local Players = game:GetService("Players")
local RunService = game:GetService("RunService")

local player = Players.LocalPlayer

-- ================= SETTINGS =================

local CHARACTER_TILT_ANGLE = math.rad(45.5)
local VEHICLE_TILT_ANGLE   = math.rad(25)

local FIRST_PERSON_SMOOTHNESS = 100
local THIRD_PERSON_SMOOTHNESS = 16
local BLOCKED_SMOOTHNESS      = 4
local VEHICLE_SMOOTHNESS      = 8

local MIN_DIR_MAGNITUDE = 0.01
local VEHICLE_TORQUE = 80000

local FIRST_PERSON_DISTANCE_THRESHOLD = 2
local BLOCK_VELOCITY_MULTIPLIER = 6 

-- ============================================

local function isFirstPerson(character)
	local camera = workspace.CurrentCamera
	local head = character:FindFirstChild("Head")
	if camera and head then
		local dist = (camera.CFrame.Position - head.Position).Magnitude
		return dist < FIRST_PERSON_DISTANCE_THRESHOLD
	end
	return false
end

local function setupCharacter(character)

	local humanoid = character:WaitForChild("Humanoid")
	local hrp      = character:WaitForChild("HumanoidRootPart")

	humanoid.AutoRotate = false

	-- Cleanup cũ
	for _,v in pairs(hrp:GetChildren()) do
		if v.Name == "LeanAttachment"
		or v.Name == "LeanAlign"
		or v.Name == "VehicleLeanAttachment"
		or v.Name == "VehicleLeanAlign" then
			v:Destroy()
		end
	end

	-- ================= CHARACTER ALIGN =================

	local attachment = Instance.new("Attachment")
	attachment.Name = "LeanAttachment"
	attachment.Parent = hrp

	local align = Instance.new("AlignOrientation")
	align.Name = "LeanAlign"
	align.Mode = Enum.OrientationAlignmentMode.OneAttachment
	align.Attachment0 = attachment
	align.RigidityEnabled = true
	align.Responsiveness = 2000
	align.MaxTorque = Vector3.new(1e6,1e6,1e6)
	align.Parent = hrp

	-- ================= VEHICLE =================

	local vehicleAlign
	local vehicleAttachment
	local seatPart
	local isSeated = false
	local currentVehicleAngle = 0
	local currentCharCF = hrp.CFrame

	local function setupVehicle(seat)
		seatPart = seat
		isSeated = true

		if vehicleAlign then vehicleAlign:Destroy() end
		if vehicleAttachment then vehicleAttachment:Destroy() end

		vehicleAttachment = Instance.new("Attachment")
		vehicleAttachment.Name = "VehicleLeanAttachment"
		vehicleAttachment.Parent = seatPart

		vehicleAlign = Instance.new("AlignOrientation")
		vehicleAlign.Name = "VehicleLeanAlign"
		vehicleAlign.Mode = Enum.OrientationAlignmentMode.OneAttachment
		vehicleAlign.Attachment0 = vehicleAttachment
		vehicleAlign.PrimaryAxisOnly = true
		vehicleAlign.PrimaryAxis = Vector3.new(1,0,0)
		vehicleAlign.RigidityEnabled = false
		vehicleAlign.Responsiveness = 40
		vehicleAlign.MaxTorque = Vector3.new(VEHICLE_TORQUE,0,0)
		vehicleAlign.Parent = seatPart

		currentVehicleAngle = 0
	end

	local function cleanupVehicle()
		isSeated = false
		seatPart = nil
		currentVehicleAngle = 0

		if vehicleAlign then
			vehicleAlign:Destroy()
			vehicleAlign = nil
		end

		if vehicleAttachment then
			vehicleAttachment:Destroy()
			vehicleAttachment = nil
		end
	end

	humanoid.Seated:Connect(function(active, seat)
		if active and seat and seat:IsA("VehicleSeat") then
			setupVehicle(seat)
		else
			cleanupVehicle()
		end
	end)

	-----------------------------------------------------

	RunService.RenderStepped:Connect(function(dt)

		if not character.Parent then return end

		-- ================= VEHICLE MODE =================
		if isSeated and seatPart and vehicleAlign and seatPart.Parent then
			align.Enabled = false

			currentVehicleAngle =
				currentVehicleAngle +
				(VEHICLE_TILT_ANGLE - currentVehicleAngle)
				* math.clamp(dt * VEHICLE_SMOOTHNESS,0,1)

			vehicleAlign.CFrame = CFrame.Angles(currentVehicleAngle,0,0)
			return
		end

		-- ================= CHARACTER MODE =================
		align.Enabled = true

		local camera = workspace.CurrentCamera
		local moveInput = humanoid.MoveDirection
		local moveDir = nil

		if camera then
			if isFirstPerson(character) then
				local camLook = camera.CFrame.LookVector
				local flatCam = Vector3.new(camLook.X,0,camLook.Z)
				if flatCam.Magnitude > 0 then
					moveDir = flatCam.Unit
				end
			else
				if moveInput.Magnitude > MIN_DIR_MAGNITUDE then
					moveDir = moveInput
				end
			end
		end

		-- ===== PHÁT HIỆN BỊ CẢN (giống engine) =====
		local realVelocity = hrp.AssemblyLinearVelocity
		local flatVelocity = Vector3.new(realVelocity.X,0,realVelocity.Z)

		local isBlocked = false
		if moveInput.Magnitude > MIN_DIR_MAGNITUDE then
			if flatVelocity.Magnitude < moveInput.Magnitude * BLOCK_VELOCITY_MULTIPLIER then
				isBlocked = true
			end
		end

		local targetCF = currentCharCF

		if moveDir then
			local lookCF = CFrame.lookAt(
				hrp.Position,
				hrp.Position + Vector3.new(moveDir.X,0,moveDir.Z)
			)

			targetCF = lookCF * CFrame.Angles(CHARACTER_TILT_ANGLE,0,0)
		end

		-- ===== SMOOTHNESS LOGIC =====
		local smoothness

		if isBlocked then
			smoothness = BLOCKED_SMOOTHNESS
		else
			smoothness = isFirstPerson(character)
				and FIRST_PERSON_SMOOTHNESS
				or THIRD_PERSON_SMOOTHNESS
		end

		currentCharCF = currentCharCF:Lerp(
			targetCF,
			math.clamp(dt * smoothness,0,1)
		)

		align.CFrame = currentCharCF
	end)
end

-- Setup
local character = player.Character or player.CharacterAdded:Wait()
setupCharacter(character)
player.CharacterAdded:Connect(setupCharacter)