-- Auto Transmission Type-E v0.8 by Vegetable Studio
-- Please visit "https://www.patreon.com/vegetable_studio" for instructions

-- Essentials
local raw = ac.accessCarPhysics()
local car = ac.getCar(0)
local engine = ac.INIConfig.carData(0, 'engine.ini')
local drivetrain = ac.INIConfig.carData(0, 'drivetrain.ini')
local tyre = ac.INIConfig.carData(0, 'tyre.ini')

local gearCount = car.gearCount
local limiter = car.rpmLimiter
local torque = ac.DataLUT11.load(engine:get('HEADER', 'POWER_CURVE', 'power.lut'))
local idleRpm = engine:get('ENGINE_DATA', 'MINIMUM', 800)
local clutchMaxTorque = drivetrain:get('CLUTCH', 'MAX_TORQUE', 600)
local gearsFinalRatio = drivetrain:get('GEARS', 'FINAL', 4.4)
local circumference = tyre:get('REAR', 'RADIUS', 0.32) * 2 * math.pi
local rpmToKmh = circumference / 1000 * 60

local gearRatios = {}
local topSpeeds = {}

for i = 1, gearCount do
    gearRatios[i] = drivetrain:get('GEARS', 'GEAR_' .. tostring(i), 0)
    topSpeeds[i] = limiter * 0.99 / gearRatios[i] / gearsFinalRatio * rpmToKmh
end

local gear, speed, rpmEngine, throttle = 1, 0, 0, 0

-- Values to calculate speed target for auto shifting
local throttleMap = ac.DataLUT11.parse('(|0.1=0.25|0.5=0.5|0.9=0.95)')
local targetSpeedUp = 0
local targetSpeedDown = 0

-- Values for torque converter simulation
local stallRpm = 2000 * math.round(idleRpm / 1000)
local stallTorque = torque:get(stallRpm)
local stallPower = stallRpm * stallTorque / 5250
local kFactor = math.round(stallRpm / math.sqrt(stallTorque), -1)
local lockUpMap = ac.DataLUT11.parse('(|' .. tostring(stallRpm * 1 / gearsFinalRatio * rpmToKmh) .. '=0|'.. tostring((stallRpm * 1.25) / gearsFinalRatio * rpmToKmh) ..'=1|)')
local speedLag = 0
local rpmWheel, rpmDiff = 0, 0
local tcPressure = 0
local tcLoad = 0
local torqueMult = 1
local torqueEngine = 0
local targetFinal = gearsFinalRatio
local torqueConverter, lockUp = 0, 0

-- Values for shifting operation
local gearLimitUp = false
local gearLimitDown = false
local delay = 0.75
local autoUp = 0
local autoDown = 0
local clutchUnlock = false
local unlockTimer = 0
local shiftSpeed = 0.5
local unlockMap = ac.DataLUT11.parse('(|0=0|' .. tostring(shiftSpeed) .. '=1)')


function script.update(dt)
    -- Disable H-shifter to stop overriding engaged gear
    if raw.isShifterSupported == true then
        raw.isShifterSupported = false
    end

    -- -- Update final ratio & top speeds when setup is changed, Not working at the moment
    -- if math.abs(raw.gearsFinalRatio - targetFinal) > 0.1 then
    --     gearsFinalRatio = raw.gearsFinalRatio
    --     for i = 1, gearCount do
    --         topSpeeds[i] = limiter * 0.99 / gearRatios[i] / gearsFinalRatio * rpmToKmh
    --     end
    -- end

    -- Essentials
    gear = math.max(1, car.gear)
    speed = math.round(car.poweredWheelsSpeed, 2)
    rpmEngine = math.max(raw.rpm, 1)
    throttle = throttleMap:get(raw.gas)
    torqueEngine = math.max(car.drivetrainTorque, 0)

