/*
  An LV2 plugin to generate a bandlimited slope-variable triangle waveform.
  Copyright 2011 David Robillard
  Copyright 2002 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/ext/morph/morph.h"
#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
#include "uris.h"
#include "wavedata.h"

#define TRIANGLE_FREQUENCY 0
#define TRIANGLE_SLOPE     1
#define TRIANGLE_OUTPUT    2

typedef struct {
	float*   frequency;
	float*   slope;
	float*   output;
	float    phase;
	float    min_slope;
	float    max_slope;
	uint32_t frequency_is_cv;
	uint32_t slope_is_cv;
	Wavedata wdat;
	URIs     uris;
} Triangle;

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

	switch (port) {
	case TRIANGLE_FREQUENCY:
		plugin->frequency = data;
		break;
	case TRIANGLE_SLOPE:
		plugin->slope = data;
		break;
	case TRIANGLE_OUTPUT:
		plugin->output = data;
		break;
	}
}

static LV2_Morph_Status
morph_port(LV2_Handle                      instance,
           uint32_t                        port,
           LV2_URID                        type,
           const LV2_Morph_Property*const* properties)
{
	Triangle* plugin = (Triangle*)instance;

	if (type != plugin->uris.lv2_ControlPort &&
	    type != plugin->uris.lv2_CVPort) {
		return LV2_MORPH_ERR_BAD_TYPE;
	}

	switch (port) {
	case TRIANGLE_FREQUENCY:
		plugin->frequency_is_cv = (type == plugin->uris.lv2_CVPort);
		break;
	case TRIANGLE_SLOPE:
		plugin->slope_is_cv = (type == plugin->uris.lv2_CVPort);
		break;
	default:
		return LV2_MORPH_ERR_BAD_PORT;
	}

	return LV2_MORPH_SUCCESS;
}

static LV2_Handle
instantiate(const LV2_Descriptor*     descriptor,
            double                    sample_rate,
            const char*               bundle_path,
            const LV2_Feature* const* features)
{
	Triangle* plugin = (Triangle*)malloc(sizeof(Triangle));
	if (!plugin) {
		return NULL;
	}

	if (wavedata_load(&plugin->wdat, bundle_path, "parabola_data",
	                  BLOP_DLSYM_PARABOLA, sample_rate)) {
		free(plugin);
		return 0;
	}

	plugin->min_slope = 2.0f / plugin->wdat.sample_rate;
	plugin->max_slope = 1.0f - plugin->min_slope;

	plugin->frequency_is_cv = 0;
	plugin->slope_is_cv     = 0;

	map_uris(&plugin->uris, features);
	wavedata_get_table(&plugin->wdat, 440.0);

	return (LV2_Handle)plugin;
}

static void
cleanup(LV2_Handle instance)
{
	Triangle* plugin = (Triangle*)instance;

	wavedata_unload(&plugin->wdat);
	free(instance);
}

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

	plugin->phase = 0.0f;
}

static void
run(LV2_Handle instance,
    uint32_t   sample_count)
{
	Triangle* plugin = (Triangle*)instance;

	/* Frequency (array of float of length 1 or sample_count) */
	const float* frequency = plugin->frequency;

	/* Slope (array of float of length 1 or sample_count) */
	const float* slope = plugin->slope;

	/* Output (pointer to float value) */
	float* output = plugin->output;

	/* Instance data */
	Wavedata*   wdat      = &plugin->wdat;
	float       phase     = plugin->phase;
	const float min_slope = plugin->min_slope;
	const float max_slope = plugin->max_slope;

	float last_slope  = slope[0];
	float slp         = f_clip(last_slope, min_slope, max_slope);
	float phase_shift = slp * wdat->sample_rate;
	float scale       = 1.0f / (8.0f * (slp - (slp * slp)));

	for (uint32_t s = 0; s < sample_count; ++s) {
		const float freq = frequency[s * plugin->frequency_is_cv];
		if (freq != wdat->frequency) {
			/* Frequency changed, look up table to play */
			wavedata_get_table(wdat, freq);
		}

		const float this_slope = slope[s * plugin->slope_is_cv];
		if (this_slope != last_slope) {
			/* Slope changed, recalculate */
			last_slope  = this_slope;
			slp         = f_clip(this_slope, min_slope, max_slope);
			phase_shift = slp * wdat->sample_rate;
			scale       = 1.0f / (8.0f * (slp - (slp * slp)));
		}

		/* Get samples from parabola and phase shifted inverted parabola,
		   and scale to compensate */
		output[s] = (wavedata_get_sample(wdat, phase)
		             - wavedata_get_sample(wdat, phase + phase_shift)) * scale;

		/* Update phase, wrapping if necessary */
		phase += wdat->frequency;
		if (phase < 0.0f) {
			phase += wdat->sample_rate;
		} else if (phase > wdat->sample_rate) {
			phase -= wdat->sample_rate;
		}
	}
	plugin->phase = phase;
}

static const void*
extension_data(const char* uri)
{
	static const LV2_Morph_Interface morph = { morph_port, NULL };
	if (!strcmp(uri, LV2_MORPH__interface)) {
		return &morph;
	}
	return NULL;
}

static const LV2_Descriptor descriptor = {
	"http://drobilla.net/plugins/blop/triangle",
	instantiate,
	connect_port,
	activate,
	run,
	NULL,
	cleanup,
	extension_data,
};

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