/*
 * atc.web.c: the update timer of Atc in the browser (fredygames.com). The game asks the system for a SIGALRM
 * every few seconds (setitimer/alarm) and runs update() in the signal handler, while it waits for a key. Here
 * there are no signals: setitimer() and alarm() only record the deadline, and atc_getchar() (which replaces
 * getchar(), see include.h) runs update() when the deadline passes while it waits for a key from the page
 * (curses-web/curses.c), which is what the signal did.
 * Copyright (C) 2026 FredyGames. Distributed under the MIT License (see curses-web/LICENSE).
 */
#include <emscripten.h>
#include <sys/time.h>
#include <unistd.h>

#include "curses.h"

extern void update(int);
extern void quit(int);

static double deadline = -1.0; /* ms (emscripten_get_now), < 0: timer off */
static double interval = 0.0;  /* ms, 0: one shot */

static double to_ms(const struct timeval *tv) {
    return tv->tv_sec * 1000.0 + tv->tv_usec / 1000.0;
}

int setitimer(int which, const struct itimerval *restrict value, struct itimerval *restrict old) {
    (void)which;
    if (old != NULL) {
        double left = deadline < 0 ? 0 : deadline - emscripten_get_now();
        if (left < 0) left = 0;
        old->it_value.tv_sec = (time_t)(left / 1000);
        old->it_value.tv_usec = (suseconds_t)((left - old->it_value.tv_sec * 1000.0) * 1000);
        old->it_interval.tv_sec = (time_t)(interval / 1000);
        old->it_interval.tv_usec = (suseconds_t)((interval - old->it_interval.tv_sec * 1000.0) * 1000);
    }
    if (value != NULL) {
        double first = to_ms(&value->it_value);
        interval = to_ms(&value->it_interval);
        deadline = first > 0 ? emscripten_get_now() + first : -1.0;
    }
    return 0;
}

unsigned int alarm(unsigned int seconds) {
    double left = deadline < 0 ? 0 : (deadline - emscripten_get_now()) / 1000;
    interval = 0;
    deadline = seconds > 0 ? emscripten_get_now() + seconds * 1000.0 : -1.0;
    return left > 0 ? (unsigned int)(left + 0.999) : 0;
}

int atc_getchar(void) {
    for (;;) {
        int wait = -1;
        if (deadline >= 0) {
            double now = emscripten_get_now();
            if (now >= deadline) {
                deadline = interval > 0 ? deadline + interval : -1.0;
                if (deadline >= 0 && deadline < now) deadline = now + interval;
                update(0);
                continue;
            }
            wait = (int)(deadline - now + 0.999);
        }
        int k = cw_getkey(wait);
        if (k == 3) { /* ^C: SIGINT, which the game catches to ask "Really quit?" */
            quit(0);
            continue;
        }
        if (k != ERR) return k == '\r' ? '\n' : k; /* the game sets ICRNL on the tty: Enter is '\n' */
    }
}

/* flex's end-of-input hook (the game links -ll on Unix). */
int yywrap(void) {
    return 1;
}