local TweenService = game:GetService("TweenService")
local UserInputService = game:GetService("UserInputService")
local CoreGui = game:GetService("Players").LocalPlayer:WaitForChild("PlayerGui")

local Nexus = {}

local Theme = {
    Background = Color3.fromRGB(13, 13, 20),
    Sidebar = Color3.fromRGB(18, 18, 28),
    Accent = Color3.fromRGB(150, 80, 255),
    Text = Color3.fromRGB(255, 255, 255),
    TextMuted = Color3.fromRGB(180, 180, 200),
    Element = Color3.fromRGB(25, 25, 40),
    Hover = Color3.fromRGB(35, 35, 55),
    Stroke = Color3.fromRGB(60, 60, 85)
}

-- Utility: Dragging Function
local function MakeDraggable(dragPart, mainPart)
    local dragging, dragInput, dragStart, startPos
    dragPart.InputBegan:Connect(function(input)
        if input.UserInputType == Enum.UserInputType.MouseButton1 then
            dragging = true
            dragStart = input.Position
            startPos = mainPart.Position
        end
    end)
    UserInputService.InputChanged:Connect(function(input)
        if dragging and input.UserInputType == Enum.UserInputType.MouseMovement then
            local delta = input.Position - dragStart
            mainPart.Position = UDim2.new(startPos.X.Scale, startPos.X.Offset + delta.X, startPos.Y.Scale, startPos.Y.Offset + delta.Y)
        end
    end)
    UserInputService.InputEnded:Connect(function(input)
        if input.UserInputType == Enum.UserInputType.MouseButton1 then dragging = false end
    end)
end

function Nexus:CreateWindow(config)
    local Title = config.Title or "NEXUS"
    local Discord = config.Discord or nil
    local Key = config.Key or nil
    
    local ScreenGui = Instance.new("ScreenGui", CoreGui)
    ScreenGui.Name = "Nexus_System"
    ScreenGui.ResetOnSpawn = false

    -- [DRAGGABLE KEY SYSTEM]
    if Key then
        local KeyMain = Instance.new("Frame", ScreenGui)
        KeyMain.Size = UDim2.new(0, 350, 0, 200)
        KeyMain.Position = UDim2.new(0.5, -175, 0.5, -100)
        KeyMain.BackgroundColor3 = Theme.Background
        Instance.new("UICorner", KeyMain).CornerRadius = UDim.new(0, 10)
        Instance.new("UIStroke", KeyMain).Color = Theme.Accent

        local KeyTop = Instance.new("Frame", KeyMain)
        KeyTop.Size = UDim2.new(1, 0, 0, 40)
        KeyTop.BackgroundTransparency = 1
        
        local KeyTitle = Instance.new("TextLabel", KeyTop)
        KeyTitle.Size = UDim2.new(1, 0, 1, 0)
        KeyTitle.Text = "AUTHENTICATION"
        KeyTitle.TextColor3 = Theme.Text
        KeyTitle.Font = Enum.Font.GothamBold
        KeyTitle.TextSize = 18 -- Bigger Text
        KeyTitle.BackgroundTransparency = 1

        local Input = Instance.new("TextBox", KeyMain)
        Input.Size = UDim2.new(0.8, 0, 0, 40)
        Input.Position = UDim2.new(0.1, 0, 0.35, 0)
        Input.BackgroundColor3 = Theme.Element
        Input.Text = ""
        Input.PlaceholderText = "Enter Key Here"
        Input.TextColor3 = Theme.Text
        Input.TextSize = 16
        Input.Font = Enum.Font.Gotham
        Instance.new("UICorner", Input)

        local Submit = Instance.new("TextButton", KeyMain)
        Submit.Size = UDim2.new(0.8, 0, 0, 40)
        Submit.Position = UDim2.new(0.1, 0, 0.65, 0)
        Submit.BackgroundColor3 = Theme.Accent
        Submit.Text = "VERIFY KEY"
        Submit.TextColor3 = Theme.Text
        Submit.TextSize = 16
        Submit.Font = Enum.Font.GothamBold
        Instance.new("UICorner", Submit)

        MakeDraggable(KeyTop, KeyMain)

        Submit.MouseButton1Click:Connect(function()
            if Input.Text == Key then
                KeyMain:Destroy()
            else
                Input.Text = ""
                Input.PlaceholderText = "INVALID KEY"
                Input.PlaceholderColor3 = Color3.fromRGB(255, 80, 80)
            end
        end)
        repeat task.wait() until not KeyMain.Parent
    end

