syntax = "proto3";

import "packet.proto";
import "shared.proto";
import "bundle.proto";

package block_engine;

message SubscribePacketsRequest {}
message SubscribePacketsResponse {
  shared.Header header = 1;
  packet.PacketBatch batch = 2;
}

message SubscribeBundlesRequest {}
message SubscribeBundlesResponse {
  repeated bundle.BundleUuid bundles = 1;
}

message AccountsOfInterest {
  // use * for all accounts
  repeated string accounts = 1;
}

message AccountsOfInterestRequest {}
message AccountsOfInterestUpdate {
  oneof msg {
    AccountsOfInterest add = 1;
    AccountsOfInterest remove = 2;
    AccountsOfInterest overwrite = 3;
  }
}

// A series of packets with an expiration attached to them.
// The header contains a timestamp for when this packet was generated.
// The expiry is how long the packet batches have before they expire and are forwarded to the validator.
// This provides a more censorship resistant method to MEV than block engines receiving packets directly.
message ExpiringPacketBatch {
  shared.Header header = 1;
  packet.PacketBatch batch = 2;
  uint32 expiry_ms = 3;
}

// Packets and heartbeats are sent over the same stream.
// ExpiringPacketBatches have an expiration attached to them so the block engine can track
// how long it has until the relayer forwards the packets to the validator.
// Heartbeats contain a timestamp from the system and is used as a simple and naive time-sync mechanism
// so the block engine has some idea on how far their clocks are apart.
message PacketBatchUpdate {
  oneof msg {
    ExpiringPacketBatch batches = 1;
    shared.Heartbeat heartbeat = 2;
  }
}

message StartExpiringPacketStreamResponse {
  shared.Heartbeat heartbeat = 1;
}

/// Validators can connect to Block Engines to receive packets and bundles.
service BlockEngineValidator {
  /// Validators can subscribe to the block engine to receive a stream of packets
  rpc SubscribePackets (SubscribePacketsRequest) returns (stream SubscribePacketsResponse) {}

  /// Validators can subscribe to the block engine to receive a stream of simulated and profitable bundles
  rpc SubscribeBundles (SubscribeBundlesRequest) returns (stream SubscribeBundlesResponse) {}
}

/// Relayers can forward packets to Block Engines.
/// Block Engines provide an AccountsOfInterest field to only send transactions that are of interest.
service BlockEngineRelayer {
  /// Relayers subscribe to a stream that contains a set of accounts they're interested in getting transactions for.
  /// They receive periodic updates for those accounts
  rpc SubscribeAccountsOfInterest (AccountsOfInterestRequest) returns (stream AccountsOfInterestUpdate) {}

  // Validators can subscribe to packets from the relayer and receive a multiplexed signal that contains a mixture
  // of packets and heartbeats.
  // NOTE: This is a bi-directional stream due to a bug with how Envoy handles half closed client-side streams.
  // The issue is being tracked here: https://github.com/envoyproxy/envoy/issues/22748. In the meantime, the
  // server will stream heartbeats to clients at some reasonable cadence.
  rpc StartExpiringPacketStream (stream PacketBatchUpdate) returns (stream StartExpiringPacketStreamResponse) {}
}