meowlib/client/matriochka.go

package client

import (
	"forge.redroom.link/yves/meowlib"
	"github.com/google/uuid"
)

func ProcessForOutput(usermessage *meowlib.UserMessage, peer *Peer, servers *ServerList, trackingLookupKey string) ([]byte, error) {
	lastIdx := len(servers.Servers) - 1
	// LAST SERVER : Message delivery as usual
	srv := &servers.Servers[lastIdx]
	// Prepare cyphered + packed user message
	packedMsg, err := peer.ProcessOutboundUserMessage(usermessage)
	if err != nil {
		return nil, err
	}
	// Creating Server message for transporting the user message
	toServerMessage := srv.BuildToServerMessageFromUserMessage(packedMsg)
	lastmsg, err := srv.ProcessOutboundMessage(toServerMessage)
	if err != nil {
		return nil, err
	}
	lastuuid := uuid.NewString()
	// ALL PREVIOUS SERVERS
	for i := lastIdx - 1; i >= 0; i-- {
		srv = &servers.Servers[i]
		var toServerMessage meowlib.ToServerMessage
		toServerMessage.MatriochkaMessage.Data = lastmsg
		toServerMessage.MatriochkaMessage.Next.Url = servers.Servers[i+1].ServerData.Url
		toServerMessage.MatriochkaMessage.Next.PublicKey = servers.Servers[i+1].ServerData.PublicKey
		toServerMessage.MatriochkaMessage.Next.Delay = int32(servers.Servers[i+1].AllowedDelay)
		if trackingLookupKey != "" {
			toServerMessage.MatriochkaMessage.Next.Uuid = lastuuid // change tracking uuid at each server
			if i > 0 {
				toServerMessage.MatriochkaMessage.Prev.Url = servers.Servers[i-1].ServerData.Url
				toServerMessage.MatriochkaMessage.Prev.PublicKey = servers.Servers[i+1].ServerData.PublicKey
				toServerMessage.MatriochkaMessage.Prev.Delay = int32(servers.Servers[i-1].AllowedDelay)
				toServerMessage.MatriochkaMessage.Prev.Uuid = uuid.NewString()
				lastuuid = toServerMessage.MatriochkaMessage.Prev.Uuid
			} else { // for first message, no previous tracking but a lookupkey to stack the tracking messages
				toServerMessage.MatriochkaMessage.LookupKey = trackingLookupKey
			}
		}
		lastmsg, err = srv.ProcessOutboundMessage(&toServerMessage)
		if err != nil {
			return nil, err
		}
	}

	return lastmsg, nil
}