Mob Counter

local m = peripheral.find("modem") -- Requires advanced pocket computer w/ modem
m.open(42) -- Customize to your liking

local _getSize = term.getSize
local _setCursorPos = term.setCursorPos
local _getCursorPos = term.getCursorPos

-- Override cursor related functions so we have the first line all to ourselves
term.getSize = function()
  local w, h = _getSize()
  return w, h-1
end

term.setCursorPos = function(x, y)
  return _setCursorPos(x, y + 1)
end

term.getCursorPos = function()
  local x, y = _getCursorPos()
  return x, y - 1
end

-- Make sure we save the current state of the terminal (e.g. colors and cursor pos)
local function save()
  return {
    colors.black, -- Implement at some point
    colors.white,
    {_getCursorPos()}
  }
end

-- Restore state of terminal
local function restore(ts)
  term.setBackgroundColor(ts[1])
  term.setTextColor(ts[2])
  _setCursorPos(ts[3][1], ts[3][2])
end

local w, h = _getSize()

-- Our function for writing to that first line
local function writeMobStatus()
  while true do
    local e = {os.pullEvent("modem_message")}
    local ts = save()
    _setCursorPos(1,1)
    term.setBackgroundColor(colors.red)
    term.write(string.rep(" ", w))
    _setCursorPos(1,1)
    term.setTextColor(colors.white)
    term.write("Mobs: " .. e[5])
    restore(ts)
  end
end

-- A helper method to run the shell
local function runTerm()
  shell.run("rom/programs/shell")
end

-- Clear the terminal so it's nice and clean that first go
term.clear()

-- And bam!
parallel.waitForAll(writeMobStatus, runTerm)