import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:hive/hive.dart';
import 'package:sheetless/core/models/change.dart';
import 'package:sheetless/core/models/config.dart';

/// Keys for secure storage (credentials and tokens).
enum SecureStorageKey { url, jwt, email }

/// Service for managing local storage operations.
///
/// Uses [FlutterSecureStorage] for sensitive data (credentials, tokens)
/// and [Hive] for general app data (config, sheet access times, change queue).
class StorageService {
  // Hive box names
  static const String _sheetAccessTimesBox = 'sheetAccessTimes';
  static const String _configBox = 'config';
  static const String _changeQueueBox = 'changeQueue';

  late final FlutterSecureStorage _secureStorage;

  StorageService() {
    _secureStorage = FlutterSecureStorage(
      aOptions: const AndroidOptions(encryptedSharedPreferences: true),
    );
  }

  // ---------------------------------------------------------------------------
  // Secure Storage (Credentials & Tokens)
  // ---------------------------------------------------------------------------

  /// Reads a value from secure storage.
  Future<String?> readSecure(SecureStorageKey key) {
    return _secureStorage.read(key: key.name);
  }

  /// Writes a value to secure storage.
  ///
  /// Pass `null` to delete the key.
  Future<void> writeSecure(SecureStorageKey key, String? value) {
    return _secureStorage.write(key: key.name, value: value);
  }

  /// Clears the JWT token from secure storage.
  Future<void> clearToken() {
    return writeSecure(SecureStorageKey.jwt, null);
  }

  // ---------------------------------------------------------------------------
  // Config
  // ---------------------------------------------------------------------------

  /// Reads the app configuration from storage.
  Future<Config> readConfig() async {
    final box = await Hive.openBox(_configBox);
    return Config(
      twoPageMode: box.get(Config.keyTwoPageMode) ?? false,
      fullscreen: box.get(Config.keyFullscreen) ?? false,
    );
  }

  /// Writes the app configuration to storage.
  Future<void> writeConfig(Config config) async {
    final box = await Hive.openBox(_configBox);
    await box.put(Config.keyTwoPageMode, config.twoPageMode);
    await box.put(Config.keyFullscreen, config.fullscreen);
  }

  // ---------------------------------------------------------------------------
  // Sheet Access Times (for sorting by recency)
  // ---------------------------------------------------------------------------

  /// Reads all sheet access times.
  ///
  /// Returns a map of sheet UUID to last access time.
  Future<Map<String, DateTime>> readSheetAccessTimes() async {
    final box = await Hive.openBox(_sheetAccessTimesBox);
    return box.toMap().map(
      (key, value) => MapEntry(key as String, DateTime.parse(value as String)),
    );
  }

  /// Records when a sheet was last accessed.
  Future<void> writeSheetAccessTime(String uuid, DateTime datetime) async {
    final box = await Hive.openBox(_sheetAccessTimesBox);
    await box.put(uuid, datetime.toIso8601String());
  }

  // ---------------------------------------------------------------------------
  // Change Queue (Offline Sync)
  // ---------------------------------------------------------------------------

  /// Adds a change to the offline queue.
  Future<void> writeChange(Change change) async {
    final box = await Hive.openBox(_changeQueueBox);
    await box.add(change.toMap());
  }

  /// Reads all pending changes from the queue.
  Future<ChangeQueue> readChangeQueue() async {
    final box = await Hive.openBox(_changeQueueBox);
    final queue = ChangeQueue();

    for (final map in box.values) {
      queue.addChange(Change.fromMap(map as Map<dynamic, dynamic>));
    }

    return queue;
  }

  /// Removes the oldest change from the queue.
  ///
  /// Call this after successfully syncing a change to the server.
  Future<void> deleteOldestChange() async {
    final box = await Hive.openBox(_changeQueueBox);
    if (box.isNotEmpty) {
      await box.deleteAt(0);
    }
  }
}