StageGui LocalScript

local UI = script.Parent

local player = game.Players.LocalPlayer

local checkpoints = workspace:WaitForChild("Checkpoints")

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Teleport = ReplicatedStorage:WaitForChild("Teleport")

local Level = UI:WaitForChild("Stage")
local Previous = UI:WaitForChild("Previous")
local Next = UI:WaitForChild("Next")
local CurrentValue = UI:WaitForChild("CurrentStage")

local function previousLevel()
    if CurrentValue.Value ~= 1 then
        CurrentValue.Value = CurrentValue.Value - 1
        Level.Text = CurrentValue.Value
        Teleport:FireServer(checkpoints:GetChildren()[CurrentValue.Value])
    end
end

local function nextLevel()
    if CurrentValue.Value ~= #checkpoints:GetChildren() then
        if (CurrentValue.Value + 1) <= player.leaderstats.Stage.Value then
            CurrentValue.Value = CurrentValue.Value + 1
            Level.Text = CurrentValue.Value
            Teleport:FireServer(checkpoints:GetChildren()[CurrentValue.Value])
        end
    end
end

Previous.MouseButton1Click:Connect(function()
    previousLevel()
end)

Next.MouseButton1Click:Connect(function()
    nextLevel()
end)

CurrentValue.Value = player:WaitForChild("leaderstats").Stage.Value
Level.Text = CurrentValue.Value

player.leaderstats.Stage:GetPropertyChangedSignal("Value"):Connect(function()
    CurrentValue.Value = player.leaderstats.Stage.Value
    Level.Text = CurrentValue.Value
end)