digListen

local maxLengthX = 15
local maxLengthY = 15
local layersToDig = 7

local function checkFuel()
    if (turtle.getFuelLevel() == 0)
    then
        rednet.open("back")
        rednet.send(48, "Refuel")
        rednet.close("back")
    end
end

local function turtleForward()
    checkFuel()
    turtle.forward()
end

local function turtleDig()
    checkFuel()
    turtle.dig()
end

local function turtleUp()
    checkFuel()
    turtle.up()
end

local function turtleDigUp()
    checkFuel()
    turtle.digUp()
end

local function turtleDown()
    checkFuel()
    turtle.up()
end

local function turtleDigDown()
    checkFuel()
    turtle.digUp()
end

local function mineLayer()
    while (turtle.detect())
    do
        turtleDig()
        os.sleep(0.5)
    end
    turtleForward()
    turtle.turnRight()

    local index2 = 0
    while (index2 < maxLengthY)
    do
        local index = 1
        while (index < maxLengthX)
        do
            while (turtle.detect())
            do
                turtleDig()
                os.sleep(0.5)
            end
            turtleForward()
            index = index + 1
        end
        if (index2 ~= maxLengthY - 1)
        then
            while (turtle.detectUp())
            do
                turtleDigUp()
                os.sleep(0.5)
            end
            turtleUp()
            turtle.turnRight()
            turtle.turnRight()
        end
        index2 = index2 + 1
    end
    turtle.turnLeft()
    while (turtle.detect())
    do
        turtleDig()
        os.sleep(0.5)
    end
    turtleForward()
    turtle.turnLeft()

    local index2 = 0
    while (index2 < maxLengthY)
    do
        local index = 1
        while (index < maxLengthX)
        do
            while (turtle.detect())
            do
                turtleDig()
                os.sleep(0.5)
            end
            turtleForward()
            index = index + 1
        end
        if (index2 ~= maxLengthY - 1)
        then
            while (turtle.detectDown())
            do
                turtleDigDown()
                os.sleep(0.5)
            end
            turtleDown()
            turtle.turnRight()
            turtle.turnRight()
        end
        index2 = index2 + 1
    end
    turtle.turnRight()
end

local layer = 0
while (layer < layersToDig)
do
    mineLayer()
    layer = layer + 1
end