// Copyright (c) 2018, 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:async';
import 'dart:convert';

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

import '../io.dart';
import '../validator.dart';

final _changelogRegexp = RegExp(r'^CHANGELOG($|\.)', caseSensitive: false);

/// A validator that validates a package's changelog file.
class ChangelogValidator extends Validator {
  @override
  Future<void> validate() async {
    final changelog = filesBeneath('.', recursive: false).firstWhereOrNull(
      (entry) => p.basename(entry).contains(_changelogRegexp),
    );

    if (changelog == null) {
      warnings.add('Please add a `CHANGELOG.md` to your package. '
          'See https://dart.dev/tools/pub/publishing#important-files.');
      return;
    }

    if (p.basename(changelog) != 'CHANGELOG.md') {
      warnings.add('Please consider renaming $changelog to `CHANGELOG.md`. '
          'See https://dart.dev/tools/pub/publishing#important-files.');
    }

    final bytes = readBinaryFile(changelog);
    String contents;

    try {
      // utf8.decode doesn't allow invalid UTF-8.
      contents = utf8.decode(bytes);
    } on FormatException catch (_) {
      warnings.add('$changelog contains invalid UTF-8.\n'
          'This will cause it to be displayed incorrectly on '
          'the Pub site (https://pub.dev).');
      // Failed to decode contents, so there's nothing else to check.
      return;
    }

    final version = package.pubspec.version.toString();

    if (!contents.contains(version)) {
      warnings.add("$changelog doesn't mention current version ($version).\n"
          'Consider updating it with notes on this version prior to '
          'publication.');
    }
  }
}