// Copyright 2014 The Flutter Authors. 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:meta/meta.dart';

import '../base/deferred_component.dart';
import '../base/file_system.dart';
import '../base/logger.dart';
import '../convert.dart';
import '../dart/pub.dart';
import '../flutter_manifest.dart';
import '../project.dart';
import 'preview_manifest.dart';

/// Builds and manages the pubspec for the widget preview scaffold
class PreviewPubspecBuilder {
  const PreviewPubspecBuilder({
    required this.logger,
    required this.verbose,
    required this.offline,
    required this.rootProject,
    required this.previewManifest,
  });

  final Logger logger;
  final bool verbose;

  /// Set to true if pub should operate in offline mode.
  final bool offline;

  /// The Flutter project that contains widget previews.
  final FlutterProject rootProject;

  /// Details about the current state of the widget preview scaffold project.
  final PreviewManifest previewManifest;

  /// Adds dependencies on:
  ///   - dtd, which is used to connect to the Dart Tooling Daemon to establish communication
  ///     with other developer tools.
  ///   - flutter_lints, which is referenced by the analysis_options.yaml generated by the 'app'
  ///     template.
  ///   - google_fonts, which is used for the Roboto Mono font.
  ///   - json_rpc_2, which is used to handle errors thrown by package:dtd
  ///   - path, which is used to normalize and compare paths.
  ///   - stack_trace, which is used to generate terse stack traces for displaying errors thrown
  ///     by widgets being previewed.
  ///   - url_launcher, which is used to open a browser to the preview documentation.
  ///   - web, which is used to access query parameters provided by the IDE.
  ///   - webview_flutter, webview_flutter_web, which is used to embed DevTools in the previewer.
  static const _kWidgetPreviewScaffoldDeps = <String>[
    'dtd',
    'flutter_lints',
    'google_fonts',
    'json_rpc_2',
    'path',
    'stack_trace',
    'url_launcher',
    'web',
    'webview_flutter',
    'webview_flutter_web',
  ];

  /// Maps asset URIs to absolute paths for the widget preview project to
  /// include.
  @visibleForTesting
  Uri transformAssetUri(Uri uri) {
    // Assets provided by packages always start with 'packages' and do not
    // require their URIs to be updated.
    if (uri.path.startsWith('packages')) {
      return uri;
    }
    // Otherwise, the asset is contained within the root project and needs
    // to be referenced from the widget preview scaffold project's pubspec.
    final Directory rootProjectDir = rootProject.directory;
    final FileSystem fs = rootProjectDir.fileSystem;
    return Uri(path: fs.path.join(rootProjectDir.absolute.path, uri.path));
  }

  @visibleForTesting
  AssetsEntry transformAssetsEntry(AssetsEntry asset) {
    return AssetsEntry(
      uri: transformAssetUri(asset.uri),
      flavors: asset.flavors,
      platforms: asset.platforms,
      transformers: asset.transformers,
    );
  }

  @visibleForTesting
  DeferredComponent transformDeferredComponent(DeferredComponent component) {
    return DeferredComponent(
      name: component.name,
      // TODO(bkonyi): verify these library paths are always package: paths from the parent project.
      libraries: component.libraries,
      assets: component.assets.map(transformAssetsEntry).toList(),
    );
  }

  PubOutputMode get _outputMode => verbose ? PubOutputMode.all : PubOutputMode.failuresOnly;

  Future<void> populatePreviewPubspec({
    required FlutterProject rootProject,
    String? updatedPubspecPath,
  }) async {
    final FlutterProject widgetPreviewScaffoldProject = rootProject.widgetPreviewScaffoldProject;

    // Overwrite the pubspec for the preview scaffold project to include assets
    // from the root project. Dependencies are removed as part of this operation
    // and they need to be added back below.
    widgetPreviewScaffoldProject.replacePubspec(
      buildPubspec(
        rootProject: rootProject,
        widgetPreviewManifest: widgetPreviewScaffoldProject.manifest,
      ),
    );

    // Adds a path dependency on the parent project so previews can be
    // imported directly into the preview scaffold.
    const pubAdd = 'add';
    final workspacePackages = <String, String>{
      for (final FlutterProject project in <FlutterProject>[
        rootProject,
        ...rootProject.workspaceProjects,
      ])
        // Don't try and depend on unnamed projects.
        if (project.manifest.appName.isNotEmpty)
          // Use `json.encode` to handle escapes correctly.
          project.manifest.appName: json.encode(<String, Object?>{
            'path': widgetPreviewScaffoldProject.directory.fileSystem.path.absolute(
              project.directory.path,
            ),
          }),
    };

    await pub.interactively(
      <String>[
        pubAdd,
        if (offline) '--offline',
        '--directory',
        widgetPreviewScaffoldProject.directory.path,
        // Ensure the path using POSIX separators, otherwise the "path_not_posix" check will fail.
        for (final MapEntry<String, String>(:String key, :String value)
            in workspacePackages.entries) ...[
          '$key:$value',
          // Add dependency overrides to handle "hosted" dependencies on other projects within the
          // workspace. These dependencies take the form of "my_workspace_project: " in the
          // pubspec's dependency list. See https://github.com/flutter/flutter/issues/176018.
          'override:$key:$value',
        ],
      ],
      context: PubContext.pubAdd,
      command: pubAdd,
      touchesPackageConfig: true,
      outputMode: _outputMode,
    );

    // Adds dependencies required by the widget preview scaffolding.
    await pub.interactively(
      <String>[
        pubAdd,
        if (offline) '--offline',
        '--directory',
        widgetPreviewScaffoldProject.directory.path,
        ..._kWidgetPreviewScaffoldDeps,
      ],
      context: PubContext.pubAdd,
      command: pubAdd,
      touchesPackageConfig: true,
      outputMode: _outputMode,
    );

    await generatePackageConfig(widgetPreviewScaffoldProject: widgetPreviewScaffoldProject);
    previewManifest.updatePubspecHash(updatedPubspecPath: updatedPubspecPath);
  }

  /// Generates `widget_preview_scaffold/.dart_tool/package_config.json`.
  Future<void> generatePackageConfig({required FlutterProject widgetPreviewScaffoldProject}) async {
    // Generate package_config.json.
    await pub.get(
      context: PubContext.create,
      project: widgetPreviewScaffoldProject,
      offline: offline,
      outputMode: _outputMode,
    );
  }

  void onPubspecChangeDetected(String path) {
    // TODO(bkonyi): trigger hot reload or restart?
    logger.printStatus('Changes to $path detected.');
    populatePreviewPubspec(rootProject: rootProject, updatedPubspecPath: path);
  }

  @visibleForTesting
  FlutterManifest buildPubspec({
    required FlutterProject rootProject,
    required FlutterManifest widgetPreviewManifest,
  }) {
    final deferredComponents = <DeferredComponent>[
      ...?rootProject.manifest.deferredComponents?.map(transformDeferredComponent),
      for (final FlutterProject project in rootProject.workspaceProjects)
        ...?project.manifest.deferredComponents?.map(transformDeferredComponent),
    ];

    // Copy the manifest with dependencies removed to handle situations where a package or
    // workspace name has changed. We'll re-add them later.
    return widgetPreviewManifest.copyWith(
      logger: logger,
      deferredComponents: deferredComponents,
      removeDependencies: true,
    );
  }
}