// Copyright (c) 2016, 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 'dart:convert';
import 'dart:typed_data';

import 'package:analyzer/dart/analysis/declared_variables.dart';
import 'package:analyzer/dart/analysis/features.dart';
import 'package:analyzer/file_system/file_system.dart';
import 'package:analyzer/src/context/packages.dart';
import 'package:analyzer/src/dart/analysis/byte_store.dart';
import 'package:analyzer/src/dart/analysis/experiments.dart';
import 'package:analyzer/src/dart/analysis/feature_set_provider.dart';
import 'package:analyzer/src/dart/analysis/file_content_cache.dart';
import 'package:analyzer/src/dart/analysis/file_state.dart';
import 'package:analyzer/src/dart/analysis/library_graph.dart';
import 'package:analyzer/src/dart/analysis/performance_logger.dart';
import 'package:analyzer/src/generated/engine.dart'
    show AnalysisOptions, AnalysisOptionsImpl;
import 'package:analyzer/src/generated/source.dart';
import 'package:analyzer/src/source/package_map_resolver.dart';
import 'package:analyzer/src/test_utilities/mock_sdk.dart';
import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
import 'package:analyzer/src/util/either.dart';
import 'package:analyzer/src/workspace/basic.dart';
import 'package:convert/convert.dart';
import 'package:crypto/crypto.dart';
import 'package:test/test.dart';
import 'package:test_reflective_loader/test_reflective_loader.dart';

main() {
  defineReflectiveSuite(() {
    defineReflectiveTests(FileSystemStateTest);
  });
}

@reflectiveTest
class FileSystemStateTest with ResourceProviderMixin {
  late final MockSdk sdk;

  final ByteStore byteStore = MemoryByteStore();
  final FileContentOverlay contentOverlay = FileContentOverlay();

  final StringBuffer logBuffer = StringBuffer();
  final _GeneratedUriResolverMock generatedUriResolver =
      _GeneratedUriResolverMock();
  late final SourceFactory sourceFactory;
  late final PerformanceLog logger;

  late final FileSystemState fileSystemState;

  void setUp() {
    logger = PerformanceLog(logBuffer);
    sdk = MockSdk(resourceProvider: resourceProvider);

    var packageMap = <String, List<Folder>>{
      'aaa': [getFolder('/aaa/lib')],
      'bbb': [getFolder('/bbb/lib')],
    };

    var workspace = BasicWorkspace.find(
      resourceProvider,
      packageMap,
      convertPath('/test'),
    );

    sourceFactory = SourceFactory([
      DartUriResolver(sdk),
      generatedUriResolver,
      PackageMapUriResolver(resourceProvider, packageMap),
      ResourceUriResolver(resourceProvider)
    ]);

    AnalysisOptions analysisOptions = AnalysisOptionsImpl();
    var featureSetProvider = FeatureSetProvider.build(
      sourceFactory: sourceFactory,
      resourceProvider: resourceProvider,
      packages: Packages.empty,
      packageDefaultFeatureSet: FeatureSet.latestLanguageVersion(),
      nonPackageDefaultLanguageVersion: ExperimentStatus.currentVersion,
      nonPackageDefaultFeatureSet: FeatureSet.latestLanguageVersion(),
    );
    fileSystemState = FileSystemState(
      logger,
      byteStore,
      resourceProvider,
      'contextName',
      sourceFactory,
      workspace,
      analysisOptions,
      DeclaredVariables(),
      Uint32List(0),
      Uint32List(0),
      featureSetProvider,
      fileContentCache: FileContentCache.ephemeral(resourceProvider),
    );
  }

  test_definedClassMemberNames() {
    String path = convertPath('/aaa/lib/a.dart');
    newFile(path, content: r'''
class A {
  int a, b;
  A();
  A.c();
  d() {}
  get e => null;
  set f(_) {}
}
class B {
  g() {}
}
''');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.definedClassMemberNames,
        unorderedEquals(['a', 'b', 'd', 'e', 'f', 'g']));
  }

  test_definedTopLevelNames() {
    String path = convertPath('/aaa/lib/a.dart');
    newFile(path, content: r'''
class A {}
class B = Object with A;
typedef C();
D() {}
get E => null;
set F(_) {}
var G, H;
''');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.definedTopLevelNames,
        unorderedEquals(['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H']));
  }

