/*
 * arngment - random music generator
 *
 * Written in 2020 by Lucas
 *
 * To the extent possible under law, the author(s) have dedicated all
 * copyright and related and neighboring rights to this software to the
 * public domain worldwide. This software is distributed without any
 * warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication
 * along with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 */

#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>

#include "err.h"
#include "note.h"
#include "synth.h"

#define nelems(_a) (sizeof(_a) / sizeof((_a)[0]))

#define GAIN 1.4
#define RATE 48000

static void
usage(void)
{
	fprintf(stderr, "Usage: %s base_note\n", __progname);
	exit(1);
}

int
main(int argc, char *argv[])
{
	int16_t buf[RATE];
	int scale[] = {
	    0, 2, 3, 5, 7, 8, 10, 12,
	    0, 2, 3, 5, 7, 8, 10, 12,
	    12, 14, 15, 17, 19, 20, 22, 24,
	};
	struct note base_note, note;
	double l, r, t;
	size_t i;
	uint32_t k;
	int ch;

	while ((ch = getopt(argc, argv, "")) != -1)
		switch (ch) {
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	if (argc != 1)
		usage();
	if (!note_parse(&base_note, argv[0]))
		errx(1, "Invalid note %s", argv[0]);

	for (;;) {
		k = arc4random_uniform(nelems(scale));
		note = base_note;
		note.offset += scale[k];
		for (i = 0; i < RATE / 2; i += 2) {
			t = i / (double)RATE;
			l = synth_distortion(GAIN,
			    synth_sinewave(t, note_pitch(note)));
			r = synth_distortion(GAIN,
			    synth_trianglewave(t, note_pitch(note)));
			buf[i] = l * INT16_MAX;
			buf[i + 1] = r * INT16_MAX;
		}

		k = arc4random_uniform(nelems(scale));
		note = base_note;
		note.offset += scale[k];
		for (; i < RATE; i += 2) {
			t = i / (double)RATE;
			l = synth_distortion(GAIN,
			    synth_sinewave(t, note_pitch(note)));
			r = synth_distortion(GAIN,
			    synth_trianglewave(t, note_pitch(note)));
			buf[i] = l * INT16_MAX;
			buf[i + 1] = r * INT16_MAX;
		}
		fwrite(buf, sizeof(buf[0]), RATE, stdout);
	}

	return 0;
}