syntax = "proto3";

package metadata.v1;

option go_package = "github.com/metadata-agregator/pkg/gen/metadata/v1;metadatav1";

enum Provider {
  PROVIDER_UNSPECIFIED = 0;
  PROVIDER_MUSICBRAINZ = 1;
}

// MetadataService provides music metadata aggregation.
service MetadataService {
  // GetArtist retrieves an artist by ID or external source ID.
  rpc GetArtist(GetArtistRequest) returns (Artist);
  
  // SearchArtists searches for artists by name.
  rpc SearchArtists(SearchArtistsRequest) returns (SearchArtistsResponse);
  
  // GetAlbum retrieves an album by ID.
  rpc GetAlbum(GetAlbumRequest) returns (Album);
  
  // GetArtistAlbums retrieves all albums by an artist.
  rpc GetArtistAlbums(GetArtistAlbumsRequest) returns (GetArtistAlbumsResponse);
  
  // GetTrack retrieves a track by ID.
  rpc GetTrack(GetTrackRequest) returns (Track);
  
  // GetAlbumTracks retrieves all tracks on an album.
  rpc GetAlbumTracks(GetAlbumTracksRequest) returns (GetAlbumTracksResponse);
  
  // SearchAlbums searches for albums by name, optionally filtered by artist.
  rpc SearchAlbums(SearchAlbumsRequest) returns (SearchAlbumsResponse);

  // SyncArtist triggers ingestion of an artist from external sources.
  rpc SyncArtist(SyncArtistRequest) returns (SyncArtistResponse);
}

// Requests

message GetArtistRequest {
  oneof identifier {
    string id = 1;           // Internal UUID
    ExternalID external = 2; // External source ID (e.g., musicbrainz MBID)
  }
  Provider provider = 3;     // UNSPECIFIED = query all providers
}

message SearchArtistsRequest {
  string query = 1;
  int32 limit = 2;
  int32 offset = 3;
  Provider provider = 4;
}

message GetAlbumRequest {
  oneof identifier {
    string id = 1;
    ExternalID external = 2;
  }
  Provider provider = 3;
}

message GetArtistAlbumsRequest {
  string artist_id = 1;
  int32 limit = 2;
  int32 offset = 3;
  Provider provider = 4;
}

message GetTrackRequest {
  oneof identifier {
    string id = 1;
    ExternalID external = 2;
    string isrc = 3;
  }
  Provider provider = 4;
}

message GetAlbumTracksRequest {
  string album_id = 1;
  Provider provider = 2;
}

message SearchAlbumsRequest {
  string query = 1;
  string artist = 2;
  int32 limit = 3;
  int32 offset = 4;
  Provider provider = 5;
}

message SearchAlbumsResponse {
  repeated Album albums = 1;
  int32 total = 2;
}

message SyncArtistRequest {
  oneof target {
    string name = 1;
    ExternalID external = 2;
  }
  Provider provider = 3;
}

// Responses

message SearchArtistsResponse {
  repeated Artist artists = 1;
  int32 total = 2;
}

message GetArtistAlbumsResponse {
  repeated Album albums = 1;
  int32 total = 2;
}

message GetAlbumTracksResponse {
  repeated Track tracks = 1;
}

message SyncArtistResponse {
  Artist artist = 1;
  int32 albums_synced = 2;
  int32 tracks_synced = 3;
}

// Core Entities

message Artist {
  string id = 1;
  string name = 2;
  string sort_name = 3;
  string artist_type = 4;  // person, group, orchestra, etc.
  string country = 5;
  string formed_date = 6;
  string disbanded_date = 7;
  string description = 8;
  string image_url = 9;
  repeated Genre genres = 10;
  repeated ExternalID external_ids = 11;
}

message Album {
  string id = 1;
  string title = 2;
  string album_type = 3;  // album, ep, single, compilation
  string release_date = 4;
  string upc = 5;
  int32 total_tracks = 6;
  int32 total_discs = 7;
  string cover_url = 8;
  repeated ArtistCredit artists = 9;
  Label label = 10;
  repeated Genre genres = 11;
  repeated ExternalID external_ids = 12;
}

message Track {
  string id = 1;
  string title = 2;
  int32 duration_ms = 3;
  string isrc = 4;
  bool explicit = 5;
  int32 disc_number = 6;
  int32 track_number = 7;
  repeated ArtistCredit artists = 8;
  Work work = 9;
  repeated ExternalID external_ids = 10;
}

message Work {
  string id = 1;
  string title = 2;
  string work_type = 3;
  string language = 4;
  repeated ArtistCredit composers = 5;
}

message Label {
  string id = 1;
  string name = 2;
  string country = 3;
}

message Genre {
  string id = 1;
  string name = 2;
}

message ArtistCredit {
  Artist artist = 1;
  string role = 2;      // primary, featured, remixer, producer
  int32 position = 3;
  string join_phrase = 4; // " & ", " feat. ", etc.
}

message ExternalID {
  string source = 1;    // musicbrainz, spotify, discogs, etc.
  string source_id = 2;
  string url = 3;
}