  test_getFileForPath_doesNotExist() {
    String path = convertPath('/aaa/lib/a.dart');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.path, path);
    expect(file.uri, Uri.parse('package:aaa/a.dart'));
    expect(file.content, '');
    expect(file.contentHash, _md5(''));
    expect(_excludeSdk(file.importedFiles), isEmpty);
    expect(file.exportedFiles, isEmpty);
    expect(file.partedFiles, isEmpty);
    expect(file.libraryFiles, [file]);
    expect(_excludeSdk(file.directReferencedFiles), isEmpty);
    expect(file.isPart, isFalse);
    expect(file.library, isNull);
    expect(file.unlinked2, isNotNull);
    expect(file.unlinked2.exports, isEmpty);
  }

  test_getFileForPath_emptyUri() {
    String path = convertPath('/test.dart');
    newFile(path, content: r'''
import '';
export '';
part '';
''');

    FileState file = fileSystemState.getFileForPath(path);
    _assertIsUnresolvedFile(file.importedFiles[0]);
    _assertIsUnresolvedFile(file.exportedFiles[0]);
    _assertIsUnresolvedFile(file.partedFiles[0]);
  }

  test_getFileForPath_hasLibraryDirective_hasPartOfDirective() {
    String a = convertPath('/test/lib/a.dart');
    newFile(a, content: r'''
library L;
part of L;
''');
    FileState file = fileSystemState.getFileForPath(a);
    expect(file.isPart, isFalse);
  }

  test_getFileForPath_invalidUri() {
    String a = convertPath('/aaa/lib/a.dart');
    String a1 = convertPath('/aaa/lib/a1.dart');
    String a2 = convertPath('/aaa/lib/a2.dart');
    String a3 = convertPath('/aaa/lib/a3.dart');
    String content_a1 = r'''
import 'package:aaa/a1.dart';
import ':[invalid uri]';

export 'package:aaa/a2.dart';
export ':[invalid uri]';

part 'a3.dart';
part ':[invalid uri]';
''';
    newFile(a, content: content_a1);

    FileState file = fileSystemState.getFileForPath(a);

    expect(_excludeSdk(file.importedFiles), hasLength(2));
    expect(file.importedFiles[0]!.path, a1);
    expect(file.importedFiles[0]!.uri, Uri.parse('package:aaa/a1.dart'));
    expect(file.importedFiles[0]!.source, isNotNull);
    _assertIsUnresolvedFile(file.importedFiles[1]);

    expect(_excludeSdk(file.exportedFiles), hasLength(2));
    expect(file.exportedFiles[0]!.path, a2);
    expect(file.exportedFiles[0]!.uri, Uri.parse('package:aaa/a2.dart'));
    expect(file.exportedFiles[0]!.source, isNotNull);
    _assertIsUnresolvedFile(file.exportedFiles[1]);

    expect(_excludeSdk(file.partedFiles), hasLength(2));
    expect(file.partedFiles[0]!.path, a3);
    expect(file.partedFiles[0]!.uri, Uri.parse('package:aaa/a3.dart'));
    expect(file.partedFiles[0]!.source, isNotNull);
    _assertIsUnresolvedFile(file.partedFiles[1]);
  }

  test_getFileForPath_library() {
    String a1 = convertPath('/aaa/lib/a1.dart');
    String a2 = convertPath('/aaa/lib/a2.dart');
    String a3 = convertPath('/aaa/lib/a3.dart');
    String a4 = convertPath('/aaa/lib/a4.dart');
    String b1 = convertPath('/bbb/lib/b1.dart');
    String b2 = convertPath('/bbb/lib/b2.dart');
    String content_a1 = r'''
import 'package:aaa/a2.dart';
import 'package:bbb/b1.dart';
export 'package:bbb/b2.dart';
export 'package:aaa/a3.dart';
part 'a4.dart';

class A1 {}
''';
    newFile(a1, content: content_a1);

