/*
 * 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 <math.h>

#include "note.h"

static int
midi(struct note n)
{
	/* C0 is MIDI note 12 */
	return 12 * (n.octave + 1) + n.offset + n.accident;
}

double
note_pitch(struct note n)
{
	int m = midi(n);
	return 440.0 * pow(2.0, (m - 69) / 12.0);
}

int
note_parse(struct note *note, const char *s)
{
	/* Semitones from C, starting at A */
	static int offsets[] = {9, 11, 0, 2, 4, 5, 7};
	struct note n;

	if (*s < 'A' || *s > 'G')
		return 0;
	n.offset = offsets[*s - 'A'];
	s++;

	if (*s == 'b') {
		n.accident = ACCIDENT_FLAT;
		s++;
	} else if (*s == '#') {
		n.accident = ACCIDENT_SHARP;
		s++;
	} else
		n.accident = ACCIDENT_NATURAL;

	if (*s < '0' || *s > '9')
		return 0;
	n.octave = *s - '0';
	s++;

	if (*s != '\0')
		return 0;
	*note = n;

	return 1;
}