Tunnel

local function checkFuel()
    repeat
        os.sleep(1)
    until turtle.getFuelLevel() <= 2000
    turtle.refuel(turtle.getItemCount(1)-1)
end

local function mineLayer()
    local maxLength = 5
    while (turtle.detect())
    do
        turtle.dig()
        os.sleep(0.5)
    end
    turtle.forward()
    turtle.turnRight()

    local index2 = 0
    while (index2 < maxLength)
    do
        local index = 1
        while (index < maxLength)
        do
            while (turtle.detect())
            do
                turtle.dig()
                os.sleep(0.5)
            end
            turtle.forward()
            index = index + 1
        end
        if (index2 ~= maxLength - 1)
        then
            while (turtle.detectUp())
            do
                turtle.digUp()
                os.sleep(0.5)
            end
            turtle.up()
            turtle.turnRight()
            turtle.turnRight()
        end
        index2 = index2 + 1
    end
    turtle.turnLeft()
    while (turtle.detect())
    do
        turtle.dig()
        os.sleep(0.5)
    end
    turtle.forward()
    turtle.turnLeft()

    local index2 = 0
    while (index2 < maxLength)
    do
        local index = 1
        while (index < maxLength)
        do
            while (turtle.detect())
            do
                turtle.dig()
                os.sleep(0.5)
            end
            turtle.forward()
            index = index + 1
        end
        if (index2 ~= maxLength - 1)
        then
            while (turtle.detectDown())
            do
                turtle.digDown()
                os.sleep(0.5)
            end
            turtle.down()
            turtle.turnRight()
            turtle.turnRight()
        end
        index2 = index2 + 1
    end
    turtle.turnRight()
end

local layersToDig = 1
local layer = 0
while (layer < layersToDig)
do
    parallel.waitForAny(mineLayer, checkFuel)
    layer = layer + 1
end