// Copyright 2014 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 '../artifacts.dart';
import '../base/common.dart';
import '../base/file_system.dart';
import '../build_info.dart';
import '../cache.dart';
import '../globals.dart' as globals;
import '../runner/flutter_command.dart';

/// The directory in the Flutter cache for each platform's artifacts.
const Map<TargetPlatform, String> flutterArtifactPlatformDirectory = <TargetPlatform, String>{
  TargetPlatform.windows_x64: 'windows-x64',
  TargetPlatform.linux_x64: 'linux-x64',
};

// TODO(jonahwilliams): this should come from a configuration in each build
// directory.
const Map<TargetPlatform, List<String>> artifactFilesByPlatform = <TargetPlatform, List<String>>{
  TargetPlatform.windows_x64: <String>[
    'flutter_windows.dll',
    'flutter_windows.dll.exp',
    'flutter_windows.dll.lib',
    'flutter_windows.dll.pdb',
    'flutter_export.h',
    'flutter_messenger.h',
    'flutter_plugin_registrar.h',
    'flutter_windows.h',
    'icudtl.dat',
    'cpp_client_wrapper/',
  ],
};

/// Copies desktop artifacts to local cache directories.
class UnpackCommand extends FlutterCommand {
  UnpackCommand() {
    argParser.addOption(
      'target-platform',
      allowed: <String>['windows-x64', 'linux-x64'],
    );
    argParser.addOption('cache-dir',
        help: 'Location to output platform specific artifacts.');
  }

  @override
  String get description => '(DEPRECATED) unpack desktop artifacts';

  @override
  String get name => 'unpack';

  @override
  bool get hidden => true;

  @override
  Future<Set<DevelopmentArtifact>> get requiredArtifacts async {
    final Set<DevelopmentArtifact> result = <DevelopmentArtifact>{};
    final TargetPlatform targetPlatform = getTargetPlatformForName(stringArg('target-platform'));
    switch (targetPlatform) {
      case TargetPlatform.windows_x64:
        result.add(DevelopmentArtifact.windows);
        break;
      case TargetPlatform.linux_x64:
        result.add(DevelopmentArtifact.linux);
        break;
      default:
    }
    return result;
  }

  @override
  Future<FlutterCommandResult> runCommand() async {
    final String targetName = stringArg('target-platform');
    final String targetDirectory = stringArg('cache-dir');
    if (!globals.fs.directory(targetDirectory).existsSync()) {
      globals.fs.directory(targetDirectory).createSync(recursive: true);
    }
    final TargetPlatform targetPlatform = getTargetPlatformForName(targetName);
    final ArtifactUnpacker flutterArtifactFetcher = ArtifactUnpacker(targetPlatform);
    bool success = true;
    if (globals.artifacts is LocalEngineArtifacts) {
      final LocalEngineArtifacts localEngineArtifacts = globals.artifacts as LocalEngineArtifacts;
      success = flutterArtifactFetcher.copyLocalBuildArtifacts(
        localEngineArtifacts.engineOutPath,
        targetDirectory,
      );
    } else {
      success = flutterArtifactFetcher.copyCachedArtifacts(
        targetDirectory,
      );
    }
    if (!success) {
      throwToolExit('Failed to unpack desktop artifacts.');
    }
    return FlutterCommandResult.success();
  }
}

/// Manages the copying of cached or locally built Flutter artifacts, including
/// tracking the last-copied versions and updating only if necessary.
class ArtifactUnpacker {
  /// Creates a new fetcher for the given configuration.
  const ArtifactUnpacker(this.platform);

  /// The platform to copy artifacts for.
  final TargetPlatform platform;

  /// Checks [targetDirectory] to see if artifacts have already been copied for
  /// the current hash, and if not, copies the artifacts for [platform] from the
  /// Flutter cache (after ensuring that the cache is present).
  ///
  /// Returns true if the artifacts were successfully copied, or were already
  /// present with the correct hash.
  bool copyCachedArtifacts(String targetDirectory) {
    String cacheStamp;
    switch (platform) {
      case TargetPlatform.windows_x64:
        cacheStamp = 'windows-sdk';
        break;
      case TargetPlatform.linux_x64:
        return true;
      default:
        throwToolExit('Unsupported target platform: $platform');
    }
    final String targetHash =
        readHashFileIfPossible(globals.cache.getStampFileFor(cacheStamp));
    if (targetHash == null) {
      globals.printError('Failed to find engine stamp file');
      return false;
    }

