#include "Engine.h"
#include "Config.h"
using namespace EngineConsts;

Engine::Engine(uint8_t throttlePin,
               uint8_t clutchPin,
               uint8_t brakePin)
  : _throttlePin(throttlePin), _clutchPin(clutchPin), _brakePin(brakePin) {}

void Engine::begin() {}

float Engine::readNormalized(uint8_t pin) const {
  return analogRead(pin) / 1023.0f;
}

void Engine::update(float dt, uint8_t gearIdx) {
  const float throttle = readNormalized(_throttlePin);
  const float clutch = readNormalized(_clutchPin);
  const float brake = readNormalized(_brakePin);

  const float targetRPM = RPM_IDLE + throttle * (RPM_MAX - RPM_IDLE);

  const float wheelRPM = (_speedMs / (2.0f * PI * WHEEL_RADIUS)) * 60.0f;

  const float gearRatio = GEAR_RATIO[gearIdx];
  const float drivenRPM = wheelRPM * fabs(gearRatio) * FINAL_DRIVE;

  _engineRPM = clutch * drivenRPM + (1.0f - clutch) * targetRPM;
  _engineRPM = constrain(_engineRPM, RPM_IDLE, 7500.0f);

  const float engineForce = (_engineRPM / RPM_MAX) * (1.0f - clutch) * ENGINE_FORCE_FACTOR;
  const float brakeForce = brake * BRAKE_FORCE_MAX;
  const float dragForce = 0.5f * DRAG_COEFF * FRONTAL_AREA * (_speedMs * _speedMs);
  const int direction = (gearIdx == -1) ? -1 : 1;
  const float netForce = direction * engineForce - brakeForce - dragForce;
  const float acceleration = netForce / CAR_MASS;

  _speedMs += acceleration * dt;
  if (_speedMs < 0.0f) _speedMs = 0.0f;

  setMotor(IN_3, IN_4, ENA_2, targetRPM, false);

  bool reverseWheel = (gearIdx == -1);
  setMotor(IN_1, IN_2, ENA_1, wheelRPM * 10.0f, reverseWheel);
}

int Engine::getRPM() const {
  return static_cast<int>(_engineRPM + 0.5f);
}

int Engine::getSpeedKmh() const {
  return static_cast<int>((_speedMs * 3.6f) + 0.5f);
}

uint8_t Engine::rpmToPwm(float rpm) {
  rpm = constrain(rpm, 0.0f, RPM_MAX);
  return static_cast<uint8_t>(roundf(rpm / RPM_MAX * 255.0f));
}

void Engine::setMotor(uint8_t inA, uint8_t inB, uint8_t ena,
                      float rpm, bool reverse) {
  digitalWrite(inA, reverse ? LOW : HIGH);
  digitalWrite(inB, reverse ? HIGH : LOW);

  analogWrite(ena, rpmToPwm(rpm));
}