/* ttym - countdown / stopwatch in a single C file.
 * See LICENSE file for copyright and license details.
 */
#define _POSIX_C_SOURCE 200809L
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>

#include "config.h"

/* ===== types & globals ===== */

typedef struct {
	int quiet;            /* -q: suppress completion bell */
	int silent;           /* -s: no bell, no extras */
	int alert_persist;    /* alert loop until keypress; --no-persist disables */
	int flash;            /* reverse-video flash during alert loop */
	char bar_style[32];   /* --bar STYLE */
} Config;

static struct termios oldtios;
static int ttyfd = -1;
static int rawset = 0;
static volatile sig_atomic_t interrupted = 0;

/* exposed for patches that read the final elapsed seconds at exit */
static long elapsed_s = 0;

/* nonzero once stdout is confirmed a tty; gates cursor/redraw escapes */
static int out_tty = 0;

/* ===== helpers ===== */

static void
sleep_ms(int ms)
{
	struct timespec ts = { ms / 1000, (long)(ms % 1000) * 1000000L };
	nanosleep(&ts, NULL);
}

static long
now_ms(void)
{
	struct timespec ts;
	clock_gettime(CLOCK_MONOTONIC, &ts);
	return ts.tv_sec * 1000L + ts.tv_nsec / 1000000L;
}

static int
term_cols(void)
{
	struct winsize ws;
	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0)
		return ws.ws_col;
	return 80;
}

static long
elapsed(long start_ms, long pause_accum, long pause_start, int paused)
{
	long ms = (paused ? pause_start : now_ms()) - start_ms - pause_accum;
	return ms < 0 ? 0 : ms;
}

static void
on_signal(int sig)
{
	(void)sig;
	interrupted = 1;
}

static int
parse_bool_str(const char *v)
{
	return !strcasecmp(v, "true") || !strcasecmp(v, "yes") ||
	       !strcmp(v, "1")        || !strcasecmp(v, "on");
}

static void
restore_tty(void)
{
	if (rawset && ttyfd >= 0)
		tcsetattr(ttyfd, TCSANOW, &oldtios);
	rawset = 0;
	if (out_tty) {
		fputs("\033[?5l\033[?7h\033[?25h", stdout);  /* clear reverse, re-enable wrap, show cursor */
		fflush(stdout);
	}
}

/* ===== duration parsing =====
 * accepts: 25m | 90s | 2h | 1h30m | 01:30:00 | 25:00
 */

static int
parse_uint(const char *s, size_t n, long *out)
{
	long v = 0;
	if (n == 0) return -1;
	for (size_t i = 0; i < n; i++) {
		if (!isdigit((unsigned char)s[i])) return -1;
		v = v * 10 + (s[i] - '0');
		if (v > 1000000) return -1;
	}
	*out = v;
	return 0;
}

static long
parse_duration(const char *s)
{
	size_t len = strlen(s);
	if (len == 0) return -1;

	if (strchr(s, ':')) {
		/* Split on ':' into 2 or 3 fields, then parse each with
		 * parse_uint. That rejects empty fields, signs and
		 * whitespace, and bounds every component -- so unlike a
		 * raw sscanf("%ld") this cannot overflow on huge input.
		 */
		const char *fld[3];
		size_t flen[3];
		int nf = 0;
		size_t fstart = 0;
		for (size_t i = 0; i <= len; i++) {
			if (i != len && s[i] != ':') continue;
			if (nf == 3) return -1;
			fld[nf] = s + fstart;
			flen[nf] = i - fstart;
			nf++;
			fstart = i + 1;
		}
		long v[3] = { 0, 0, 0 };
		for (int k = 0; k < nf; k++)
			if (parse_uint(fld[k], flen[k], &v[k]) < 0)
				return -1;
		long total;
		if (nf == 3) {
			if (v[1] >= 60 || v[2] >= 60) return -1;
			total = v[0] * 3600 + v[1] * 60 + v[2];
		} else {
			if (v[1] >= 60) return -1;
			total = v[0] * 60 + v[1];
		}
		return total > 0 ? total : -1;
	}

	long total = 0;
	size_t i = 0, start = 0;
	while (i < len) {
		if (isdigit((unsigned char)s[i])) { i++; continue; }
		if (s[i] != 'h' && s[i] != 'm' && s[i] != 's') return -1;
		long v;
		if (parse_uint(s + start, i - start, &v) < 0) return -1;
		switch (s[i]) {
		case 'h': total += v * 3600; break;
		case 'm': total += v * 60;   break;
		case 's': total += v;        break;
		}
		i++;
		start = i;
	}
	if (start != len) return -1;
	return total > 0 ? total : -1;
}

