#include <td/simulation/RealTimeSimulation.h>

#include <chrono>

namespace td {
namespace sim {

std::uint64_t GetTime() {
	return static_cast<std::uint64_t>(
		std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock().now().time_since_epoch()).count());
}

RealTimeSimulation::RealTimeSimulation(game::World& a_World, GameHistory&& a_History, std::uint64_t a_StepTime) :
	m_StepTime(a_StepTime),
	m_World(a_World),
	m_History(std::move(a_History)),
	m_CurrentTime(0),
	m_LastTime(GetTime()),
	m_CurrentStep(0) {
	Step();
}

float RealTimeSimulation::Update() {
	// TODO: handle freezes (m_CurrentTime > 2 * m_StepTime)
	m_CurrentTime += GetTime() - m_LastTime;
	m_LastTime = GetTime();
	if (m_CurrentTime > m_StepTime) {
		Step();
		m_CurrentTime -= m_StepTime;
	}
	return (float) m_CurrentTime / (float) m_StepTime;
}

void RealTimeSimulation::Step() {
	m_World.Tick(m_History[m_CurrentStep], FpFloat(m_StepTime) / FpFloat(1000));
	m_CurrentStep++;
}

}  // namespace sim
}  // namespace td