/*
 * Copyright (C) 2015, 2016 "IoT.bzh"
 * Author "Romain Forlot" <romain.forlot@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	 http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdlib.h> 

#include "timer.hpp"

#define MS_PER_SECOND 1000

long long int system_time_ms()
{
	struct timeb t_msec;
	long long int timestamp_msec;
	
	if(!::ftime(&t_msec))
	{
		timestamp_msec = (t_msec.time) * 1000ll + 
			t_msec.millitm;
	}
	return timestamp_msec;
}

frequency_clock_t::frequency_clock_t()
	: frequency_{10.0}, last_tick_{0}, time_function_{nullptr}
{}


frequency_clock_t::frequency_clock_t(float frequency)
	: frequency_{frequency}, last_tick_{0}, time_function_{nullptr}
{}

/// @brief Return the period in ms given the frequency in hertz.
float frequency_clock_t::frequency_to_period(float frequency)
{
	return 1 / frequency * MS_PER_SECOND;
}

bool frequency_clock_t::started()
{
	return last_tick_ != 0;
}

time_function_t frequency_clock_t::get_time_function()
{
	return time_function_ != nullptr ? time_function_ : system_time_ms;
}

bool frequency_clock_t::elapsed(bool stagger)
{
	float period = frequency_to_period(frequency_);
	float elapsed_time = 0;
	if(!started() && stagger)
		last_tick_ = get_time_function()() - (rand() % int(period));
	else
		// Make sure it ticks the the first call to conditionalTick(...)
		elapsed_time = !started() ? period : get_time_function()() - last_tick_;

	return frequency_ == 0 || elapsed_time >= period;
}

/// @brief Force the clock to tick, regardless of it its time has actually
/// elapsed.
void frequency_clock_t::tick()
{
	last_tick_ = get_time_function()();
}