witherfarm.lua

-- Time to wait between checking if we can spawn (in seconds)
local checkDelayS = 10 -- 10 seconds

-- Time to wait between spawns (in seconds)
local spawnDelayS = 60 * 2 -- 2 minutes

-- Slots
skullSlot = 1
soulSandSlot = 2

-- Bring in required modules.
local robot = require("robot")
local os = require("os")
local term = require("term")
local sides = require("sides")
local component = require("component")


-- Function to keep trying to move
-- forward until success.
local function moveForward(count)
  for i=1, count do
    while not (robot.forward()) do
      os.sleep(1)
    end
  end
end

-- Function to keep trying to move
-- back until success.
local function moveBack(count)
  for i=1, count do
    while not (robot.back()) do
      os.sleep(1)
    end
  end
end

-- Function to keep trying to move
-- up until success.
local function moveUp(count)
  for i=1, count do
    while not (robot.up()) do
      os.sleep(1)
    end
  end
end

-- Function to keep trying to move
-- down until success.
local function moveDown(count)
  for i=1, count do
    while not (robot.down()) do
      os.sleep(1)
    end
  end
end

-- Function to keep trying to place
-- until success.
local function placeBlock(inventorySlot, side)
  robot.select(inventorySlot)
  while not (robot.place(side)) do
    os.sleep()
  end
end

local function gatherMaterial(inventoryLocation, slotNumber, desiredAmount)
  -- Select desired slot
  robot.select(slotNumber)

  -- Get the current amount
  local currentCount = robot.count()

  -- Loop until we have enough (we'll return if we get to a point where we can't retrieve any more
  while currentCount < desiredAmount do
    -- Determine how much more we need
    local remainingNeeded = desiredAmount - currentCount

    -- Try to get some more
    local gotItems = component.robot.suck(inventoryLocation, remainingNeeded)

    -- Return failure if we got nothing
    if gotItems == false then
      return false
    end

    -- Update count
    currentCount = robot.count()
  end

  -- Success!
  return true
end

local function moveIntoPosition()
  moveUp(1)
  moveForward(1)
  robot.turnLeft()
  moveForward(3)
  moveDown(2)
  moveForward(1)
  robot.turnRight()
  moveForward(3)
  robot.turnRight()
  moveForward(2)
  robot.turnLeft()
end

local function constructWither()

  placeBlock(soulSandSlot, sides.front)
  moveUp(1)
  placeBlock(soulSandSlot, sides.front)
  robot.turnLeft()
  moveForward(1)
  robot.turnRight()
  placeBlock(soulSandSlot, sides.front)
  robot.turnRight()
  moveForward(2)
  robot.turnLeft()
  placeBlock(soulSandSlot, sides.front)
  moveUp(1)
  placeBlock(skullSlot, sides.front)
  robot.turnLeft()
  moveForward(1)
  robot.turnRight()
  placeBlock(skullSlot, sides.front)
  robot.turnLeft()
  moveForward(1)
  robot.turnRight()
  placeBlock(skullSlot, sides.front)
end

local function retreat()
  moveBack(1)
  moveDown(2)
  robot.turnLeft()
  moveForward(1)
  robot.turnLeft()
  moveForward(2)
  robot.turnLeft()
  moveForward(1)
  moveUp(2)
  moveForward(3)
  robot.turnLeft()
  moveBack(1)
  moveDown(1)
end

local function checkIfEnabled()
  -- Check for redstone signal on left side of robot
  rs = component.redstone
  enableSignal = rs.getInput(sides.left)
  if enableSignal > 7 then
    return true
  end

  return false
end

-- Clear screen
term.clear()
term.setCursor(1, 1)

-- Header
term.write("Wither Farm\n\n")

-- Loop forever
while true do

  -- Check if we are enabled
  term.write("Checking status\n")
  enabled = checkIfEnabled()
  if enabled then
    term.write("Spawn enabled\n")

    -- Gather materials
    term.write("Gathering materials\n")
    enoughSkulls = gatherMaterial(sides.bottom, skullSlot, 3)
    enoughSoulSand = gatherMaterial(sides.front, soulSandSlot, 4)

    -- Do we have enough?
    if enoughSkulls and enoughSoulSand then
      -- Move into position
      term.write("Moving into position")
      moveIntoPosition()

      -- Construct the wither
      term.write("Constructing wither\n")
      constructWither()

      -- Retreat
      term.write("Retreating\n")
      retreat()

      -- Wait awhile before spawning again
      term.write("Waiting for spawn cooldown\n")
      os.sleep(spawnDelayS)
    else
      term.write("Not enough materials yet\n")
    end

  else
    term.write("Spawn disabled!\n")
  end

  -- Check delay
  term.write("Waiting before next check\n")
  os.sleep(checkDelayS)

end