#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <lv2.h>

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

struct tap_t {
	float *t_gain[TAPS];
	float *l_gain;
	float *r_gain;
	float *gain;
	float *delay;
};

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

struct ptap_t
{
	double sample_rate;
	size_t buffer_max;

	struct tap_t tap[TAPS];
	struct tap_t l_out;
	struct tap_t r_out;

	float *buffers[TAPS];   ///< Tap audio buffers
	float *rp[TAPS];        ///< Read pointers
	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 */
	struct ptap_t *ptap = malloc(sizeof *ptap);
	if (ptap == NULL) {
		return NULL;
	}

	memset(ptap, 0, sizeof *ptap);

	ptap->sample_rate = sample_rate;
	ptap->buffer_max = ptap->sample_rate * BUFFER_SECONDS + 1;

	int i, j;
	for (i = 0; i < TAPS; i++) {
		ptap->buffers[i] = malloc(ptap->buffer_max * sizeof (float));

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

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

		memset(ptap->buffers[i], 0, ptap->buffer_max * sizeof (float));

		ptap->rp[i] = ptap->buffers[i];
		ptap->wp[i] = ptap->buffers[i];
	}

	return (LV2_Handle)ptap;
}

static void ptap_connect_port(LV2_Handle lv2instance, uint32_t port, void *data)
{
	struct ptap_t *ptap = (struct ptap_t *)lv2instance;
	struct tap_t *tap;

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

	port -= 4;

	int tap_index = port / CONTROLS_PER_TAP;

	if (tap_index < TAPS) {
		tap = &ptap->tap[tap_index];
	} else if (tap_index - TAPS == 0) {
		tap = &ptap->l_out;
	} else if (tap_index - TAPS == 1) {
		tap = &ptap->r_out;
	} else {
		return;
	}

	int tap_port = port % CONTROLS_PER_TAP;

	if (tap_port < TAPS) {
		tap->t_gain[tap_port] = data;
	} else if (tap_port - TAPS == 0) {
		tap->l_gain = data;
	} else if (tap_port - TAPS == 1) {
		tap->r_gain = data;
	} else if (tap_port - TAPS == 2) {
		tap->gain = data;
	} else if (tap_port - TAPS == 3) {
		tap->delay = data;
	} else {
		return;
	}
}

static void ptap_run(LV2_Handle lv2instance, uint32_t sample_count)
{
	struct ptap_t *ptap = (struct ptap_t *)lv2instance;
	const struct tap_t *tap;
	float *wp;
	int i, j;

	/* Position read pointers behind write pointers */
	for (i = 0; i < TAPS; i++) {
		int delay = *ptap->tap[i].delay * ptap->sample_rate;
		ptap->rp[i] = ptap->wp[i] - delay;
		if (ptap->rp[i] < ptap->buffers[i]) {
			ptap->rp[i] += ptap->buffer_max;
		}
	}

	float *il = ptap->in_l;
	float *ir = ptap->in_r;
	float *ol = ptap->out_l;
	float *or = ptap->out_r;

	while (sample_count--) {
		for (i = 0; i < TAPS; i++) {
			wp = ptap->wp[i];
			tap = &ptap->tap[i];

			*wp  = *il * *tap->l_gain;
			*wp += *ir * *tap->r_gain;
			for (j = 0; j < TAPS; j++) {
				*wp += *ptap->rp[j] * *tap->t_gain[j];
			}
			*wp *= *tap->gain;
		}

		/* Write to left output */
		tap = &ptap->l_out;
		*ol  = *il * *tap->l_gain;
		*ol += *ir * *tap->r_gain;
		for (j = 0; j < TAPS; j++) {
			*ol += *ptap->rp[j] * *tap->t_gain[j];
		}
		*ol *= *tap->gain;

		/* Write to right output */
		tap = &ptap->r_out;
		*or  = *il * *tap->l_gain;
		*or += *ir * *tap->r_gain;
		for (j = 0; j < TAPS; j++) {
			*or += *ptap->rp[j] * *tap->t_gain[j];
		}
		*or *= *tap->gain;

		/* Progress read pointers */
		for (i = 0; i < TAPS; i++) {
			ptap->wp[i]++;
			if (ptap->wp[i] >= ptap->buffers[i] + ptap->buffer_max) {
				ptap->wp[i] = ptap->buffers[i];
			}

			ptap->rp[i]++;
			if (ptap->rp[i] >= ptap->buffers[i] + ptap->buffer_max) {
				ptap->rp[i] = ptap->buffers[i];
			}
		}

		il++;
		ir++;
		ol++;
		or++;
	}
}

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

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

	free(ptap);
}

static const LV2_Descriptor s_lv2descriptor =
{
	.URI = "urn:fuzzle:ptap",
	.instantiate = &ptap_instantiate,
	.connect_port = &ptap_connect_port,
	.run = &ptap_run,
	.cleanup = &ptap_cleanup,
};

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

	return NULL;
}