Vertical Strip Mine (CC Turtle)

local distanceLimit = 500;
if arg[2] then distanceLimit = tonumber(arg[2]) end

function isFiller(block)
    return block.name == "minecraft:diorite" or block.name == "minecraft:deepslate" or block.name == "minecraft:stone" or block.name == "minecraft:granite" or block.name == "minecraft:cobblestone" or block.name == "minecraft:cobbled_deepslate" or block.name == "minecraft:netherrack"
end

function digahole()
    local distance = 0
    local blockLevel = 0

    while true do

        while turtle.digDown() do
            if blockLevel == 0 then
                blockLevel = distance
            end
        end

        if turtle.getItemCount(16) > 0 then
            for i=1,distance do
                while turtle.digUp() do end
                turtle.up()
            end

            print("Waiting for items to be unloaded (Press Enter to continue)")
            local eventData = {"key", 0}
            while eventData[2] ~= 257 do eventData = {os.pullEvent("key")} end

            for i=1,distance do
                while turtle.digDown() do end
                turtle.down()
            end
        end

        if turtle.getFuelLevel() - 2 < distance then
            for i=1,distance do
                while turtle.digUp() do end
                turtle.up()
            end
            while turtle.getFuelLevel() - 2 < distance*2 do

            print("Waiting for more fuel (press Enter to continue)")
            local eventData = {"key", 0}
            while eventData[2] ~= 257 do eventData = {os.pullEvent("key")} end

                for i=1,16 do
                    turtle.select(i)
                    turtle.refuel(64)
                end
                turtle.select(1)
            end
            for i=1,distance do
                while turtle.digDown() do end
                turtle.down()
            end
        end

        if not turtle.down() then break end
        distance = distance + 1

        for i=1,4 do
            turtle.turnLeft()
            local isBlock, block = turtle.inspect();
            if isBlock and not isFiller(block) then
                turtle.dig()
            end
        end

        if distance == distanceLimit then break end
    end

    for i=1,distance do
        while turtle.digUp() do end
        turtle.up()
        if distance-i-1 == blockLevel then turtle.placeDown() end
    end
end

local step = 0

turtle.select(1);

for i=1,tonumber(arg[1]) do
    if i>1 then
        step = (step + 1) % 3
        print(tostring(step))
        if step == 0 then
            turtle.forward()
            turtle.turnLeft()
            turtle.forward()
            turtle.forward()
            turtle.turnRight()
        else
            turtle.forward()
            turtle.forward()
            turtle.turnRight()
            turtle.forward()
            turtle.turnLeft()
        end
    end
    digahole()
end
turtle.turnLeft()
for i=1,step do
    turtle.forward()
end
turtle.turnRight()
for i=2,arg[1] do
    turtle.back()
    turtle.back()
end