startup

function tlen(tabl)
  local count = 0
  for _ in pairs(tabl) do
    count = count+1
  end
  return count
end

function getEnts(tabl)
  entArr = {}
  for i,v in pairs(tabl) do
    ent = string.sub(i,0,3)
    if ent ~= "Cow" and ent ~= "Bat" and ent ~= "Ske" and ent ~= "Cre" and ent ~= "Zom" and ent ~= "Sli" and ent ~= "Spi" and ent ~= "End" then
     table.insert(entArr, i)
    end
  end
  return entArr
end

function getXYZ(tabl, entName)
  retXYZ = {}
  retXYZ["x"] = math.floor(tabl[entName]["Position"]["X"])
  retXYZ["y"] = math.floor(tabl[entName]["Position"]["Y"])
  retXYZ["z"] = math.floor(tabl[entName]["Position"]["Z"])
  return retXYZ
end

function colorOn(col, side)
  rs.setBundledOutput(side, colors.combine(rs.getBundledOutput(side),col))
end
function colorOff(col, side)
  rs.setBundledOutput(side, colors.subtract(rs.getBundledOutput(side),col))
end

monitor = peripheral.wrap("top")
monitor.clear()
monitor.setCursorPos(1,1)
monitor.setTextScale(1)

os.loadAPI("ocs/apis/sensor")
mySensor = sensor.wrap("right")
alarmIsOn = false

while true do
--if true then
  tgts = mySensor.getTargets()
  ents = getEnts(tgts)

  maxX, maxY = monitor.getSize()
  currentY = 1
  monitor.clear()

  for pos = 1, #ents do
    monitor.setCursorPos(1, currentY)
    entXYZ = getXYZ(tgts, ents[pos])
    monitor.write(ents[pos].." X: "..entXYZ["x"].." Y: "..entXYZ["y"].." Z: "..entXYZ["z"])
    currentY = currentY+1
  end

  if #ents == 1 and tgts["arbarr3"] then

      ownerPos = getXYZ(tgts, "arbarr3")
      local ownerX = ownerPos["x"]
      local ownerY = ownerPos["y"]
      local ownerZ = ownerPos["z"]

      if (ownerX >= -2 and ownerX <= 0) and (ownerY == -2 or ownerY == -3) and (ownerZ >= -1 and ownerZ <= 1) then
        if redstone.getBundledOutput("back") ~= colors.white then
          colorOn(colors.white, "back")
        end
      else
        if redstone.getBundledOutput("back") == colors.white then
          colorOff(colors.white, "back")
        end
      end
      colorOff(colors.red, "back")
      alarmIsOn = false
  elseif #ents > 0 then
    monitor.setCursorPos(1, maxY)
    monitor.setTextColor(colors.red)
    monitor.write("You are in arbarr3's house.  Please leave.")
    monitor.setTextColor(colors.white)

    alarmIsOn = true
    colorOn(colors.red, "back")
  else
    colorOff(colors.red, "back")
  end
end

print(textutils.serialize(mySensor.getTargets()))