os.pullEvent = os.pullEventRaw

local w, h = term.getSize()
local nOption = 1
local isStartMenuOpen = false
local isPowerMenuOpen = false
local menuOptions = {"Command", "Programs", "Power Menu"}
local powerOptions = {"Shutdown", "Reboot", "Sign Out", "Cancel"}

-- Create windows for taskbar, start menu, and power menu
local taskbar = window.create(term.current(), 1, h, w, 1)
local startMenu = window.create(term.current(), 1, h - 10, 20, 10, false)
local powerMenu = window.create(term.current(), math.floor(w / 2) - 12, math.floor(h / 2) - 7, 24, 15, false)

-- Helper function to draw the taskbar with the current time
local function drawTaskbar()
    taskbar.setBackgroundColor(colors.green)
    taskbar.clear()
    taskbar.setCursorPos(1, 1)
    taskbar.setTextColor(colors.white)
    taskbar.write("[ Start ]")

    -- Display the current time on the right side
    local currentTime = os.date("%H:%M:%S")
    local timeX = w - string.len(currentTime) - 1
    taskbar.setCursorPos(timeX, 1)
    taskbar.write(currentTime)
end

-- Helper function to draw the start menu
local function drawStartMenu()
    if not isStartMenuOpen then
        startMenu.setVisible(false)
        return
    end

    startMenu.setVisible(true)
    startMenu.setBackgroundColor(colors.green)
    startMenu.clear()

    startMenu.setTextColor(colors.white)
    startMenu.setCursorPos(2, 1)
    startMenu.write("=== Start Menu ===")

    for i, option in ipairs(menuOptions) do
        startMenu.setCursorPos(2, 2 + i)
        if nOption == i then
            startMenu.setTextColor(colors.black)
            startMenu.setBackgroundColor(colors.white)
            startMenu.write("[ " .. option .. " ]")
            startMenu.setBackgroundColor(colors.green)
            startMenu.setTextColor(colors.white)
        else
            startMenu.write("[ " .. option .. " ]")
        end
    end
end

-- Helper function to draw the power menu
local function drawPowerMenu()
    if not isPowerMenuOpen then
        powerMenu.setVisible(false)
        return
    end

    powerMenu.setVisible(true)
    powerMenu.setBackgroundColor(colors.black)
    powerMenu.clear()

    powerMenu.setTextColor(colors.white)
    powerMenu.setCursorPos(2, 1)
    powerMenu.write("=== Power Menu ===")

    for i, option in ipairs(powerOptions) do
        powerMenu.setCursorPos(2, 3 + i)
        if nOption == i then
            powerMenu.setTextColor(colors.black)
            powerMenu.setBackgroundColor(colors.white)
            powerMenu.write("[ " .. option .. " ]")
            powerMenu.setBackgroundColor(colors.black)
            powerMenu.setTextColor(colors.white)
        else
            powerMenu.write("[ " .. option .. " ]")
        end
    end
end

-- Helper function to draw ASCII art in the center
local function drawASCIIArt()
    local art = {
        "     |\\_/|                  ",
        "     | @ @   Woof!         ",
        "     |   <>              _  ",
        "     |  _/\\------____ ((| |))",
        "     |               `--' |   ",
        " ____|_       ___|   |___.'  ",
        "/_/_____/____/_______|        "
    }
    local startX = math.floor((w - 26) / 2)  -- Centering the art horizontally
    local startY = math.floor((h - #art) / 2)  -- Centering the art vertically

    term.setTextColor(colors.white)
    for i, line in ipairs(art) do
        term.setCursorPos(startX, startY + i - 1)
        term.write(line)
    end
end

-- Function to redraw the entire UI
local function redrawUI()
    term.setBackgroundColor(colors.blue)
    term.clear()
    drawTaskbar()
    drawASCIIArt()  -- Draw ASCII art
    if isPowerMenuOpen then
        drawPowerMenu()
    else
        drawStartMenu()
    end
end

-- Function to display an error message in the GUI window
local function showError(message)
    local errorWindow = window.create(term.current(), math.floor(w / 2) - 15, math.floor(h / 2) - 5, 30, 10, true)

    errorWindow.setBackgroundColor(colors.red)
    errorWindow.setTextColor(colors.white)
    errorWindow.clear()

    -- Title
    errorWindow.setCursorPos(2, 2)
    errorWindow.write("=== ERROR ===")

    -- Message
    local lines = {}
    for line in message:gmatch("[^\n]+") do
        table.insert(lines, line)
    end

    for i, line in ipairs(lines) do
        errorWindow.setCursorPos(2, 3 + i)
        errorWindow.write(line:sub(1, 28)) -- Limit line length to fit the box
    end

    -- Close instruction
    errorWindow.setCursorPos(2, 9)
    errorWindow.write("Press any key to continue...")

