syntax = "proto3";

package messages;

option go_package = "git.tornberg.me/go-cart-actor/proto;messages";
import "messages.proto";

// -----------------------------------------------------------------------------
// Cart Actor gRPC API (oneof Envelope Variant)
// -----------------------------------------------------------------------------
// This version removes the legacy numeric MutationType enum + raw bytes payload
// approach and replaces it with a strongly typed oneof envelope. Each concrete
// mutation proto is embedded directly, enabling:
//   * Type-safe routing server-side (simple type switch on the oneof).
//   * Direct persistence of MutationEnvelope messages (no custom binary header).
//   * Elimination of the legacy message handler registry.
//
// NOTE: Regenerate Go code after editing:
//   protoc --go_out=. --go_opt=paths=source_relative \
//          --go-grpc_out=. --go-grpc_opt=paths=source_relative \
//          proto/cart_actor.proto proto/messages.proto
// -----------------------------------------------------------------------------

// MutationEnvelope carries exactly one mutation plus metadata.
// client_timestamp:
//   - Optional Unix timestamp provided by the client.
//   - If zero the server MAY overwrite with its local time.
message MutationEnvelope {
  string cart_id = 1;
  int64 client_timestamp = 2;

  oneof mutation {
    AddRequest add_request = 10;
    AddItem add_item = 11;
    RemoveItem remove_item = 12;
    RemoveDelivery remove_delivery = 13;
    ChangeQuantity change_quantity = 14;
    SetDelivery set_delivery = 15;
    SetPickupPoint set_pickup_point = 16;
    CreateCheckoutOrder create_checkout_order = 17;
    SetCartRequest set_cart_items = 18;
    OrderCreated order_completed = 19;
  }
}

// MutationReply returns a legacy-style status code plus a JSON payload
// holding either the updated cart state (on success) or an error string.
message MutationReply {
  int32 status_code = 1;

  // Exactly one of state or error will be set.
  oneof result {
    CartState state = 2;
    string error = 3;
  }
}

// StateRequest fetches current cart state without mutating.
message StateRequest {
  string cart_id = 1;
}

// -----------------------------------------------------------------------------
// CartState represents the full cart snapshot returned by state/mutation replies.
// Replaces the previous raw JSON payload.
// -----------------------------------------------------------------------------
message CartState {
  string cart_id = 1;
  repeated CartItemState items = 2;
  int64 total_price = 3;
  int64 total_tax = 4;
  int64 total_discount = 5;
  repeated DeliveryState deliveries = 6;
  bool payment_in_progress = 7;
  string order_reference = 8;
  string payment_status = 9;
}

// Lightweight representation of an item in the cart
message CartItemState {
  int64 id = 1;
  int64 source_item_id = 2;
  string sku = 3;
  string name = 4;
  int64 unit_price = 5;
  int32 quantity = 6;
  int64 total_price = 7;
  int64 total_tax = 8;
  int64 org_price = 9;
  int32 tax_rate = 10;
  int64 total_discount = 11;
  string brand = 12;
  string category = 13;
  string category2 = 14;
  string category3 = 15;
  string category4 = 16;
  string category5 = 17;
  string image = 18;
  string article_type = 19;
  string seller_id = 20;
  string seller_name = 21;
  string disclaimer = 22;
  string outlet = 23;
  string store_id = 24;
  int32 stock = 25;
}

// Delivery / shipping entry
message DeliveryState {
  int64 id = 1;
  string provider = 2;
  int64 price = 3;
  repeated int64 item_ids = 4;
  PickupPoint pickup_point = 5;
}

// StateReply mirrors MutationReply for consistency.
message StateReply {
  int32 status_code = 1;

  oneof result {
    CartState state = 2;
    string error = 3;
  }
}

// CartActor exposes mutation and state retrieval for remote grains.
service CartActor {
  // Mutate applies a single mutation to a cart, creating the cart lazily if needed.
  rpc Mutate(MutationEnvelope) returns (MutationReply);

  // GetState retrieves the cart's current state (JSON).
  rpc GetState(StateRequest) returns (StateReply);
}

// -----------------------------------------------------------------------------
// Future Enhancements:
//   * Replace JSON state payload with a strongly typed CartState proto.
//   * Add streaming RPC (e.g., WatchState) for live updates.
//   * Add batch mutations (repeated MutationEnvelope) if performance requires.
//   * Introduce optimistic concurrency via version fields if external writers appear.
// -----------------------------------------------------------------------------