/* ===== formatting ===== */

static void
fmt_clock(long s, char *buf, size_t bufsz)
{
	long h = s / 3600; s %= 3600;
	long m = s / 60;  long sec = s % 60;
	if (h > 0) snprintf(buf, bufsz, "%02ld:%02ld:%02ld", h, m, sec);
	else       snprintf(buf, bufsz, "%02ld:%02ld", m, sec);
}

/* ===== drawing ===== */

static void
draw_countdown(long total, long elapsed_ms, int paused, int barw,
               const char *fill_glyph, const char *empty_glyph, int minimal)
{
	if (total <= 0) return;
	long total_ms = total * 1000L;
	if (elapsed_ms < 0) elapsed_ms = 0;
	if (elapsed_ms > total_ms) elapsed_ms = total_ms;
	long es = elapsed_ms / 1000;
	long remaining = total - es;
	long pct = (elapsed_ms * 100) / total_ms;
	int fill = (int)((long)barw * elapsed_ms / total_ms);
	if (fill > barw) fill = barw;
	int empty = barw - fill;

	char rem[24], el[24];
	fmt_clock(remaining, rem, sizeof(rem));
	fmt_clock(es, el, sizeof(el));

	const char *color  = paused ? "\033[36m" : "\033[33m";
	const char *status = paused ? "PAUSED " : "       ";

	printf("\r%sT-%s\033[0m \033[2m+%s\033[0m [", color, rem, el);
	if (minimal) {
		fputs("\033[7m", stdout);
		for (int i = 0; i < fill;  i++) fputc(' ', stdout);
		fputs("\033[27m", stdout);
		for (int i = 0; i < empty; i++) fputc(' ', stdout);
	} else {
		for (int i = 0; i < fill;  i++) fputs(fill_glyph,  stdout);
		for (int i = 0; i < empty; i++) fputs(empty_glyph, stdout);
	}
	printf("] %3ld%% %s", pct, status);
	fflush(stdout);
}

static void
draw_stopwatch(long elapsed_ms, int paused)
{
	long es = elapsed_ms / 1000;
	char el[24];
	fmt_clock(es, el, sizeof(el));
	const char *color  = paused ? "\033[36m" : "\033[32m";
	const char *status = paused ? "PAUSED " : "       ";
	printf("\r%sT+%s\033[0m %s\033[K", color, el, status);
	fflush(stdout);
}

/* ===== alert loop =====
 * Bell + poll for keypress, ~1.5s per beat; 4-min safety cap.
 */

static int
is_foreground(void)
{
	if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO)) return 0;
	pid_t pgrp = tcgetpgrp(STDIN_FILENO);
	if (pgrp < 0) return 0;
	return pgrp == getpgrp();
}

static void
alert_loop(int flash)
{
	fputs("\033[?25h\033[?7h", stdout);
	int ticks = 0;
	while (!interrupted) {
		fputc('\a', stdout);
		if (flash) fputs("\033[?5h", stdout);
		fflush(stdout);
		sleep_ms(150);
		if (flash) fputs("\033[?5l", stdout);
		fflush(stdout);

		int acked = 0;
		for (int i = 0; i < 15 && !interrupted; i++) {
			if (ttyfd < 0) { sleep_ms(100); continue; }
			struct pollfd pfd = { .fd = ttyfd, .events = POLLIN };
			int pr = poll(&pfd, 1, 100);
			if (pr > 0 && (pfd.revents & POLLIN)) {
				char ch;
				ssize_t rd = read(ttyfd, &ch, 1);
				if (rd >= 0) { acked = 1; break; }
			} else if (pr < 0) {
				sleep_ms(100);
			}
		}
		if (acked) break;
		if (++ticks > 160) break;
	}
	fflush(stdout);
}

