import 'dart:convert';

import 'package:flutter_secure_storage/flutter_secure_storage.dart';

import '../presentation/claims_overview/claims_overview_cache.dart';
import 'package:nhancepolicy/logger.dart';

class TokenStorageService {
  static final TokenStorageService _instance = TokenStorageService._internal();
  factory TokenStorageService() => _instance;
  TokenStorageService._internal();

  // 🔐 Secure storage instance
  static const FlutterSecureStorage _secureStorage = FlutterSecureStorage();

  // Storage keys
  static const String _preEnrollmentKey = 'pre_enrollment_data';
  static const String _postEnrollmentKey = 'post_enrollment_data';
  static const String _selectedBranchKey = 'selected_branch';
  static const String _decodedTokenKey = 'decoded_token';
  static const String _branchNameKey = 'branch_name';

  // In-memory cache
  List<dynamic>? _preEnrollmentData;
  List<dynamic>? _postEnrollmentData;
  Map<String, dynamic>? _selectedBranch;
  Map<String, dynamic>? _decodedToken;

  // 🔄 Initialize from secure storage
  Future<void> initialize() async {
    final preData = await _secureStorage.read(key: _preEnrollmentKey);
    if (preData != null) {
      _preEnrollmentData = json.decode(preData);
    }

    final postData = await _secureStorage.read(key: _postEnrollmentKey);
    if (postData != null) {
      _postEnrollmentData = json.decode(postData);
    }

    final branchData = await _secureStorage.read(key: _selectedBranchKey);
    if (branchData != null) {
      _selectedBranch = json.decode(branchData);
    }

    final tokenData = await _secureStorage.read(key: _decodedTokenKey);
    if (tokenData != null) {
      _decodedToken = json.decode(tokenData);
    }
  }

  // 💾 Save enrollment data
  Future<void> saveEnrollmentData(
    List<dynamic> preData,
    List<dynamic> postData,
  ) async {
    _preEnrollmentData = preData;
    _postEnrollmentData = postData;

    await _secureStorage.write(
        key: _preEnrollmentKey, value: json.encode(preData));
    await _secureStorage.write(
        key: _postEnrollmentKey, value: json.encode(postData));
  }

  List<Map<String, dynamic>> getCombinedBranches() {
    List<Map<String, dynamic>> combined = [];
    Set<String> seenTokens = {};
    Set<String> seenIds = {};

    // Helper: check valid token
    bool hasValidToken(dynamic token) {
      return token != null && token.toString().trim().isNotEmpty;
    }

    // Add pre-enrollment data
    if (_preEnrollmentData != null) {
      for (var item in _preEnrollmentData!) {
        final token = item['token'];

        // ❌ SKIP if token is empty or null
        if (!hasValidToken(token)) continue;

        String uniqueId =
            '${item['id']}_${item['client_id']}_${item['client_branch_id']}';

        if (seenIds.contains(uniqueId)) continue;
        if (token.isNotEmpty && seenTokens.contains(token)) continue;

        if (token.isNotEmpty) seenTokens.add(token);
        seenIds.add(uniqueId);

        combined.add({...item, 'enrollment_type': 'pre'});
      }
    }

    // Add post-enrollment data
    if (_postEnrollmentData != null) {
      for (var item in _postEnrollmentData!) {
        final token = item['token'];

        // ❌ SKIP if token is empty or null
        if (!hasValidToken(token)) continue;

        String uniqueId =
            '${item['id']}_${item['client_id']}_${item['client_branch_id']}';

        if (seenIds.contains(uniqueId)) continue;
        if (token.isNotEmpty && seenTokens.contains(token)) continue;

        if (token.isNotEmpty) seenTokens.add(token);
        seenIds.add(uniqueId);

        combined.add({...item, 'enrollment_type': 'post'});
      }
    }

    return combined;
  }

  // 🌿 Save selected branch + decode JWT
  Future<void> saveSelectedBranch(Map<String, dynamic> branch) async {
    _selectedBranch = branch;

    String token = branch['token']?.toString() ?? '';
    _decodedToken = token.isNotEmpty ? _decodeJWT(token) : null;

    await _secureStorage.write(
        key: _selectedBranchKey, value: json.encode(branch));

    if (_decodedToken != null) {
      await _secureStorage.write(
          key: _decodedTokenKey, value: json.encode(_decodedToken));
    }

    await _secureStorage.write(
      key: _branchNameKey,
      value: branch['branch_name']?.toString() ?? '',
    );

    // Prefer claims_sub_menu from branch payload when available.
    final claimsSubMenu = branch['claims_sub_menu'];
    if (claimsSubMenu is List) {
      await _secureStorage.write(
        key: 'claims_sub_menu',
        value: jsonEncode(claimsSubMenu),
      );
    }
  }

