import 'dart:async';
import 'package:flutter/foundation.dart';
import '../../data/nostr/nostr_service.dart';
import '../../data/nostr/models/nostr_relay.dart';
import '../../data/sync/sync_engine.dart';

/// Controller for managing Nostr relay UI state and operations.
/// 
/// This controller separates business logic from UI presentation,
/// making the UI module testable and modular.
class RelayManagementController extends ChangeNotifier {
  /// Nostr service for relay operations.
  final NostrService nostrService;

  /// Sync engine for triggering manual syncs.
  final SyncEngine? syncEngine;

  /// List of relays being managed.
  List<NostrRelay> _relays = [];

  /// Whether a sync operation is in progress.
  bool _isSyncing = false;

  /// Error message if any operation fails.
  String? _error;

  /// Whether health check is in progress.
  bool _isCheckingHealth = false;

  /// Creates a [RelayManagementController] instance.
  RelayManagementController({
    required this.nostrService,
    this.syncEngine,
  }) {
    _loadRelays();
  }

  /// List of relays.
  List<NostrRelay> get relays => List.unmodifiable(_relays);

  /// Whether sync is in progress.
  bool get isSyncing => _isSyncing;

  /// Current error message, if any.
  String? get error => _error;

  /// Whether health check is in progress.
  bool get isCheckingHealth => _isCheckingHealth;

  /// Loads relays from the Nostr service.
  void _loadRelays() {
    _relays = nostrService.getRelays();
    notifyListeners();
  }

  /// Adds a relay to the service.
  /// 
  /// [relayUrl] - The WebSocket URL of the relay.
  /// 
  /// Returns true if the relay was added successfully, false if it already exists.
  bool addRelay(String relayUrl) {
    try {
      _error = null;
      
      // Validate URL format
      if (!relayUrl.startsWith('wss://') && !relayUrl.startsWith('ws://')) {
        _error = 'Invalid relay URL. Must start with wss:// or ws://';
        notifyListeners();
        return false;
      }

      nostrService.addRelay(relayUrl);
      _loadRelays();
      return true;
    } catch (e) {
      _error = 'Failed to add relay: $e';
      notifyListeners();
      return false;
    }
  }

  /// Removes a relay from the service.
  /// 
  /// [relayUrl] - The URL of the relay to remove.
  void removeRelay(String relayUrl) {
    try {
      _error = null;
      nostrService.removeRelay(relayUrl);
      _loadRelays();
    } catch (e) {
      _error = 'Failed to remove relay: $e';
      notifyListeners();
    }
  }

  /// Connects to a relay and updates status.
  /// 
  /// [relayUrl] - The URL of the relay to connect to.
  /// 
  /// Throws if connection fails (for use in health checks where we want to catch individual failures).
  Future<void> connectRelay(String relayUrl) async {
    _error = null;
    await nostrService.connectRelay(relayUrl);
    _loadRelays();
  }

  /// Disconnects from a relay.
  /// 
  /// [relayUrl] - The URL of the relay to disconnect from.
  void disconnectRelay(String relayUrl) {
    try {
      _error = null;
      nostrService.disconnectRelay(relayUrl);
      _loadRelays();
    } catch (e) {
      _error = 'Failed to disconnect from relay: $e';
      notifyListeners();
    }
  }

  /// Checks health of all relays by attempting to connect.
  /// 
  /// Updates relay connection status.
  /// 
  /// Never throws - all connection failures are handled gracefully.
  Future<void> checkRelayHealth() async {
    _isCheckingHealth = true;
    _error = null;
    notifyListeners();

    // Process each relay health check, catching all errors
    final futures = <Future<void>>[];
    for (final relay in _relays) {
      // Wrap each connection attempt to ensure all exceptions are caught
      futures.add(
        Future<void>(() async {
          try {
            // Attempt to connect - this may throw synchronously or asynchronously
            // Wrap in another try-catch to catch synchronous exceptions from WebSocket.connect
            try {
              final stream = await nostrService
                  .connectRelay(relay.url)
                  .timeout(
                    const Duration(seconds: 2),
                    onTimeout: () {
                      throw Exception('Connection timeout');
                    },
                  );
              // If we get here, connection succeeded
              _loadRelays();
              // Cancel the stream subscription to clean up
              stream.listen(null).cancel();
            } catch (e) {
              // Connection failed - disconnect to mark as unhealthy
              try {
                nostrService.disconnectRelay(relay.url);
                _loadRelays();
              } catch (_) {
                // Ignore disconnect errors
              }
              // Re-throw to be caught by outer catch
              throw e;
            }
          } catch (e) {
            // Catch all exceptions - connection failures are expected in tests
            // Disconnect relay to mark as unhealthy
            try {
              nostrService.disconnectRelay(relay.url);
              _loadRelays();
            } catch (_) {
              // Ignore disconnect errors
            }
            // Don't re-throw - this method should never throw
          }
        }).catchError((_) {
          // Final safety net - ensure no exceptions escape
          try {
            nostrService.disconnectRelay(relay.url);
            _loadRelays();
          } catch (_) {
            // Ignore all errors
          }
          return Future<void>.value();
        }),
      );
    }

    // Wait for all health checks to complete (or fail gracefully)
    // Use eagerError: false so one failure doesn't stop others
    try {
      await Future.wait(futures, eagerError: false);
    } catch (_) {
      // Swallow any errors - all individual failures already handled above
    }

    _isCheckingHealth = false;
    notifyListeners();
  }

  /// Triggers a manual sync using the sync engine.
  /// 
  /// Returns true if sync was triggered successfully.
  Future<bool> triggerManualSync() async {
    if (syncEngine == null) {
      _error = 'Sync engine not configured';
      notifyListeners();
      return false;
    }

    _isSyncing = true;
    _error = null;
    notifyListeners();

    try {
      // Trigger sync to all configured relays via Nostr
      // This is a simplified sync - in a real app, you'd sync specific items
      await syncEngine!.syncAll();
      return true;
    } catch (e) {
      _error = 'Sync failed: $e';
      return false;
    } finally {
      _isSyncing = false;
      notifyListeners();
    }
  }

  /// Clears the current error message.
  void clearError() {
    _error = null;
    notifyListeners();
  }

  @override
  void dispose() {
    // Don't dispose nostrService or syncEngine - they're managed elsewhere
    super.dispose();
  }
}