    -- Torque converter simulation
    speedLag = math.applyLag(speedLag, speed, 0.95, dt)
    rpmWheel = math.max(speed / rpmToKmh * gearsFinalRatio * gearRatios[gear], 1)
    rpmDiff = math.max(rpmEngine - rpmWheel, 0)

    tcPressure = math.pow(rpmDiff / kFactor, 2)
    tcLoad = math.min(car.drivetrainPower / stallPower, 1)

    torqueMult = 1 + (rpmDiff / stallRpm) * (1 - math.min(rpmWheel / stallRpm, 1))
    targetFinal = gearsFinalRatio * torqueMult
    torqueConverter = math.clamp((tcPressure / clutchMaxTorque * (1 - tcLoad) + math.sqrt(torqueEngine / clutchMaxTorque) * tcLoad), 0, 1)

    -- Clutch lock-up feature
    if gearRatios[gear] < 1 then
        lockUp = 1
    else
        lockUp = lockUpMap:get(speedLag * gearRatios[gear])
    end

    -- Calculate speed target for auto shifting
    targetSpeedUp = (topSpeeds[gear] - gearRatios[gear] * gearsFinalRatio) * throttle
    
    if gear > 1 then
        targetSpeedDown = (topSpeeds[gear - 1] - gearRatios[gear - 1] * gearsFinalRatio) * throttle - 5
    else
        targetSpeedDown = 0
    end

    -- Shifting mechanism
    if car.gear > 0 then
        if ac.isControllerGearUpPressed() then
            raw.gearUp = false
            gearLimitUp = true
        end
    
        if gearLimitUp and ac.isControllerGearUpPressed() == false then
            if speed > 1 then gearCount = math.min(car.gearCount, gearCount + 1) end
            gearLimitUp = false
        end
    
        if ac.isControllerGearDownPressed() then
            raw.gearDown = false
            gearLimitDown = true
        end
    
        if gearLimitDown and ac.isControllerGearDownPressed() == false then
            if speed > 1 then
                gearCount = math.max(1, gearCount - 1)
            else
                raw.gearDown = true
            end
            gearLimitDown = false
        end

        if speed > targetSpeedUp and gear < gearCount then
            autoUp = autoUp + dt
            autoDown = 0
        elseif (speed < targetSpeedDown and gear > 1 ) or (gear > gearCount and speed < topSpeeds[gear - 1]) then
            autoDown = autoDown + dt
            autoUp = 0
        else
            autoUp = 0
            autoDown = 0
        end

        if autoUp > delay then
            raw.gearUp = true
            clutchUnlock = true
            autoUp = delay - 0.01
        end
    
        if autoDown > delay then
            raw.gearDown = true
            clutchUnlock = true
            autoDown = delay - 0.01
        end
    
        if clutchUnlock then
            unlockTimer = unlockTimer + dt
            lockUp = lockUp * unlockMap:get(unlockTimer)
        end
    
        if unlockTimer > shiftSpeed then
            clutchUnlock = false
            unlockTimer = 0
        end
    end

    -- Actual physics override
    ac.setGearsFinalRatio(targetFinal)
    raw.clutch = torqueConverter + (1 - torqueConverter) * lockUp

     --Debug
    ac.debug("Shift Mode", 'D' .. gearCount)
    -- ac.debug("Current Gear", gear)
    -- ac.debug("Current Gear Ratio", gearRatios[gear])
    -- ac.debug("Current Gear Top Speed", math.round(topSpeeds[gear]))
    -- ac.debug("Target Speed Up", math.round(targetSpeedUp))
    -- ac.debug("Target Speed Down", math.round(targetSpeedDown))
    -- ac.debug("Shift Threshold Up", math.round(autoUp, 1))
    -- ac.debug("Shift Threshold Down", math.round(autoDown, 1))
    -- ac.debug("K Factor", kFactor)
    -- ac.debug("Stator Pressure", math.round(tcPressure) .. ' Nm')
    -- ac.debug("Torque Multiplication", math.round(torqueMult, 2))
    -- ac.debug("Clutch Lock-Up", math.round(lockUp * 100) .. '%')
    -- ac.debug("Torque Converter", math.round(torqueConverter, 2))
    -- ac.debug("Slippage", math.round(((rpmEngine / rpmWheel) - 1) * 100) .. '%')
    -- ac.debug("Torque Output", math.round(torqueEngine * torqueMult) .. ' Nm')
end