    try {
      final String currentHash = _lastCopiedHash(targetDirectory);
      if (currentHash == null || targetHash != currentHash) {
        // Copy them to the target directory.
        final String flutterCacheDirectory = globals.fs.path.join(
          Cache.flutterRoot,
          'bin',
          'cache',
          'artifacts',
          'engine',
          flutterArtifactPlatformDirectory[platform],
        );
        if (!_copyArtifactFiles(flutterCacheDirectory, targetDirectory)) {
          return false;
        }
        _setLastCopiedHash(targetDirectory, targetHash);
        globals.printTrace('Copied artifacts for version $targetHash.');
      } else {
        globals.printTrace('Artifacts for version $targetHash already present.');
      }
    } on Exception catch (error, stackTrace) {
      globals.printError(stackTrace.toString());
      globals.printError(error.toString());
      return false;
    }
    return true;
  }

  /// Acts like [copyCachedArtifacts], replacing the artifacts and updating
  /// the version stamp, except that it pulls the artifact from a local engine
  /// build with the given [buildConfiguration] (e.g., host_debug_unopt) whose
  /// checkout is rooted at [engineRoot].
  bool copyLocalBuildArtifacts(String buildOutput, String targetDirectory) {
    if (!_copyArtifactFiles(buildOutput, targetDirectory)) {
      return false;
    }

    // Update the hash file to indicate that it's a local build, so that it's
    // obvious where it came from.
    _setLastCopiedHash(targetDirectory, 'local build: $buildOutput');

    return true;
  }

  /// Copies the artifact files for [platform] from [sourceDirectory] to
  /// [targetDirectory].
  bool _copyArtifactFiles(String sourceDirectory, String targetDirectory) {
    final List<String> artifactFiles = artifactFilesByPlatform[platform];
    if (artifactFiles == null) {
      globals.printError('Unsupported platform: $platform.');
      return false;
    }

    try {
      globals.fs.directory(targetDirectory).createSync(recursive: true);
      for (final String entityName in artifactFiles) {
        final String sourcePath = globals.fs.path.join(sourceDirectory, entityName);
        final String targetPath = globals.fs.path.join(targetDirectory, entityName);
        if (entityName.endsWith('/')) {
          globals.fsUtils.copyDirectorySync(
            globals.fs.directory(sourcePath),
            globals.fs.directory(targetPath),
          );
        } else {
          globals.fs.file(sourcePath)
            .copySync(globals.fs.path.join(targetDirectory, entityName));
        }
      }

      globals.printTrace('Copied artifacts from $sourceDirectory.');
    } on Exception catch (e, stackTrace) {
      globals.printError(e.toString());
      globals.printError(stackTrace.toString());
      return false;
    }
    return true;
  }

  /// Returns a File object for the file containing the last copied hash
  /// in [directory].
  File _lastCopiedHashFile(String directory) {
    return globals.fs.file(globals.fs.path.join(directory, '.last_artifact_version'));
  }

  /// Returns the hash of the artifacts last copied to [directory], or null if
  /// they haven't been copied.
  String _lastCopiedHash(String directory) {
    // Sanity check that at least one file is present; this won't catch every
    // case, but handles someone deleting all the non-hidden cached files to
    // force fresh copy.
    final String artifactFilePath = globals.fs.path.join(
      directory,
      artifactFilesByPlatform[platform].first,
    );
    if (!globals.fs.file(artifactFilePath).existsSync()) {
      return null;
    }
    final File hashFile = _lastCopiedHashFile(directory);
    return readHashFileIfPossible(hashFile);
  }

  /// Writes [hash] to the file that stores the last copied hash for
  /// in [directory].
  void _setLastCopiedHash(String directory, String hash) {
    _lastCopiedHashFile(directory).writeAsStringSync(hash);
  }

  /// Returns the engine hash from [file] as a String, or null.
  ///
  /// If the file is missing, or cannot be read, returns null.
  String readHashFileIfPossible(File file) {
    if (!file.existsSync()) {
      return null;
    }
    try {
      return file.readAsStringSync().trim();
    } on FileSystemException {
      // If the file can't be read for any reason, just treat it as missing.
      return null;
    }
  }
}