import math

class Engine:
    def __init__(self,
                 idle_rpm=750,
                 max_rpm=7000,
                 redline_rpm=6500,
                 flywheel_inertia=0.025,
                 fuel_efficiency=0.3,
                 torque_curve=None):
        
        # General stuff
        self.rpm = idle_rpm
        self.throttle = 0.0
        self.load = 0.0
        self.gear = None
        self.ignition = True
        self.revCut = False

        self.idle_rpm = idle_rpm
        self.max_rpm = max_rpm
        self.redline_rpm = redline_rpm
        self.flywheel_inertia = flywheel_inertia
        self.fuel_efficiency = fuel_efficiency
        self.torque_curve = torque_curve or self.default_torque_curve
        self.instant_torque = 0
        self.engineFriction = 5
        self.peak_torque = 163 # Nm -> 120 ft/lb
        self.engine_brake_strength = 40 # Nm
        self.engine_brake_torque = 0
        self.starting = False

        # Fluids
        self.oil_temp = 0
        self.oil_pressure = 0
        self.oil_capacity = 0

        self.coolant_temp = 0
        self.coolant_pressure = 0
        self.coolant_capacity = 0

        self.max_fuel_capacity = 68 # Liter
        self.fuel_capacity = self.max_fuel_capacity

        # Fuel

        self.fuel_rate = 0
        self.afr = 0

        # Timing stuff
        self.kr = 0
        self.timing_advance = 0
        self.ignition_timing = 0

        # Exhaust stuff
        self.exhaust_temp = 0
        self.turbo_boost = 0

        # Environment
        self.ambient_temp = 0
        self.altitude = 0
        self.intake_pressure = 0
        self.vehicle_mass = 0
        self.drivetrain_loss = 0


    # Just a parabolic curve for now
    def default_torque_curve(self, rpm):
        rpm_ratio = rpm / self.max_rpm
        return max(0.0, -4 * (rpm_ratio - 0.5) ** 2 + 1)

    def start(self, dt):
        self.ignition = True
        self.starting = True            
    
    def update(self, throttle, load, dt):
        self.throttle = throttle
        self.load = load

        if self.starting:
            available_torque = self.torque_curve(self.rpm)
            self.instant_torque = (available_torque * self.peak_torque) + 10
            rpm_change = (self.instant_torque / self.flywheel_inertia)
            self.rpm += rpm_change * dt
            if self.rpm > 2000:
                self.starting = False
                throttle = 0

        # Idle -- Eventually should have learning alg to find the % throttle needed
        if (self.rpm < self.idle_rpm):
            self.throttle = 0.1

        # Rev limit
        if (self.rpm > self.redline_rpm):
            self.revCut = True
        
        if self.revCut and self.rpm > self.redline_rpm - 100:
            self.throttle = 0
        else:
            self.revCut = False


        # Engine friction
        if (self.rpm > 0):
            friction_force = self.engineFriction
        else: 
            friction_force = 0

        # Engine braking torque (If throttle closed)
        if self.throttle == 0 and self.rpm > self.idle_rpm + 200 or not self.ignition:
            engine_brake_torque = self.engine_brake_strength * (self.rpm / self.max_rpm)
        else:
            engine_brake_torque = 0

        # Transmission Load



        # Calculate torque
        if self.ignition:
            available_torque = self.torque_curve(self.rpm)
        else:
            available_torque = 0

        self.instant_torque = (self.throttle * available_torque * self.peak_torque) - engine_brake_torque - friction_force
        rpm_change = (self.instant_torque / self.flywheel_inertia)
        self.rpm += rpm_change * dt

        self.fuel_rate = self.rpm * throttle * self.fuel_efficiency
        # self.fuel_capacity -= self.fuel_rate

        #self._update_temps(dt)