double
ttywait (struct timeval prev, struct timeval cur, double speed)
{
    static struct timeval drift = {0, 0};
    struct timeval start;
    struct timeval diff = timeval_diff(prev, cur);
    fd_set readfs;

    gettimeofday(&start, NULL);

    assert(speed != 0);
    diff = timeval_diff(drift, timeval_div(diff, speed));
    if (diff.tv_sec < 0) {
	diff.tv_sec = diff.tv_usec = 0;
    }

    FD_SET(STDIN_FILENO, &readfs);
    /* 
     * We use select() for sleeping with subsecond precision.
     * select() is also used to wait user's input from a keyboard.
     *
     * Save "diff" since select(2) may overwrite it to {0, 0}. 
     */
    struct timeval orig_diff = diff;
    select(1, &readfs, NULL, NULL, &diff);
    diff = orig_diff;  /* Restore the original diff value. */
    if (FD_ISSET(0, &readfs)) { /* a user hits a character? */
        char c;
        read(STDIN_FILENO, &c, 1); /* drain the character */
        switch (c) {
        case '+':
        case 'f':
            speed *= 2;
            break;
        case '-':
        case 's':
            speed /= 2;
            break;
        case '1':
            speed = 1.0;
            break;
        }
	drift.tv_sec = drift.tv_usec = 0;
    } else {
	struct timeval stop;
	gettimeofday(&stop, NULL);
	/* Hack to accumulate the drift */
	if (diff.tv_sec == 0 && diff.tv_usec == 0) {
            diff = timeval_diff(drift, diff);  // diff = 0 - drift.
        }
	drift = timeval_diff(diff, timeval_diff(start, stop));
    }
    return speed;
}

double
ttynowait (struct timeval prev, struct timeval cur, double speed)
{
    /* do nothing */
    return 0; /* Speed isn't important. */
}

int
ttyread (FILE *fp, Header *h, char **buf)
{
    if (read_header(fp, h) == 0) {
	return 0;
    }

    *buf = malloc(h->len);
    if (*buf == NULL) {
	perror("malloc");
    }
	
    if (fread(*buf, 1, h->len, fp) == 0) {
	perror("fread");
    }
    return 1;
}

int
ttypread (FILE *fp, Header *h, char **buf)
{
    /*
     * Read persistently just like tail -f.
     */
    while (ttyread(fp, h, buf) == 0) {
	struct timeval w = {0, 250000};
	select(0, NULL, NULL, NULL, &w);
	clearerr(fp);
    }
    return 1;
}

void
ttywrite (char *buf, int len)
{
    fwrite(buf, 1, len, stdout);
}

void
ttynowrite (char *buf, int len)
{
    /* do nothing */
}

void
ttyplay (FILE *fp, double speed, ReadFunc read_func, 
	 WriteFunc write_func, WaitFunc wait_func)
{
    int first_time = 1;
    struct timeval prev;

    setbuf(stdout, NULL);
    setbuf(fp, NULL);

    while (1) {
	char *buf;
	Header h;

	if (read_func(fp, &h, &buf) == 0) {
	    break;
	}

	if (!first_time) {
	    speed = wait_func(prev, h.tv, speed);
	}
	first_time = 0;

	write_func(buf, h.len);
	prev = h.tv;
	free(buf);
    }
}

void
ttyskipall (FILE *fp)
{
    /*
     * Skip all records.
     */
    ttyplay(fp, 0, ttyread, ttynowrite, ttynowait);
}

void ttyplayback (FILE *fp, double speed, 
		  ReadFunc read_func, WaitFunc wait_func)
{
    ttyplay(fp, speed, ttyread, ttywrite, wait_func);
}

void ttypeek (FILE *fp, double speed, 
	      ReadFunc read_func, WaitFunc wait_func)
{
    ttyskipall(fp);
    ttyplay(fp, speed, ttypread, ttywrite, ttynowait);
}


void
usage (void)
{
    printf("Usage: ttyplay [OPTION] [FILE]\n");
    printf("  -s SPEED Set speed to SPEED [1.0]\n");
    printf("  -n       No wait mode\n");
    printf("  -p       Peek another person's ttyrecord\n");
    exit(EXIT_FAILURE);
}

/*
 * We do some tricks so that select(2) properly works on
 * STDIN_FILENO in ttywait().
 */
FILE *
input_from_stdin (void)
{
    FILE *fp;
    int fd = edup(STDIN_FILENO);
    edup2(STDOUT_FILENO, STDIN_FILENO);
    return efdopen(fd, "r");
}

int 
main (int argc, char **argv)
{
    double speed = 1.0;
    ReadFunc read_func  = ttyread;
    WaitFunc wait_func  = ttywait;
    ProcessFunc process = ttyplayback;
    FILE *input = NULL;
    struct termios old, new;

    set_progname(argv[0]);
    while (1) {
        int ch = getopt(argc, argv, "s:np");
        if (ch == EOF) {
            break;
	}
	switch (ch) {
	case 's':
	    if (optarg == NULL) {
		perror("-s option requires an argument");
		exit(EXIT_FAILURE);
	    }
	    sscanf(optarg, "%lf", &speed);
	    break;
	case 'n':
	    wait_func = ttynowait;
	    break;
	case 'p':
	    process = ttypeek;
	    break;
	default:
	    usage();
	}
    }

    if (optind < argc) {
	input = efopen(argv[optind], "r");
    } else {
        input = input_from_stdin();
    }
    assert(input != NULL);

    tcgetattr(0, &old); /* Get current terminal state */
    new = old;          /* Make a copy */
    new.c_lflag &= ~(ICANON | ECHO | ECHONL); /* unbuffered, no echo */
    tcsetattr(0, TCSANOW, &new); /* Make it current */

    process(input, speed, read_func, wait_func);
    tcsetattr(0, TCSANOW, &old);  /* Return terminal state */

    return 0;
}