mine

function checkFuel()

currentFuel = turtle.getFuelLevel()
currentSlot = turtle.getSelectedSlot()

if turtle.getFuelLevel() < 1 then
  for slot = 1,16 do
    if turtle.refuel() then
      return true, "Fueled"
        elseif slot == 16 then
          return false, "No fuel left"
          end
       end
    else
      print("there is still "..currentFuel.." Fuel left")
      return false
  end
end

function isValuable()
local isValuable = true

succes, data = turtle.inspect()

  if data["name"] == "minecraft:grass" or data.name == "minecraft:stone" or data.name == "minecraft:cobblestone" or data.name == "minecraft:dirt" or turtle.detect() == false then
    isValuable = false
  else
    isValuable = true
  end

return isValuable
end

function checkWalls()

  for checking = 1,4 do
    if isValuable() == true then
      turtle.dig()
    end
    turtle.turnRight()
  end

end

function printinv()

print("Printing the inventory: ")

currentSlot = turtle.getSelectedSlot()

for slot = 1,16 do
  turtle.select(slot)
  data = turtle.getItemDetail()
    if data then
     print("slot "..slot.." has "..data.count.." "..data.name)
    else
      print("slot "..slot.." has no items")
   end
  end
turtle.select(currentSlot)
end

depth = 0

checkFuel()

turtle.digDown()

  while turtle.detectDown() == false do
    if turtle.down() then
      depth = depth + 1
      print("I am "..depth.." levels deep")
    end
   checkFuel()
   checkWalls()
   succes, data = turtle.inspect()
     if not turtle.digDown() and data.name == "minecraft:bedrock" then
     break
    end
  end

 checkFuel()
  for surface = 1,depth do
   turtle.up()
  if surface == depth then
    turtle.placeDown()
  end
 end
printinv()