#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <poll.h>
#include <string.h>

struct timer {
  int m;
  int s;
  void (*u)(struct timer *t);
  int (*c)(struct timer *t);
};

struct settings {
  int e:1; /* use escape (v assumed) */
  int v:1; /* verbose */
  int d:1; /* count down/up (1/0) */
  int b:1; /* ascii bel when done */
  int f:1; /* display hours */
  int m; /* minutes */
  int s; /* seconds */
} settings = {
  .e = 0,
  .v = 0,
  .d = 0,
  .b = 0,
  .f = 0,
  .m = 0,
  .s = 0
};

void timerdec(struct timer *t) {
  if(t->s > 0) t->s--;
  else if(t->s == 0) {
    t->s = 59;
    t->m--;
  }
}

void timerinc(struct timer *t) {
  if(t->s < 59) t->s++;
  else if(t->s == 59) {
    t->s = 0;
    t->m++;
  }
}

void timerupdate(struct timer *t) {
  if(t->u != NULL) t->u(t);
}

int timerstate(struct timer *t) {
  if(t->c != NULL) {
    if(t->c(t)) return 1;
    else return 0;
  }
  return 0;
}

int timerzero(struct timer *t) {
  if(t->m == 0 && t->s == 0) return 1;
  return 0;
}

int timerissettings(struct timer *t) {
  if(t->m == 0 && t->s == 0) return 0;
  if(t->m == settings.m &&
    t->s == settings.s) return 1;
  return 0;
}

char *timerdisp(struct timer *t) {
  char *str = malloc(20);
  if(settings.f) snprintf(str, 20, "%02i:%02i:%02i",
    (t->m / 60), (t->m % 60), t->s);
  else snprintf(str, 20, "%02i:%02i", t->m, t->s);
  return str;
}

struct timer *timerinit(void) {
  struct timer *t = malloc(sizeof t);
  t->m = 0;
  t->s = 0;
  t->u = NULL;
  t->c = NULL;
  return t;
}

void timerloop() {
  struct timer *t = timerinit();
  if(settings.d) {
    t->u = timerdec;
    t->m = settings.m;
    t->s = settings.s;
    t->c = timerzero;
  } else {
    t->u = timerinc;
    t->c = timerissettings;
  }
  char *c;
  struct pollfd *p = malloc(sizeof p);
  p->fd = STDIN_FILENO;
  p->events = POLLIN;
  for(;;) {
    poll(p, 1, 60);
    if(p->revents == POLLIN) {
      /* TODO: make this nicer */
      getchar();
      if(settings.e) {
        c = timerdisp(t);
        printf("\r\e[1A* %s", c);
      }
      getchar();
      /* TODO: stop relying on hard assumptions */
      if(settings.e) printf("\r\e[1A           \r", c);
    }
    c = timerdisp(t);
    if(settings.e) {
      printf("%s\r", c);
      fflush(stdout);
    }
    else if(settings.v) printf("%s\n", c);
    if(timerstate(t)) break;
    timerupdate(t);
    sleep(1);
  }
  if(settings.b) putchar('\a');
}

int main(int argc, char **argv) {
  char c;
  while((c = getopt (argc, argv, "evdbfm:s:")) != -1) {
    switch(c) {
      case 'e':
        settings.e = 1;
        break;
      case 'v':
        settings.v = 1;
        break;
      case 'd':
        settings.d = 1;
        break;
      case 'b':
        settings.b = 1;
        break;
      case 'f':
        settings.f = 1;
        break;
      case 'm':
        settings.m = atoi(optarg);
        break;
      case 's':
        settings.s = atoi(optarg);
        break;
      case '?':
        return 1;
      default:
        abort();
        break;
    }
  }
  timerloop();
  return 0;
}