#include "play.h"
#include <stdlib.h>
#include <string.h>

const static uint16_t lengths[10] = { 313, 625, 938, 1250, 1875, 2500, 3750, 5000, 7500, 10000 };
const static uint16_t tempos[10] = { 13230, 8820, 6615, 5292, 4410, 3780, 3308, 2940, 2646, 2406 };
const float periods[108] = { 1348.49207, 1272.80688, 1201.37, 1133.94214, 1070.29871, 1010.22772, 953.527893, 900.010376, 849.496887, 801.818176, 756.815613, 714.338745, 674.246033, 636.403564, 600.684875, 566.971069, 535.149475, 505.11377, 476.763947, 450.005249, 424.748352, 400.909088, 378.407806, 357.169373, 337.123016, 318.201782, 300.342438, 283.485535, 267.574738, 252.556885, 238.381973, 225.002625, 212.374176, 200.454544, 189.203888, 178.584702, 168.561508, 159.100876, 150.171234, 141.742767, 133.787354, 126.278458, 119.190987, 112.501305, 106.187096, 100.227272, 94.6019516, 89.2923508, 84.2807541, 79.5504379, 75.0856171, 70.8713837, 66.8936768, 63.139225, 59.5954933, 56.2506561, 53.0935478, 50.113636, 47.3009758, 44.6461754, 42.140377, 39.775219, 37.5428085, 35.4356918, 33.4468384, 31.5696125, 29.7977467, 28.1253281, 26.5467739, 25.056818, 23.650486, 22.3230877, 21.0701885, 19.8876095, 18.7714043, 17.7178459, 16.7234192, 15.7848072, 14.8988733, 14.0626631, 13.273387, 12.528409, 11.8252439, 11.1615429, 10.5350943, 9.94380569, 9.38570118, 8.85892296, 8.36171055, 7.89240265, 7.44943666, 7.03133202, 6.636693, 6.2642045, 5.91262197, 5.58077145, 5.26754713, 4.97190285, 4.69285059, 4.42946148, 4.18085527, 3.94620132, 3.72471833, 3.51566601, 3.3183465, 3.13210225, 2.95631051, 2.7903862 };

static float default_length = 0.25f;
static uint8_t volume = 64;
static uint8_t octave = 4;
static uint32_t tempo = tempos[4]*10;
static uint8_t wave_type = 0;
static char* song_ptr = NULL;
static char song[256];

uint8_t generate_square_wave(unsigned int i, uint16_t period, uint8_t volume) {
	return ( (i % period) < (period >> 1) ? volume : -volume );
}

uint8_t generate_saw_wave(unsigned int i, uint16_t period, uint8_t volume) {
    uint16_t t = i % period;

    // Mapea t (0..period-1) a un rango lineal -volume..+volume
    int16_t v = -volume + (2 * volume * t) / period;

    return (int8_t)v;
}

uint8_t generate_triangle_wave(unsigned int i, uint16_t period, uint8_t volume) {
    uint16_t t = i % period;
    int16_t v = (t < period/2)
        ? (-volume + (2 * volume * t) / (period/2))
        : ( volume - (2 * volume * (t - period/2)) / (period/2));
    return (int8_t)v;
}

uint8_t generate_periodic_noise(unsigned int i, uint16_t period, uint8_t volume) {
    static int8_t current = 0;

    if (i % period == 0) {
        current = (rand() % (2 * volume + 1)) - volume;
    }

    return current;
}

uint8_t generate_wave(unsigned int i, uint16_t period, uint8_t volume) {
	switch (wave_type) {
		case 1: return generate_saw_wave(i, period, volume);
		case 2: return generate_periodic_noise(i, period, volume);
		default:return generate_square_wave(i, period, volume);
	}
}

uint32_t interpret_note(uint8_t* buffer, const char note, const char param ) {
	const uint32_t length = ( param == -1 ? default_length : ((float)lengths[uint8_t(param)])/10000.0f ) * tempo;
	if( note == 100 ) { memset( buffer, 0, length ); return length; }
	const uint16_t period = periods[note + octave*12];
	
	for( unsigned int i = 0; i < length; i++ ) buffer[i] = generate_wave(i, period, volume);
	return length;
}

void play_init(const char* new_song) {
	default_length = 0.25f;
	volume=64;
	octave=4;
	tempo=tempos[4]*10;
	wave_type = 0;

	int len = strlen( new_song ) + 1;
	if (len > 256) len = 256;
	strncpy(song, new_song, len);
    song_ptr = song;
}

int32_t interpret_next_token(uint8_t* buffer) {
    char** token = &song_ptr;
	char note = 0;
	char param = -1;
	
	switch( **token ) {
		case 'b': note += 2;
		case 'a': note += 2;
		case 'g': note += 2;
		case 'f': note += 1;
		case 'e': note += 2;
		case 'd': note += 2;
		case 'c':
			param = *++*token;
			if( param == '#' || param == '+' ) { note++; param = *++*token; } else if( param == '-' ) { note--; param = *++*token; }
			if( param >= 48 && param <= 57 ) { param -= 48; ++*token; } else { param = -1; }
			return interpret_note( buffer, note, param );
		case 'r':
			param = *++*token;
			if( param >= 48 && param <= 57 ) { param -= 48; ++*token; } else { param = -1; }
			return interpret_note( buffer, 100, param );
		case 'o':
			param = *++*token;
			if( param >= 48 && param <= 57 ) { octave = (param - 48) % 8; ++*token; }
			return 0;
		case '>':
			octave = (octave+1) % 8; ++*token;
			return 0;
		case '<':
			octave = (octave-1) % 8; ++*token;
			return 0;
		case 'l':
			param = *++*token;
			if( param >= 48 && param <= 57 ) { default_length = ((float)lengths[param - 48])/10000.0f; ++*token; }
			return 0;
		case 'v':
			param = *++*token;
			if( param >= 48 && param <= 57 ) { volume = (param - 48) << 4; ++*token; }
			return 0;
		case 't':
			param = *++*token;
			if( param >= 48 && param <= 57 ) { tempo = tempos[param - 48] * 10; ++*token; }
			return 0;
		case 'w':
			param = *++*token;
			if( param >= 48 && param <= 50 ) { wave_type = param - 48; ++*token; }
			return 0;
		case '\0':
			return -1;
		default:
			++*token;
			return 0;
	};
}