test_common/lib/sdk_asset_generator.dart

import 'dart:convert';
import 'dart:io';

import 'package:dwds/expression_compiler.dart';
import 'package:file/file.dart';
import 'package:file/local.dart';
import 'package:logging/logging.dart';
import 'package:path/path.dart' as p;
import 'package:test_common/test_sdk_layout.dart';

/// Generates sdk.js, sdk.map, files.

class SdkAssetGenerator {
  bool _sdkAssetsGenerated = false;
  final _logger = Logger('SdkAssetGenerator');

  final FileSystem fileSystem;
  final bool canaryFeatures;
  final ModuleFormat ddcModuleFormat;
  final bool verbose;

  late final TestSdkLayout sdkLayout;

  SdkAssetGenerator({
    this.fileSystem = const LocalFileSystem(),
    required this.sdkLayout,
    required this.canaryFeatures,
    required this.ddcModuleFormat,
    this.verbose = false,
  });

  /// Generate all SDK assets, once for the current executable run.
  Future<void> generateSdkAssets() async {
    if (!_sdkAssetsGenerated) {
      _sdkAssetsGenerated = true;

      // SDK full and outline .dill files are shipped with the SDK,
      // but the JavaScript and sourcemaps are generated by other tooling
      // i.e. flutter SDK or build_web_compilers.
      // Generate missing files for tests if needed.
      await _generateSdkJavaScript(canaryFeatures: canaryFeatures);
    }
  }

  String resolveSdkJsPath({required bool canaryFeatures}) =>
      switch (ddcModuleFormat) {
        ModuleFormat.amd => sdkLayout.amdJsPath,
        ModuleFormat.ddc => sdkLayout.ddcJsPath,
        _ => throw Exception('Unsupported DDC module format $ddcModuleFormat.'),
      };

  String resolveSdkSourcemapPath({required bool canaryFeatures}) =>
      switch (ddcModuleFormat) {
        ModuleFormat.amd => sdkLayout.amdJsMapPath,
        ModuleFormat.ddc => sdkLayout.ddcJsMapPath,
        _ => throw Exception('Unsupported DDC module format $ddcModuleFormat.'),
      };

  String resolveSdkJsFilename({required bool canaryFeatures}) =>
      switch (ddcModuleFormat) {
        ModuleFormat.amd => sdkLayout.amdJsFileName,
        ModuleFormat.ddc => sdkLayout.ddcJsFileName,
        _ => throw Exception('Unsupported DDC module format $ddcModuleFormat.'),
      };

  Future<void> _generateSdkJavaScript({required bool canaryFeatures}) async {
    Directory? outputDir;
    try {
      // Files to copy generated files to.
      final outputJsPath = resolveSdkJsPath(canaryFeatures: canaryFeatures);
      final outputJsMapPath = resolveSdkSourcemapPath(
        canaryFeatures: canaryFeatures,
      );
      final outputFullDillPath = sdkLayout.fullDillPath;

      final hasJsAsset = _exists(outputJsPath);
      final hasJsMapAsset = _exists(outputJsMapPath);
      final hasFullDillAsset = _exists(outputFullDillPath);
      final hasAssets = hasFullDillAsset && hasJsAsset && hasJsMapAsset;

      // Files already exist.
      if (hasAssets) return;

      // Generate missing files.
      outputDir = fileSystem.systemTempDirectory.createTempSync();

      // Files to generate
      final jsPath = p.join(
        outputDir.path,
        resolveSdkJsFilename(canaryFeatures: canaryFeatures),
      );
      final jsMapPath = p.setExtension(jsPath, '.js.map');

      _logger.info('Generating SDK JavaScript and sourcemap files...');

      final sdkDirectoryUri = fileSystem.directory(sdkLayout.sdkDirectory).uri;
      final args = <String>[
        'compile',
        'js-dev',
        '--compile-sdk',
        '--multi-root',
        '$sdkDirectoryUri',
        '--multi-root-scheme',
        'org-dartlang-sdk',
        '--libraries-file',
        'org-dartlang-sdk:///lib/libraries.json',
        '--modules',
        ddcModuleFormat.name,
        'dart:core',
        '-o',
        jsPath,
        if (canaryFeatures) '--canary',
      ];

      final output = <String>[];
      _logger.fine('Executing dart ${args.join(' ')}');
      final process = await Process.start(
        sdkLayout.dartPath,
        args,
        workingDirectory: sdkLayout.sdkDirectory,
      );

      process.stdout
          .transform<String>(utf8.decoder)
          .transform<String>(const LineSplitter())
          .listen((line) {
            _logger.fine(line);
            output.add(line);
          });

      process.stderr
          .transform<String>(utf8.decoder)
          .transform<String>(const LineSplitter())
          .listen((line) {
            _logger.warning(line);
            output.add(line);
          });

      await process.exitCode.then((int code) {
        if (code != 0) {
          _logger.warning('Error generating $jsPath: ${output.join('\n')}');
          throw Exception('The Dart compiler exited unexpectedly');
        }
      });

      final outputJsDir = fileSystem.directory(p.dirname(outputJsPath));
      if (!outputJsDir.existsSync()) {
        outputJsDir.createSync(recursive: true);
      }
      await _moveAndValidate(jsPath, outputJsPath);
      await _moveAndValidate(jsMapPath, outputJsMapPath);

      _logger.info('Done generating SDK JavaScript and sourcemap files.');
    } catch (e, s) {
      _logger.severe(
        'Failed to generate SDK JavaScript and sourcemap files',
        e,
        s,
      );
      rethrow;
    } finally {
      outputDir?.deleteSync(recursive: true);
    }
  }

  bool _exists(String path) => fileSystem.file(path).existsSync();
  void _delete(String path) => fileSystem.file(path).deleteSync();

  Future<void> _moveAndValidate(String from, String to) async {
    _logger.fine('Renaming $from to $to');

    if (!_exists(from)) {
      _logger.severe('Failed to generate SDK asset at $to');
      throw Exception('File "$from" does not exist.');
    }

    if (_exists(to)) _delete(to);
    await fileSystem.file(from).rename(to);

    if (!_exists(to)) {
      _logger.severe('Failed to generate SDK asset at $to');
      throw Exception('File "$to" does not exist.');
    }
  }
}