// 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:io' as io;
import 'dart:math';

import 'package:args/command_runner.dart';
import 'package:file/file.dart';
import 'package:git/git.dart';
import 'package:path/path.dart' as p;
import 'package:platform/platform.dart';
import 'package:yaml/yaml.dart';

import 'core.dart';
import 'git_version_finder.dart';
import 'process_runner.dart';
import 'repository_package.dart';

/// An entry in package enumeration for APIs that need to include extra
/// data about the entry.
class PackageEnumerationEntry {
  /// Creates a new entry for the given package.
  PackageEnumerationEntry(this.package, {required this.excluded});

  /// The package this entry corresponds to. Be sure to check `excluded` before
  /// using this, as having an entry does not necessarily mean that the package
  /// should be included in the processing of the enumeration.
  final RepositoryPackage package;

  /// Whether or not this package was excluded by the command invocation.
  final bool excluded;
}

/// Interface definition for all commands in this tool.
// TODO(stuartmorgan): Move most of this logic to PackageLoopingCommand.
abstract class PluginCommand extends Command<void> {
  /// Creates a command to operate on [packagesDir] with the given environment.
  PluginCommand(
    this.packagesDir, {
    this.processRunner = const ProcessRunner(),
    this.platform = const LocalPlatform(),
    GitDir? gitDir,
  }) : _gitDir = gitDir {
    argParser.addMultiOption(
      _packagesArg,
      splitCommas: true,
      help:
          'Specifies which packages the command should run on (before sharding).\n',
      valueHelp: 'package1,package2,...',
      aliases: <String>[_pluginsArg],
    );
    argParser.addOption(
      _shardIndexArg,
      help: 'Specifies the zero-based index of the shard to '
          'which the command applies.',
      valueHelp: 'i',
      defaultsTo: '0',
    );
    argParser.addOption(
      _shardCountArg,
      help: 'Specifies the number of shards into which plugins are divided.',
      valueHelp: 'n',
      defaultsTo: '1',
    );
    argParser.addMultiOption(
      _excludeArg,
      abbr: 'e',
      help: 'A list of packages to exclude from from this command.\n\n'
          'Alternately, a list of one or more YAML files that contain a list '
          'of packages to exclude.',
      defaultsTo: <String>[],
    );
    argParser.addFlag(_runOnChangedPackagesArg,
        help: 'Run the command on changed packages/plugins.\n'
            'If no packages have changed, or if there have been changes that may\n'
            'affect all packages, the command runs on all packages.\n'
            'The packages excluded with $_excludeArg is also excluded even if changed.\n'
            'See $_kBaseSha if a custom base is needed to determine the diff.\n\n'
            'Cannot be combined with $_packagesArg.\n');
    argParser.addFlag(_packagesForBranchArg,
        help:
            'This runs on all packages (equivalent to no package selection flag)\n'
            'on master, and behaves like --run-on-changed-packages on any other branch.\n\n'
            'Cannot be combined with $_packagesArg.\n\n'
            'This is intended for use in CI.\n',
        hide: true);
    argParser.addOption(_kBaseSha,
        help: 'The base sha used to determine git diff. \n'
            'This is useful when $_runOnChangedPackagesArg is specified.\n'
            'If not specified, merge-base is used as base sha.');
  }

  static const String _pluginsArg = 'plugins';
  static const String _packagesArg = 'packages';
  static const String _shardIndexArg = 'shardIndex';
  static const String _shardCountArg = 'shardCount';
  static const String _excludeArg = 'exclude';
  static const String _runOnChangedPackagesArg = 'run-on-changed-packages';
  static const String _packagesForBranchArg = 'packages-for-branch';
  static const String _kBaseSha = 'base-sha';

  /// The directory containing the plugin packages.
  final Directory packagesDir;

  /// The process runner.
  ///
  /// This can be overridden for testing.
  final ProcessRunner processRunner;

  /// The current platform.
  ///
  /// This can be overridden for testing.
  final Platform platform;

  /// The git directory to use. If unset, [gitDir] populates it from the
  /// packages directory's enclosing repository.
  ///
  /// This can be mocked for testing.
  GitDir? _gitDir;

  int? _shardIndex;
  int? _shardCount;

  // Cached set of explicitly excluded packages.
  Set<String>? _excludedPackages;

  /// A context that matches the default for [platform].
  p.Context get path => platform.isWindows ? p.windows : p.posix;

