startup

rednet.open('top')
print('This is the master server')

local function receiveMessage()
    local id,msg,d=rednet.receive()
    rednet.send(id,true)
    return id,msg,d
end

local function sendMessage(id,msg)
    rednet.send(id,msg,5)
    local tid,tmsg,td=rednet.receive(5)
    if tid==id and msg then
        return true
    else
        return false
    end
end

local function createFile(name)
    if not fs.exists(name) then
        f=fs.open(name,'w')
        f.writeLine('{}')
        f.close()
    end
end

local function loadFromFile(variable,file)
    local file_path=fs.open(file,'r')
    local values=textutils.unserialize(file_path.readLine())
    for i,v in pairs(values) do
        if i==variable then
            file_path.close()
            return v
        end
    end
    file_path.close()
    return nil
end

local function saveToFile(variable,value,file)
    print('Saving to file ',file)
    local file=file or 'config'
    createFile(file)
    local file_path=fs.open(file,'r')
    local values=textutils.unserialize(file_path.readLine())
    values[variable]=value
    file_path.close()

    local file_path=fs.open(file,'w')
    file_path.writeLine(textutils.serialize(values))
    file_path.close()
end

local function checkId(id)
    if fs.exists("ids") then
        local f = fs.open("ids", "r")
        for line in f.readLine do
            if line:find(id) then
                return true
            end
        end
        return false
    end
end

local function checkValidIds(id)
    local file=fs.open('server_ids','r')

    for _,v in pairs(file.readLine()) do
        if id==v then
            return true
        end
    end
    for _,v in ipairs(loadFromFile('router_ids')) do
        if id==v then
            return true
        end
    end
    if not checkId(id) then
        return false
    end
    return false
end

local function saveId(id)
    if not checkId(id) then
        local f=fs.open('ids','a')
        f.writeLine(id..'')
        f.close()
        return true
    else
        return false
    end
end

local function rerout(values)
    local server_id=loadFromFile(values['action'],'server_ids')
    if not server_id then
        print('requested sub-server does not exist')
        return false
    else
        print(values['id'],' to ',server_id)
        local msg=textutils.serialize(values)
        sendMessage(server_id,msg)
    end
end

local function actionHandler(msg)
    local values=textutils.unserialize(msg)
    print('unserialized')
    print('Action is ',values['action'])
    if values['action']=='register' then
        saveId(values['id'])
    elseif values['action']=='registerSubServer' then
        saveToFile(values['value'],values['id'],'server_ids')
        print('Registered Sub-Server')
    elseif values['action']=='registerComputer' then
        if not checkId(values['id']) then
            saveId(values['id'])
            print('Adding computer ID # '..tostring(values['id'])..' to the id list')
        end
        local msg=textutils.serialize({id=os.getComputerID(),action='computerAdded'})
        sendMessage(values['id'],msg)
    elseif values['action']=='registerRouter' then
        if not loadFromFile('router_ids','config') then
            saveToFile('router_ids',{values['id']},'config')
        else
            local exists=false
            for _,v in ipairs(loadFromFile('router_ids','config')) do
                if v==values['id'] then
                    exists=true
                end
            end
            if not exists then
                local tmp=loadFromFile('router_ids','config')
                table.insert(tmp,values['id'])
                saveToFile('router_ids',tmp,'config')
            end
        end
    elseif values['action']=='return' then
        if checkId(values['id']) then
            sendMessage(values['id'],msg)
        else
            for _,v in ipairs(loadFromFile('router_ids','config')) do
                sendMessage(v,msg)
            end
        end
    else
        print('rerouting')
        rerout(values)
    end
end

createFile('server_ids')
createFile('ids')
print('This computer\'s ID is: '..tostring(os.getComputerID()))

while true do
    local id,msg=receiveMessage()
    print('Got a message')
    actionHandler(msg)
end