AltProto_Client

local ALTPROTO_PORT = 16660

local function Log(text)
    print(text)
end


local proto_id

local file = fs.open("altproto_id", "r")
if file then
    proto_id = tonumber(file.readAll())
    file.close()

    if not proto_id then
        Log("Invalid protocol id, setting to computer id")
        proto_id = os.getComputerID()
    end
else
    Log("No protocol id found, setting to computer id")
    proto_id = os.getComputerID()
    file = fs.open("altproto_id", "w")
    file.write(tostring(proto_id))
    file.close()
end

local modem = peripheral.find("modem", function(_, p) return p.isWireless() end)
if not modem then
    Log("No modem found.. waiting")

    repeat
        local event, side = os.pullEvent("peripheral")
        if peripheral.getType(side) == "modem" and peripheral.call(side, "isWireless") then
            modem = peripheral.wrap(side)
        end
    until modem
end





modem.open(ALTPROTO_PORT)


local RECIPIENT_ALL = 0
local function SendMessage(id, recipient, data)
    modem.transmit(ALTPROTO_PORT, 0, {id = id, data = data, recipient = recipient, sender = proto_id})
end


local timers = {}
local event_listeners = {}
local message_handlers = {}

local module_env = setmetatable({
    CreateTimer = function(callback, timeout, loop)
        local id = os.startTimer(timeout)
        timers[id] = {callback, timeout, loop}
    end;

    OnEvent = function(callback, filter)
        table.insert(event_listeners, {callback, filter})
    end;

    OnMessage = function(callback, id)
        if not id then
            id = "all"
        end

        if not message_handlers[id] then
            message_handlers[id] = {}
        end
        table.insert(message_handlers[id], callback)
    end;

    Log = Log;

    SendMessage = SendMessage;

    RECIPIENT_ALL = RECIPIENT_ALL;
}, {__index = _G})


local function LoadModules()
    if not fs.exists("modules") then
        Log("Creating modules directory")
        fs.makeDir("modules")
    end

    for _, name in ipairs(fs.list("modules")) do
        if not fs.isDir("modules/" .. name) then
            Log("Loading module: " .. name)
            local file = fs.open("modules/" .. name, "r")
            local data = file.readAll()
            file.close()

            local func, err = loadstring(data, name)
            if func then
                local env = {}
                setmetatable(env, {__index = module_env})
                setfenv(func, env)

                local success, err = pcall(func)
                if not success then
                    Log("ERROR: in module " .. name .. ": " .. err)
                end
            else
                Log("ERROR: " .. err)
            end
        end
    end
end

local function ReloadModules()
    timers = {}
    event_listeners = {}
    message_handlers = {}

    LoadModules()
end


LoadModules()

local function HandleMessage(id, real_id, recipient, sender, data)
    if message_handlers[id] then
        for i,v in pairs(message_handlers[id]) do
            local success, err = pcall(v, real_id, recipient, sender, data)
            if not success then
                Log("Error in message handler: " .. err)
            end
        end
    end
end

while true do
    local success, err = pcall(function()
        local event = {os.pullEvent()}

        if event[1] == "modem_message" then
            local event, side, sender, reply, message, distance = unpack(event)

            if sender == ALTPROTO_PORT then
                if type(message) ~= "table" then
                    Log("ERROR: Message was not a table")
                    return
                end

                local recipient = message.recipient
                if not recipient then
                    Log("ERROR: Message has no recipient")
                    return
                end
                local sender = message.sender
                if not sender then
                    Log("ERROR: Message has no sender")
                    return
                end

                if recipient == proto_id or recipient == RECIPIENT_ALL then
                    local id = message.id
                    if not id then
                        Log("ERROR: Message has no ID")
                        return
                    end

                    if id == "GPING" then
                        SendMessage("GPONG", RECIPIENT_ALL, os.getComputerLabel())
                        Log("Send GPONG")
                    elseif id == "UPDATE" then
                        local func, err = loadstring(message.data)
                        if not func then
                            Log("Attempt to update with bad code: " .. err)
                        else
                            local file = fs.open("startup", "w")
                            file.write(message.data)
                            file.close()

                            os.reboot()
                        end
                    elseif id == "UPDATEMOD" then
                        local data = message.data
                        local file = fs.open("modules/" .. data.name, "w")
                        file.write(data.code)
                        file.close()

                        ReloadModules()
                    elseif id == "EXEC" then
                        if type(message.data) == "string" then
                            local func, err = loadstring(message.data, "exec")
                            if func then
                                local success, err = pcall(func)
                                if not success then
                                    Log("Error executing: " .. err)
                                end
                            else
                                Log("Cannot execute: " .. err)
                            end
                        else
                            Log("Cannot execute: not a string")
                        end
                    end

                    HandleMessage("all", id, recipient, sender, message.data)
                    HandleMessage(id, id, recipient, sender, message.data)
                end
            end
        elseif event[1] == "timer" then
            local timer = timers[event[2]]
            if timer then
                local success, err = pcall(timer[1])
                if not success then
                    Log("Error in timer: " .. err)
                end

                timers[event[2]] = nil
                if timer[3] then
                    timers[os.startTimer(timer[2])] = timer
                end
            end
        end

        for i,v in pairs(event_listeners) do
            if v[2] == event[1] or not v[2] then
                local success, err = pcall(v[1], unpack(event))
                if not success then
                    Log("Error in event handler: " .. err)
                end
            end
        end
    end)

    if err == "Terminated" then
        break
    end

    if not success then
        Log("Fatal error: " .. err)
    end
end