syntax = "proto3";

package users;

option go_package = "git.be.kaien.ru/l-ai/l-ai-core-proto/proto";

import "google/protobuf/empty.proto";
import "google/protobuf/timestamp.proto";

// UsersService manages global users and their linked platform accounts
service UsersService {
  rpc CreateGlobalUser(CreateGlobalUserRequest) returns (GlobalUser);
  rpc GetGlobalUser(GetGlobalUserRequest) returns (GlobalUser);
  rpc GetAllGlobalUsers(google.protobuf.Empty) returns (GetAllGlobalUsersResponse);
  rpc UpdateDisplayName(UpdateDisplayNameRequest) returns (google.protobuf.Empty);

  rpc LinkAccount(LinkAccountRequest) returns (LinkedAccount);
  rpc UnlinkAccount(UnlinkAccountRequest) returns (google.protobuf.Empty);
  rpc GetLinkedAccount(GetLinkedAccountRequest) returns (LinkedAccount);
  rpc GetLinkedAccountsByPlatform(GetLinkedAccountsByPlatformRequest) returns (GetLinkedAccountsResponse);
  rpc GetLinkedAccountsByUserAndPlatform(GetLinkedAccountsByUserAndPlatformRequest) returns (GetLinkedAccountsResponse);

  // ResolveLinkedAccount resolves the global user owning a platform account
  // (e.g. platform="telegram", account_id="<numeric Telegram user id>").
  // This is a read-only, non-creating server-to-server identity lookup used
  // by other services (e.g. l-ai-chat Telegram bridge) to map a transport
  // identity to the stable global_user_id. It NEVER creates a global user or
  // a linked account.
  //
  // Identity boundary invariant: (platform, account_id) -> at most one
  // canonical global_user_id.
  //   - no rows            -> linked=false (account not linked; nothing created)
  //   - one distinct global user -> that user; if several legacy link rows
  //     exist for the SAME user, the oldest (smallest linked_account id) wins,
  //     deterministic across retries
  //   - more than one distinct global user -> FAILS CLOSED with
  //     FailedPrecondition (ambiguous identity); callers must not persist
  //     anything under a guessed identity
  rpc ResolveLinkedAccount(ResolveLinkedAccountRequest) returns (ResolveLinkedAccountResponse);

  // ResolveLinkedAccountByUsername resolves the global user owning a platform
  // account addressed by its username rather than its id (e.g.
  // platform="telegram", username="kaien"). Read-only: it never creates a
  // global user or a linked account.
  //
  // Callers that only know how a person is addressed in chat need this; the
  // id-based lookup above cannot serve them. Same fail-closed identity rule:
  //   - no match                    -> found=false
  //   - one global user             -> that user
  //   - more than one global user   -> FailedPrecondition (ambiguous), so a
  //     caller never acts on a guessed identity. Acting on the wrong one here
  //     can mean phoning a person who never asked to be called.
  rpc ResolveLinkedAccountByUsername(ResolveLinkedAccountByUsernameRequest) returns (ResolveLinkedAccountResponse);
}

message GlobalUser {
  int64 id = 1;
  string display_name = 2;
  google.protobuf.Timestamp created_at = 3;
  google.protobuf.Timestamp updated_at = 4;
  repeated LinkedAccount linked_accounts = 5;
}

message LinkedAccount {
  int64 id = 1;
  int64 global_user_id = 2;
  string platform = 3;
  string account_id = 4;
  string account_username = 5;
  string account_url = 6;
  google.protobuf.Timestamp linked_at = 7;
  google.protobuf.Timestamp updated_at = 8;
}

message CreateGlobalUserRequest {
  string display_name = 1;
}

message GetGlobalUserRequest {
  int64 id = 1;
}

message GetAllGlobalUsersResponse {
  repeated GlobalUser users = 1;
}

message UpdateDisplayNameRequest {
  int64 id = 1;
  string display_name = 2;
}

message LinkAccountRequest {
  int64 global_user_id = 1;
  string platform = 2;
  string account_id = 3;
  string account_username = 4;
  string account_url = 5;
}

message UnlinkAccountRequest {
  int64 global_user_id = 1;
  string platform = 2;
  string account_id = 3;
}

message GetLinkedAccountRequest {
  int64 global_user_id = 1;
  string platform = 2;
}

message GetLinkedAccountsByPlatformRequest {
  string platform = 1;
}

message GetLinkedAccountsByUserAndPlatformRequest {
  int64 global_user_id = 1;
  string platform = 2;
}

message GetLinkedAccountsResponse {
  repeated LinkedAccount accounts = 1;
}

message ResolveLinkedAccountRequest {
  string platform = 1;
  string account_id = 2;
}

message ResolveLinkedAccountByUsernameRequest {
  string platform = 1;
  // Username without a leading "@"; matched case-insensitively, the way
  // people write it in chat.
  string username = 2;
}

message ResolveLinkedAccountResponse {
  bool linked = 1;
  int64 global_user_id = 2;
  string display_name = 3;
}