wither.lua

-- local id=1 -- obviously set per turtle's position as explained above, moved into a .txt config file assigned below

-- 7 turtles, id set's it's position
-- 7 6 5
-- 4 3 2
--   1
-- 1 just places soul sand if it's block is clear
-- 2,3, and 4 place soul sand if they're block is clear and then blip a redstone signal up
-- 5,6, and 7 wait for redstone blip on bottom and then place wither skull's
-- Note there's no need to verify inventory since they don't pick stuff up, just fill the inventory with sand for 1-4
-- and skulls for 5-7 and it should construct withers.
-- This really only works if explosions are disabled in your claim...
-- I added the requirement for a redstone signal at the back to allow a way to turn it on and off.
-- I also added a dig command to clear out the block in front of it, this helps 'reset' things in case the skulls are placed first
-- (possibly due to running out of soulsand or something)
-- I added a dig at the 'off' redstone state to make accessing the turtles easier since there's a block in the back to transmit the
-- redstone signal and with the sandstone in the front accessing turtle 3 in particular was a bother

local function getTurtleID()
    local file = fs.open("turtleID.txt", "r")
    if not file then
        error("Failed to open turtleID.txt. Please create the file with a number from 1 to 7.")
    end
    local id = tonumber(file.readLine())
    file.close()
    if not id or id < 1 or id > 7 then
        error("Invalid turtle ID in turtleID.txt. Must be a number from 1 to 7.")
    end
    return id
end

local turtleID = getTurtleID()

function findNextItem()
    local currentSlot = turtle.getSelectedSlot()
    local totalSlots = 16  -- Turtle has 16 slots

    -- Check all slots, starting from current
    for i = 0, totalSlots - 1 do
        local slotToCheck = (currentSlot + i - 1) % totalSlots + 1
        turtle.select(slotToCheck)
        if turtle.getItemCount() > 0 then
            return true  -- Found a non-empty slot
        end
    end

    -- No non-empty slots found
    turtle.select(currentSlot)  -- Return to original slot
    return false
end


-- debug function
local function pauseMe()
  print("Press any key...")
  os.pullEvent("key")
end

local function placeForward()
  local has_block, data = turtle.inspect()
  if not has_block then
    turtle.place()
    return 1
  end
  return 0
end

while findNextItem() do -- might as well exit if we run out of stuff

  while redstone.getInput("back")==true do
    if turtleID>4 then
      local loop=0
      print("Waiting for redstone signal from below.")
      while redstone.getInput("bottom")==false do
        sleep(.5) -- wait for go signal
        -- periodically the skulls get placed too soon, so we'll let #6 do an intermittent dig to reset things
        if turtleID==6 then
          loop=loop+1 -- 20 loops should be ~10 seconds in .5 second steps
          if loop==20 then
            turtle.dig()
            turtle.place()
            loop=0
          end
        end
      end
      print("Redstone signal received.")
      redstone.setOutput("bottom",true)
      while redstone.getInput("bottom")==true do
        sleep(.5) -- wait for signal to stop=ack below
      end
      print("Redstone signal acknowledged.")
      redstone.setOutput("bottom",false)
      while placeForward()==0 do
        sleep(.5) -- try until successful
 -- the loop==20 above should cover this, if this fails it's probably empty the outer loop should catch that  turtle.dig() -- if it's failing try to clear the blockage
      end
      print("Block placed forward")
    else
      if placeForward()==1 then
        print("placed inventory forward")
        if turtleID>1 and turtleID<5 then -- need to exclude 1 since it doesn't get signaled back by turtleID 3 (not necessary)
          redstone.setOutput("top",true)
          while redstone.getInput("top")==false do
            sleep(.5)
          end
          redstone.setOutput("top",false) -- wait for turtle above to acknowledge signal
        end
      else
        print("Space blocked")
      end
      sleep(5)
-- still not need with loop=20 above      turtle.dig() -- not 100% sure this may require a mining turtle...so splurge and invest in a diamond pick
    end

    print("Turtle ",turtleID," Waiting for redstone startup at 5 second intervals")
    sleep(5)

  -- redstone signal present loop
  end

print("available item slot selected (or exit)")
-- inventory not empty loop
end
print("exit it is.")
pauseMe()