Random public turtle quarry (untested)

-- though this was written to dig up, it isn't going down far enough to need to...adding more depth between passes to utilize that.
-- WIP!! there's also a quadrant error I haven't located yet.
turtle.digDown()
turtle.down()
turtle.digDown()
turtle.down()

local tArgs = {...}
local size = tonumber(tArgs[1])
local meter = tonumber(tArgs[2])

local stepSize = size - 1
local area = size * size
local diggedLevel = 0

function frwd(steps)
    for i = 1, steps do
        local success,blockInfo = turtle.inspectUp()
        if success then
          local blockName=blockInfo.name
          if blockName~="minecraft:stone" and blockName~="minecraft:dirt" then
            turtle.digUp()
          end
        end
        local success,blockInfo = turtle.inspectDown()
        if success then
          local blockName=blockInfo.name
          if blockName~="minecraft:stone" and blockName~="minecraft:dirt" then
            turtle.digDown()
          end
        end

        while not turtle.forward() do
            turtle.dig()
        end
    end
end

function turnRight()
    turtle.turnRight()
    frwd(1)
    turtle.turnRight()
end

function turnLeft()
    turtle.turnLeft()
    frwd(1)
    turtle.turnLeft()
end

function refuel(limit)
    local fuel = turtle.getFuelLevel()
    local refueled = false

    for i = 1, 16 do
        turtle.select(i)

        if turtle.getFuelLevel() <= limit and turtle.refuel(0) then
            local fuelNeeded = limit - turtle.getFuelLevel()
            local fuelAmount = math.min(fuelNeeded, turtle.getItemCount(i))
            turtle.refuel(fuelAmount)
            print("Turtle> Fuel: " .. turtle.getFuelLevel())

            if turtle.getFuelLevel() >= limit then
                refueled = true
                break
            end
        end
    end

    turtle.select(1)

    return refueled
end

function ejectUnwantedItems()
    local unwantedItems = {
        "minecraft:cobblestone",
        "minecraft:gravel",
        "minecraft:dirt"
    }

    turtle.turnLeft()
    turtle.turnLeft()

    for i = 1, 16 do
        turtle.select(i)

        if turtle.getItemCount(i) > 0 then
            local itemDetail = turtle.getItemDetail()
            itemName = itemDetail.name

            for _, unwantedItem in ipairs(unwantedItems) do
                if itemName == unwantedItem then
                    turtle.dropUp()
                    break
                end
            end
        end
    end

    turtle.turnRight()
    turtle.turnRight()
    turtle.select(1)
end

function emptySlots()
    local empty = 16

    for i = 1, 16 do
        if turtle.getItemCount(i) ~= 0 then
            empty = empty - 1
        end
    end

    return empty
end

function mineLevel()
    for i = 1, size do
        frwd(stepSize)

        if i == size then
        --    turtle.turnRight()
        --    turtle.turnRight()
            ejectUnwantedItems()
        --    turtle.turnRight()
        --    turtle.turnRight()
        end
        -- end of first row, output 1 error("Checkpiont: diggedLevel%2.."..diggedLevel % 2)
        if diggedLevel % 2 ~= 0 then
            if i ~= size then
                if i % 2 == 0 then
                    turnRight()
                else
                    turnLeft()
                end
            end
        else
            if i ~= size then
                if i % 2 == 0 then
                    turnLeft()
                else
                    turnRight()
                end
            end
        end
    end
end

-- Main program
refuel(6)

-- Main loop
while diggedLevel < meter do
    local startLevel = diggedLevel
levelsToDig=meter -- this doesn't seem to make sense to me...    local levelsToDig = math.min(2, meter - startLevel)

    for level = 1, levelsToDig do
        diggedLevel = diggedLevel + 1
        mineLevel()
turtle.digUp()
        if level ~= levelsToDig then

--            turtle.digUp()
            turtle.digDown()
            turtle.down()
            turtle.digDown()
            turtle.down()
            turtle.digDown()
            turtle.down()
       end
--      error("checkpoint")
     if diggedLevel %2 ~= 0 then
       turtle.turnLeft()
       turtle.turnLeft()
     else
      turtle.turnRight()
      turtle.turnRight()
-- error("level.."..level..", levelsToDig"..levelsToDig)
     end
    end

--    turtle.turnRight()
  --  turtle.turnRight()
    turtle.digUp()
    turtle.digDown()

    if emptySlots() == 0 then
        print("\nTurtle> Inventory full! Ejecting unwanted items.")
        ejectUnwantedItems()
    else
        refuel(area + 3)
    end

    print("\nTurtle> Dug: " .. diggedLevel .. " / " .. meter .. " levels")
end

print("\nTurtle> Mining complete! Terminating!")