// 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 'dart:io' as io;

import 'package:meta/meta.dart';
import 'package:colorize/colorize.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 'package:yaml/yaml.dart';

import 'common.dart';

const String _kBaseSha = 'base_sha';

class GitVersionFinder {
  GitVersionFinder(this.baseGitDir, this.baseSha);

  final GitDir baseGitDir;
  final String baseSha;

  static bool isPubspec(String file) {
    return file.trim().endsWith('pubspec.yaml');
  }

  Future<List<String>> getChangedPubSpecs() async {
    final io.ProcessResult changedFilesCommand = await baseGitDir
        .runCommand(<String>['diff', '--name-only', '$baseSha', 'HEAD']);
    final List<String> changedFiles =
        changedFilesCommand.stdout.toString().split('\n');
    return changedFiles.where(isPubspec).toList();
  }

  Future<Version> getPackageVersion(String pubspecPath, String gitRef) async {
    final io.ProcessResult gitShow =
        await baseGitDir.runCommand(<String>['show', '$gitRef:$pubspecPath']);
    final String fileContent = gitShow.stdout;
    final String versionString = loadYaml(fileContent)['version'];
    return versionString == null ? null : Version.parse(versionString);
  }
}

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(),
    this.gitDir,
  }) : super(packagesDir, fileSystem, processRunner: processRunner) {
    argParser.addOption(_kBaseSha);
  }

  /// The git directory to use. By default it uses the parent directory.
  ///
  /// This can be mocked for testing.
  final 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\n'
      'This command requires "pub" and "flutter" to be in your path.';

  @override
  Future<Null> run() async {
    checkSharding();

    final String rootDir = packagesDir.parent.absolute.path;
    final String baseSha = argResults[_kBaseSha];

    GitDir baseGitDir = gitDir;
    if (baseGitDir == null) {
      if (!await GitDir.isGitDir(rootDir)) {
        print('$rootDir is not a valid Git repository.');
        throw ToolExit(2);
      }
      baseGitDir = await GitDir.fromExisting(rootDir);
    }

    final GitVersionFinder gitVersionFinder =
        GitVersionFinder(baseGitDir, baseSha);

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

    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';
          final Colorize redError = Colorize(error)..red();
          print(redError);
          throw ToolExit(1);
        }

        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';
          final Colorize redError = Colorize(error)..red();
          print(redError);
          throw ToolExit(1);
        }
      } on io.ProcessException {
        print('Unable to find pubspec in master for $pubspecPath.'
            ' Safe to ignore if the project is new.');
      }
    }

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