--@include ./powertrain_component.txt
--@include /koptilnya/libs/constants.txt

require('./powertrain_component.txt')
require('/koptilnya/libs/constants.txt')

Engine = class('Engine', PowertrainComponent)

function Engine:initialize(config, clutch)
    PowertrainComponent.initialize(self, 'Engine')

    self.wireInputs = {
        Throttle = 'number'
    }
    self.wireOutputs = {
        Engine_RPM = 'number',
        Engine_Torque = 'number',
        Engine_MasterThrottle = 'number'
    }

    self.idleRPM = config.IdleRPM or 900
    self.maxRPM = config.MaxRPM or 7000
    self.inertia = config.Inertia or 0.4
    self.startFriction = config.StartFriction or -50
    self.frictionCoeff = config.FrictionCoeff or 0.02
    self.limiterDuration = config.LimiterDuration or 0.05
    self.torqueMap = config.TorqueMap or {}

    self.rpmFrac = 0
    self.friction = 0
    self.masterThrottle = 0

    self.limiterTimer = 0
end

function Engine:updateWireOutputs()
    wire.ports.Engine_RPM = self:getRPM()
    wire.ports.Engine_Torque = self.torque
    wire.ports.Engine_MasterThrottle = self.masterThrottle
end

function Engine:getThrottle()
    return wire.ports.Throttle
end

function Engine:_generateTorque()
    local throttle = self:getThrottle()
    local rpm = self:getRPM()

    local rpmFrac = math.clamp((rpm - self.idleRPM) / (self.maxRPM - self.idleRPM), 0, 1)
    self.friction = self.startFriction - self:getRPM() * self.frictionCoeff

    local tqIdx = math.clamp(math.floor(rpmFrac * #self.torqueMap), 1, #self.torqueMap)
    local maxInitialTorque = self.torqueMap[tqIdx] - self.friction
    local idleFadeStart = math.clamp(math.remap(rpm, self.idleRPM - 300, self.idleRPM, 1, 0), 0, 1)
    local idleFadeEnd = math.clamp(math.remap(rpm, self.idleRPM, self.idleRPM + 600, 1, 0), 0, 1)
    local additionalEnergySupply = idleFadeEnd * (-self.friction / maxInitialTorque) + idleFadeStart

    if rpm > self.maxRPM then
        throttle = 0
        self.limiterTimer = timer.systime()
    else
        throttle = timer.systime() >= self.limiterTimer + self.limiterDuration and throttle or 0
    end

    self.masterThrottle = math.clamp(additionalEnergySupply + throttle, 0, 1)

    local realInitialTorque = maxInitialTorque * self.masterThrottle

    self.torque = realInitialTorque + self.friction

    return self.torque
end

function Engine:integrateDownwards()
    if self.output == nil then
        local generatedTorque = self:_generateTorque()

        self.angularVelocity = self.angularVelocity + generatedTorque / self.inertia * TICK_INTERVAL
        self.angularVelocity = math.max(self.angularVelocity, 0)
    end

    local outputInertia = self.output:queryInertia()
    local inertiaSum = self.inertia + outputInertia
    local outputW = self.output:queryAngularVelocity(self.angularVelocity)
    local targetW = self.inertia / inertiaSum * self.angularVelocity + outputInertia / inertiaSum * outputW

    local generatedTorque = self:_generateTorque()
    local reactTorque = (targetW - self.angularVelocity) * self.inertia / TICK_INTERVAL
    local returnedTorque = self.output:forwardStep(generatedTorque - reactTorque, 0) -- ??? 0 -> self.inertia
    local finalTorque = generatedTorque + returnedTorque + reactTorque

    self.angularVelocity = self.angularVelocity + finalTorque / inertiaSum * TICK_INTERVAL
    self.angularVelocity = math.max(self.angularVelocity, 0)
end