    FileState file = fileSystemState.getFileForPath(a1);
    expect(file.path, a1);
    expect(file.content, content_a1);
    expect(file.contentHash, _md5(content_a1));

    expect(file.isPart, isFalse);
    expect(file.library, isNull);
    expect(file.unlinked2, isNotNull);

    expect(_excludeSdk(file.importedFiles), hasLength(2));
    expect(file.importedFiles[0]!.path, a2);
    expect(file.importedFiles[0]!.uri, Uri.parse('package:aaa/a2.dart'));
    expect(file.importedFiles[0]!.source, isNotNull);
    expect(file.importedFiles[1]!.path, b1);
    expect(file.importedFiles[1]!.uri, Uri.parse('package:bbb/b1.dart'));
    expect(file.importedFiles[1]!.source, isNotNull);

    expect(file.exportedFiles, hasLength(2));
    expect(file.exportedFiles[0]!.path, b2);
    expect(file.exportedFiles[0]!.uri, Uri.parse('package:bbb/b2.dart'));
    expect(file.exportedFiles[0]!.source, isNotNull);
    expect(file.exportedFiles[1]!.path, a3);
    expect(file.exportedFiles[1]!.uri, Uri.parse('package:aaa/a3.dart'));
    expect(file.exportedFiles[1]!.source, isNotNull);

    expect(file.partedFiles, hasLength(1));
    expect(file.partedFiles[0]!.path, a4);
    expect(file.partedFiles[0]!.uri, Uri.parse('package:aaa/a4.dart'));

    expect(file.libraryFiles, [file, file.partedFiles[0]]);

    expect(_excludeSdk(file.directReferencedFiles), hasLength(5));

    expect(fileSystemState.getFilesForPath(a1), [file]);
  }

  test_getFileForPath_onlyDartFiles() {
    String not_dart = convertPath('/test/lib/not_dart.txt');
    String a = convertPath('/test/lib/a.dart');
    String b = convertPath('/test/lib/b.dart');
    String c = convertPath('/test/lib/c.dart');
    String d = convertPath('/test/lib/d.dart');
    newFile(a, content: r'''
library lib;
import 'dart:math';
import 'b.dart';
import 'not_dart.txt';
export 'c.dart';
export 'not_dart.txt';
part 'd.dart';
part 'not_dart.txt';
''');
    FileState file = fileSystemState.getFileForPath(a);
    expect(_excludeSdk(file.importedFiles).map((f) => f!.path), [b, not_dart]);
    expect(file.exportedFiles.map((f) => f!.path), [c, not_dart]);
    expect(file.partedFiles.map((f) => f!.path), [d, not_dart]);
    expect(_excludeSdk(fileSystemState.knownFilePaths),
        unorderedEquals([a, b, c, d, not_dart]));
  }

  test_getFileForPath_part() {
    String a1 = convertPath('/aaa/lib/a1.dart');
    String a2 = convertPath('/aaa/lib/a2.dart');
    newFile(a1, content: r'''
library a1;
part 'a2.dart';
''');
    newFile(a2, content: r'''
part of a1;
class A2 {}
''');

    FileState file_a2 = fileSystemState.getFileForPath(a2);
    expect(file_a2.path, a2);
    expect(file_a2.uri, Uri.parse('package:aaa/a2.dart'));

    expect(file_a2.unlinked2, isNotNull);

    expect(_excludeSdk(file_a2.importedFiles), isEmpty);
    expect(file_a2.exportedFiles, isEmpty);
    expect(file_a2.partedFiles, isEmpty);
    expect(_excludeSdk(file_a2.directReferencedFiles), isEmpty);

    // The library is not known yet.
    expect(file_a2.isPart, isTrue);
    expect(file_a2.library, isNull);

    // Ask for the library.
    FileState file_a1 = fileSystemState.getFileForPath(a1);
    expect(file_a1.partedFiles, hasLength(1));
    expect(file_a1.partedFiles[0], same(file_a2));
    expect(
        _excludeSdk(file_a1.directReferencedFiles), unorderedEquals([file_a2]));

    // Now the part knows its library.
    expect(file_a2.library, same(file_a1));

    // Now update the library, and refresh its file.
    // The 'a2.dart' is not referenced anymore.
    // So the part file does not have the library anymore.
    newFile(a1, content: r'''
library a1;
part 'not-a2.dart';
''');
    file_a1.refresh();
    expect(file_a2.library, isNull);
  }

  test_getFileForPath_samePath() {
    String path = convertPath('/aaa/lib/a.dart');
    FileState file1 = fileSystemState.getFileForPath(path);
    FileState file2 = fileSystemState.getFileForPath(path);
    expect(file2, same(file1));
  }

  test_getFileForUri_invalidUri() {
    var uri = Uri.parse('package:x');
    fileSystemState.getFileForUri(uri).map(
      (file) {
        expect(file, isNull);
      },
      (_) {
        fail('Expected null.');
      },
    );
  }

  test_getFileForUri_packageVsFileUri() {
    String path = convertPath('/aaa/lib/a.dart');
    var packageUri = Uri.parse('package:aaa/a.dart');
    var fileUri = toUri(path);

