Turtle Server (ComputerCraft)

-- Turtle Tracking
-- ----------------------------------------------------------

-- Which turtles are alive?

-- ----------------------------------------------------------

-- Initialise important values:

local turtles = {
["BBCrafter1"] = {["timer"] = os.startTimer(300), ["strike"] = 1},
["BBFarmer1"] = {["timer"] = os.startTimer(300), ["strike"] = 1},
["BBChopper1"] = {["timer"] = os.startTimer(300), ["strike"] = 1},
["BBChopper2"] = {["timer"] = os.startTimer(300), ["strike"] = 1},
["BBChopper3"] = {["timer"] = os.startTimer(300), ["strike"] = 1}}

local bgs = {colours.green,colours.orange,colours.red,colours.grey}

local mon, myEvent = peripheral.wrap("left")

local function monPrint(someText)
    mon.write(someText)
    local monX,monY = mon.getCursorPos()
    mon.setCursorPos(1,monY+1)
end

mon.setTextScale(1.5)

rednet.open("top")

term.clear()
term.setCursorPos(1,1)

print("I'm a turtle server.")
print("")
print("My goal is to keep track of which turtles are active.")

os.startTimer(0)

while true do
    myEvent = {os.pullEvent()}

    if myEvent[1] == "rednet_message" and type(myEvent[3]) == "table" and myEvent[3][1] == "Hello TurtleServer" then
        turtles[myEvent[3][2]].id = myEvent[2]
        turtles[myEvent[3][2]].timer = os.startTimer(300)
        turtles[myEvent[3][2]].strike = 1
        os.startTimer(0)
    elseif myEvent[1] == "timer" then
        mon.setBackgroundColor(colours.black)
        mon.clear()
        mon.setCursorPos(1,1)

        monPrint("Alive Turtles")
        monPrint("=============")
        monPrint("")

        for aTurtle,data in pairs(turtles) do
            if data.timer == myEvent[2] then
                if data.id then rednet.send(data.id,"Hey, you still there?") end
                data.strike = data.strike + 1
                if data.strike > 4 then
                    data.strike = 4
                    if aTurtle:sub(1,9) == "BBChopper" and turtles["BBCrafter1"].id then rednet.send(turtles["BBCrafter1"].id,{"We need a new turtle.",aTurtle}) end
                    data.timer = os.startTimer(1800)
                else
                    data.timer = os.startTimer(300)
                end
            end

            mon.setBackgroundColor(bgs[data.strike])
            monPrint(aTurtle)
            monPrint("")
        end
    end
end