/* ===== bar styles ===== */

typedef struct { const char *name, *fill, *empty; } BarStyle;

static const BarStyle bar_styles[] = {
	{ "unicode", "\xe2\x96\x88", "\xe2\x96\x91" },  /* U+2588 U+2591 */
	{ "ascii",   "=",            "-"            },
	{ "hash",    "#",            "."            },
	{ "dots",    "\xe2\x80\xa2", "\xc2\xb7"     },  /* U+2022 U+00B7 */
	{ "line",    "\xe2\x94\x81", "\xe2\x94\x80" },  /* U+2501 U+2500 */
	{ "block",   "\xe2\x96\x93", "\xe2\x96\x91" },  /* U+2593 U+2591 */
	{ "arrow",   "\xe2\x96\xb6", "\xe2\x96\xb7" },  /* U+25B6 U+25B7 */
	{ "minimal", "",             ""             },
	{ NULL,      NULL,           NULL           }
};

static const BarStyle *
find_bar_style(const char *name)
{
	if (!name || !*name) return NULL;
	for (int i = 0; bar_styles[i].name; i++)
		if (!strcmp(bar_styles[i].name, name)) return &bar_styles[i];
	return NULL;
}

static int
is_utf8(void)
{
	const char *l = setlocale(LC_CTYPE, "");
	if (!l) return 0;
	return strstr(l, "UTF-8") || strstr(l, "utf8") || strstr(l, "utf-8");
}

static void
resolve_bar(const Config *c, const char **fill, const char **empty, int *minimal)
{
	*minimal = 0;
	const char *name = (c->bar_style[0]) ? c->bar_style : BAR_STYLE;
	const BarStyle *s = find_bar_style(name);
	if (!s) s = find_bar_style(is_utf8() ? "unicode" : "ascii");
	if (s && !strcmp(s->name, "minimal")) {
		*minimal = 1;
		*fill = " "; *empty = " ";
		return;
	}
	*fill  = s ? s->fill  : BAR_FILL;
	*empty = s ? s->empty : BAR_EMPTY;
}

/* ===== usage =====
 * Patches MUST update this in lockstep with new flags so -h always
 * reflects the build.
 */

static void
usage(FILE *f)
{
	fprintf(f,
"usage:\n"
"  timer [FLAGS] DURATION    countdown\n"
"  timer [FLAGS]             stopwatch\n"
"\n"
"DURATION:  25m | 90s | 2h | 1h30m | 01:30:00 | 25:00\n"
"FLAGS:\n"
"  -q              no sound\n"
"  -s              silent\n"
"  --no-persist    skip alert-until-keypress loop\n"
"  --flash on|off  terminal flash during alert loop\n"
"  --bar STYLE     bar style: unicode|ascii|hash|dots|line|block|arrow|minimal\n"
"  --              end of options\n"
"  -h              help\n"
"\n"
"controls:  [space] pause/resume   [q | Ctrl+C] quit\n");
}

/* ===== run loop ===== */

static int
run(long total, int stopwatch, const Config *cfg)
{
	out_tty = isatty(STDOUT_FILENO);
	int cols = term_cols();
	int barw = cols - 40;
	if (barw < 10) barw = 10;

	const char *fill_glyph, *empty_glyph;
	int minimal = 0;
	resolve_bar(cfg, &fill_glyph, &empty_glyph, &minimal);

	ttyfd = open("/dev/tty", O_RDONLY);
	if (ttyfd >= 0 && isatty(ttyfd)) {
		if (tcgetattr(ttyfd, &oldtios) == 0) {
			struct termios raw = oldtios;
			raw.c_lflag &= ~(ICANON | ECHO);
			raw.c_cc[VMIN] = 0;
			raw.c_cc[VTIME] = 0;
			if (tcsetattr(ttyfd, TCSANOW, &raw) == 0)
				rawset = 1;
		}
	}

	atexit(restore_tty);
	struct sigaction sa = {0};
	sa.sa_handler = on_signal;
	sigaction(SIGINT,  &sa, NULL);
	sigaction(SIGTERM, &sa, NULL);
	sigaction(SIGQUIT, &sa, NULL);
	sigaction(SIGHUP,  &sa, NULL);

	if (out_tty)
		fputs("\033[?25l\033[?7l", stdout);

	long start_ms    = now_ms();
	long pause_accum = 0;
	long pause_start = 0;
	int  paused      = 0;
	int  user_quit   = 0;

	for (;;) {
		if (interrupted) { user_quit = 1; break; }

		long elapsed_ms = elapsed(start_ms, pause_accum, pause_start, paused);