    // The files with `package:` and `file:` URIs are different.
    var filePackageUri = fileSystemState.getFileForUri(packageUri).asFileState;
    var fileFileUri = fileSystemState.getFileForUri(fileUri).asFileState;
    expect(filePackageUri, isNot(same(fileFileUri)));

    expect(filePackageUri.path, path);
    expect(filePackageUri.uri, packageUri);

    expect(fileFileUri.path, path);
    expect(fileFileUri.uri, fileUri);

    // The file with the `package:` style URI is canonical, and is the first.
    var files = fileSystemState.getFilesForPath(path);
    expect(files, [filePackageUri, fileFileUri]);
  }

  test_getFilesSubtypingName() {
    String a = convertPath('/a.dart');
    String b = convertPath('/b.dart');

    newFile(a, content: r'''
class A {}
class B extends A {}
''');
    newFile(b, content: r'''
class A {}
class D implements A {}
''');

    FileState aFile = fileSystemState.getFileForPath(a);
    FileState bFile = fileSystemState.getFileForPath(b);

    expect(
      fileSystemState.getFilesSubtypingName('A'),
      unorderedEquals([aFile, bFile]),
    );

    // Change b.dart so that it does not subtype A.
    newFile(b, content: r'''
class C {}
class D implements C {}
''');
    bFile.refresh();
    expect(
      fileSystemState.getFilesSubtypingName('A'),
      unorderedEquals([aFile]),
    );
    expect(
      fileSystemState.getFilesSubtypingName('C'),
      unorderedEquals([bFile]),
    );
  }

  test_hasUri() {
    Uri uri = Uri.parse('package:aaa/foo.dart');
    String templatePath = convertPath('/aaa/lib/foo.dart');
    String generatedPath = convertPath('/generated/aaa/lib/foo.dart');

    Source generatedSource = _SourceMock(generatedPath, uri);

    generatedUriResolver.resolveAbsoluteFunction = (uri) => generatedSource;

    expect(fileSystemState.hasUri(templatePath), isFalse);
    expect(fileSystemState.hasUri(generatedPath), isTrue);
  }

  test_libraryCycle() {
    String pa = convertPath('/aaa/lib/a.dart');
    String pb = convertPath('/aaa/lib/b.dart');
    String pc = convertPath('/aaa/lib/c.dart');
    String pd = convertPath('/aaa/lib/d.dart');

    FileState fa = fileSystemState.getFileForPath(pa);
    FileState fb = fileSystemState.getFileForPath(pb);
    FileState fc = fileSystemState.getFileForPath(pc);
    FileState fd = fileSystemState.getFileForPath(pd);

    // Compute library cycles for all files.
    fa.libraryCycle;
    fb.libraryCycle;
    fc.libraryCycle;
    fd.libraryCycle;
    _assertFilesWithoutLibraryCycle([]);

    // No imports, so just a single file.
    newFile(pa);
    _assertLibraryCycle(fa, [fa], []);

    // Import b.dart into a.dart, two files now.
    newFile(pa, content: "import 'b.dart';");
    fa.refresh();
    _assertFilesWithoutLibraryCycle([fa]);
    _assertLibraryCycle(fa, [fa], [fb.libraryCycle]);

    // Update b.dart so that it imports c.dart now.
    newFile(pb, content: "import 'c.dart';");
    fb.refresh();
    _assertFilesWithoutLibraryCycle([fa, fb]);
    _assertLibraryCycle(fa, [fa], [fb.libraryCycle]);
    _assertLibraryCycle(fb, [fb], [fc.libraryCycle]);
    _assertFilesWithoutLibraryCycle([]);

    // Update b.dart so that it exports d.dart instead.
    newFile(pb, content: "export 'd.dart';");
    fb.refresh();
    _assertFilesWithoutLibraryCycle([fa, fb]);
    _assertLibraryCycle(fa, [fa], [fb.libraryCycle]);
    _assertLibraryCycle(fb, [fb], [fd.libraryCycle]);
    _assertFilesWithoutLibraryCycle([]);

