// Copyright 2013 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 'dart:async';

import 'package:file/file.dart';
import 'package:git/git.dart';
import 'package:http/http.dart' as http;
import 'package:meta/meta.dart';
import 'package:pub_semver/pub_semver.dart';
import 'package:pubspec_parse/pubspec_parse.dart';

import 'common.dart';

/// Categories of version change types.
enum NextVersionType {
  /// A breaking change.
  BREAKING_MAJOR,

  /// A minor change (e.g., added feature).
  MINOR,

  /// A bugfix change.
  PATCH,

  /// The release of an existing prerelease version.
  RELEASE,
}

/// Returns the set of allowed next versions, with their change type, for
/// [masterVersion].
///
/// [headVerison] is used to check whether this is a pre-1.0 version bump, as
/// those have different semver rules.
@visibleForTesting
Map<Version, NextVersionType> getAllowedNextVersions(
    {required Version masterVersion, required Version headVersion}) {
  final Map<Version, NextVersionType> allowedNextVersions =
      <Version, NextVersionType>{
    masterVersion.nextMajor: NextVersionType.BREAKING_MAJOR,
    masterVersion.nextMinor: NextVersionType.MINOR,
    masterVersion.nextPatch: NextVersionType.PATCH,
  };

  if (masterVersion.major < 1 && headVersion.major < 1) {
    int nextBuildNumber = -1;
    if (masterVersion.build.isEmpty) {
      nextBuildNumber = 1;
    } else {
      final int currentBuildNumber = masterVersion.build.first as int;
      nextBuildNumber = currentBuildNumber + 1;
    }
    final Version preReleaseVersion = Version(
      masterVersion.major,
      masterVersion.minor,
      masterVersion.patch,
      build: nextBuildNumber.toString(),
    );
    allowedNextVersions.clear();
    allowedNextVersions[masterVersion.nextMajor] = NextVersionType.RELEASE;
    allowedNextVersions[masterVersion.nextMinor] =
        NextVersionType.BREAKING_MAJOR;
    allowedNextVersions[masterVersion.nextPatch] = NextVersionType.MINOR;
    allowedNextVersions[preReleaseVersion] = NextVersionType.PATCH;
  }
  return allowedNextVersions;
}

/// A command to validate version changes to packages.
class VersionCheckCommand extends PluginCommand {
  /// Creates an instance of the version check command.
  VersionCheckCommand(
    Directory packagesDir, {
    ProcessRunner processRunner = const ProcessRunner(),
    GitDir? gitDir,
    http.Client? httpClient,
  })  : _pubVersionFinder =
            PubVersionFinder(httpClient: httpClient ?? http.Client()),
        super(packagesDir, processRunner: processRunner, gitDir: gitDir) {
    argParser.addFlag(
      _againstPubFlag,
      help: 'Whether the version check should run against the version on pub.\n'
          'Defaults to false, which means the version check only run against the previous version in code.',
      defaultsTo: false,
      negatable: true,
    );
  }

  static const String _againstPubFlag = 'against-pub';

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

  @override
  final String description =
      'Checks if the versions of the plugins have been incremented per pub specification.\n'
      'Also checks if the latest version in CHANGELOG matches the version in pubspec.\n\n'
      'This command requires "pub" and "flutter" to be in your path.';

  final PubVersionFinder _pubVersionFinder;

  @override
  Future<void> run() async {
    final GitVersionFinder gitVersionFinder = await retrieveVersionFinder();

    final List<String> changedPubspecs =
        await gitVersionFinder.getChangedPubSpecs();

    final List<String> badVersionChangePubspecs = <String>[];

    const String indentation = '  ';
    for (final String pubspecPath in changedPubspecs) {
      print('Checking versions for $pubspecPath...');
      final File pubspecFile = packagesDir.fileSystem.file(pubspecPath);
      if (!pubspecFile.existsSync()) {
        print('${indentation}Deleted; skipping.');
        continue;
      }
      final Pubspec pubspec = Pubspec.parse(pubspecFile.readAsStringSync());
      if (pubspec.publishTo == 'none') {
        print('${indentation}Found "publish_to: none"; skipping.');
        continue;
      }