  /// The command to use when running `flutter`.
  String get flutterCommand => platform.isWindows ? 'flutter.bat' : 'flutter';

  /// The shard of the overall command execution that this instance should run.
  int get shardIndex {
    if (_shardIndex == null) {
      _checkSharding();
    }
    return _shardIndex!;
  }

  /// The number of shards this command is divided into.
  int get shardCount {
    if (_shardCount == null) {
      _checkSharding();
    }
    return _shardCount!;
  }

  /// Returns the [GitDir] containing [packagesDir].
  Future<GitDir> get gitDir async {
    GitDir? gitDir = _gitDir;
    if (gitDir != null) {
      return gitDir;
    }

    // Ensure there are no symlinks in the path, as it can break
    // GitDir's allowSubdirectory:true.
    final String packagesPath = packagesDir.resolveSymbolicLinksSync();
    if (!await GitDir.isGitDir(packagesPath)) {
      printError('$packagesPath is not a valid Git repository.');
      throw ToolExit(2);
    }
    gitDir =
        await GitDir.fromExisting(packagesDir.path, allowSubdirectory: true);
    _gitDir = gitDir;
    return gitDir;
  }

  /// Convenience accessor for boolean arguments.
  bool getBoolArg(String key) {
    return (argResults![key] as bool?) ?? false;
  }

  /// Convenience accessor for String arguments.
  String getStringArg(String key) {
    return (argResults![key] as String?) ?? '';
  }

  /// Convenience accessor for List<String> arguments.
  List<String> getStringListArg(String key) {
    return (argResults![key] as List<String>?) ?? <String>[];
  }

  void _checkSharding() {
    final int? shardIndex = int.tryParse(getStringArg(_shardIndexArg));
    final int? shardCount = int.tryParse(getStringArg(_shardCountArg));
    if (shardIndex == null) {
      usageException('$_shardIndexArg must be an integer');
    }
    if (shardCount == null) {
      usageException('$_shardCountArg must be an integer');
    }
    if (shardCount < 1) {
      usageException('$_shardCountArg must be positive');
    }
    if (shardIndex < 0 || shardCount <= shardIndex) {
      usageException(
          '$_shardIndexArg must be in the half-open range [0..$shardCount[');
    }
    _shardIndex = shardIndex;
    _shardCount = shardCount;
  }

  /// Returns the set of plugins to exclude based on the `--exclude` argument.
  Set<String> getExcludedPackageNames() {
    final Set<String> excludedPackages = _excludedPackages ??
        getStringListArg(_excludeArg).expand<String>((String item) {
          if (item.endsWith('.yaml')) {
            final File file = packagesDir.fileSystem.file(item);
            return (loadYaml(file.readAsStringSync()) as YamlList)
                .toList()
                .cast<String>();
          }
          return <String>[item];
        }).toSet();
    // Cache for future calls.
    _excludedPackages = excludedPackages;
    return excludedPackages;
  }

  /// Returns the root diretories of the packages involved in this command
  /// execution.
  ///
  /// Depending on the command arguments, this may be a user-specified set of
  /// packages, the set of packages that should be run for a given diff, or all
  /// packages.
  ///
  /// By default, packages excluded via --exclude will not be in the stream, but
  /// they can be included by passing false for [filterExcluded].
  Stream<PackageEnumerationEntry> getTargetPackages(
      {bool filterExcluded = true}) async* {
    // To avoid assuming consistency of `Directory.list` across command
    // invocations, we collect and sort the plugin folders before sharding.
    // This is considered an implementation detail which is why the API still
    // uses streams.
    final List<PackageEnumerationEntry> allPlugins =
        await _getAllPackages().toList();
    allPlugins.sort((PackageEnumerationEntry p1, PackageEnumerationEntry p2) =>
        p1.package.path.compareTo(p2.package.path));
    final int shardSize = allPlugins.length ~/ shardCount +
        (allPlugins.length % shardCount == 0 ? 0 : 1);
    final int start = min(shardIndex * shardSize, allPlugins.length);
    final int end = min(start + shardSize, allPlugins.length);

    for (final PackageEnumerationEntry plugin
        in allPlugins.sublist(start, end)) {
      if (!(filterExcluded && plugin.excluded)) {
        yield plugin;
      }
    }
  }