    // Update a.dart so that it does not import b.dart anymore.
    newFile(pa);
    fa.refresh();
    _assertFilesWithoutLibraryCycle([fa]);
    _assertLibraryCycle(fa, [fa], []);
  }

  test_libraryCycle_cycle() {
    String pa = convertPath('/aaa/lib/a.dart');
    String pb = convertPath('/aaa/lib/b.dart');

    newFile(pa, content: "import 'b.dart';");
    newFile(pb, content: "import 'a.dart';");

    FileState fa = fileSystemState.getFileForPath(pa);
    FileState fb = fileSystemState.getFileForPath(pb);

    // Compute library cycles for all files.
    fa.libraryCycle;
    fb.libraryCycle;
    _assertFilesWithoutLibraryCycle([]);

    // It's a cycle.
    _assertLibraryCycle(fa, [fa, fb], []);
    _assertLibraryCycle(fb, [fa, fb], []);

    // Update a.dart so that it does not import b.dart anymore.
    newFile(pa);
    fa.refresh();
    _assertFilesWithoutLibraryCycle([fa, fb]);
    _assertLibraryCycle(fa, [fa], []);
    _assertLibraryCycle(fb, [fb], [fa.libraryCycle]);
  }

  test_libraryCycle_invalidPart_withPart() {
    var pa = convertPath('/aaa/lib/a.dart');

    newFile(pa, content: r'''
part of lib;
part 'a.dart';
''');

    var fa = fileSystemState.getFileForPath(pa);

    _assertLibraryCycle(fa, [fa], []);
  }

  test_referencedNames() {
    String path = convertPath('/aaa/lib/a.dart');
    newFile(path, content: r'''
A foo(B p) {
  foo(null);
  C c = new C(p);
  return c;
}
''');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.referencedNames, unorderedEquals(['A', 'B', 'C']));
  }

  test_refresh_differentApiSignature() {
    String path = convertPath('/aaa/lib/a.dart');
    newFile(path, content: r'''
class A {}
''');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.definedTopLevelNames, contains('A'));
    List<int> signature = file.apiSignature;

    // Update the resource and refresh the file state.
    newFile(path, content: r'''
class B {}
''');
    bool apiSignatureChanged = file.refresh();
    expect(apiSignatureChanged, isTrue);

    expect(file.definedTopLevelNames, contains('B'));
    expect(file.apiSignature, isNot(signature));
  }

  test_refresh_sameApiSignature() {
    String path = convertPath('/aaa/lib/a.dart');
    newFile(path, content: r'''
class C {
  foo() {
    print(111);
  }
}
''');
    FileState file = fileSystemState.getFileForPath(path);
    List<int> signature = file.apiSignature;

    // Update the resource and refresh the file state.
    newFile(path, content: r'''
class C {
  foo() {
    print(222);
  }
}
''');
    bool apiSignatureChanged = file.refresh();
    expect(apiSignatureChanged, isFalse);

    expect(file.apiSignature, signature);
  }

  test_store_zeroLengthUnlinked() {
    String path = convertPath('/test.dart');
    newFile(path, content: 'class A {}');

    // Get the file, prepare unlinked.
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.unlinked2, isNotNull);

    // Make the unlinked unit in the byte store zero-length, damaged.
    byteStore.put(file.test.unlinkedKey, <int>[]);

    // Refresh should not fail, zero bytes in the store are ignored.
    file.refresh();
    expect(file.unlinked2, isNotNull);
  }

  test_subtypedNames() {
    String path = convertPath('/test.dart');
    newFile(path, content: r'''
class X extends A {}
class Y extends A with B {}
class Z implements C, D {}
''');
    FileState file = fileSystemState.getFileForPath(path);
    expect(file.referencedNames, unorderedEquals(['A', 'B', 'C', 'D']));
  }

  test_transitiveSignature() {
    String pa = convertPath('/aaa/lib/a.dart');
    String pb = convertPath('/aaa/lib/b.dart');
    String pc = convertPath('/aaa/lib/c.dart');
    String pd = convertPath('/aaa/lib/d.dart');

    newFile(pa, content: "class A {}");
    newFile(pb, content: "import 'a.dart';");
    newFile(pc, content: "import 'b.dart';");
    newFile(pd, content: "class D {}");

