/// An AI generated digest of the day's news, grouped into topics.
class DailyBriefing {
  const DailyBriefing({
    required this.createdAt,
    required this.intro,
    required this.topics,
    required this.generatedBy,
  });

  final DateTime createdAt;
  final String intro;
  final List<BriefingTopic> topics;

  /// Human readable name of the summarizer, e.g. "Claude (claude-opus-5-5)".
  final String generatedBy;

  Map<String, dynamic> toJson() => {
        'createdAt': createdAt.toIso8601String(),
        'intro': intro,
        'generatedBy': generatedBy,
        'topics': topics.map((t) => t.toJson()).toList(),
      };

  factory DailyBriefing.fromJson(Map<String, dynamic> json) => DailyBriefing(
        createdAt: DateTime.parse(json['createdAt'] as String),
        intro: json['intro'] as String? ?? '',
        generatedBy: json['generatedBy'] as String? ?? '',
        topics: (json['topics'] as List? ?? [])
            .map((t) => BriefingTopic.fromJson(t as Map<String, dynamic>))
            .toList(),
      );
}

class BriefingTopic {
  const BriefingTopic({
    required this.title,
    required this.summary,
    required this.sources,
  });

  final String title;
  final String summary;
  final List<ArticleRef> sources;

  Map<String, dynamic> toJson() => {
        'title': title,
        'summary': summary,
        'sources': sources.map((s) => s.toJson()).toList(),
      };

  factory BriefingTopic.fromJson(Map<String, dynamic> json) => BriefingTopic(
        title: json['title'] as String? ?? '',
        summary: json['summary'] as String? ?? '',
        sources: (json['sources'] as List? ?? [])
            .map((s) => ArticleRef.fromJson(s as Map<String, dynamic>))
            .toList(),
      );
}

/// A lightweight pointer to an article, stored with the briefing so links
/// still work after the feed has been refreshed.
class ArticleRef {
  const ArticleRef({
    required this.title,
    required this.url,
    required this.sourceName,
  });

  final String title;
  final String url;
  final String sourceName;

  Map<String, dynamic> toJson() =>
      {'title': title, 'url': url, 'sourceName': sourceName};

  factory ArticleRef.fromJson(Map<String, dynamic> json) => ArticleRef(
        title: json['title'] as String? ?? '',
        url: json['url'] as String? ?? '',
        sourceName: json['sourceName'] as String? ?? '',
      );
}