/*
  An LV2 plugin to calculate the difference of two signals.
  Copyright 2011 David Robillard
  Copyright 2004 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"

#define DIFFERENCE_MINUEND    0
#define DIFFERENCE_SUBTRAHEND 1
#define DIFFERENCE_DIFFERENCE 2

typedef struct {
	float*   minuend;
	float*   subtrahend;
	float*   difference;
	uint32_t minuend_is_cv;
	uint32_t subtrahend_is_cv;
	uint32_t difference_is_cv;
	URIs     uris;
} Difference;

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

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

	switch (port) {
	case DIFFERENCE_MINUEND:
		plugin->minuend = data;
		break;
	case DIFFERENCE_SUBTRAHEND:
		plugin->subtrahend = data;
		break;
	case DIFFERENCE_DIFFERENCE:
		plugin->difference = data;
		break;
	}
}

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

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

	switch (port) {
	case DIFFERENCE_MINUEND:
		plugin->minuend_is_cv = (type == plugin->uris.lv2_CVPort);
		break;
	case DIFFERENCE_SUBTRAHEND:
		plugin->subtrahend_is_cv = (type == plugin->uris.lv2_CVPort);
		break;
	default:
		return LV2_MORPH_ERR_BAD_PORT;
	}

	plugin->difference_is_cv = (plugin->minuend_is_cv ||
	                            plugin->subtrahend_is_cv);

	return LV2_MORPH_SUCCESS;
}

static LV2_URID
port_type(LV2_Handle                instance,
          uint32_t                  port,
          LV2_Morph_Property*const* properties)
{
	Difference* plugin = (Difference*)instance;

	switch (port) {
	case DIFFERENCE_DIFFERENCE:
		return (plugin->difference_is_cv
		        ? plugin->uris.lv2_CVPort
		        : plugin->uris.lv2_ControlPort);
	default:
		return 0;
	}
}

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

	plugin->minuend_is_cv    = 0;
	plugin->subtrahend_is_cv = 0;
	plugin->difference_is_cv = 0;

	map_uris(&plugin->uris, features);

	return (LV2_Handle)plugin;
}

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

	/* Minuend (array of floats of length 1 or sample_count) */
	const float* minuend = plugin->minuend;

	/* Subtrahend (array of floats of length 1 or sample_count) */
	const float* subtrahend = plugin->subtrahend;

	/* Difference (array of floats of length 1 or sample_count) */
	float* difference = plugin->difference;

	if (!plugin->difference_is_cv) {  /* TODO: Avoid this branch */
		sample_count = 1;
	}

	for (uint32_t s = 0; s < sample_count; ++s) {
		const float min = minuend[s * plugin->minuend_is_cv];
		const float sub = subtrahend[s * plugin->subtrahend_is_cv];

		difference[s] = min - sub;
	}
}

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

static const LV2_Descriptor descriptor = {
	"http://drobilla.net/plugins/blop/difference",
	instantiate,
	connect_port,
	NULL,
	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;
	}
}