  // 🔓 Decode JWT
  Map<String, dynamic>? _decodeJWT(String token) {
    try {
      final parts = token.split('.');
      if (parts.length != 3) return null;

      final payload = base64Url.normalize(parts[1]);
      final decoded = utf8.decode(base64Url.decode(payload));

      return json.decode(decoded);
    } catch (e) {
      logDebug('JWT decode error: $e');
      return null;
    }
  }

  // Getters
  Map<String, dynamic>? getSelectedBranch() => _selectedBranch;
  Map<String, dynamic>? getDecodedToken() => _decodedToken;
  String? getCurrentToken() => _selectedBranch?['token'];

  bool isLoggedIn() =>
      _selectedBranch != null &&
      _selectedBranch!['token'] != null &&
      _selectedBranch!['token'].toString().isNotEmpty;

  // 🚪 Logout (clear everything)
  Future<void> clearAll() async {
    _preEnrollmentData = null;
    _postEnrollmentData = null;
    _selectedBranch = null;
    _decodedToken = null;

    await _secureStorage.deleteAll();
  }

  Future<void> saveDecodedSessionData(
    Map<String, dynamic> decodedToken,
    String token,
  ) async {
    // Handle allowed_modules safely
    dynamic allowedModules = decodedToken['allowed_modules'];
    if (allowedModules is String) {
      allowedModules = jsonDecode(allowedModules);
    }

    await _secureStorage.write(
        key: 'empClientBranchId',
        value: decodedToken['post_branch_id']?.toString());

    await _secureStorage.write(
        key: 'empPrimaryId', value: decodedToken['post_hr_id']?.toString());

    await _secureStorage.write(
        key: 'empClientId', value: decodedToken['post_client_id']?.toString());

    await _secureStorage.write(
        key: 'empHrId', value: decodedToken['post_hr_id']?.toString());

    await _secureStorage.write(
        key: 'empAllowed_modules',
        value: jsonEncode(allowedModules?['post'] ?? []));

    // ================= PRE (Enrollment) =================

    await _secureStorage.write(
        key: 'enrollmentEmpClientBranchId',
        value: decodedToken['pre_branch_id']?.toString());

    await _secureStorage.write(
        key: 'enrollmentEmpPrimaryId',
        value: decodedToken['pre_hr_id']?.toString());

    await _secureStorage.write(
        key: 'enrollmentClient_id',
        value: decodedToken['pre_client_id']?.toString());

    await _secureStorage.write(
        key: 'enrollmentHrId', value: decodedToken['pre_hr_id']?.toString());

    await _secureStorage.write(
        key: 'enrollmentAllowed_modules',
        value: jsonEncode(allowedModules?['pre'] ?? []));

    // ================= TOKEN =================
    await _secureStorage.write(key: 'token', value: token);

    // ================= CLAIMS SUB MENU =================
    if (decodedToken.containsKey('claims_sub_menu')) {
      final claimsSubMenu = decodedToken['claims_sub_menu'];
      await _secureStorage.write(
        key: 'claims_sub_menu',
        value: jsonEncode(claimsSubMenu is List ? claimsSubMenu : []),
      );
    }
  }

  Future<String?> readValue(String key) async {
    return await _secureStorage.read(key: key);
  }

  Future<void> writeValue(String key, String value) async {
    await _secureStorage.write(key: key, value: value);
  }

  Future<void> removeValue(String key) async {
    await _secureStorage.delete(key: key);
  }

  Future<void> clearBranchSession() async {
    final keysToRemove = [
      'selected_branch',
      'decoded_token',
      'clientLogo',
      'clientName',
      'empAllowed_modules',
      'empClientBranchId',
      'empClientId',
      'empEmail',
      'empHrId',
      'empPrimaryId',
      'enrollmentAllowed_modules',
      'enrollmentClient_id',
      'enrollmentEmpClientBranchId',
      'enrollmentEmpPrimaryId',
      'enrollmentHrId',
      'token',
      'claims_sub_menu',
    ];

    for (final key in keysToRemove) {
      await _secureStorage.delete(key: key);
    }
  }

  Future<void> resetSessionAndSwitchBranch(
    Map<String, dynamic> newBranch,
  ) async {
    // 1️⃣ Clear ONLY branch/session related keys
    await clearBranchSession();

    // 2️⃣ Clear claims overview cache so the dashboard fetches fresh data
    await ClaimsOverviewCache.clearAll();

    // 3️⃣ Save selected branch
    await saveSelectedBranch(newBranch);

    // 3️⃣ Rebuild decoded session data from token
    final token = newBranch['token']?.toString();
    if (token != null && token.isNotEmpty) {
      final decoded = _decodeJWT(token);
      if (decoded != null) {
        await saveDecodedSessionData(decoded, token);
      }
    }

    // 4️⃣ Update in-memory cache
    _selectedBranch = newBranch;
  }
}