dwds/lib/src/loaders/strategy.dart

// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:shelf/shelf.dart';

import '../debugging/metadata/provider.dart';
import '../readers/asset_reader.dart';
import '../services/expression_compiler.dart';

late LoadStrategy _globalLoadStrategy;

set globalLoadStrategy(LoadStrategy strategy) => _globalLoadStrategy = strategy;

LoadStrategy get globalLoadStrategy => _globalLoadStrategy;

abstract class LoadStrategy {
  final AssetReader _assetReader;
  final _providers = <String, MetadataProvider>{};

  LoadStrategy(this._assetReader);

  /// The ID for this strategy.
  ///
  /// This ID is passed to the injected client so that it can react accordingly.
  String get id;

  /// Module format for JS generated by the compiler.
  ///
  /// Module format is passed to the expression compilation worker during
  /// expression evaluation.
  String get moduleFormat;

  /// Module containing code for loading libraries.
  ///
  /// Used for preventing stepping into the library loading code.
  String get loadLibrariesModule;

  /// Returns a snippet of JS code that loads all Dart libraries into a `libs`
  /// variable.
  String get loadLibrariesSnippet;

  /// Returns a snippet of JS code that can be used to load a JS module.
  ///
  /// The snippet should be a reference to a function that takes a single
  /// argument which is the module name to load.
  String get loadModuleSnippet;

  /// The reload configuration for this strategy, e.g. liveReload.
  ReloadConfiguration get reloadConfiguration;

  /// Returns a snippet of JS code that initializes a `library` variable that
  /// has the actual library object in DDC for [libraryUri].
  ///
  /// In DDC we have module libraries indexed by names of the form
  /// 'packages/package/mainFile' with no .dart suffix on the file, or
  /// 'directory/packageName/mainFile', also with no .dart suffix, and relative
  /// to the serving root, normally /web within the package. These modules have
  /// a map from the URI with a Dart-specific scheme
  /// (package: or org-dartlang-app:) to the library objects. The [libraryUri]
  /// parameter should be one of these Dart-specific scheme URIs, and we set
  /// `library` the corresponding library.
  String loadLibrarySnippet(String libraryUri) => '''
   var sdkUtils = $loadModuleSnippet('dart_sdk').dart;
   var library = sdkUtils.getLibrary('$libraryUri');
   if (!library) throw 'cannot find library for $libraryUri';
  ''';

  /// Returns the bootstrap required for this [LoadStrategy].
  ///
  /// The bootstrap is appended to the end of the entry point module.
  Future<String> bootstrapFor(String entrypoint);

  /// A handler for strategy specific requests.
  ///
  /// Used as a part of the injected_handler middleware.
  Handler get handler;

  /// JS code snippet for loading the injected client script.
  String loadClientSnippet(String clientScript);

  /// Returns the module for the corresponding server path.
  ///
  /// For example:
  ///
  /// /packages/path/path.ddc.js -> packages/path/path
  ///
  Future<String?> moduleForServerPath(String entrypoint, String serverPath);

  /// Returns the server path for the provided module.
  ///
  /// For example:
  ///
  ///   web/main -> main.ddc.js
  ///
  Future<String?> serverPathForModule(String entrypoint, String module);

  /// Returns the source map path for the provided module.
  ///
  /// For example:
  ///
  ///   web/main -> main.ddc.js.map
  ///
  Future<String?> sourceMapPathForModule(String entrypoint, String module);

  /// Returns a map from module id to module info for the provided entrypoint.
  ///
  /// For example:
  ///
  ///   web/main -> {main.ddc.full.dill, main.ddc.dill}
  ///
  Future<Map<String, ModuleInfo>> moduleInfoForEntrypoint(String entrypoint);

  /// Returns the server path for the app uri.
  ///
  /// For example:
  ///
  ///   org-dartlang-app://web/main.dart -> main.dart
  ///
  /// Will return `null` if the provided uri is not
  /// an app URI.
  String? serverPathForAppUri(String appUri);

  /// Returns the [MetadataProvider] for the application located at the provided
  /// [entrypoint].
  MetadataProvider metadataProviderFor(String entrypoint) {
    if (_providers.containsKey(entrypoint)) {
      return _providers[entrypoint]!;
    } else {
      throw StateError('No metadata provider for $entrypoint');
    }
  }

  /// Initializes a [MetadataProvider] for the application located at the
  /// provided [entrypoint].
  void trackEntrypoint(String entrypoint) {
    final metadataProvider = MetadataProvider(entrypoint, _assetReader);
    _providers[metadataProvider.entrypoint] = metadataProvider;
  }
}

enum ReloadConfiguration { none, hotReload, hotRestart, liveReload }