#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <alsa/asoundlib.h>
#include <X11/Xlib.h>

static void die(const char *errmsg)
{
	fputs(errmsg, stderr);
	exit(EXIT_FAILURE);
}

static snd_mixer_t *alsainit(const char *card)
{
	snd_mixer_t *handle;

	snd_mixer_open(&handle, 0);
	snd_mixer_attach(handle, card);
	snd_mixer_selem_register(handle, NULL, NULL);
	snd_mixer_load(handle);
	return handle;
}

static void alsaclose(snd_mixer_t *handle)
{
	snd_mixer_close(handle);
}

static snd_mixer_elem_t *alsamixer(snd_mixer_t *handle, const char *mixer)
{
	snd_mixer_selem_id_t *sid;

	snd_mixer_selem_id_alloca(&sid);
	snd_mixer_selem_id_set_index(sid, 0);
	snd_mixer_selem_id_set_name(sid, mixer);
	return snd_mixer_find_selem(handle, sid);
}

static int ismuted(snd_mixer_elem_t *mixer)
{
	int on;

	snd_mixer_selem_get_playback_switch(mixer, SND_MIXER_SCHN_MONO, &on);
	return !on;
}

static int getvol(snd_mixer_elem_t *mixer)
{
	long vol, min, max;

	snd_mixer_selem_get_playback_volume_range(mixer, &min, &max);
	snd_mixer_selem_get_playback_volume(mixer, SND_MIXER_SCHN_MONO, &vol);

	vol = vol < max ? (vol > min ? vol : min) : max;
	return vol * 100.0 / max + 0.5;
}

static char *gettime()
{
	static char timestr[60];
	time_t rawtime;

	time(&rawtime);
	strftime(timestr, sizeof(timestr), "%d %B %H:%M", localtime(&rawtime));
	return timestr;
}

int main(int argc, char *argv[])
{
	char buf[100];
	static Display *dpy;
	snd_mixer_t *alsa;
	snd_mixer_elem_t *mixer;

	if (!(dpy = XOpenDisplay(NULL)))
		die("dstatus: cannot open display \n");
	if (!(alsa = alsainit("default")))
		die("dstatus: cannot initialize alsa\n");
	if (!(mixer = alsamixer(alsa, "Master")))
		die("dstatus: cannot get mixer\n");

	while (1) {
		snprintf(buf, sizeof(buf), "%s | %d%%%s", gettime(),
				getvol(mixer), ismuted(mixer) ? " [off]" : "");
		XStoreName(dpy, DefaultRootWindow(dpy), buf);
		XSync(dpy, False);

		snd_mixer_wait(alsa, 10000);
		snd_mixer_handle_events(alsa);
	}

	alsaclose(alsa);
	XCloseDisplay(dpy);
	return 0;
}