// Copyright 2018 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 'package:completion/completion.dart';

import '../base/common.dart';
import '../base/file_system.dart';
import '../base/io.dart';
import '../runner/flutter_command.dart';

class ShellCompletionCommand extends FlutterCommand {
  ShellCompletionCommand() {
    argParser.addFlag(
      'overwrite',
      defaultsTo: false,
      negatable: true,
      help: 'Causes the given shell completion setup script to be overwritten if it already exists.',
    );
  }

  @override
  final String name = 'bash-completion';

  @override
  final String description = 'Output command line shell completion setup scripts.\n\n'
      'This command prints the flutter command line completion setup script for Bash and Zsh. To\n'
      'use it, specify an output file and follow the instructions in the generated output file to\n'
      'install it in your shell environment. Once it is sourced, your shell will be able to\n'
      'complete flutter commands and options.';

  @override
  final List<String> aliases = <String>['zsh-completion'];

  @override
  bool get shouldUpdateCache => false;

  /// Return null to disable analytics recording of the `bash-completion` command.
  @override
  Future<String> get usagePath => null;

  @override
  Future<Null> runCommand() async {
    if (argResults.rest.length > 1) {
      throwToolExit('Too many arguments given to bash-completion command.', exitCode: 1);
    }

    if (argResults.rest.isEmpty || argResults.rest.first == '-') {
      stdout.write(generateCompletionScript(<String>['flutter']));
      return;
    }

    final File outputFile = fs.file(argResults.rest.first);
    if (outputFile.existsSync() && !argResults['overwrite']) {
      throwToolExit(
        'Output file ${outputFile.path} already exists, will not overwrite. '
            'Use --overwrite to force overwriting existing output file.',
        exitCode: 1,
      );
    }
    try {
      outputFile.writeAsStringSync(generateCompletionScript(<String>['flutter']));
    } on FileSystemException catch (error) {
      throwToolExit('Unable to write shell completion setup script.\n$error', exitCode: 1);
    }
  }
}