// 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 'dart:io' as io;

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

import 'common.dart';

const String _kBaseSha = 'base-sha';

enum NextVersionType {
  BREAKING_MAJOR,
  MAJOR_NULLSAFETY_PRE_RELEASE,
  MINOR_NULLSAFETY_PRE_RELEASE,
  MINOR,
  PATCH,
  RELEASE,
}

Version getNextNullSafetyPreRelease(Version current, Version next) {
  String nextNullsafetyPrerelease = 'nullsafety';
  if (current.isPreRelease &&
      current.preRelease.first is String &&
      current.preRelease.first == 'nullsafety') {
    if (current.preRelease.length == 1) {
      nextNullsafetyPrerelease = 'nullsafety.1';
    } else if (current.preRelease.length == 2 &&
        current.preRelease.last is int) {
      nextNullsafetyPrerelease = 'nullsafety.${current.preRelease.last + 1}';
    }
  }
  return Version(
    next.major,
    next.minor,
    next.patch,
    pre: nextNullsafetyPrerelease,
  );
}

@visibleForTesting
Map<Version, NextVersionType> getAllowedNextVersions(
    Version masterVersion, Version headVersion) {
  final Version nextNullSafetyMajor =
      getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMajor);
  final Version nextNullSafetyMinor =
      getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMinor);
  final Map<Version, NextVersionType> allowedNextVersions =
      <Version, NextVersionType>{
    masterVersion.nextMajor: NextVersionType.BREAKING_MAJOR,
    nextNullSafetyMajor: NextVersionType.MAJOR_NULLSAFETY_PRE_RELEASE,
    nextNullSafetyMinor: NextVersionType.MINOR_NULLSAFETY_PRE_RELEASE,
    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;
      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;

    final Version nextNullSafetyMajor =
        getNextNullSafetyPreRelease(masterVersion, masterVersion.nextMinor);
    final Version nextNullSafetyMinor =
        getNextNullSafetyPreRelease(masterVersion, masterVersion.nextPatch);

    allowedNextVersions[nextNullSafetyMajor] =
        NextVersionType.MAJOR_NULLSAFETY_PRE_RELEASE;
    allowedNextVersions[nextNullSafetyMinor] =
        NextVersionType.MINOR_NULLSAFETY_PRE_RELEASE;
  }
  return allowedNextVersions;
}

class VersionCheckCommand extends PluginCommand {
  VersionCheckCommand(
    Directory packagesDir,
    FileSystem fileSystem, {
    ProcessRunner processRunner = const ProcessRunner(),
    GitDir gitDir,
  }) : super(packagesDir, fileSystem,
            processRunner: processRunner, gitDir: gitDir);

  @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.';

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

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

    final String baseSha = argResults[_kBaseSha];
    for (final String pubspecPath in changedPubspecs) {
      try {
        final File pubspecFile = fileSystem.file(pubspecPath);
        if (!pubspecFile.existsSync()) {
          continue;
        }
        final Pubspec pubspec = Pubspec.parse(pubspecFile.readAsStringSync());
        if (pubspec.publishTo == 'none') {
          continue;
        }

        final Version masterVersion =
            await gitVersionFinder.getPackageVersion(pubspecPath, baseSha);
        final Version headVersion =
            await gitVersionFinder.getPackageVersion(pubspecPath, 'HEAD');
        if (headVersion == null) {
          continue; // Example apps don't have versions
        }

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

        if (!allowedNextVersions.containsKey(headVersion)) {
          final String error = '$pubspecPath incorrectly updated version.\n'
              'HEAD: $headVersion, master: $masterVersion.\n'
              'Allowed versions: $allowedNextVersions';
          printErrorAndExit(errorMessage: error);
        }

        bool isPlatformInterface = pubspec.name.endsWith("_platform_interface");
        if (isPlatformInterface &&
            allowedNextVersions[headVersion] ==
                NextVersionType.BREAKING_MAJOR) {
          final String error = '$pubspecPath breaking change detected.\n'
              'Breaking changes to platform interfaces are strongly discouraged.\n';
          printErrorAndExit(errorMessage: error);
        }
      } on io.ProcessException {
        print('Unable to find pubspec in master for $pubspecPath.'
            ' Safe to ignore if the project is new.');
      }
    }

    await for (Directory plugin in getPlugins()) {
      await _checkVersionsMatch(plugin);
    }

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

  Future<void> _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) {
      final String error = 'Cannot parse version from pubspec.yaml';
      printErrorAndExit(errorMessage: error);
    }
    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 iterator = lines.iterator;
    while (iterator.moveNext()) {
      if ((iterator.current as String).trim().isNotEmpty) {
        firstLineWithText = iterator.current;
        break;
      }
    }
    // Remove all leading mark down syntax from the version line.
    final String versionString = firstLineWithText.split(' ').last;
    Version fromChangeLog = Version.parse(versionString);
    if (fromChangeLog == null) {
      final String error =
          'Cannot find version on the first line of ${plugin.path}/CHANGELOG.md';
      printErrorAndExit(errorMessage: error);
    }

    if (fromPubspec != fromChangeLog) {
      final String error = '''
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 $fromChangeLog.
''';
      printErrorAndExit(errorMessage: error);
    }
    print('${packageName} passed version check');
  }

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

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