function getItemSlots()
  local slots = 16
  for i = 1, 16 do
    if turtle.getItemCount(i) > 0 then
      slots = slots - 1
    end
  end
  return slots
end

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

while true do
  while getItemSlots() > 0 do

    while true do if not turtle.dig() then break end end
    while true do if not turtle.digUp() then break end end
    turtle.forward()
  end
  --Turtle ran out of space
  turtle.turnRight()
  turtle.turnRight()
  --Turn Back
  while turtle.inspect.name ~= "minecraft:chest" do
    turtle.forward()
  end
  dropAllItems()
  turtle.turnRight()
  turtle.turnRight()
end