placeyboi.lua

local en = ... -- get input.  If there is any input, move down instead of up
local et

-- find the first block in inventory, select it.
local function find()
  for i = 1, 16 do
    if turtle.getItemCount(i) > 0 then
      turtle.select(i)
      return
    end
  end
  -- if nothing found, error.
  error("We have run out of items.", 0)
end

-- make turtle.place/etc find the item before placing each time.
function turtle.place()
  find()
  return turtle.native.place()
end

function turtle.placeDown()
  find()
  return turtle.native.placeDown()
end

function turtle.placeUp()
  find()
  return turtle.native.placeUp()
end

-- if input, go down, else up
if en then
  en = turtle.down
  et = turtle.placeUp
else
  en = turtle.up
  et = turtle.placeDown
end

local fails = 0
while true do
  turtle.place() -- place
  if turtle.back() then
    fails = 0 -- if we went back, reset fails to 0
  else
    turtle.turnRight() -- if we failed to move back, turn and increase fails
    fails = fails + 1
  end
  if fails > 3 then
    en() -- if we've turned 4 times, go up/down, then place a block there
    et()
    break
  end
end

-- reset turtle funcs
turtle.place = turtle.native.place
turtle.placeDown = turtle.native.placeDown