quarry

print("enter the size (NxN):")

n = tonumber(read())

per_layer = n*n

x = 0
y = 0
z = 0

depth = 0

dir = 0

function updatePos()
    if dir == 0 then
        y = y + 1
    elseif dir == 1 then
        x = x + 1
    elseif dir == 2 then
        y = y - 1
    elseif dir == 3 then
        x = x - 1
    end
end

function dig()
    turtle.digUp()
    turtle.digDown()
end

function refuel()
    local fuel = turtle.getFuelLevel()

    if fuel == 0 then
        turtle.refuel(1)
    end
end

function forward()
    refuel()

    turtle.dig()

    while turtle.attack() do
        turtle.attack()
    end

    turtle.forward()

    updatePos()
end

function right()
    turtle.turnRight()

    if dir == 3 then
        dir = 0
    else
        dir = dir + 1
    end
end

function left()
    turtle.turnLeft()

    if dir == 0 then
        dir = 3
    else
        dir = dir - 1
    end
end

function down()
    local success, data = turtle.inspectDown()

    if success then
        if data.name == "minecraft:bedrock" then
            return false
        end
    end

    refuel()

    turtle.digDown()

    while turtle.attackDown() do
        turtle.attackDown()
    end

    turtle.down()

    z = z - 1

    return true
end

function up()
    refuel()

    turtle.digUp()

    while turtle.attackDown() do
        turtle.attackDown()
    end

    turtle.up()

    z = z + 1
end

function deposit()
    for i=2,16 do
        turtle.select(i)
        turtle.drop()
    end
end

function getFuel()
    turtle.select(1)

    count = turtle.getItemCount()

    if count ~= 64 then
        turtle.suck(64 - count)
    end
end

function returnToChest()
    if dir == 0 then
        left()
    elseif dir == 1 then
        right()
        right()
    elseif dir == 2 then
        right()
    end

    for i=1,x do
        forward()
    end

    left()

    for i=1,y do
        forward()
    end

    right()
    right()

    for i=z,-1 do
        up()
    end

    right()
    right()

    deposit()

    right()

    getFuel()

    right()
end

function returnToDepth()
    for i=1,depth do
        down()
    end
end

function shouldReturn()
    if (turtle.getItemCount(1)-1) * 80 < per_layer + x + y + z + 1 then
        return true
    end

    stacks_needed = math.floor(per_layer / 64)

    if turtle.getItemCount(16 - stacks_needed) ~= 0 then
        return true
    end

    return false
end

while true do
    for x=1,n do
        for y=1,n do
            dig()

            if y ~= n then
                forward()
            end
        end

        if x ~= n then
            if x % 2 == 1 then
                right()
                forward()
                right()
            else
                left()
                forward()
                left()
            end
        end
    end

    if shouldReturn() then
        returnToChest()
        returnToDepth()
    else
        if dir == 0 then
            left()
        elseif dir == 1 then
            right()
            right()
        elseif dir == 2 then
            right()
        end

        for i=1,x do
            forward()
        end

        left()

        for i=1,y do
            forward()
        end

        right()
        right()
    end

    if not down() then
        returnToChest()
        break
    end

    depth = depth + 1
end