--[[
Copyright (c) 2025 Dmitrii A.

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ScriptSettings = ac.INIConfig.scriptSettings():mapSection('SETTINGS', {
	sideForceK = 0.3,
	frontForceK = 0.4,
	dampK = 0.07,
	suspTravelK = 0.15,
	baseForceK = 1
})

ac.debug('settings', ScriptSettings)

-- Setup
local mainFfbK = 1.6        -- Main FFB multiplier, similar to the Gain setting
local frontForceLimit = 0.7 -- Front force limit. 1 = 100%
local suspForceLimit = 0.5  -- Suspension force limit. 1 = 100%
local slipMultK = 3000      -- Base multiplier for lateral force from slip
local turnMultK = 20        -- Steering force multiplier
local turnMultMax = 1.2     -- Limit for the steering force
local osMult = 1.8          -- Multiplier for lateral force reduction after slip (0 disables the effect)
local rsMultK = 0.2         -- Multiplier for lateral force when rear wheels lose grip (0 disables the effect)
local iceMult = 2           -- Force multiplier on ice
local gravelMult = 0.5      -- Force multiplier on gravel
local gravelVK = 0.1        -- Vibration effect on gravel (0 disables the effect)
local dampSlowSpeedK = 0.3  -- Additional damping at low speed
-- Warning: Changing these settings may cause unpredictable steering wheel behavior.
-- This can be dangerous and may lead to injuries, especially with direct drive wheels. Adjust with caution!

-- Implementation:
local carPh = ac.getCarPhysicsRate()

-- Use this line if you want to use `ffbValue`, but exclude suspension forces from it:
-- ac.setPureFFBMultiplier(0)

local carIni = ac.INIConfig.carData(car.index, 'car.ini')
local carIniFfbMult = math.min(carIni:get('CONTROLS', 'FFMULT', 1), 10)

local steerFfb = { 0, 0 }
local frontFfb = { 0, 0 }
local lastSuspT = { 0, 0 }
local ssRearMain = { 0, 0 }
local rsMult = 1
local wheelLoad = { 0, 0 }
local surfaceMult = { 0, 0 }
local vibrationS = { 0, 0 }

local gravelS = { ac.SurfaceExtendedType.Grass, ac.SurfaceExtendedType.Gravel, ac.SurfaceExtendedType.Sand }
local iceS = { ac.SurfaceExtendedType.Ice, ac.SurfaceExtendedType.Snow }
local function checkSurface(s)
	for i = 1, #gravelS do
		if s == gravelS[i] then
			return gravelMult
		end
	end
	for i = 1, #iceS do
		if s == iceS[i] then
			return iceMult
		end
	end
	return 1
end

rsMultK = math.ceil(rsMultK * 10) / 10

local function ffbState(i)
	local lastSide = vec3()
	local lastTMult = 0
	local fsSmooth = 0

	---@param wheel ac.StateWheel
	---@param tyre ac.StateWheelPhysicsRate
	local function update(dt, wheel, tyre)
		local roadSide = (tyre.side - tyre.contactNormal * tyre.side:dot(tyre.contactNormal)):normalize()
		local sideSlip = math.dot(roadSide, tyre.velocity)

		local turnMultBase = math.pow(1 + #(roadSide - lastSide) * turnMultK, 2)
		local turnMult = math.min(turnMultBase, lastTMult)
		turnMult = math.min(turnMult, turnMultMax)
		lastSide = roadSide
		lastTMult = turnMultBase

		local sideForce = tyre.fy * ScriptSettings.baseForceK
		local frontForce = -tyre.fx
		local rsosMult = rsMultK > 0 and (1 - (rsMult - 1) / rsMultK) or 1
		local overSlip = 1 + math.smoothstep(math.saturate((math.abs(sideSlip) - 3) / 6)) * osMult * rsosMult
		local slipMult = math.abs(sideSlip) * slipMultK
		local forceMult = slipMult > math.abs(sideForce) and math.abs(sideForce) / slipMult or 1
		slipMult = slipMult * forceMult * math.sign(sideSlip) * turnMult / overSlip
		fsSmooth = fsSmooth + (frontForce - fsSmooth) * 0.1

