--!strict
local Players = game:GetService("Players")
local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")

local player = Players.LocalPlayer

local flying = false
local speed = 100

local attachment: Attachment? = nil
local velocity: LinearVelocity? = nil
local connection: RBXScriptConnection? = nil

local function stopFlying()
    flying = false

    if connection then
        connection:Disconnect()
        connection = nil
    end

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

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

local function startFlying()
    local character = player.Character
    local humanoid = character
        and character:FindFirstChildOfClass("Humanoid")
    local root = character
        and character:FindFirstChild("HumanoidRootPart")

    if not humanoid or not root or not root:IsA("BasePart") then
        return
    end

    flying = true

    attachment = Instance.new("Attachment")
    attachment.Parent = root

    velocity = Instance.new("LinearVelocity")
    velocity.Attachment0 = attachment
    velocity.RelativeTo = Enum.ActuatorRelativeTo.World
    velocity.MaxForce = 100000
    velocity.VectorVelocity = Vector3.zero
    velocity.Parent = root

    connection = RunService.RenderStepped:Connect(function()
        if not flying or not velocity then
            return
        end

        local camera = workspace.CurrentCamera
        if not camera then return end

        local direction = Vector3.zero

        if UserInputService:IsKeyDown(Enum.KeyCode.W) then
            direction += camera.CFrame.LookVector
        end
        if UserInputService:IsKeyDown(Enum.KeyCode.S) then
            direction -= camera.CFrame.LookVector
        end
        if UserInputService:IsKeyDown(Enum.KeyCode.D) then
            direction += camera.CFrame.RightVector
        end
        if UserInputService:IsKeyDown(Enum.KeyCode.A) then
            direction -= camera.CFrame.RightVector
        end
        if UserInputService:IsKeyDown(Enum.KeyCode.Space) then
            direction += Vector3.yAxis
        end
        if UserInputService:IsKeyDown(Enum.KeyCode.LeftControl) then
            direction -= Vector3.yAxis
        end

        velocity.VectorVelocity =
            direction.Magnitude > 0
            and direction.Unit * speed
            or Vector3.zero
    end)
end

UserInputService.InputBegan:Connect(function(input, processed)
    if processed then return end

    if input.KeyCode == Enum.KeyCode.K then
        if flying then
            stopFlying()
        else
            startFlying()
        end
    end
end)

player.CharacterAdded:Connect(function()
    stopFlying()
end)