--[[
	verify_rwd.luau -- verify the RWD steering fix, bypassing the require cache.

	check_live_source proved the pushed source IS in the DataModel (40307
	bytes, RWD marker present, single copy). But diag_steering still saw
	4 motors because require() caches per module INSTANCE for the life of the
	Play session, and CarManager was first required before the push -- so the
	old build closure was still running.

	Clone() produces a NEW instance, so require(clone) re-executes the current
	source. That gives a true read of the fix without restarting Play mode.
]]

local ServerScriptService = game:GetService("ServerScriptService")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local RunService = game:GetService("RunService")

local out = {}
local function log(...)
	local parts = {}
	for i = 1, select("#", ...) do
		parts[#parts + 1] = tostring((select(i, ...)))
	end
	table.insert(out, table.concat(parts, " "))
end

local Shared = ReplicatedStorage:FindFirstChild("Shared")
local Cars = require(Shared.Cars)
local Chassis = require(Shared.Chassis)

local orig = ServerScriptService:FindFirstChild("Server", true):FindFirstChild("CarManager")
local clone = orig:Clone()
clone.Parent = orig.Parent
local CarManager = require(clone)
log("required a FRESH clone of CarManager (" .. #clone.Source .. " bytes)")

local pad = Instance.new("Part")
pad.Size = Vector3.new(6000, 8, 6000)
pad.Position = Vector3.new(0, 5000, 0)
pad.Anchored = true
pad.Material = Enum.Material.Concrete
pad.Parent = workspace
local padTop = pad.Position.Y + 4

local car = Cars.Get("gtr_r34")
local tuning = Chassis.tuningFor(car)

local model = CarManager._buildForDiag(car, tuning)
model.Parent = workspace
model:PivotTo(CFrame.new(0, padTop + 3, 0))

local servos, motors = {}, {}
for _, d in ipairs(model:GetDescendants()) do
	if d:IsA("HingeConstraint") then
		if d.Name == Chassis.STEER_SERVO_NAME then
			table.insert(servos, d)
		elseif d.Name == Chassis.WHEEL_MOTOR_NAME then
			table.insert(motors, d)
		end
	end
end

local motorCorners = {}
for _, mo in ipairs(motors) do
	table.insert(motorCorners, mo.Parent and mo.Parent.Name or "?")
end
log(string.format("servos %d | motors %d  [%s]", #servos, #motors, table.concat(motorCorners, ", ")))
log(
	string.format(
		"expected: 2 servos, 2 motors on REAR corners only -> %s",
		(#motors == 2 and #servos == 2) and "OK" or "WRONG"
	)
)
log("")

local body = model.PrimaryPart
for _ = 1, 90 do
	RunService.Heartbeat:Wait()
end

-- Drive the rears and hold a steady steer angle, exactly like diag_steering.
local TARGET = -14
local wheelR = Chassis.WHEEL_RADIUS
local topW = tuning.MaxWheelAngularVelocity

log("t(s)   speed   yawRate   targetAng  curAng    radius")
local samples = 0
local errSum, errMax = 0, 0
local startLook = body.CFrame.LookVector

for step = 1, 300 do
	for _, mo in ipairs(motors) do
		mo.MotorMaxTorque = tuning.MotorMaxTorque
		mo.AngularVelocity = -topW
	end
	for _, s in ipairs(servos) do
		s.TargetAngle = TARGET
	end
	if step % 30 == 0 then
		local speed = body.AssemblyLinearVelocity.Magnitude
		local yaw = body.AssemblyAngularVelocity.Y
		local cur = servos[1].CurrentAngle
		local radius = (math.abs(yaw) > 1e-4) and (speed / math.abs(yaw)) or math.huge
		log(string.format("%4.1f  %6.1f  %7.3f   %8.1f %8.1f  %9.1f", step / 60, speed, yaw, TARGET, cur, radius))
		samples += 1
		local e = math.abs(cur - TARGET)
		errSum += e
		errMax = math.max(errMax, e)
	end
	RunService.Heartbeat:Wait()
end

local finalLook = body.CFrame.LookVector
local heading = math.deg(math.acos(math.clamp(startLook:Dot(finalLook), -1, 1)))

log("")
log(string.format("SERVO tracking: mean err %.2f deg, max %.2f deg", errSum / samples, errMax))
log(string.format("heading change over run: %.1f deg", heading))

local speed = body.AssemblyLinearVelocity.Magnitude
local yaw = math.abs(body.AssemblyAngularVelocity.Y)
local actualR = (yaw > 1e-4) and (speed / yaw) or math.huge
local wheelbase = Chassis.WHEELBASE or 11.8
local ackR = wheelbase / math.tan(math.rad(math.abs(servos[1].CurrentAngle)))
log(
	string.format(
		"Ackermann radius at %.1f deg = %.1f | ACTUAL %.1f | understeer %.2fx",
		servos[1].CurrentAngle,
		ackR,
		actualR,
		actualR / ackR
	)
)

model:Destroy()
pad:Destroy()
clone:Destroy()
return table.concat(out, "\n")