    -- Wait for user input
    os.pullEvent("key")
    redrawUI() -- Restore the UI after closing the error message
end

-- Function to handle running programs and power options
local function runProgramOrAction(option)
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.white)
    term.clear()

    local success, err
    if isPowerMenuOpen then
        if option == 1 then
            success, err = pcall(shell.run, "/disk/ACPI/shutdown")
        elseif option == 2 then
            success, err = pcall(shell.run, "/disk/ACPI/reboot")
        elseif option == 3 then
            success, err = pcall(shell.run, "/disk/ACPI/logoff")
        elseif option == 4 then
            shell.run("/disk/os/gui")
            return true
        end
    else
        if option == 1 then
            success, err = pcall(shell.run, "/disk/os/command.lua")
        elseif option == 2 then
            success, err = pcall(shell.run, "/disk/os/programs.lua")
        end
    end

    if not success then
        showError("An error occurred:\n" .. (err or "Unknown error"))
        return false
    end

    return true
end

-- Function to handle running applications from the Start Menu
local function runAppFromStartMenu(option)
    local success, err
    if option == 1 then
        success, err = pcall(shell.run, "/disk/os/command.lua")
    elseif option == 2 then
        success, err = pcall(shell.run, "/disk/os/programs.lua")
    end

    if not success then
        showError("An error occurred when running the app:\n" .. (err or "Unknown error"))
    end
end

-- Initial UI drawing
redrawUI()

-- Start the timer for updating the time every second
local timerId = os.startTimer(1)

-- Function to handle mouse clicks
local function handleMouseClick(x, y)
    if y == h and x >= 1 and x <= 7 then
        isStartMenuOpen = not isStartMenuOpen
        isPowerMenuOpen = false
        redrawUI()
    elseif isStartMenuOpen and x >= 1 and x <= 20 and y >= h - 10 and y <= h - 1 then
        local clickedOption = y - (h - 10) - 1
        if clickedOption >= 1 and clickedOption <= #menuOptions then
            nOption = clickedOption
            if nOption == 3 then
                isStartMenuOpen = false
                isPowerMenuOpen = true
                redrawUI()
            else
                runAppFromStartMenu(nOption)  -- Run selected app with error handling
            end
        end
    end
    return false
end

-- Start listening for events and handle termination event
parallel.waitForAny(function()
    while true do
        local e, p1, p2, p3 = os.pullEventRaw()

        if e == "mouse_click" then
            local button, x, y = p1, p2, p3
            handleMouseClick(x, y)  -- Handle mouse clicks for menu options
        elseif e == "key" and (isStartMenuOpen or isPowerMenuOpen) then
            local key = p1

            if key == keys.up then
                if nOption > 1 then
                    nOption = nOption - 1
                else
                    nOption = #menuOptions
                end
                redrawUI()
            elseif key == keys.down then
                if isPowerMenuOpen then
                    if nOption < #powerOptions then
                        nOption = nOption + 1
                    else
                        nOption = 1 -- Wrap around to "Shutdown"
                    end
                else
                    if nOption < #menuOptions then
                        nOption = nOption + 1
                    else
                        nOption = 1
                    end
                end
                redrawUI()
            elseif key == keys.enter then
                if runProgramOrAction(nOption) then
                    -- Do nothing, action taken
                else
                    break  -- Exit loop only if no action taken
                end
            end
        elseif e == "timer" and p1 == timerId then
            drawTaskbar()  -- Redraw taskbar to update time
            timerId = os.startTimer(1)  -- Reset the timer for the next second
        elseif e == "terminate" then
            showError("Access Denied")  -- Show termination message in GUI
        end
    end
end, function()
    while true do
        local event = os.pullEventRaw("terminate")
        if event == "terminate" then
            showError("Access Denied")  -- Show termination message in GUI
        end
    end
end)