syntax = "proto3";

option csharp_namespace = "Svrnty.CQRS.Events.Grpc";

package svrnty.cqrs.events;

import "google/protobuf/timestamp.proto";

// Bidirectional streaming service for event subscriptions
service EventService {
  // Subscribe to events with bidirectional streaming
  // Client sends subscription requests, server sends events
  rpc Subscribe(stream SubscriptionRequest) returns (stream EventMessage);
}

// Client-to-server messages
message SubscriptionRequest {
  oneof request_type {
    SubscribeCommand subscribe = 1;
    UnsubscribeCommand unsubscribe = 2;
    CatchUpCommand catch_up = 3;
    AcknowledgeCommand acknowledge = 4;
    NackCommand nack = 5;
  }
}

message SubscribeCommand {
  string subscription_id = 1;
  string correlation_id = 2;  // Workflow correlation ID
  repeated string event_types = 3;  // Empty = all types
  repeated string terminal_event_types = 4;  // For workflow completion
  DeliveryMode delivery_mode = 5;
  optional int32 timeout_seconds = 6;
  optional string consumer_id = 7;  // Phase 1.7: Optional consumer identifier
  map<string, string> metadata = 8;  // Phase 1.7: Consumer metadata (hostname, version, etc.)
}

message UnsubscribeCommand {
  string subscription_id = 1;
}

message CatchUpCommand {
  repeated string subscription_ids = 1;
}

message AcknowledgeCommand {
  string subscription_id = 1;
  string event_id = 2;
  string consumer_id = 3;
}

message NackCommand {
  string subscription_id = 1;
  string event_id = 2;
  string consumer_id = 3;
  bool requeue = 4;  // True = requeue for retry, False = dead letter
}

// Server-to-client messages
message EventMessage {
  oneof message_type {
    EventDelivery event = 1;
    SubscriptionCompleted completed = 2;
    ErrorMessage error = 3;
  }
}

message EventDelivery {
  string subscription_id = 1;
  string correlation_id = 2;
  string event_type = 3;
  string event_id = 4;
  int64 sequence = 5;
  google.protobuf.Timestamp occurred_at = 6;

  // Dynamic event payload will be a oneof with all registered event types
  // This will be generated by the source generator
  // For now, we use a placeholder to make the proto valid
  oneof event_data {
    // Placeholder - will be replaced/extended by source generator
    PlaceholderEvent placeholder = 100;
    // Generated event messages will be added here by source generator
    // Example:
    // UserInvitationSentEvent user_invitation_sent = 101;
    // UserInvitationAcceptedEvent user_invitation_accepted = 102;
  }
}

// Placeholder event type (will be removed when real events are generated)
message PlaceholderEvent {
  string data = 1;
}

message SubscriptionCompleted {
  string subscription_id = 1;
  string reason = 2;
  optional string terminal_event_type = 3;
}

message ErrorMessage {
  string code = 1;
  string message = 2;
  optional string subscription_id = 3;
}

enum DeliveryMode {
  DELIVERY_MODE_UNSPECIFIED = 0;
  DELIVERY_MODE_IMMEDIATE = 1;
  DELIVERY_MODE_BATCHED = 2;
  DELIVERY_MODE_ON_RECONNECT = 3;
}