import 'dart:convert';

/// Represents an emergency contact for a trip (person or service).
///
/// Stores basic contact details and optional notes for quick access during
/// critical situations.
class EmergencyContact {
  /// Unique identifier for the contact entry.
  final String id;

  /// Display name (ex: "Ambassade", "Marie", "Assurance Europ").
  final String name;

  /// Phone number in international format when possible.
  final String phone;

  /// Optional description or role (ex: "Assistance médicale", "Famille").
  final String? note;

  /// Creation timestamp for stable ordering.
  final DateTime createdAt;

  /// Creates an emergency contact entry.
  const EmergencyContact({
    required this.id,
    required this.name,
    required this.phone,
    required this.createdAt,
    this.note,
  });

  /// Builds a new contact with current timestamp.
  factory EmergencyContact.newContact({
    required String id,
    required String name,
    required String phone,
    String? note,
  }) {
    return EmergencyContact(
      id: id,
      name: name,
      phone: phone,
      note: note,
      createdAt: DateTime.now().toUtc(),
    );
  }

  /// Returns a copy with updated fields.
  EmergencyContact copyWith({
    String? id,
    String? name,
    String? phone,
    String? note,
    DateTime? createdAt,
  }) {
    return EmergencyContact(
      id: id ?? this.id,
      name: name ?? this.name,
      phone: phone ?? this.phone,
      note: note ?? this.note,
      createdAt: createdAt ?? this.createdAt,
    );
  }

  /// Serializes contact to JSON.
  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'name': name,
      'phone': phone,
      'note': note,
      'createdAt': createdAt.toIso8601String(),
    };
  }

  /// Deserializes contact from JSON.
  factory EmergencyContact.fromJson(Map<String, dynamic> json) {
    return EmergencyContact(
      id: json['id'] as String,
      name: json['name'] as String,
      phone: json['phone'] as String,
      note: json['note'] as String?,
      createdAt: DateTime.parse(json['createdAt'] as String),
    );
  }

  /// Encodes list to JSON string.
  static String encodeList(List<EmergencyContact> contacts) {
    return json.encode(contacts.map((c) => c.toJson()).toList());
  }

  /// Decodes list from JSON string.
  static List<EmergencyContact> decodeList(String raw) {
    final decoded = json.decode(raw) as List<dynamic>;
    return decoded
        .cast<Map<String, dynamic>>()
        .map(EmergencyContact.fromJson)
        .toList();
  }
}