// Copyright 2020 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 'sub_rip.dart';
export 'sub_rip.dart' show SubRipCaptionFile;

/// A structured representation of a parsed closed caption file.
///
/// A closed caption file includes a list of captions, each with a start and end
/// time for when the given closed caption should be displayed.
///
/// The [captions] are a list of all captions in a file, in the order that they
/// appeared in the file.
///
/// See:
/// * [SubRipCaptionFile].
abstract class ClosedCaptionFile {
  /// The full list of captions from a given file.
  ///
  /// The [captions] will be in the order that they appear in the given file.
  List<Caption> get captions;
}

/// A representation of a single caption.
///
/// A typical closed captioning file will include several [Caption]s, each
/// linked to a start and end time.
class Caption {
  /// Creates a new [Caption] object.
  ///
  /// This is not recommended for direct use unless you are writing a parser for
  /// a new closed captioning file type.
  const Caption(
      {required this.number,
      required this.start,
      required this.end,
      required this.text});

  /// The number that this caption was assigned.
  final int number;

  /// When in the given video should this [Caption] begin displaying.
  final Duration start;

  /// When in the given video should this [Caption] be dismissed.
  final Duration end;

  /// The actual text that should appear on screen to be read between [start]
  /// and [end].
  final String text;

  /// A no caption object. This is a caption with [start] and [end] durations of zero,
  /// and an empty [text] string.
  static const Caption none =
      Caption(number: 0, start: Duration.zero, end: Duration.zero, text: '');

  @override
  String toString() {
    return '$runtimeType('
        'number: $number, '
        'start: $start, '
        'end: $end, '
        'text: $text)';
  }
}