local pos = {0, 0, 0}
local turn = 0
local axis = 1

function left()
  turtle.turnLeft()
  turn = turn - 1
end

function right()
  turtle.turnRight()
  turn = turn + 1
end

function forward()
  if not turtle.forward() then
    print("There is something in front of me")
  else
    if turn % 4 == 0 or turn % 4 == 1 then
      axis = 1
    else
      axis = -1
    end
    if turn % 4 == 1 or turn % 4 == 3 then
      pos[1] = pos[1] + axis
    else
      pos[2] = pos[2] + axis
    end
  end
end

function up()
  if not turtle.up() then
    print("There is something on top of me")
  else
    pos[3] = pos[3] + 1
  end
end

function down()
  if not turtle.down() then
    print("There is something underneath me")
  else
    pos[3] = pos[3] - 1
  end
end

if turtle.getFuelLevel() < 1 then
  turtle.refuel()
end