      final Version? headVersion =
          await gitVersionFinder.getPackageVersion(pubspecPath, gitRef: 'HEAD');
      if (headVersion == null) {
        printError('${indentation}No version found. A package that '
            'intentionally has no version should be marked '
            '"publish_to: none".');
        badVersionChangePubspecs.add(pubspecPath);
        continue;
      }
      Version? sourceVersion;
      if (getBoolArg(_againstPubFlag)) {
        final String packageName = pubspecFile.parent.basename;
        final PubVersionFinderResponse pubVersionFinderResponse =
            await _pubVersionFinder.getPackageVersion(package: packageName);
        switch (pubVersionFinderResponse.result) {
          case PubVersionFinderResult.success:
            sourceVersion = pubVersionFinderResponse.versions.first;
            print(
                '$indentation$packageName: Current largest version on pub: $sourceVersion');
            break;
          case PubVersionFinderResult.fail:
            printError('''
${indentation}Error fetching version on pub for $packageName.
${indentation}HTTP Status ${pubVersionFinderResponse.httpResponse.statusCode}
${indentation}HTTP response: ${pubVersionFinderResponse.httpResponse.body}
''');
            badVersionChangePubspecs.add(pubspecPath);
            continue;
          case PubVersionFinderResult.noPackageFound:
            sourceVersion = null;
            break;
        }
      } else {
        sourceVersion = await gitVersionFinder.getPackageVersion(pubspecPath);
      }
      if (sourceVersion == null) {
        String safeToIgnoreMessage;
        if (getBoolArg(_againstPubFlag)) {
          safeToIgnoreMessage =
              '${indentation}Unable to find package on pub server.';
        } else {
          safeToIgnoreMessage =
              '${indentation}Unable to find pubspec in master.';
        }
        print('$safeToIgnoreMessage Safe to ignore if the project is new.');
        continue;
      }

      if (sourceVersion == headVersion) {
        print('${indentation}No version change.');
        continue;
      }

      // Check for reverts when doing local validation.
      if (!getBoolArg(_againstPubFlag) && headVersion < sourceVersion) {
        final Map<Version, NextVersionType> possibleVersionsFromNewVersion =
            getAllowedNextVersions(
                masterVersion: headVersion, headVersion: sourceVersion);
        // Since this skips validation, try to ensure that it really is likely
        // to be a revert rather than a typo by checking that the transition
        // from the lower version to the new version would have been valid.
        if (possibleVersionsFromNewVersion.containsKey(sourceVersion)) {
          print('${indentation}New version is lower than previous version. '
              'This is assumed to be a revert.');
          continue;
        }
      }

      final Map<Version, NextVersionType> allowedNextVersions =
          getAllowedNextVersions(
              masterVersion: sourceVersion, headVersion: headVersion);

      if (!allowedNextVersions.containsKey(headVersion)) {
        final String source = (getBoolArg(_againstPubFlag)) ? 'pub' : 'master';
        printError('${indentation}Incorrectly updated version.\n'
            '${indentation}HEAD: $headVersion, $source: $sourceVersion.\n'
            '${indentation}Allowed versions: $allowedNextVersions');
        badVersionChangePubspecs.add(pubspecPath);
        continue;
      } else {
        print('$indentation$headVersion -> $sourceVersion');
      }

      final bool isPlatformInterface =
          pubspec.name.endsWith('_platform_interface');
      if (isPlatformInterface &&
          allowedNextVersions[headVersion] == NextVersionType.BREAKING_MAJOR) {
        printError('$pubspecPath breaking change detected.\n'
            'Breaking changes to platform interfaces are strongly discouraged.\n');
        badVersionChangePubspecs.add(pubspecPath);
        continue;
      }
    }
    _pubVersionFinder.httpClient.close();

