nwaku/waku/waku_lightpush/callbacks.nim

{.push raises: [].}

import
 ../waku_core,
 ../waku_relay,
 ./common,
 ./protocol,
 ../waku_rln_relay,
 ../waku_rln_relay/protocol_types,
 ../common/ratelimit
import
 std/times,
 libp2p/peerid,
 stew/byteutils

proc checkAndGenerateRLNProof*(rlnPeer: Option[WakuRLNRelay], message: WakuMessage): Result[WakuMessage, string] =
  # check if the message already has RLN proof
  if message.proof.len > 0:
    return ok(message)
  
  if rlnPeer.isNone():
    notice "Publishing message without RLN proof"
    return ok(message)
  # generate and append RLN proof
  let
    time = getTime().toUnix()
    senderEpochTime = float64(time)
  var msgWithProof = message
  rlnPeer.get().appendRLNProof(msgWithProof, senderEpochTime).isOkOr:
    return err(error)
  return ok(msgWithProof)

proc getNilPushHandler*(): PushMessageHandler =
  return proc(
    peer: PeerId, pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult[void]] {.async.} =
    return err("no waku relay found")

proc getRelayPushHandler*(
  wakuRelay: WakuRelay,
  rlnPeer: Option[WakuRLNRelay] = none[WakuRLNRelay]()
): PushMessageHandler =
  return proc(
    peer: PeerId, pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult[void]] {.async.} =
    # append RLN proof
    let msgWithProof = checkAndGenerateRLNProof(rlnPeer, message)
    if msgWithProof.isErr():
      return err(msgWithProof.error)

    (await wakuRelay.validateMessage(pubSubTopic, msgWithProof.value)).isOkOr:
      return err(error)

    let publishedCount = await wakuRelay.publish(pubsubTopic, msgWithProof.value)
    if publishedCount == 0:
      ## Agreed change expected to the lightpush protocol to better handle such case. https://github.com/waku-org/pm/issues/93
      let msgHash = computeMessageHash(pubsubTopic, message).to0xHex()
      notice "Lightpush request has not been published to any peers", msg_hash = msgHash

    return ok()