		if (stopwatch) {
			if (out_tty)
				draw_stopwatch(elapsed_ms, paused);
		} else {
			if (out_tty)
				draw_countdown(total, elapsed_ms, paused, barw,
				               fill_glyph, empty_glyph, minimal);
			if (!paused && elapsed_ms >= total * 1000L) break;
		}

		long frame_end = now_ms() + 100;
		for (;;) {
			if (interrupted) break;
			long rem_frame = frame_end - now_ms();
			if (rem_frame <= 0) break;
			if (ttyfd < 0) { sleep_ms((int)rem_frame); break; }

			struct pollfd pfd = { .fd = ttyfd, .events = POLLIN };
			int pr = poll(&pfd, 1, (int)rem_frame);
			if (pr > 0 && (pfd.revents & POLLIN)) {
				char c;
				ssize_t n = read(ttyfd, &c, 1);
				if (n == 1) {
					if (c == ' ') {
						long t = now_ms();
						if (paused)
							pause_accum += t - pause_start;
						pause_start = t;
						paused = !paused;
					} else if (c == 'q' || c == 'Q') {
						user_quit = 1;
						goto done;
					}
				}
			} else if (pr == 0 || (pr < 0 && errno == EINTR)) {
				break;
			} else {
				sleep_ms((int)rem_frame);
				break;
			}
		}
	}
done:

	elapsed_s = elapsed(start_ms, pause_accum, pause_start, paused) / 1000;

	if (stopwatch) {
		char el[24];
		fmt_clock(elapsed_s, el, sizeof(el));
		if (out_tty)
			printf("\r\033[32mSTOP %s\033[0m\033[K\n", el);
		else
			printf("STOP %s\n", el);
	} else if (user_quit) {
		char el[24];
		fmt_clock(elapsed_s, el, sizeof(el));
		if (out_tty)
			printf("\r\033[33mQUIT at %s\033[0m\033[K\n", el);
		else
			printf("QUIT at %s\n", el);
	} else {
		char tb[24];
		fmt_clock(total, tb, sizeof(tb));
		if (out_tty)
			printf("\r\033[32mDONE %s 100%%\033[0m\033[K\n", tb);
		else
			printf("DONE %s 100%%\n", tb);
		if (!cfg->silent && !cfg->quiet && out_tty) {
			fputc('\a', stdout);
			fflush(stdout);
			sleep_ms(50);
		}
		if (!cfg->silent && cfg->alert_persist && is_foreground()) {
			interrupted = 0;
			alert_loop(cfg->flash);
		}
	}

	return user_quit ? 130 : 0;
}

/* ===== main ===== */

int
main(int argc, char **argv)
{
	Config cfg = {0};
	cfg.alert_persist = ALERT_PERSIST;
	cfg.flash         = FLASH;

	/* Pre-strip long-form flags before getopt. Stop at "--". */
	int nargc = 0, past_dd = 0;
	for (int i = 0; i < argc; i++) {
		if (!past_dd && !strcmp(argv[i], "--"))
			past_dd = 1;
		if (!past_dd && !strcmp(argv[i], "--no-persist")) {
			cfg.alert_persist = 0;
			continue;
		}
		if (!past_dd && !strncmp(argv[i], "--flash=", 8)) {
			cfg.flash = parse_bool_str(argv[i] + 8);
			continue;
		}
		if (!past_dd && !strcmp(argv[i], "--flash") && i + 1 < argc) {
			cfg.flash = parse_bool_str(argv[++i]);
			continue;
		}
		if (!past_dd && !strcmp(argv[i], "--bar") && i + 1 < argc) {
			snprintf(cfg.bar_style, sizeof(cfg.bar_style), "%s", argv[++i]);
			continue;
		}
		argv[nargc++] = argv[i];
	}
	argv[nargc] = NULL;

	int opt;
	while ((opt = getopt(nargc, argv, "qsh")) != -1) {
		switch (opt) {
		case 'q': cfg.quiet  = 1; break;
		case 's': cfg.silent = 1; break;
		case 'h': usage(stdout); return 0;
		default:  usage(stderr); return 1;
		}
	}
	int rem_argc = nargc - optind;
	char **rem_argv = argv + optind;

	int stopwatch = (rem_argc < 1);
	long total = 0;
	if (!stopwatch) {
		total = parse_duration(rem_argv[0]);
		if (total < 0) {
			fprintf(stderr, "bad duration: %s\n", rem_argv[0]);
			return 1;
		}
	}

	return run(total, stopwatch, &cfg);
}