  /// Returns the root Dart package folders of the packages involved in this
  /// command execution, assuming there is only one shard. Depending on the
  /// command arguments, this may be a user-specified set of packages, the
  /// set of packages that should be run for a given diff, or all packages.
  ///
  /// This will return packages that have been excluded by the --exclude
  /// parameter, annotated in the entry as excluded.
  ///
  /// Packages can exist in the following places relative to the packages
  /// directory:
  ///
  /// 1. As a Dart package in a directory which is a direct child of the
  ///    packages directory. This is a non-plugin package, or a non-federated
  ///    plugin.
  /// 2. Several plugin packages may live in a directory which is a direct
  ///    child of the packages directory. This directory groups several Dart
  ///    packages which implement a single plugin. This directory contains an
  ///    "app-facing" package which declares the API for the plugin, a
  ///    platform interface package which declares the API for implementations,
  ///    and one or more platform-specific implementation packages.
  /// 3./4. Either of the above, but in a third_party/packages/ directory that
  ///    is a sibling of the packages directory. This is used for a small number
  ///    of packages in the flutter/packages repository.
  Stream<PackageEnumerationEntry> _getAllPackages() async* {
    final Set<String> packageSelectionFlags = <String>{
      _packagesArg,
      _runOnChangedPackagesArg,
      _packagesForBranchArg,
    };
    if (packageSelectionFlags
            .where((String flag) => argResults!.wasParsed(flag))
            .length >
        1) {
      printError('Only one of --$_packagesArg, --$_runOnChangedPackagesArg, or '
          '--$_packagesForBranchArg can be provided.');
      throw ToolExit(exitInvalidArguments);
    }

    Set<String> plugins = Set<String>.from(getStringListArg(_packagesArg));

    final bool runOnChangedPackages;
    if (getBoolArg(_runOnChangedPackagesArg)) {
      runOnChangedPackages = true;
    } else if (getBoolArg(_packagesForBranchArg)) {
      final String? branch = await _getBranch();
      if (branch == null) {
        printError('Unabled to determine branch; --$_packagesForBranchArg can '
            'only be used in a git repository.');
        throw ToolExit(exitInvalidArguments);
      } else {
        runOnChangedPackages = branch != 'master';
        // Log the mode for auditing what was intended to run.
        print('--$_packagesForBranchArg: running on '
            '${runOnChangedPackages ? 'changed' : 'all'} packages');
      }
    } else {
      runOnChangedPackages = false;
    }

    final Set<String> excludedPluginNames = getExcludedPackageNames();

    if (runOnChangedPackages) {
      final GitVersionFinder gitVersionFinder = await retrieveVersionFinder();
      final String baseSha = await gitVersionFinder.getBaseSha();
      print(
          'Running for all packages that have changed relative to "$baseSha"\n');
      final List<String> changedFiles =
          await gitVersionFinder.getChangedFiles();
      if (!_changesRequireFullTest(changedFiles)) {
        plugins = _getChangedPackages(changedFiles);
      }
    }

    final Directory thirdPartyPackagesDirectory = packagesDir.parent
        .childDirectory('third_party')
        .childDirectory('packages');

    for (final Directory dir in <Directory>[
      packagesDir,
      if (thirdPartyPackagesDirectory.existsSync()) thirdPartyPackagesDirectory,
    ]) {
      await for (final FileSystemEntity entity
          in dir.list(followLinks: false)) {
        // A top-level Dart package is a plugin package.
        if (_isDartPackage(entity)) {
          if (plugins.isEmpty || plugins.contains(p.basename(entity.path))) {
            yield PackageEnumerationEntry(
                RepositoryPackage(entity as Directory),
                excluded: excludedPluginNames.contains(entity.basename));
          }
        } else if (entity is Directory) {
          // Look for Dart packages under this top-level directory.
          await for (final FileSystemEntity subdir
              in entity.list(followLinks: false)) {
            if (_isDartPackage(subdir)) {
              // If --plugin=my_plugin is passed, then match all federated
              // plugins under 'my_plugin'. Also match if the exact plugin is
              // passed.
              final String relativePath =
                  path.relative(subdir.path, from: dir.path);
              final String packageName = path.basename(subdir.path);
              final String basenamePath = path.basename(entity.path);
              if (plugins.isEmpty ||
                  plugins.contains(relativePath) ||
                  plugins.contains(basenamePath)) {
                yield PackageEnumerationEntry(
                    RepositoryPackage(subdir as Directory),
                    excluded: excludedPluginNames.contains(basenamePath) ||
                        excludedPluginNames.contains(packageName) ||
                        excludedPluginNames.contains(relativePath));
              }
            }
          }
        }
      }
    }
  }

