#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/wait.h>

/* sysexits.h conventions */
#define EX_OK          0
#define EX_USAGE       64
#define EX_UNAVAILABLE 69
#define EX_OSERR       71

static int qflag = 0;
static long int tvalue = -1;

static void die(const int, const char *, ...);
static int getyes(void);
static int respawn(void);

void
die(const int ret, const char *errstr, ...)
{
	va_list ap;

	va_start(ap, errstr);
	vfprintf(stderr, errstr, ap);
	va_end(ap);
	exit(ret);
}

int
getyes(void)
{
    int yes;
    char *line = NULL;
    size_t len = 0;

    getline(&line, &len, stdin);
    yes = !strcmp(line, "yes\n");
    free(line);
    return yes;
}

int
respawn(void)
{
	if (!qflag) {
		printf("The command finished. "
		        "Please enter \"yes\" if you want to exit: ");
		fflush(stdout);
	}

	if (!tvalue) {
		printf("\n");
		return 0;
	} else if (tvalue < 0) {
		return getyes();
	} else {
		fd_set rfds;
		int retval;
		struct timeval tv;

		tv.tv_sec = tvalue;
		tv.tv_usec = 0;

		FD_ZERO(&rfds);
		FD_SET(0, &rfds);

		if ((retval = select(1, &rfds, NULL, NULL, &tv)) < 0) {
			die(EX_OSERR, "Unable to read input\n");
			/* NOTREACHED */
			return 0;
		} else if (retval) {
			return getyes();
		} else {
			printf("\n");
			return 0;
		}
	}
}

int
main(int argc, char **argv)
{
	char *cmd = NULL;
	char *ptr = NULL;
	int c, i, returnStatus;
	int mvalue = -1;
	pid_t pid;

	if (!isatty(1))
		die(EX_UNAVAILABLE, "%s: not connected to a terminal", argv[0]);

	while ((c = getopt(argc, argv, "+hm:qst:Vy")) != -1) {
		switch(c) {
		case 'h':
			die(EX_USAGE,
			    "%s: [-hqVy] [-m max] [-t timeout] "
			    "utility [argument...]\n", argv[0]);
		case 'm':
			if ((mvalue = strtol(optarg, &ptr, 10)) < 1)
				die(EX_USAGE, "-m value must be positive\n");
			if (!strcmp(optarg, ptr) || errno == EINVAL)
				die(EX_USAGE, "-m value must be a number\n");
			if (errno == ERANGE)
				die(EX_USAGE, "-m value out of range\n");
			break;
		case 'q':
			qflag = 1;
			break;
		case 't':
			if ((tvalue = strtol(optarg, &ptr, 10)) < 0)
				die(EX_USAGE, "-t value may not be negative\n");
			if (!strcmp(optarg, ptr) || errno == EINVAL)
				die(EX_USAGE, "-t value must be a number\n");
			if (errno == ERANGE)
				die(EX_USAGE, "-t value out of range\n");
			break;
		case 'V':
			die(EX_USAGE, "fenix 0.2\n");
		case 'y':
			tvalue = 0;
			break;
		case '?':
			exit(EX_USAGE);
		}
	}

	if (argc <= optind) die(EX_USAGE, "No command provided\n");
	cmd = argv[optind];
	for (i = 0; i < optind; ++i) ++argv;

	while (mvalue) {
		switch (pid = fork()) {
		case -1:
			die(EX_OSERR, "failed to fork\n");
		case 0:
			if (!qflag) {
				printf("Running \"");
				for (i = 0; i < argc - optind; ++i)
					printf("%s ", argv[i]);
				printf("\b\"\n");
			}
			if (execvp(argv[0], argv) < 0)
				_exit(EX_UNAVAILABLE);
			else
				_exit(EX_OK);
		default:
			waitpid(pid, &returnStatus, 0);
			if (WEXITSTATUS(returnStatus) == EX_UNAVAILABLE)
				die(EX_UNAVAILABLE,
				    "Cannot execute file \"%s\"\n", cmd);
			if (mvalue && mvalue != 1 && tvalue)
				if (respawn() || feof(stdin))
					exit(EX_OK);
			if (mvalue > 0) --mvalue;
		}
	}
}