Tunnel down

distance = 62;

function turtle.forwards(numForw)
    for i = 1, numForw do
        turtle.forward()
    end
end

function turtle.upwards(numUpw)
    for i = 1, numUpw do
        turtle.up()
    end
end

function turtle.downwards(numDownw)
    for i = 1, numDownw do
        turtle.down()
    end
end

function turtle.turns180()
    for i = 1, 2 do
        turtle.turnRight()
    end
end

function scanDown()
    if turtle.detectDown() then
        turtle.digDown()
    end
end
function scan()
    if turtle.detect() then
        turtle.dig()
    end
end

function emptyInventory()
    turtle.select(1)
    for i = 1, 16 do
        turtle.select(i)
        turtle.drop()
    end
end


function mining()
    for i = 1, distance do
        turtle.turnRight()
        scan();
        turtle.turns180()
        scan();
        turtle.turnRight()
        scanDown();
        turtle.down()
        i = i + 1;
     end
     for i = 1, distance do
        turtle.up()
        i = i + 1;
     end
end

function selectCobblestone()
    for i = 1, 16 do
        local itemDetail = turtle.getItemDetail(i)
        if itemDetail and itemDetail.name == "minecraft:cobblestone" then
            turtle.select(i)
            break
        end
    end
end

function fillFloor()
    selectCobblestone()
    turtle.placeDown()
    turtle.turnLeft()
    turtle.forward()
    turtle.placeDown()
    turtle.turns180()
    turtle.forwards(2)
    turtle.placeDown()
    turtle.turns180()
    turtle.forward()
    turtle.turnRight()
end

function mining3by3()
    turtle.select(1)
    mining()
    fillFloor()
    turtle.forward()
    mining()
    fillFloor()
    turtle.forward()
    mining()
    fillFloor()
    turtle.turns180()
    turtle.forwards(2)
    emptyInventory()
    turtle.turns180()
end

mining3by3()