lib/src/cli/output.dart

// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
// for details. 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:convert';
import 'dart:io';

import '../source_code.dart';

/// Where formatted code results should go.
class Output {
  /// Overwrite files on disc.
  static const Output write = _WriteOutput();

  /// Print the code to the terminal as human-friendly text.
  static const Output show = _ShowOutput();

  /// Print the code to the terminal as JSON.
  static const Output json = _JsonOutput();

  /// Do nothing. (Used when the user just wants the list of files that would
  /// be changed.)
  static const Output none = Output._();

  const Output._();

  /// Write the file to disc.
  bool writeFile(File file, String displayPath, SourceCode result) => false;

  /// Print the file to the terminal in some way.
  void showFile(String path, SourceCode result) {}
}

class _WriteOutput extends Output {
  const _WriteOutput() : super._();

  @override
  bool writeFile(File file, String displayPath, SourceCode result) {
    try {
      file.writeAsStringSync(result.text);
    } on FileSystemException catch (err) {
      stderr.writeln('Could not overwrite $displayPath: '
          '${err.osError.message} (error code ${err.osError.errorCode})');
    }

    return true;
  }
}

class _ShowOutput extends Output {
  const _ShowOutput() : super._();

  @override
  void showFile(String path, SourceCode result) {
    // Don't add an extra newline.
    stdout.write(result.text);
  }
}

class _JsonOutput extends Output {
  const _JsonOutput() : super._();

  @override
  void showFile(String path, SourceCode result) {
    // TODO(rnystrom): Put an empty selection in here to remain compatible with
    // the old formatter. Since there's no way to pass a selection on the
    // command line, this will never be used, which is why it's hard-coded to
    // -1, -1. If we add support for passing in a selection, put the real
    // result here.
    print(jsonEncode({
      'path': path,
      'source': result.text,
      'selection': {
        'offset': result.selectionStart ?? -1,
        'length': result.selectionLength ?? -1
      }
    }));
  }
}