		ac.debug('slipMult', slipMult, nil, nil, 5, ac.DebugCollectMode.Average)
		ac.debug('sideForce', math.abs(sideForce), nil, nil, 5, ac.DebugCollectMode.Average)

		if i < 2 then
			local sType = checkSurface(tyre.surfaceExtendedType)
			steerFfb[i + 1] = slipMult * dt * sType
			frontFfb[i + 1] = -fsSmooth * dt * sType
			wheelLoad[i + 1] = tyre.load
			surfaceMult[i + 1] = sType
			vibrationS[i + 1] = tyre.surfaceExtendedType == ac.SurfaceExtendedType.Gravel and 1 or 0
		end
		if i > 1 then
			ssRearMain[i - 1] = math.abs(sideSlip)
		end
	end

	return update
end

local wheels = { ffbState(0), ffbState(1), ffbState(2), ffbState(3) }
local ffbCounter = 0
local ffbSwitcher = 1

function script.update(ffbValue, ffbDamper, steerInput, steerInputSpeed, dt)
	local sideForceK = ScriptSettings.sideForceK * 0.05
	local frontForceK = ScriptSettings.frontForceK * 0.1
	local dampK = ScriptSettings.dampK
	local suspTravelK = ScriptSettings.suspTravelK * 1000

	for i = 1, 4 do
		wheels[i](dt, car.wheels[i - 1], carPh.wheels[i - 1])
	end

	local baseGain = ac.getFFBGain()
	local ffbMultFinal = baseGain * (0.5 + carIniFfbMult / 4) * mainFfbK

	local slowSpeedMult = (1 - math.smoothstep(math.saturate((carPh.speedKmh - 3) / 50)))
	rsMult = 1 + math.saturate((ssRearMain[1] + ssRearMain[2] - 6) / 6) * rsMultK
	local ffbSideForce = (steerFfb[1] + steerFfb[2]) * sideForceK * rsMult * ffbMultFinal * (1 + slowSpeedMult)
	local ffbFrontForce = (frontFfb[1] - frontFfb[2]) * frontForceK * ffbMultFinal
	ffbFrontForce = math.clamp(ffbFrontForce, -frontForceLimit, frontForceLimit)
	local dampSpeedMult = (1 + #car.velocity * 0.02) * dampK
	local ffbDamp = steerInputSpeed * dampSpeedMult / rsMult

	local suspensionSpeed = { carPh.wheels[0].suspensionTravel - lastSuspT[1], carPh.wheels[1].suspensionTravel -
	lastSuspT[2] }
	local sSpeedMain = suspensionSpeed[1] - suspensionSpeed[2]
	local ffbSusp = sSpeedMain * suspTravelK * math.pow(ffbMultFinal, 0.5)
	ffbSusp = math.clamp(ffbSusp, -suspForceLimit, suspForceLimit)
	lastSuspT = { carPh.wheels[0].suspensionTravel, carPh.wheels[1].suspensionTravel }

	if surfaceMult[1] ~= 1 or surfaceMult[2] ~= 1 then
		ffbSusp = math.abs(math.pow(1 + ffbSusp, 0.5) - 1) * math.sign(ffbSusp)
	end

	-- Gravel vibration
	local vibrationMult = (vibrationS[1] + vibrationS[2]) / 2
	if vibrationMult > 0 then
		local loadMult = math.pow((math.saturate(wheelLoad[1] / 1000) + math.saturate(wheelLoad[2] / 1000)) / 2, 0.5)
		if ffbCounter > 1 then
			ffbSwitcher = -1
		elseif ffbCounter < -1 then
			ffbSwitcher = 1
		end
		ffbCounter = ffbCounter + 0.0025 * carPh.speedKmh * ffbSwitcher * math.random(0, 2)
		ffbCounter = ffbCounter * math.saturate(math.random(0, 5))
		ffbSideForce = ffbSideForce + (ffbCounter * gravelVK * loadMult * vibrationMult * baseGain) / (1 + math.abs(ffbSideForce))
	end

	local ffbFinal = (ffbSideForce + ffbSusp + ffbFrontForce) * math.saturate(carPh.speedKmh - 3)
	ffbDamper = math.abs(ffbDamp) + slowSpeedMult * dampSlowSpeedK
	return ffbFinal, ffbDamper
end