-- Tunnel Mining Program for ComputerCraft Turtle

-- Define the width and height of the tunnel
local width = 3
local height = 3

-- Function to refuel the turtle if it has fuel items
local function refuel()
    for i = 1, 16 do
        turtle.select(i)
        if turtle.refuel(1) then
            print("Refueled.")
            return true
        end
    end
    return false
end

-- Function to check fuel and halt if out of fuel
local function checkFuel()
    if turtle.getFuelLevel() == 0 then
        print("Out of fuel. Attempting to refuel...")
        if not refuel() then
            print("Still out of fuel. Please add fuel items.")
            return false
        end
    end
    return true
end

-- Function to dig a 3x3 tunnel
local function digTunnel()
    while true do
        for h = 1, height do
            for w = 1, width do
                if not checkFuel() then return end
                turtle.dig()
                turtle.forward()
                if h < height then
                    turtle.digUp()
                    turtle.up()
                end
            end

            for w = 1, width do
                if not checkFuel() then return end
                if w < width then
                    turtle.back()
                end
                if h < height then
                    turtle.down()
                end
            end
        end

        turtle.turnRight()
        if not checkFuel() then return end
        turtle.dig()
        turtle.forward()
        turtle.turnLeft()
    end
end

-- Start digging the tunnel
print("Starting to dig 3x3 tunnel...")
digTunnel()