ComputerCraft Router

--Computer Craft Router Application
--By snipy67/Horsemeat
--V1.0
BROADCAST_PORT = 2

--Layer 1
lowLevelListeners = {}
routerComputerId = 0

function detectModem()
    return peripheral.find("modem")
end
function lowLevelMessageSplit(message)
    local tab = {}
    local current = ""
    for i = 1, #message, 1 do
        if message:sub(i,i) == ':' then
            table.insert(tab,current)
            current = ""
        else
            current = current .. message:sub(i,i)
        end
    end
    if #current > 0 then
        table.insert(tab,current)
    end
    return tab
end

function lowLevelListenerCheckForMethod(modem,port,tab,verbose)
    for k, v in pairs(lowLevelListeners) do
        if v.message == tab[1] then
            if verbose then
                print("function " .. v.message .. "found")
            end
            if v.func ~= nil then
                local t = {}
                t.message = tab[1]
                t.senderId = tab[2]
                t.reciverId = tab[3]
                t.data = tab[4]
                v.func(t)
                if t.data ~= nil then
                    local responseText = tab[1] .. "~response:" .. os.getComputerID() .. ":".. tab[2] .. ":".. t.data;
                    modem.transmit(port,port,responseText)
                else
                    local responseText = tab[1] .. "~response:" .. os.getComputerID() .. ":".. tab[2]
                    modem.transmit(port,port,responseText)
                end
            else
                local responseText = tab[1] .. "~response:" .. os.getComputerID() .. ":".. tab[2]
                modem.transmit(port,port,responseText)
            end
            return true
        else
            if verbose then
                print("v.message:" .. v.message .. " != tab[1]:"..tab[1])
            end
        end
    end
    return false
end

function lowLevelListener(modem,port,verbose)
    while true do
        local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent()--listens for a actions
        if event == "modem_message" then--gets the message
            if senderChannel == port then
                if verbose then
                    print("message recived: " .. message)
                end
                local tab = lowLevelMessageSplit(message)
                if #tab > 2 then
                    if verbose then
                        print("There is more then 2 arguments in the message")
                    end
                    if tonumber(tab[3]) == os.getComputerID() then
                        if verbose then
                            print("id matches")
                        end
                        lowLevelListenerCheckForMethod(modem,port,tab,verbose)
                    elseif tonumber(tab[3]) == -1 then
                        if verbose then
                            print("broadcast")
                        end
                        lowLevelListenerCheckForMethod(modem,port,tab,verbose)
                    end
                elseif #tab == 2 then
                    lowLevelListenerCheckForMethod(modem,port,tab,verbose)
                end
            end
        end
    end
end

function lowLevelRequest(modem,request,port,maxTimeOut,timeBetweenResend,numberOfResendsBeforeTimeOut,id,data,verbose)
    local str = ""
    if id ~= nil and id ~= -1 then
        str = request .. ":" .. os.getComputerID() .. ":" .. id -- adds the computer id and the id of the reciver
    else
        str = request .. ":" .. os.getComputerID() .. ":" .. -1-- adds the computer id to the requests
    end

    if data ~= nil then
        str = str .. ":" .. data
    end

    modem.transmit(port,port,str);--transmits the request
    local responseText = request .. "~response"--creates text on how a response will look like
    local count = 0--count is to keep track of how many times the request timed out
    local timer = -1
    if timeBetweenResend > 0 and numberOfResendsBeforeTimeOut > 0 then
        timer = os.startTimer(timeBetweenResend) -- to keep track of the number of seconds before a time out
    end
    local atLeastOne = false--this determines if atleast one computer recived the request
    local timeOutTimer
    if maxTimeOut > 0 then
        timeOutTimer = os.startTimer(maxTimeOut)--this timer is the number of seconds it should wait for return requests
    end
    local all = {} -- this is all the data that will be returned
    all.package = {}--this is where the data from each request is stored
    while true do
        local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent()--listens for a actions
        if event == "timer" then--check if the timer is up
            local timerId = modemSide; --modemSide is the timerid when timer event is called (prevents confusion)
            if timerId == timer then--checks if the timer is the timer that handels resends
                if atLeastOne == false then--checks if there are no records recovered
                    if count ~= numberOfResendsBeforeTimeOut then--check to make sure the count is not at the timeout stage
                        modem.transmit(port,port,str);--transmits the request again
                        count = count + 1 -- adds one to the #of time outs
                        timer = os.startTimer(timeBetweenResend)--resets the timer
                        if verbose then
                            print("Message Transmission failed resending...")
                        end
                    else
                        if verbose then
                            print("Message Transmission failed")
                        end
                        all.sucess = false
                        return all
                    end
                end
            elseif timerId == timeOutTimer then--this is the maximum amount of time it was going to wait and not it's going to return the data
                if atLeastone == false then
                    all.sucess = false
                else
                    all.sucess = true
                end
                return all
            end
        elseif event == "modem_message" then--gets the message
            if senderChannel == port then
                local tab = lowLevelMessageSplit(message)
                if verbose then
                    print("Modem message: " .. message)
                end
                if tab[1] == responseText then
                    if tonumber(tab[3]) == os.getComputerID() then
                        local p = {}
                        p.sucess = true
                        p.tab = tab
                        atLeastOne = true
                        table.insert(all.package,p)
                        if verbose then
                            print("This computer: " .. tab[3] .. ". Request response recived from " .. tab[2])
                        end
                        if timeOutTimer == -1 then
                            all.sucess = true
                            return all;
                        end
                    end
                end
            end
        end
    end
end