    FileState fa = fileSystemState.getFileForPath(pa);
    FileState fb = fileSystemState.getFileForPath(pb);
    FileState fc = fileSystemState.getFileForPath(pc);
    FileState fd = fileSystemState.getFileForPath(pd);

    // Compute transitive closures for all files.
    // This implicitly computes library cycles.
    expect(fa.transitiveSignature, isNotNull);
    expect(fb.transitiveSignature, isNotNull);
    expect(fc.transitiveSignature, isNotNull);
    expect(fd.transitiveSignature, isNotNull);
    _assertFilesWithoutLibraryCycle([]);

    // Make an update to a.dart that does not change its API signature.
    // All library cycles are still valid.
    newFile(pa, content: "class A {} // the same API signature");
    fa.refresh();
    _assertFilesWithoutLibraryCycle([]);

    // Change a.dart API signature.
    // This flushes signatures of b.dart and c.dart, but d.dart is still OK.
    newFile(pa, content: "class A2 {}");
    fa.refresh();
    _assertFilesWithoutLibraryCycle([fa, fb, fc]);
  }

  test_transitiveSignature_part() {
    var aPath = convertPath('/test/lib/a.dart');
    var bPath = convertPath('/test/lib/b.dart');

    newFile(aPath, content: r'''
part 'b.dart';
''');
    newFile(bPath, content: '''
part of 'a.dart';
''');

    var aFile = fileSystemState.getFileForPath(aPath);
    var bFile = fileSystemState.getFileForPath(bPath);

    var aSignature = aFile.transitiveSignature;
    var bSignature = bFile.transitiveSignature;

    // It is not valid to use a part as a library, and so ask its signature.
    // But when this happens, we should compute the transitive signature anyway.
    // And it should not be the signature of the containing library.
    expect(bSignature, isNot(aSignature));
  }

  void _assertFilesWithoutLibraryCycle(List<FileState> expected) {
    var actual = fileSystemState.test.filesWithoutLibraryCycle;
    expect(_excludeSdk(actual), unorderedEquals(expected));
  }

  void _assertIsUnresolvedFile(FileState? file) {
    expect(file, isNull);
  }

  void _assertLibraryCycle(
    FileState file,
    List<FileState> expectedLibraries,
    List<LibraryCycle> expectedDirectDependencies,
  ) {
    expect(file.libraryCycle.libraries, unorderedEquals(expectedLibraries));
    expect(
      _excludeSdk(file.libraryCycle.directDependencies),
      unorderedEquals(expectedDirectDependencies),
    );
  }

  List<T> _excludeSdk<T>(Iterable<T> files) {
    return files.where((file) {
      if (file is LibraryCycle) {
        return !file.libraries.any((file) => file.uri.isScheme('dart'));
      } else if (file is FileState) {
        return file.uri.scheme != 'dart';
      } else if (file == null) {
        return true;
      } else {
        return !(file as String).startsWith(convertPath('/sdk'));
      }
    }).toList();
  }

  static String _md5(String content) {
    return hex.encode(md5.convert(utf8.encode(content)).bytes);
  }
}

class _GeneratedUriResolverMock implements UriResolver {
  Source? Function(Uri)? resolveAbsoluteFunction;

  Uri? Function(Source)? restoreAbsoluteFunction;

  @override
  noSuchMethod(Invocation invocation) {
    throw StateError('Unexpected invocation of ${invocation.memberName}');
  }

  @override
  Source? resolveAbsolute(Uri uri) {
    if (resolveAbsoluteFunction != null) {
      return resolveAbsoluteFunction!(uri);
    }
    return null;
  }

  @override
  Uri? restoreAbsolute(Source source) {
    if (restoreAbsoluteFunction != null) {
      return restoreAbsoluteFunction!(source);
    }
    return null;
  }
}

class _SourceMock implements Source {
  @override
  final String fullName;

  @override
  final Uri uri;

  _SourceMock(this.fullName, this.uri);

  @override
  noSuchMethod(Invocation invocation) {
    throw StateError('Unexpected invocation of ${invocation.memberName}');
  }
}

extension on Either2<FileState?, ExternalLibrary> {
  FileState get asFileState {
    return map(
      (file) => file!,
      (_) => fail('Expected a file'),
    );
  }
}