-- Clear the terminal screen
local function clear()
    term.clear()
    term.setCursorPos(1, 1)
end

-- Draw the main GUI border and header
local function drawBorder()
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.white)
    term.setCursorPos(1, 1)
    term.write(string.rep("=", 30)) -- Top border
    term.setCursorPos(1, 2)
    term.write("|" .. string.rep(" ", 28) .. "|") -- Empty space for header
    term.setCursorPos(1, 3)
    term.write("|    Turtle Control Panel    |") -- Title
    term.setCursorPos(1, 4)
    term.write("|" .. string.rep(" ", 28) .. "|") -- Empty space
    for i = 5, 8 do
        term.setCursorPos(1, i)
        term.write("|" .. string.rep(" ", 28) .. "|") -- Side borders
    end
    term.setCursorPos(1, 9)
    term.write(string.rep("=", 30)) -- Bottom border
end

-- Display the fuel level
local function displayFuelLevel()
    local fuelLevel = turtle.getFuelLevel()
    term.setCursorPos(3, 5)
    term.setTextColor(fuelLevel < 10 and colors.red or colors.green)
    term.write("Fuel Level: " .. fuelLevel .. " units")
    term.setTextColor(colors.white) -- Reset to default color
end

-- Display the direction the turtle is facing
local function displayDirection(direction)
    term.setCursorPos(3, 6)
    term.write("Direction: " .. ({"North", "East", "South", "West"})[direction + 1])
end

-- Display the amount of backup fuel available
local function displayBackupFuel()
    local coalCount = turtle.getItemCount(1) -- Assuming coal is in slot 1
    term.setCursorPos(3, 7)
    term.write("Backup Fuel (Coal): " .. coalCount)
end

-- Load fuel into the turtle
local function loadFuel()
    if turtle.getItemCount(1) > 0 then
        turtle.select(1)
        turtle.refuel()
        displayFuelLevel()
    else
        term.setCursorPos(3, 8)
        term.setTextColor(colors.red)
        term.write("No fuel in slot 1.")
        term.setTextColor(colors.white) -- Reset to default color
    end
end

-- Unload all fuel (like coal) from the turtle's inventory to the ground
local function unloadFuel()
    for i = 1, 16 do
        turtle.select(i)
        local itemCount = turtle.getItemCount(i)
        if itemCount > 0 and turtle.getItemDetail(i) and turtle.getItemDetail(i).name == "minecraft:coal" then
            turtle.drop(itemCount) -- Drop all coal items in the selected slot
            term.setCursorPos(3, 8)
            term.setTextColor(colors.green)
            term.write("Unloaded " .. itemCount .. " coal from slot " .. i .. ".")
            term.setTextColor(colors.white) -- Reset to default color
        end
    end
end

-- Move the turtle forward
local function moveForward()
    if turtle.forward() then
        displayFuelLevel()
    else
        term.setCursorPos(3, 8)
        term.setTextColor(colors.red)
        term.write("Move failed!")
        term.setTextColor(colors.white) -- Reset to default color
    end
end

-- Move the turtle backward
local function moveBackward()
    if turtle.back() then
        displayFuelLevel()
    else
        term.setCursorPos(3, 8)
        term.setTextColor(colors.red)
        term.write("Move failed!")
        term.setTextColor(colors.white) -- Reset to default color
    end
end

-- Turn the turtle left and update direction
local function turnLeft(direction)
    turtle.turnLeft()
    direction = (direction - 1) % 4
    return direction
end

-- Turn the turtle right and update direction
local function turnRight(direction)
    turtle.turnRight()
    direction = (direction + 1) % 4
    return direction
end

-- Initialize direction
local direction = 0 -- 0: North, 1: East, 2: South, 3: West

-- Start the GUI
clear()
drawBorder()
displayFuelLevel()
displayDirection(direction)
displayBackupFuel()

-- Main loop to handle user input
while true do
    local event, key = os.pullEvent("key")

    if key == keys.w then
        moveForward()
    elseif key == keys.s then
        moveBackward()
    elseif key == keys.a then
        direction = turnLeft(direction)
    elseif key == keys.d then
        direction = turnRight(direction)
    elseif key == keys.l then
        loadFuel()
    elseif key == keys.u then
        unloadFuel() -- Unload coal when 'U' is pressed
    elseif key == keys.q then
        break -- Exit the program
    end

    -- Refresh the display
    clear()
    drawBorder()
    displayFuelLevel()
    displayDirection(direction)
    displayBackupFuel()
end