import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

class PdfHistoryEntry {
  PdfHistoryEntry({
    required this.at,
    required this.title,
    required this.rechnungsnummer,
  });

  final DateTime at;
  final String title;
  final String rechnungsnummer;

  Map<String, dynamic> toJson() => {
        'at': at.toIso8601String(),
        'title': title,
        'rechnungsnummer': rechnungsnummer,
      };

  factory PdfHistoryEntry.fromJson(Map<String, dynamic> m) {
    return PdfHistoryEntry(
      at: DateTime.tryParse(m['at'] as String? ?? '') ?? DateTime.now(),
      title: m['title'] as String? ?? '',
      rechnungsnummer: m['rechnungsnummer'] as String? ?? '',
    );
  }
}

/// Lokaler Verlauf geteilter/erzeugter PDFs (nur Metadaten, keine Dateiablage).
class PdfHistoryService {
  PdfHistoryService._();
  static const _key = 'handwerkpro_pdf_history_v1';
  static const _max = 30;

  static Future<List<PdfHistoryEntry>> load() async {
    final p = await SharedPreferences.getInstance();
    final raw = p.getString(_key);
    if (raw == null || raw.isEmpty) return [];
    try {
      final list = jsonDecode(raw) as List<dynamic>;
      return list
          .map((e) => PdfHistoryEntry.fromJson(Map<String, dynamic>.from(e as Map)))
          .toList();
    } catch (_) {
      return [];
    }
  }

  static Future<void> add({
    required String title,
    required String rechnungsnummer,
  }) async {
    final p = await SharedPreferences.getInstance();
    final existing = await load();
    existing.insert(
      0,
      PdfHistoryEntry(
        at: DateTime.now(),
        title: title,
        rechnungsnummer: rechnungsnummer,
      ),
    );
    final trimmed = existing.take(_max).toList();
    await p.setString(
      _key,
      jsonEncode(trimmed.map((e) => e.toJson()).toList()),
    );
  }

  static Future<void> clear() async {
    final p = await SharedPreferences.getInstance();
    await p.remove(_key);
  }
}