#include <X11/X.h>
#include <X11/XKBlib.h>
#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <X11/XF86keysym.h>

#include <sys/wait.h>
#include <pty.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <termios.h>
#include <string.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

#define ARRLEN(a) (sizeof(a)/sizeof(*(a)))

static pid_t child_pid = -1;
static int child_fd = -1;
static FILE *child_io = NULL;

static const char *play_arg = "-p";
static bool ptty = false;

static void
die(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	fputs("xf86ctrl: ", stderr);
	vfprintf(stderr, fmt, ap);
	if (*fmt && fmt[strlen(fmt) - 1] == ':') {
		fputc(' ', stderr);
		perror(NULL);
	} else {
		fputc('\n', stderr);
	}
	va_end(ap);

	exit(1);
}

static void
child_exit(int sig)
{
	int status, rc;

	do {
		rc = waitpid(child_pid, &status, 0);
		if (rc < 0 && errno == ECHILD) exit(123);
	} while (rc < 0 || !WIFEXITED(status) && !WIFSIGNALED(status));

	if (WIFSIGNALED(status))
		exit(128 + WTERMSIG(status));

	exit(WEXITSTATUS(status));
}

int
main(int argc, char **argv)
{
	char **arg;
	struct termios childterm;
	struct winsize ws;
	int child_pipe[2];
	ssize_t nwrite;
	Display *d;
	Window win;
	XEvent e;
	KeySym key;

	for (arg = argv + 1; *arg && strcmp(*arg, "--"); arg++) {
		if (!strcmp(*arg, "-h") || !strcmp(*arg, "--help")) {
			*arg = NULL;
			break;
		} else if (!strcmp(*arg, "-p")) {
			play_arg = *++arg;
		} else if (!strcmp(*arg, "-t")) {
			ptty = true;
		} else {
			break;
		}
	}
	if (!*arg) {
		fprintf(stderr, "Usage: xf86ctrl [-p PLAY] [-t] CMD [ARGS..]\n");
		return 1;
	}

	signal(SIGCHLD, child_exit);

	if (ptty) {
		cfmakeraw(&childterm);
		ws.ws_col = 80;
		ws.ws_row = 40;
		child_pid = forkpty(&child_fd, NULL, &childterm, &ws);
		if (child_pid < 0) die("forkpty:");
		if (!child_pid) {
			signal(SIGCHLD, SIG_DFL);
			execvp(*arg, arg);
			die("execvp:");
		}
	} else {
		pipe(child_pipe);
		child_pid = fork();
		if (child_pid < 0) die("fork:");
		if (!child_pid) {
			signal(SIGCHLD, SIG_DFL);
			close(1);
			close(2);
			dup2(child_pipe[0], 0);
			close(child_pipe[1]);
			close(child_pipe[0]);
			execvp(*arg, arg);
			die("execvp:");
		}
		child_fd = child_pipe[1];
		close(child_pipe[0]);
	}

	child_io = fdopen(child_fd, "w");
	if (!child_io) die("fdopen:");

	d = XOpenDisplay(NULL);
	if (!d) die("XOpenDisplay(NULL)");

	win = DefaultRootWindow(d);
	if (!win) die("XDefaultRootWindow no result");

	XGrabKey(d, XKeysymToKeycode(d, XF86XK_AudioNext), 0,
		 win, False, GrabModeAsync, GrabModeAsync);
	XGrabKey(d, XKeysymToKeycode(d, XF86XK_AudioPlay), 0,
		 win, False, GrabModeAsync, GrabModeAsync);

	while (1) {
		XNextEvent(d, &e);
		if (e.type == KeyPress) {
			key = XkbKeycodeToKeysym(d,
				(KeyCode) e.xkey.keycode, 0,
				!!(e.xkey.state & ShiftMask));
			switch (key) {
			case XF86XK_AudioNext:
				goto exit;
			case XF86XK_AudioPlay:
				nwrite = fputs(play_arg, child_io);
				if (nwrite != strlen(play_arg)) goto exit;
				fflush(child_io);
				break;
			}
		}
	}
exit:

	XCloseDisplay(d);
}