LevelHandler

local Players = game:GetService("Players")
local DataStoreService = game:GetService("DataStoreService")
local SaveDataStore = DataStoreService:GetDataStore("SaveData")


local function SavePlayerData(player)

    local success, errormsg = pcall(function()

        local SaveData = {}

        for i, stats in pairs(player.leaderstats:GetChildren()) do

            SaveData[stats.Name] = stats.Value
        end
        SaveDataStore:SetAsync(player.UserId, SaveData)
    end)

    if not success then
        return errormsg
    end
end


Players.PlayerAdded:Connect(function(player)

    local Stats = Instance.new("Folder")
    Stats.Name = "leaderstats"
    Stats.Parent = player

    local level = Instance.new("IntValue")
    level.Name = "Level"
    level.Value = 0
    level.Parent = Stats

    local experience = Instance.new("IntValue")
    experience.Name = "Total XP"
    experience.Value = 0
    experience.Parent = Stats


    local Data = SaveDataStore:GetAsync(player.UserId)

    if Data then

        for i, stats in pairs(Stats:GetChildren()) do

            stats.Value = Data[stats.Name]
        end

    else
        print(player.Name .. " has no data.")
    end


    local expToLevelUp

    local expForPreviousLevel = 0


    while wait() do

        local levelBar = player.PlayerGui:WaitForChild("LevelBar")

        if level.Value < 1 then

            expToLevelUp = 100

        else

            expToLevelUp = math.floor(level.Value ^ 1.3) * 200 + math.floor(level.Value ^ 4)
        end


        if experience.Value >= expToLevelUp then

            level.Value = level.Value + 1
        end

        expForPreviousLevel = math.floor((level.Value - 1) ^ 1.3) * 200 + math.floor((level.Value - 1) ^ 4)


        local expDifference = expToLevelUp - expForPreviousLevel

        local expDifference2 = experience.Value - expForPreviousLevel


        levelBar.Bar:TweenSize(
            UDim2.new(levelBar.BarBackground.Size.X.Scale * (expDifference2 / expDifference), 0, levelBar.BarBackground.Size.Y.Scale, 0),
            Enum.EasingDirection.InOut, Enum.EasingStyle.Quint, 0.001
        )

        levelBar.Experience.Text = expDifference2 .. "/" .. expDifference

        levelBar.Level.Text = "Level: " .. level.Value


        experience.Value = experience.Value + 1
    end
end)


Players.PlayerRemoving:Connect(function(player)

    local errormsg = SavePlayerData(player)

    if errormsg then
        warn(errormsg)
    end
end)

game:BindToClose(function()
    for i, player in pairs(Players:GetPlayers()) do

        local errormsg = SavePlayerData(player)
        if errormsg then
            warn(errormsg)
        end
    end
    wait(2)
end)