halkyon/packages/halkyon_app/lib/src/app/app_scope.dart

import 'package:flutter/widgets.dart';
import 'package:halkyon_app/src/auth/data/auth_repository.dart';
import 'package:halkyon_app/src/auth/data/signed_out_mark.dart';
import 'package:halkyon_app/src/auth/model/auth_status.dart';
import 'package:halkyon_app/src/files/file_saver.dart';
import 'package:halkyon_app/src/password/data/password_repository.dart';

/// What can be closed once it is no longer needed: an app's dependencies on
/// an instance, or a person's.
abstract interface class Disposable() {
  /// Closes it; nothing of it is used afterwards.
  Future<void> dispose();
}

/// What this package needs of an app's dependencies on one instance (its
/// composition root), which `InstanceGate` opens for the instance in use and
/// [AppScope] hands down. An app's own class implements it beside its
/// features' repositories.
abstract interface class AppDependencies<P extends Disposable>()
    implements Disposable {
  /// The instance's name as people know it (its host), for messages about
  /// it.
  String get serverName;

  /// Who is signed in, and signing in and out.
  AuthRepository get auth;

  /// Whether the person here signed out, so the app asks how to start.
  SignedOutMark get signedOut;

  /// Signing in with a password and TOTP, signing up, getting back in, and
  /// what keeps an account (ADR 0017).
  PasswordRepository get passwords;

  /// Keeps a file the app made where the person chooses (a recovery phrase,
  /// recovery codes, an app's exports).
  FileSaver get fileSaver;

  /// Where the source of what the instance runs is, as it names it (its
  /// basics, halkyon_base's): both licences require offering it to the
  /// people who use the instance, which About does (`showAppAbout`).
  Future<String> sourceCodeUrl();

  /// Opens the dependencies of [person], once the previous person's have
  /// closed; `PersonScope` disposes them when the person goes.
  Future<P> openPerson(SignedIn person);
}

/// Hands an app's [dependencies] on the instance in use down the widget
/// tree; `InstanceGate` puts it above the app.
class const AppScope({
  /// The app's dependencies.
  required final AppDependencies<Disposable> dependencies,
  required super.child,
  super.key,
}) extends InheritedWidget {
  /// The dependencies above [context], as the app's own type [D]
  /// (`AppScope.of<Dependencies>(context)`), or as [AppDependencies] where
  /// that is all that is needed.
  ///
  /// Doesn't register [context] for rebuilds: the dependencies of one app run
  /// never change.
  static D of<D extends AppDependencies<Disposable>>(BuildContext context) {
    final scope = context.getInheritedWidgetOfExactType<AppScope>();
    assert(scope != null, 'No AppScope above this widget.');
    return scope!.dependencies as D;
  }

  @override
  bool updateShouldNotify(AppScope oldWidget) =>
      dependencies != oldWidget.dependencies;
}