/*
 * melisma - extensible and scriptable audio engine
 * Copyright (C) 2026  Ludvig Gunne Lindström
 *
 * This program 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 program 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 program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <string.h>
#include <lua.h>
#include <lauxlib.h>
#include "melisma.h"
#include "mutil.h"

#define NULLSINK_TYPENAME "nullsink"

static int l_init(lua_State *s)
{
	ml_node *node = ml_create_node(NULL,NULL);
	ml_label_node(node,"nullsink");
	ml_node *root = ml_get_root_node();

	ml_channel *src = ml_add_output(node);
	ml_channel *dst = ml_add_input(root);

	ml_connect(src,dst);

	*(void**) lua_newuserdata(s,sizeof(void*)) = node;
	luaL_setmetatable(s,NULLSINK_TYPENAME);

	return 1;
}

static int l_ref(lua_State *s)
{
	ml_node *node = *(void**) luaL_checkudata(s,1,NULLSINK_TYPENAME);
	ml_channel *src = mutil_get_channel(s,2);
	ml_channel *dst = ml_add_input(node);
	ml_connect(src,dst);
	*(void**) lua_newuserdata(s,sizeof(void*)) = node;
	luaL_setmetatable(s,NULLSINK_TYPENAME);
	return 1;
}

int luaopen_melisma_nullsink(lua_State *s)
{
	ml_check_version();

/*** Reference otherwise disconnected nodes.

	local mnullsink = require 'melisma.nullsink'
	local minterp = require 'melisma.interp'
	local mevent = require 'melisma.event'

	local interp = minterp.init(0)
	interp:linear(1,60)

	-- The output of interp is disconnected.
	-- Need to connect it to a nullsink so we
	-- can sample it in the event callback below.
	local nullsink = mnullsink.init()
	nullsink:ref(interp)

	mevent.schedule(30, function()
		print('current value:', interp:sample())
	end)

@classmod nullsink
*/
	lua_newtable(s);
	int tbl = lua_gettop(s);

/*** Create a nullsink.
@static
@function init
@treturn nullsink The newly created nullsink.
*/
	lua_pushcfunction(s,l_init);
	lua_setfield(s,tbl,"init");

/*** Connect an input signal.

This makes sure the input signal is processed
even if it's not connected to anything else.

@function ref
@tparam channel input Input signal.
@treturn nullsink
*/
	lua_pushcfunction(s,l_ref);
	lua_setfield(s,tbl,"ref");

	luaL_newmetatable(s,NULLSINK_TYPENAME);
	int mt = lua_gettop(s);

	lua_pushvalue(s,tbl);
	lua_setfield(s,mt,"__index");

	lua_settop(s,tbl);
	return 1;
}