Miner 2

local size
local forward

local layers
local curLayer = 0

local x = 0
local y = 0
local z = 0


function refuel()
    for i=1,16,1 do
        turtle.select(i)
        while (turtle.refuel(1) and turtle.getFuelLevel() < (size * size)+10) do
        end
    end
end


function empty()
    local foundFuel = false
    for i=1,16,1 do
        turtle.select(i)
        if (not foundFuel and turtle.refuel(1)) then
            foundFuel = true;
        else
            turtle.drop()
        end
    end
end

function moveForward()
    while not turtle.forward() do turtle.attack() end
end
function moveDown()
    while not turtle.down() do turtle.attackDown() end
end

function main()
    print("Size:")
    size = tonumber(read())
    print("Layers:")
    layers = tonumber(read())

    refuel()
    -- Climb off the chest
    turtle.dig()
    moveForward()
    turtle.digDown()
    moveDown()

    while(curLayer < layers) do
        refuel()

        -- Return to the last layer
        while(y < curLayer) do
            turtle.digDown()
            moveDown()
            y=y+1
        end

        -- Do the rows
        while (z < size) do
            turtle.turnRight()

            -- Dig all the way to the right(-2 because you don't want to move the last, and because starting is 0)
            while (true) do
                turtle.dig()
                if(x < size-2) then
                    moveForward()
                    x=x+1
                else break end
            end

            -- Turn and go back to 0
            turtle.turnLeft()
            turtle.turnLeft()
            while (x > 0) do
                turtle.dig()
                moveForward()
                x=x-1
            end
            --Line up to go again
            turtle.turnRight()

            -- If doing next row, dig and move
            if (z < size-1) then
                turtle.dig()
                moveForward()
            end
            z=z+1
        end

        -- If all rows are done, move backwards
        while (z > 0) do
            turtle.back()
            z=z-1
        end

        -- Save current Y, and go back up to 0
        curLayer = y
        while(y > 0) do
            turtle.up()
            y=y-1
        end

        -- Deposit items
        turtle.turnRight()
        turtle.turnRight()
        empty()
        turtle.turnLeft()
        turtle.turnLeft()

        curLayer=curLayer+1
    end

    turtle.up()
    turtle.back()
end

main()