/*
  An LV2 plugin to shape a signal in various ways.
  Copyright 2011 David Robillard
  Copyright 2003 Mike Rawes

  This is free software: you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This software is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this software.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
#include "common.h"

#define TRACKER_GATE    0
#define TRACKER_HATTACK 1
#define TRACKER_HDECAY  2
#define TRACKER_LATTACK 3
#define TRACKER_LDECAY  4
#define TRACKER_INPUT   5
#define TRACKER_OUTPUT  6

typedef struct {
	float* gate;
	float* hattack;
	float* hdecay;
	float* lattack;
	float* ldecay;
	float* input;
	float* output;
	float  coeff;
	float  last_value;
} Tracker;

static void
cleanup(LV2_Handle instance)
{
	free(instance);
}

static void
connect_port(LV2_Handle instance,
             uint32_t   port,
             void*      data)
{
	Tracker* plugin = (Tracker*)instance;

	switch (port) {
	case TRACKER_GATE:
		plugin->gate = data;
		break;
	case TRACKER_HATTACK:
		plugin->hattack = data;
		break;
	case TRACKER_HDECAY:
		plugin->hdecay = data;
		break;
	case TRACKER_LATTACK:
		plugin->lattack = data;
		break;
	case TRACKER_LDECAY:
		plugin->ldecay = data;
		break;
	case TRACKER_INPUT:
		plugin->input = data;
		break;
	case TRACKER_OUTPUT:
		plugin->output = data;
		break;
	}
}

static LV2_Handle
instantiate(const LV2_Descriptor*     descriptor,
            double                    sample_rate,
            const char*               bundle_path,
            const LV2_Feature* const* features)
{
	Tracker* plugin = (Tracker*)malloc(sizeof(Tracker));

	plugin->coeff = 2.0f * M_PI / (float)sample_rate;

	return (LV2_Handle)plugin;
}

static void
activate(LV2_Handle instance)
{
	Tracker* plugin = (Tracker*)instance;

	plugin->last_value = 0.0f;
}

static void
runTracker_gaaadaia_oa(LV2_Handle instance,
                       uint32_t   sample_count)
{
	Tracker* plugin = (Tracker*)instance;

	/* Gate (array of floats of length sample_count) */
	float* gate = plugin->gate;

	/* Gate High Attack Rate (array of floats of length sample_count) */
	float* hattack = plugin->hattack;

	/* Gate High Decay Rate (array of floats of length sample_count) */
	float* hdecay = plugin->hdecay;

	/* Gate Low Attack Rate (array of floats of length sample_count) */
	float* lattack = plugin->lattack;

	/* Gate Low Decay Rate (array of floats of length sample_count) */
	float* ldecay = plugin->ldecay;

	/* Input (array of floats of length sample_count) */
	float* input = plugin->input;

	/* Output (array of floats of length sample_count) */
	float* output = plugin->output;

	/* Instance Data */
	float coeff      = plugin->coeff;
	float last_value = plugin->last_value;

	float rate;
	float in;

	for (uint32_t s = 0; s < sample_count; ++s) {
		in = input[s];

		if (gate[s] > 0.0f) {
			rate = in > last_value ? hattack[s] : hdecay[s];
		} else {
			rate = in > last_value ? lattack[s] : ldecay[s];
		}

		rate       = f_min(1.0f, rate * coeff);
		last_value = last_value * (1.0f - rate) + in * rate;

		output[s] = last_value;
	}

	plugin->last_value = last_value;
}

static void
runTracker_gaacdcia_oa(LV2_Handle instance,
                       uint32_t   sample_count)
{
	Tracker* plugin = (Tracker*)instance;

	/* Gate (array of floats of length sample_count) */
	float* gate = plugin->gate;

	/* Gate High Attack Rate (float value) */
	float hattack = *(plugin->hattack);

	/* Gate High Decay Rate (float value) */
	float hdecay = *(plugin->hdecay);

	/* Gate Low Attack Rate (float value) */
	float lattack = *(plugin->lattack);

	/* Gate Low Decay Rate (float value) */
	float ldecay = *(plugin->ldecay);

	/* Input (array of floats of length sample_count) */
	float* input = plugin->input;

	/* Output (array of floats of length sample_count) */
	float* output = plugin->output;

	/* Instance Data */
	float coeff      = plugin->coeff;
	float last_value = plugin->last_value;

	float in;
	float rate;

	hattack = f_min(1.0f, hattack * coeff);
	hdecay  = f_min(1.0f, hdecay * coeff);
	lattack = f_min(1.0f, lattack * coeff);
	ldecay  = f_min(1.0f, ldecay * coeff);

	for (uint32_t s = 0; s < sample_count; ++s) {
		in = input[s];

		if (gate[s] > 0.0f) {
			rate = in > last_value ? hattack : hdecay;
		} else {
			rate = in > last_value ? lattack : ldecay;
		}

		last_value = last_value * (1.0f - rate) + in * rate;

		output[s] = last_value;
	}

	plugin->last_value = last_value;
}

static const LV2_Descriptor descriptor = {
	"http://drobilla.net/plugins/blip/tracker",
	instantiate,
	connect_port,
	activate,
	runTracker_gaacdcia_oa,
	NULL,
	cleanup,
	NULL,
};

LV2_SYMBOL_EXPORT const LV2_Descriptor*
lv2_descriptor(uint32_t index)
{
	switch (index) {
	case 0:  return &descriptor;
	default: return NULL;
	}
}