// markov.c

/* TODO:
 * remove hardcoded FRAME_SAMPLES
*/


// !!!YOU WERE HERE!!!! //
// write a proper markov chain, only run for 256 samples per chain
// - make sure we DONT EVER fall into a zero len state
// - test with sine wave, should work on any freq

// s8 to u8 conversion macros ?
// lo / hi nibble extracion macros

void markov_gen(Markov_4 *m, s8 *audio) {
	const u8 cur_1st = (u8)(((s32) audio[0]) + 128);
	const u8 cur_2nd = (u8)(((s32) audio[1]) + 128);
	// 1st goes in low bits, 2nd in high
	m -> start = (cur_1st >> 4) | (cur_2nd & 0xf0);

	for int sam = 0; sam < 512; sam += 2 do {
		const u8 cur_1st = (u8)(((s32) audio[sam]) + 128);
		const u8 cur_2nd = (u8)(((s32) audio[sam + 1]) + 128);
		// 1st goes in low bits, 2nd in high
		const u8 cur = (cur_1st >> 4) | (cur_2nd & 0xf0);

		const int nex_sam = sam == 510 ?
			0 : // loop back to first sample
			sam + 2;
		const u8 nex_1st = (u8)(((s32) audio[nex_sam]) + 128);
		const u8 nex_2nd = (u8)(((s32) audio[nex_sam + 1]) + 128);
		// 1st goes in low bits, 2nd in high
		const u8 nex = (nex_1st >> 4) | (nex_2nd & 0xf0);

		m->chain[cur][nex] = MIN(m->chain[cur][nex] + 1, 255);
	}

	for int x = 0; x < 256; x++ do {
		static u8 x_copy[256];
		for int i = 0; i < 256; i++ do
			x_copy[i] = m->chain[x][i];

		u8 len = 0;
		for int y = 0; y < 256; y++ do
			for ; len < x_copy[y]; len++ do
				m -> chain[x][len] = y;

		m -> lens[x] = len;
	}
}

void markov_synth(Markov_4 *m, s8 *audio_out) {
	if SDL_GetKeyboardState(NULL)[SDL_SCANCODE_SPACE] do return;

	u8 x = m -> start;
	for int sam = 0; sam < FRAME_SAMPLES; sam += 2 do {
		if m->lens[x] == 0 do {
			puts("asdsdgsdgKLJASDUGEAKLJASKLJSDILKWJASDKLJ, WHY IS THERE A ZERO");
			break;
		}

		// split x into low + hi
		s8 lo = (x & 0xf), hi = ((x & 0xf0) >> 4);
		//audio_out[sam] = (lo - 8) << 4;
		//audio_out[sam + 1] = (hi - 8) << 4;

		if 1 do { // bit crush
			const int b = 4;
			audio_out[sam] = (audio_out[sam] >> b) << b;
			audio_out[sam + 1] = (audio_out[sam + 1] >> b) << b;
		}

		u8 rnd_y = rnd_u8() % m->lens[x];
		x = m->chain[x][rnd_y];
	}
}

void markov_draw(Markov_4 *mar, SDL_Renderer *r) {
	const int w = 256;

	for int x = 0; x < 256; x += 1 do
		//for int y = 0; y < mar->lens[x]; y += 1 do {
		for int y = 0; y < 256; y += 1 do {
			s32 m = mar->chain[x][y];
			SDL_SetRenderDrawColor(r,
				m >= 10 ? m : 0,
				MIN(255, m < 4 ? m * 100 : 0),
				MIN(255, m < 10 and m >= 4 ? m * 100 : 0), 255);
			//SDL_SetRenderDrawColor(r, m * 32, 0, 0, 255);
			if m != 0 do {
				const int y2 = 255 - y;
				SDL_RenderDrawPoint(r, x * 2, y2 * 2);
				SDL_RenderDrawPoint(r, x * 2 + 1, y2 * 2);
				SDL_RenderDrawPoint(r, x * 2, y2 * 2 + 1);
				SDL_RenderDrawPoint(r, x * 2 + 1, y2 * 2 + 1);
			}
		}
}