script/tool/lib/src/license_check_command.dart

// Copyright 2017 The Chromium 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 'dart:async';

import 'package:file/file.dart';
import 'package:path/path.dart' as p;

import 'common.dart';

const Set<String> _codeFileExtensions = <String>{
  '.c',
  '.cc',
  '.cpp',
  '.dart',
  '.h',
  '.html',
  '.java',
  '.m',
  '.mm',
  '.swift',
  '.sh',
};

// Basenames without extensions of files to ignore.
const Set<String> _ignoreBasenameList = <String>{
  'flutter_export_environment',
  'GeneratedPluginRegistrant',
  'generated_plugin_registrant',
};

// File suffixes that otherwise match _codeFileExtensions to ignore.
const Set<String> _ignoreSuffixList = <String>{
  '.g.dart', // Generated API code.
  '.mocks.dart', // Generated by Mockito.
};

// Full basenames of files to ignore.
const Set<String> _ignoredFullBasenameList = <String>{
  'resource.h', // Generated by VS.
};

// Copyright and license regexes.
//
// These are intentionally very simple, since almost all source in this
// repository should be using the same license text, comment style, etc., so
// they shouldn't need to be very flexible. Complexity can be added as-needed
// on a case-by-case basis.
final RegExp _copyrightRegex =
    RegExp(r'^(?://|#|<!--) Copyright \d+,? ([^.]+)', multiLine: true);
// Non-Flutter code. When adding license regexes here, include the copyright
// info to ensure that any new additions are flagged for added scrutiny in
// review.
// -----
// Third-party code used in url_launcher_web.
final RegExp _workivaLicenseRegex = RegExp(
    r'^// Copyright 2017 Workiva Inc..*'
    '^// Licensed under the Apache License, Version 2.0',
    multiLine: true,
    dotAll: true);

// TODO(stuartmorgan): Replace this with a single string once all the copyrights
// are standardized.
final List<String> _firstPartyAuthors = <String>[
  'The Chromium Authors',
  'the Chromium project authors',
  'The Flutter Authors',
  'the Flutter project authors',
];

/// Validates that code files have copyright and license blocks.
class LicenseCheckCommand extends PluginCommand {
  /// Creates a new license check command for [packagesDir].
  LicenseCheckCommand(
    Directory packagesDir,
    FileSystem fileSystem, {
    Print print = print,
  })  : _print = print,
        super(packagesDir, fileSystem);

  final Print _print;

  @override
  final String name = 'license-check';

  @override
  final String description =
      'Ensures that all code files have copyright/license blocks.';

  @override
  Future<Null> run() async {
    Iterable<File> codeFiles = (await _getAllFiles()).where((File file) =>
        _codeFileExtensions.contains(p.extension(file.path)) &&
        !_shouldIgnoreFile(file));

    bool succeeded = await _checkLicenses(codeFiles);

    if (!succeeded) {
      throw ToolExit(1);
    }
  }

  // Creates the expected license block (without copyright) for first-party
  // code.
  String _generateLicense(String comment, {String suffix = ''}) {
    return '${comment}Use of this source code is governed by a BSD-style license that can be\n'
        '${comment}found in the LICENSE file.$suffix\n';
  }

  // Checks all license blocks for [codeFiles], returning false if any of them
  // fail validation.
  Future<bool> _checkLicenses(Iterable<File> codeFiles) async {
    final List<File> filesWithoutDetectedCopyright = <File>[];
    final List<File> filesWithoutDetectedLicense = <File>[];
    final List<File> misplacedThirdPartyFiles = <File>[];

    // Most code file types in the repository use '//' comments.
    final String defaultBsdLicenseBlock = _generateLicense('// ');
    // A few file types have a different comment structure.
    final Map<String, String> bsdLicenseBlockByExtension = <String, String>{
      '.sh': _generateLicense('# '),
      '.html': _generateLicense('', suffix: ' -->'),
    };

    for (final File file in codeFiles) {
      _print('Checking ${file.path}');
      final String content = await file.readAsString();

      final RegExpMatch copyright = _copyrightRegex.firstMatch(content);
      if (copyright == null) {
        filesWithoutDetectedCopyright.add(file);
        continue;
      }
      final String author = copyright.group(1);
      if (!_firstPartyAuthors.contains(author) &&
          !p.split(file.path).contains('third_party')) {
        misplacedThirdPartyFiles.add(file);
      }

      final String bsdLicense =
          bsdLicenseBlockByExtension[p.extension(file.path)] ??
              defaultBsdLicenseBlock;
      if (!content.contains(bsdLicense) &&
          !_workivaLicenseRegex.hasMatch(content)) {
        filesWithoutDetectedLicense.add(file);
      }
    }
    _print('\n\n');

    // Sort by path for more usable output.
    final pathCompare = (File a, File b) => a.path.compareTo(b.path);
    filesWithoutDetectedCopyright.sort(pathCompare);
    filesWithoutDetectedLicense.sort(pathCompare);
    misplacedThirdPartyFiles.sort(pathCompare);

    if (filesWithoutDetectedCopyright.isNotEmpty) {
      _print('No copyright line was found for the following files:');
      for (final File file in filesWithoutDetectedCopyright) {
        _print('  ${file.path}');
      }
      _print('Please check that they have a copyright and license block. '
          'If they do, the license check may need to be updated to recognize its '
          'format.\n');
    }

    if (filesWithoutDetectedLicense.isNotEmpty) {
      _print('No recognized license was found for the following files:');
      for (final File file in filesWithoutDetectedLicense) {
        _print('  ${file.path}');
      }
      _print('Please check that they have a license at the top of the file. '
          'If they do, the license check may need to be updated to recognize '
          'either the license or the specific format of the license '
          'block.\n');
    }

    if (misplacedThirdPartyFiles.isNotEmpty) {
      _print('The following files do not have a recognized first-party author '
          'but are not in a "third_party/" directory:');
      for (final File file in misplacedThirdPartyFiles) {
        _print('  ${file.path}');
      }
      _print('Please move these files to "third_party/".\n');
    }

    bool succeeded = filesWithoutDetectedCopyright.isEmpty &&
        filesWithoutDetectedLicense.isEmpty &&
        misplacedThirdPartyFiles.isEmpty;
    if (succeeded) {
      _print('All files passed validation!');
    }
    return succeeded;
  }

  bool _shouldIgnoreFile(File file) {
    final String path = file.path;
    return _ignoreBasenameList.contains(p.basenameWithoutExtension(path)) ||
        _ignoreSuffixList.any((String suffix) =>
            path.endsWith(suffix) ||
            _ignoredFullBasenameList.contains(p.basename(path)));
  }

  Future<List<File>> _getAllFiles() => packagesDir.parent
      .list(recursive: true, followLinks: false)
      .where((FileSystemEntity entity) => entity is File)
      .map((FileSystemEntity file) => file as File)
      .toList();
}