#include "dtmflib.h"
#include <math.h>
#include "compat.h"
#include "log.h"

struct dtmf_freq {
	unsigned int prim,
		     sec;
};

static const struct dtmf_freq dtmf_freqs[] = {
	{ 941, 1336 }, /* 0 */
	{ 697, 1209 }, /* 1 */
	{ 697, 1336 }, /* 2 */
	{ 697, 1477 }, /* 3 */
	{ 770, 1209 }, /* 4 */
	{ 770, 1336 }, /* 5 */
	{ 770, 1477 }, /* 6 */
	{ 852, 1209 }, /* 7 */
	{ 852, 1336 }, /* 8 */
	{ 852, 1477 }, /* 9 */
	{ 941, 1209 }, /* 10 = * */
	{ 941, 1477 }, /* 11 = # */
	{ 697, 1633 }, /* 12 = A */
	{ 770, 1633 }, /* 13 = B */
	{ 852, 1633 }, /* 14 = C */
	{ 941, 1633 }, /* 15 = D */
};


INLINE double freq2iter(unsigned int hz, unsigned int sample_rate) {
	double ret = hz;
	ret *= 2 * M_PI;
	ret /= sample_rate;
	return ret;
}

void dtmf_samples(void *buf, unsigned long offset, unsigned long num, unsigned int event, unsigned int volume,
		unsigned int sample_rate)
{
	int16_t *samples = buf;
	const struct dtmf_freq *df;

	if (event == 0xff) {
		// pause - silence samples
		memset(samples, 0, num * 2);
		return;
	}

	if (event >= G_N_ELEMENTS(dtmf_freqs)) {
		ilog(LOG_WARN | LOG_FLAG_LIMIT, "Unsupported DTMF event %u", event);
		memset(buf, 0, num * 2);
		return;
	}
	df = &dtmf_freqs[event];

	// XXX initialise/save these when the DTMF event starts
	double vol = pow(1.122018, volume) * 2.0;

	double prim_freq = freq2iter(df->prim, sample_rate);
	double sec_freq = freq2iter(df->sec, sample_rate);

	num += offset; // end here
	while (offset < num) {
		double prim = sin(prim_freq * offset) / vol;
		double sec = sin(sec_freq * offset) / vol;
		int16_t sample = prim * 32767.0 + sec * 32767.0;
		*samples++ = sample;
		offset++;
	}
}