/*
 * 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 <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <lauxlib.h>
#include "melisma.h"

#define TIMER_TYPENAME "timer"

struct timer
{
	bool     on;
	uint64_t t;
};

static void proc(const ml_proc_args *args)
{
	struct timer *tmr = args->userp;

	if (tmr->on)
	{
		tmr->t += args->nframes;
	}
}

static int l_init(lua_State *s)
{
	struct timer *tmr = calloc(1,sizeof(*tmr));

	tmr->on = false;
	tmr->t = 0;

	ml_node *node = ml_create_node(proc,tmr);
	ml_channel *src = ml_add_output(node);
	ml_channel *dst = ml_add_input(ml_get_root_node());
	ml_connect(src,dst);

	*(void**) lua_newuserdata(s,sizeof(void*)) = tmr;
	luaL_setmetatable(s,TIMER_TYPENAME);

	return 1;
}

static int l_start(lua_State *s)
{
	struct timer *tmr = *(void**) luaL_checkudata(s,1,TIMER_TYPENAME);
	tmr->on = true;
	return 0;
}

static int l_stop(lua_State *s)
{
	struct timer *tmr = *(void**) luaL_checkudata(s,1,TIMER_TYPENAME);
	tmr->on = false;
	return 0;
}

static int l_reset(lua_State *s)
{
	struct timer *tmr = *(void**) luaL_checkudata(s,1,TIMER_TYPENAME);
	tmr->t = 0;
	return 0;
}

static int l_read(lua_State *s)
{
	struct timer *tmr = *(void**) luaL_checkudata(s,1,TIMER_TYPENAME);
	double t = (double) tmr->t / (double) ml_sample_rate();
	lua_pushnumber(s,t);
	return 1;
}

int luaopen_melisma_timer(lua_State *s)
{
/*** Time measurement.

	local mtimer = require 'melisma.timer'
	local mkeycallback = require 'melisma.keycallback'

	local timer = mtimer.init()
	timer:start()

	mkeycallback.set(function()
		print(timer:read())
		timer:reset()
	end)

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

/*** Create a new timer.
@static
@function init
@treturn timer
*/
	lua_pushcfunction(s,l_init);
	lua_setfield(s,tbl,"init");

/*** Start timer.
@function start
*/
	lua_pushcfunction(s,l_start);
	lua_setfield(s,tbl,"start");

/*** Stop timer.
@function stop
*/
	lua_pushcfunction(s,l_stop);
	lua_setfield(s,tbl,"stop");

/*** Reset timer.
@function reset
*/
	lua_pushcfunction(s,l_reset);
	lua_setfield(s,tbl,"reset");


/*** Read timer.
@function read
@treturn number Elapsed seconds.
*/
	lua_pushcfunction(s,l_read);
	lua_setfield(s,tbl,"read");

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

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

	lua_settop(s,tbl);
	return 1;
}