    // TODO(stuartmorgan): Unify the way iteration works for these checks; the
    // two checks shouldn't be operating independently on different lists.
    final List<String> mismatchedVersionPlugins = <String>[];
    await for (final Directory plugin in getPlugins()) {
      if (!(await _checkVersionsMatch(plugin))) {
        mismatchedVersionPlugins.add(plugin.basename);
      }
    }

    bool passed = true;
    if (badVersionChangePubspecs.isNotEmpty) {
      passed = false;
      printError('''
The following pubspecs failed validaton:
$indentation${badVersionChangePubspecs.join('\n$indentation')}
''');
    }
    if (mismatchedVersionPlugins.isNotEmpty) {
      passed = false;
      printError('''
The following pubspecs have different versions in pubspec.yaml and CHANGELOG.md:
$indentation${mismatchedVersionPlugins.join('\n$indentation')}
''');
    }
    if (!passed) {
      throw ToolExit(1);
    }

    print('No version check errors found!');
  }

  /// Returns whether or not the pubspec version and CHANGELOG version for
  /// [plugin] match.
  Future<bool> _checkVersionsMatch(Directory plugin) async {
    // get version from pubspec
    final String packageName = plugin.basename;
    print('-----------------------------------------');
    print(
        'Checking the first version listed in CHANGELOG.md matches the version in pubspec.yaml for $packageName.');

    final Pubspec? pubspec = _tryParsePubspec(plugin);
    if (pubspec == null) {
      printError('Cannot parse version from pubspec.yaml');
      return false;
    }
    final Version? fromPubspec = pubspec.version;

    // get first version from CHANGELOG
    final File changelog = plugin.childFile('CHANGELOG.md');
    final List<String> lines = changelog.readAsLinesSync();
    String? firstLineWithText;
    final Iterator<String> iterator = lines.iterator;
    while (iterator.moveNext()) {
      if (iterator.current.trim().isNotEmpty) {
        firstLineWithText = iterator.current.trim();
        break;
      }
    }
    // Remove all leading mark down syntax from the version line.
    String? versionString = firstLineWithText?.split(' ').last;

    // Skip validation for the special NEXT version that's used to accumulate
    // changes that don't warrant publishing on their own.
    final bool hasNextSection = versionString == 'NEXT';
    if (hasNextSection) {
      print('Found NEXT; validating next version in the CHANGELOG.');
      // Ensure that the version in pubspec hasn't changed without updating
      // CHANGELOG. That means the next version entry in the CHANGELOG pass the
      // normal validation.
      while (iterator.moveNext()) {
        if (iterator.current.trim().startsWith('## ')) {
          versionString = iterator.current.trim().split(' ').last;
          break;
        }
      }
    }

    final Version? fromChangeLog =
        versionString == null ? null : Version.parse(versionString);
    if (fromChangeLog == null) {
      printError(
          'Cannot find version on the first line of ${plugin.path}/CHANGELOG.md');
      return false;
    }

    if (fromPubspec != fromChangeLog) {
      printError('''
versions for $packageName in CHANGELOG.md and pubspec.yaml do not match.
The version in pubspec.yaml is $fromPubspec.
The first version listed in CHANGELOG.md is $fromChangeLog.
''');
      return false;
    }

    // If NEXT wasn't the first section, it should not exist at all.
    if (!hasNextSection) {
      final RegExp nextRegex = RegExp(r'^#+\s*NEXT\s*$');
      if (lines.any((String line) => nextRegex.hasMatch(line))) {
        printError('''
When bumping the version for release, the NEXT section should be incorporated
into the new version's release notes.
''');
        return false;
      }
    }

    print('$packageName passed version check');
    return true;
  }

  Pubspec? _tryParsePubspec(Directory package) {
    final File pubspecFile = package.childFile('pubspec.yaml');

    try {
      final Pubspec pubspec = Pubspec.parse(pubspecFile.readAsStringSync());
      return pubspec;
    } on Exception catch (exception) {
      printError(
          'Failed to parse `pubspec.yaml` at ${pubspecFile.path}: $exception}');
    }
    return null;
  }
}