MAX_TIME_OUT = 0.8
TIME_BETWEEN_RESENDS = 0.2
NUMBER_OF_RESENDS = 4
VERBOSE = false

--easy to use methods
--> the low level lowLevelListener returns true if atleast 1 tramission has been valid and in this case only 1 transmision
function basicListener(modem)
    return lowLevelListener(modem,BROADCAST_PORT,VERBOSE)--this will never finish, it will listen forever
end

-->Low level request return
--.sucess
--.package[instance].sucess = true
--.package[instance].tab = tab
function basicBroadcast(modem,request)

    return lowLevelRequest(modem,request,BROADCAST_PORT,MAX_TIME_OUT,TIME_BETWEEN_RESENDS,NUMBER_OF_RESENDS,nil,nil,VERBOSE)--A broadcast request which will conenct to everyone
end

function basicRequest(modem,request,computer)
    return lowLevelRequest(modem,request,BROADCAST_PORT,MAX_TIME_OUT,TIME_BETWEEN_RESENDS,NUMBER_OF_RESENDS,computer,nil,VERBOSE)-- a message for a certian computer
end

function basicBroadcastWithData(modem,request,data)
    return lowLevelRequest(modem,request,BROADCAST_PORT,MAX_TIME_OUT,TIME_BETWEEN_RESENDS,NUMBER_OF_RESENDS,nil,data,VERBOSE)-- this a a broadcast with data
end

function basicRequestWithData(modem,request,computer,data)
    return lowLevelRequest(modem,request,BROADCAST_PORT,MAX_TIME_OUT,TIME_BETWEEN_RESENDS,NUMBER_OF_RESENDS,computer,data,VERBOSE) -- this is a message for a certian computer with data
end

function addActionListener(message,func)
    --function parameters required (data)
    --.message -- the message that was transmitted
    --.senderId -- the sender of the message
    --.reciverId -- the reciver of the message
    --.data -- the data that might have been passed along
    local tab = {}
    tab.message = message
    tab.func = func
    table.insert(lowLevelListeners,tab)
    return #lowLevelListeners
end

function removeActionListener(index)
    table.remove(lowLevelListeners,index)
end
--End Of Layer 1

--Routeing layer
portsTaken = {}
computerId = {}

function openBroadcastNode(modem)
    portsTaken[BROADCAST_PORT] = true
    modem.open(BROADCAST_PORT)
end

function portInit(modem)
    for i = 1, 128, 1 do
        portsTaken[i] = false
        if modem.isOpen(i) then
            modem.close(i)
        end
    end
end

function findEmptyPort(modem)
    for i = 1,128, 1 do
        if portsTaken[i] == false then
            return i
        end
    end
    return -1
end

function routerServer(modem)
    portInit(modem)
    openBroadcastNode(modem)
    local requestRoute = function(data)
        local port = findEmptyPort(modem)
        computerId[port] = data.senderId
        portsTaken[port] = true
        data.data = tostring(port)
        print("Port Found: " .. port)
    end
    addActionListener("addport",requestRoute)
    local deleteRoute = function(data)
        local port = tonumber(data.data)
        if port ~= nil or port ~= -1 then
            if data.senderId == computerId[port] then
                computerId[data.senderId] = -1
                portsTaken[port] = false
                data.data = "true"
                print("Port Deleted: " .. port)
            else
                data.data = "false"
            end
        end
    end
    addActionListener("removeport",deleteRoute)
    addActionListener("ping",nil)
    basicListener(modem)
end

function deletePort(modem,port)
    local d = basicBroadcastWithData(modem,"removeport",tostring(port))
    for k, v in pairs(d.package) do
        if #v.tab > 3 then
            local state = v.tab[4]
            if state ~=nil then
                if state == "true" then
                    return true
                else
                    return false
                end
            end
        end
    end
    print("router error")
    return false
end

function getRouterPort(modem)
    local d = basicRequest(modem,"addport",routerComputerId)
    for k, v in pairs(d.package) do
        if #v.tab > 3 then
            local p = v.tab[4]
            if p ~= nil and p ~= "" then
                return tonumber(p)
            end
        end
    end
    print("router error")
    return -1
end

function routerInit(modem)
    portInit(modem)
    openBroadcastNode(modem)
    local d = basicBroadcast(modem,"ping")
    if d.sucess then
        if #d.package > 0 then
            local id = -1
            for k, v in pairs(d.package) do
                if id == -1 or id == tonumber(v.tab[2]) then
                    id = tonumber(v.tab[2])
                    if id ~= -1 and id < 128 then
                        routerComputerId = id
                        return true
                    end
                else
                    print("Too many routers")
                    return false
                end
            end
            print("unknown router Error")
            return false
        elseif #d.package == 0 then
            print("No Routers detected")
            return false
        else
            return false
        end
    else
        print("Router not found")
        return false
    end
end
--End of routeing layer
function runServer()
    local modem = detectModem()
    routerServer(modem)
end

function runClient()
    local modem = detectModem()
    if routerInit(modem) then
        local port = getRouterPort(modem)
        print("retrived Port: " .. port)
        os.sleep(2)
        deletePort(modem,port)
    else
        print("error to init router")
    end
end