//#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <math.h>
#include <lv2.h>

#define CHANNELS 2
#define TAPS 6
#define BUFFER_SECONDS 10

struct Tap {
	float *t_gain[TAPS + CHANNELS];
	float *gain;
	float *delay;
};

static const int CONTROLS_PER_TAP = sizeof (Tap) / sizeof (float *);

struct PTap
{
	double sample_rate;
	size_t buffer_max;

	Tap tap[TAPS + CHANNELS];

	float *buffers[TAPS];           ///< Tap audio buffers
	const float *buffers_end[TAPS]; ///< Audio buffer end points
	float *wp[TAPS];                ///< Write pointers

	float *in_l;
	float *in_r;
	float *out_l;
	float *out_r;
};

static LV2_Handle ptap_instantiate(
	const LV2_Descriptor *descriptor,
	double sample_rate,
	const char *bundle_path,
	const LV2_Feature *const *host_features)
{
	/* Allocate local data */
	PTap *ptap = new PTap();
	ptap->sample_rate = sample_rate;
	ptap->buffer_max = ptap->sample_rate * BUFFER_SECONDS + 1;

	for (int i = 0; i < TAPS; i++) {
		ptap->buffers[i] = new float[ptap->buffer_max]();

		if (ptap->buffers[i] == NULL) {
			for (int j = 0; j < i; j++) {
				delete ptap->buffers[i];
			}
			delete ptap;

			printf("Failed to allocate buffers\n");
			return NULL;
		}

		ptap->buffers_end[i] = ptap->buffers[i] + ptap->buffer_max;
		ptap->wp[i] = ptap->buffers[i];
	}

	return (LV2_Handle)ptap;
}

static void ptap_connect_port(LV2_Handle lv2instance, uint32_t port, void *data)
{
	PTap *ptap = (PTap *)lv2instance;
	Tap *tap;
	float *fdata = (float *)data;

	/* Audio ports */
	if (port < 4) {
		switch (port) {
			case 0: ptap->in_l = fdata; break;
			case 1: ptap->in_r = fdata; break;
			case 2: ptap->out_l = fdata; break;
			case 3: ptap->out_r = fdata; break;
		}
		return;
	}

	port -= 4;

	int tap_index = port / CONTROLS_PER_TAP;

	if (tap_index < TAPS + CHANNELS) {
		tap = &ptap->tap[tap_index];
	} else {
		return;
	}

	int tap_port = port % CONTROLS_PER_TAP;

	if (tap_port < TAPS + CHANNELS) {
		tap->t_gain[tap_port] = fdata;
	} else if (tap_port - TAPS == 2) {
		tap->gain = fdata;
	} else if (tap_port - TAPS == 3) {
		tap->delay = fdata;
	} else {
		return;
	}
}

static void ptap_run(LV2_Handle lv2instance, uint32_t sample_count)
{
	PTap *ptap = (PTap *)lv2instance;

	const float *readp[TAPS + CHANNELS];
	float gain[TAPS + CHANNELS];
	bool check_overflow = false;

	/* Position read pointers behind write pointers */
	for (int i = 0; i < TAPS; i++) {
		int delay = *ptap->tap[i].delay * ptap->sample_rate;
		/* Zero delay results in processing order dependencies. Tapiir doesn't permit it either... */
		if (delay < 1) delay = 1;
		readp[i] = ptap->wp[i] - delay;
		if (readp[i] < ptap->buffers[i]) {
			readp[i] += ptap->buffer_max;
		}
		if (ptap->wp[i] + sample_count >= ptap->buffers_end[i]) check_overflow = true;
		if (readp[i] + sample_count >= ptap->buffers_end[i]) check_overflow = true;
		gain[i] = *ptap->tap[i].gain;
	}

	float *out_l = ptap->out_l;
	float *out_r = ptap->out_r;

	readp[TAPS    ] = ptap->in_l;
	readp[TAPS + 1] = ptap->in_r;
	gain[TAPS    ] = *ptap->tap[TAPS    ].gain;
	gain[TAPS + 1] = *ptap->tap[TAPS + 1].gain;

	while (sample_count--) {
		float rp[TAPS + CHANNELS];
		float wp[TAPS + CHANNELS];

		/* Read input to local buffers */
		for (int i = 0; i < TAPS + CHANNELS; i++) rp[i] = *readp[i]++;

		/* Process delays */
		for (int i = 0; i < TAPS + CHANNELS; i++) {
			const Tap *tap = &ptap->tap[i];

			float sample = 0;
			for (int j = 0; j < TAPS + CHANNELS; j++) sample += rp[j] * *tap->t_gain[j];
			wp[i] = sample * gain[i];
		}

		/* Write outputs */
		for (int i = 0; i < TAPS; i++) *ptap->wp[i]++ = wp[i];
		*out_l++ = wp[TAPS];
		*out_r++ = wp[TAPS + 1];

		/* Check read/write pointers */
		if (check_overflow) {
			for (int i = 0; i < TAPS; i++) {
				if (ptap->wp[i] >= ptap->buffers_end[i]) ptap->wp[i] = ptap->buffers[i];
				if (readp[i] >= ptap->buffers_end[i]) readp[i] = ptap->buffers[i];
			}
		}
	}
}

static void ptap_cleanup(LV2_Handle lv2instance)
{
	PTap *ptap = (PTap *)lv2instance;

	for (int i = 0; i < TAPS; i++) {
		delete ptap->buffers[i];
	}

	delete ptap;
}

static const LV2_Descriptor s_lv2descriptor =
{
	"urn:fuzzle:ptap",
	&ptap_instantiate,
	&ptap_connect_port,
	NULL,
	&ptap_run,
	NULL,
	&ptap_cleanup,
	NULL,
};

const LV2_Descriptor *lv2_descriptor(uint32_t index)
{
	if (index == 0) {
		return &s_lv2descriptor;
	}

	return NULL;
}