    -- [MAIN WINDOW]
    local Main = Instance.new("Frame", ScreenGui)
    Main.Size = UDim2.new(0, 600, 0, 400) -- Slightly bigger window
    Main.Position = UDim2.new(0.5, -300, 0.5, -200)
    Main.BackgroundColor3 = Theme.Background
    Instance.new("UICorner", Main).CornerRadius = UDim.new(0, 12)
    Instance.new("UIStroke", Main).Color = Theme.Stroke

    local TopBar = Instance.new("Frame", Main)
    TopBar.Size = UDim2.new(1, 0, 0, 50)
    TopBar.BackgroundTransparency = 1

    local TitleLabel = Instance.new("TextLabel", TopBar)
    TitleLabel.Size = UDim2.new(1, -120, 1, 0)
    TitleLabel.Position = UDim2.new(0, 20, 0, 0)
    TitleLabel.Text = Title
    TitleLabel.TextColor3 = Theme.Text
    TitleLabel.Font = Enum.Font.GothamBold
    TitleLabel.TextSize = 20 -- Bigger Text
    TitleLabel.TextXAlignment = Enum.TextXAlignment.Left
    TitleLabel.BackgroundTransparency = 1

    local CloseBtn = Instance.new("TextButton", TopBar)
    CloseBtn.Name = "CloseButton"
    CloseBtn.Size = UDim2.new(0, 35, 0, 35)
    CloseBtn.Position = UDim2.new(1, -45, 0, 7)
    CloseBtn.BackgroundColor3 = Color3.fromRGB(180, 40, 40)
    CloseBtn.Text = "X" -- Standard X for rendering
    CloseBtn.TextColor3 = Color3.fromRGB(255, 255, 255)
    CloseBtn.Font = Enum.Font.GothamBold
    CloseBtn.TextSize = 18
    Instance.new("UICorner", CloseBtn).CornerRadius = UDim.new(0, 8)
    CloseBtn.MouseButton1Click:Connect(function() ScreenGui:Destroy() end)

    MakeDraggable(TopBar, Main)

    -- Layout
    local Sidebar = Instance.new("Frame", Main)
    Sidebar.Size = UDim2.new(0, 160, 1, -60)
    Sidebar.Position = UDim2.new(0, 10, 0, 50)
    Sidebar.BackgroundColor3 = Theme.Sidebar
    Instance.new("UICorner", Sidebar).CornerRadius = UDim.new(0, 8)

    local SidebarLayout = Instance.new("UIListLayout", Sidebar)
    SidebarLayout.Padding = UDim.new(0, 5)
    SidebarLayout.HorizontalAlignment = Enum.HorizontalAlignment.Center

    local Container = Instance.new("Frame", Main)
    Container.Size = UDim2.new(1, -190, 1, -70)
    Container.Position = UDim2.new(0, 180, 0, 60)
    Container.BackgroundTransparency = 1

    local Tabs = {}
    function Tabs:CreateTab(name)
        local TabBtn = Instance.new("TextButton", Sidebar)
        TabBtn.Size = UDim2.new(0.9, 0, 0, 40)
        TabBtn.BackgroundTransparency = 1
        TabBtn.Text = name
        TabBtn.TextColor3 = Theme.TextMuted
        TabBtn.Font = Enum.Font.GothamSemibold
        TabBtn.TextSize = 16 -- Bigger Text

        local Page = Instance.new("ScrollingFrame", Container)
        Page.Size = UDim2.new(1, 0, 1, 0)
        Page.Visible = false
        Page.BackgroundTransparency = 1
        Page.ScrollBarThickness = 2
        Page.ScrollBarImageColor3 = Theme.Accent
        Instance.new("UIListLayout", Page).Padding = UDim.new(0, 10)

        TabBtn.MouseButton1Click:Connect(function()
            for _, v in pairs(Container:GetChildren()) do v.Visible = false end
            for _, b in pairs(Sidebar:GetChildren()) do if b:IsA("TextButton") then b.TextColor3 = Theme.TextMuted end end
            Page.Visible = true
            TabBtn.TextColor3 = Theme.Accent
        end)

        local Elements = {}
        function Elements:CreateButton(text, callback)
            local Btn = Instance.new("TextButton", Page)
            Btn.Size = UDim2.new(1, -10, 0, 45)
            Btn.BackgroundColor3 = Theme.Element
            Btn.Text = text
            Btn.TextColor3 = Theme.Text
            Btn.Font = Enum.Font.GothamMedium
            Btn.TextSize = 16 -- Bigger Text
            Instance.new("UICorner", Btn).CornerRadius = UDim.new(0, 6)
            Instance.new("UIStroke", Btn).Color = Theme.Stroke
            Btn.MouseButton1Click:Connect(callback)
        end
        
        return Elements
    end

    return Tabs
end

return Nexus