  /// Returns all Dart package folders (typically, base package + example) of
  /// the packages involved in this command execution.
  ///
  /// By default, packages excluded via --exclude will not be in the stream, but
  /// they can be included by passing false for [filterExcluded].
  Stream<PackageEnumerationEntry> getTargetPackagesAndSubpackages(
      {bool filterExcluded = true}) async* {
    await for (final PackageEnumerationEntry plugin
        in getTargetPackages(filterExcluded: filterExcluded)) {
      yield plugin;
      yield* plugin.package.directory
          .list(recursive: true, followLinks: false)
          .where(_isDartPackage)
          .map((FileSystemEntity directory) => PackageEnumerationEntry(
              // _isDartPackage guarantees that this cast is valid.
              RepositoryPackage(directory as Directory),
              excluded: plugin.excluded));
    }
  }

  /// Returns the files contained, recursively, within the packages
  /// involved in this command execution.
  Stream<File> getFiles() {
    return getTargetPackages().asyncExpand<File>(
        (PackageEnumerationEntry entry) => getFilesForPackage(entry.package));
  }

  /// Returns the files contained, recursively, within [package].
  Stream<File> getFilesForPackage(RepositoryPackage package) {
    return package.directory
        .list(recursive: true, followLinks: false)
        .where((FileSystemEntity entity) => entity is File)
        .cast<File>();
  }

  /// Returns whether the specified entity is a directory containing a
  /// `pubspec.yaml` file.
  bool _isDartPackage(FileSystemEntity entity) {
    return entity is Directory && entity.childFile('pubspec.yaml').existsSync();
  }

  /// Retrieve an instance of [GitVersionFinder] based on `_kBaseSha` and [gitDir].
  ///
  /// Throws tool exit if [gitDir] nor root directory is a git directory.
  Future<GitVersionFinder> retrieveVersionFinder() async {
    final String baseSha = getStringArg(_kBaseSha);

    final GitVersionFinder gitVersionFinder =
        GitVersionFinder(await gitDir, baseSha);
    return gitVersionFinder;
  }

  // Returns packages that have been changed given a list of changed files.
  //
  // The paths must use POSIX separators (e.g., as provided by git output).
  Set<String> _getChangedPackages(List<String> changedFiles) {
    final Set<String> packages = <String>{};
    for (final String path in changedFiles) {
      final List<String> pathComponents = p.posix.split(path);
      final int packagesIndex =
          pathComponents.indexWhere((String element) => element == 'packages');
      if (packagesIndex != -1) {
        packages.add(pathComponents[packagesIndex + 1]);
      }
    }
    if (packages.isEmpty) {
      print('No changed packages.');
    } else {
      final String changedPackages = packages.join(',');
      print('Changed packages: $changedPackages');
    }
    return packages;
  }

  Future<String?> _getBranch() async {
    final io.ProcessResult branchResult = await (await gitDir).runCommand(
        <String>['rev-parse', '--abbrev-ref', 'HEAD'],
        throwOnError: false);
    if (branchResult.exitCode != 0) {
      return null;
    }
    return (branchResult.stdout as String).trim();
  }

  // Returns true if one or more files changed that have the potential to affect
  // any plugin (e.g., CI script changes).
  bool _changesRequireFullTest(List<String> changedFiles) {
    const List<String> specialFiles = <String>[
      '.ci.yaml', // LUCI config.
      '.cirrus.yml', // Cirrus config.
      '.clang-format', // ObjC and C/C++ formatting options.
      'analysis_options.yaml', // Dart analysis settings.
    ];
    const List<String> specialDirectories = <String>[
      '.ci/', // Support files for CI.
      'script/', // This tool, and its wrapper scripts.
    ];
    // Directory entries must end with / to avoid over-matching, since the
    // check below is done via string prefixing.
    assert(specialDirectories.every((String dir) => dir.endsWith('/')));

    return changedFiles.any((String path) =>
        specialFiles.contains(path) ||
        specialDirectories.any((String dir) => path.startsWith(dir)));
  }
}