import 'dart:convert';

import 'package:shared_preferences/shared_preferences.dart';

class ClaimsOverviewCacheEntry {
  final String policyId;
  final Map<String, dynamic> claimsKpiBySlug;
  final Map<String, dynamic> enrollmentKpiBySlug;
  /// Raw `generated_at` from the claims API (e.g. `01-07-2026`), if present.
  final String? generatedAt;
  final String? claimsLoadError;
  final String? enrollmentLoadError;

  const ClaimsOverviewCacheEntry({
    required this.policyId,
    required this.claimsKpiBySlug,
    required this.enrollmentKpiBySlug,
    this.generatedAt,
    this.claimsLoadError,
    this.enrollmentLoadError,
  });

  factory ClaimsOverviewCacheEntry.fromJson(Map<String, dynamic> json) {
    final raw = json['generatedAt']?.toString().trim();
    return ClaimsOverviewCacheEntry(
      policyId: json['policyId']?.toString() ?? '',
      claimsKpiBySlug: Map<String, dynamic>.from(json['claimsKpiBySlug'] ?? {}),
      enrollmentKpiBySlug:
          Map<String, dynamic>.from(json['enrollmentKpiBySlug'] ?? {}),
      generatedAt: (raw != null && raw.isNotEmpty) ? raw : null,
      claimsLoadError: json['claimsLoadError']?.toString(),
      enrollmentLoadError: json['enrollmentLoadError']?.toString(),
    );
  }

  Map<String, dynamic> toJson() => {
        'policyId': policyId,
        'claimsKpiBySlug': claimsKpiBySlug,
        'enrollmentKpiBySlug': enrollmentKpiBySlug,
        'generatedAt': generatedAt,
        'claimsLoadError': claimsLoadError,
        'enrollmentLoadError': enrollmentLoadError,
      };
}

abstract final class ClaimsOverviewCache {
  static const _keyPrefix = 'claims_overview_cache_v2_';

  static String _key(String branchId, String policyId) =>
      '$_keyPrefix${branchId}_$policyId';

  static Future<ClaimsOverviewCacheEntry?> read(
    String branchId,
    String policyId,
  ) async {
    if (branchId.isEmpty || policyId.isEmpty) return null;
    final prefs = await SharedPreferences.getInstance();
    final raw = prefs.getString(_key(branchId, policyId));
    if (raw == null || raw.isEmpty) return null;
    try {
      final decoded = jsonDecode(raw);
      if (decoded is! Map) return null;
      return ClaimsOverviewCacheEntry.fromJson(
        Map<String, dynamic>.from(decoded),
      );
    } catch (_) {
      return null;
    }
  }

  static Future<void> write(
    String branchId,
    ClaimsOverviewCacheEntry entry,
  ) async {
    if (branchId.isEmpty || entry.policyId.isEmpty) return;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(
      _key(branchId, entry.policyId),
      jsonEncode(entry.toJson()),
    );
  }

  static Future<void> clear(String branchId, String policyId) async {
    if (branchId.isEmpty || policyId.isEmpty) return;
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_key(branchId, policyId));
  }

  static Future<void> clearAll() async {
    final prefs = await SharedPreferences.getInstance();
    final keys = prefs
        .getKeys()
        .where((key) => key.startsWith(_keyPrefix))
        .toList();
    for (final key in keys) {
      await prefs.remove(key);
    }
  }
}