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';
import '../../core/logger.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() {
    // Create a new list with new relay objects to ensure Flutter detects the change
    final serviceRelays = nostrService.getRelays();
    _relays = serviceRelays.map((relay) => NostrRelay(
      url: relay.url,
      isConnected: relay.isConnected,
      isEnabled: relay.isEnabled,
      retryCount: relay.retryCount,
    )).toList();
    notifyListeners();
  }

  /// Adds a relay to the service.
  /// 
  /// [relayUrl] - The WebSocket URL of the relay.
  /// 
  /// Tests the connection and enables the relay if successful.
  /// 
  /// Returns true if the relay was added successfully, false if it already exists or connection failed.
  Future<bool> addRelay(String relayUrl) async {
    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;
      }

      // Add the relay (it will be disabled by default)
      nostrService.addRelay(relayUrl);
      _loadRelays();
      
      // Test the connection
      Logger.info('Testing connection to relay: $relayUrl');
      try {
        final stream = await nostrService
            .connectRelay(relayUrl)
            .timeout(
              const Duration(seconds: 3),
              onTimeout: () {
                Logger.warning('Connection timeout for relay: $relayUrl');
                throw Exception('Connection timeout');
              },
            );
        Logger.debug('WebSocket stream created for relay: $relayUrl');
        
        // Wait a bit to see if connection actually works (check for errors)
        Logger.debug('Setting up stream listener for relay: $relayUrl');
        final completer = Completer<bool>();
        late StreamSubscription subscription;
        bool gotError = false;
        
        subscription = stream.listen(
          (data) {
            // Got data - connection is working
            Logger.info('Received data from relay $relayUrl during add - connection confirmed');
            if (!completer.isCompleted) {
              completer.complete(true);
            }
          },
          onError: (error) {
            // Connection error occurred
            Logger.error('Stream error for relay $relayUrl during add', error);
            gotError = true;
            if (!completer.isCompleted) {
              completer.complete(false);
            }
          },
          onDone: () {
            // Stream closed - connection failed
            Logger.warning('Stream closed for relay $relayUrl during add - connection failed');
            if (!completer.isCompleted) {
              completer.complete(false);
            }
          },
        );
        
        // Wait for either data (success) or error/timeout (failure)
        Logger.debug('Waiting for connection confirmation for relay: $relayUrl (timeout: 2 seconds)');
        final connected = await completer.future.timeout(
          const Duration(seconds: 2),
          onTimeout: () {
            Logger.warning('Timeout waiting for connection confirmation for relay: $relayUrl during add');
            subscription.cancel();
            // If no error occurred but no data either, check if relay is marked as connected
            _loadRelays();
            final relay = _relays.firstWhere(
              (r) => r.url == relayUrl,
              orElse: () => throw Exception('Relay not found'),
            );
            Logger.debug('Relay $relayUrl connection state during add: isConnected=${relay.isConnected}, isEnabled=${relay.isEnabled}');
            return relay.isConnected;
          },
        );
        
        subscription.cancel();
        
        if (connected && !gotError) {
          // Connection successful - enable the relay
          Logger.info('Connection successful for relay: $relayUrl - enabling relay');
          nostrService.setRelayEnabled(relayUrl, true);
      _loadRelays();
      return true;
        } else {
          // Connection failed - leave it disabled
          Logger.warning('Connection failed for relay: $relayUrl (connected=$connected, gotError=$gotError) - leaving disabled');
          nostrService.disconnectRelay(relayUrl);
          nostrService.setRelayEnabled(relayUrl, false);
          _loadRelays();
          _error = 'Failed to connect to relay';
          notifyListeners();
          return false;
        }
      } catch (e) {
        // Connection test failed - leave relay disabled
        Logger.error('Exception during connection test for relay: $relayUrl', e);
        try {
          nostrService.disconnectRelay(relayUrl);
          nostrService.setRelayEnabled(relayUrl, false);
          _loadRelays();
        } catch (_) {
          // Ignore disconnect errors
        }
        _error = 'Failed to connect to relay: ${e.toString().replaceAll('Exception: ', '')}';
        notifyListeners();
        return false;
      }
    } 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();
    }
  }

  /// Tests connectivity to a single relay.
  /// 
  /// [relayUrl] - The URL of the relay to test.
  /// 
  /// Returns true if connection successful, false otherwise.
  Future<bool> testRelay(String relayUrl) async {
    _error = null;
    notifyListeners();

    try {
      final stream = await nostrService
          .connectRelay(relayUrl)
          .timeout(
            const Duration(seconds: 3),
            onTimeout: () {
              throw Exception('Connection timeout');
            },
          );
      _loadRelays();
      // Cancel the stream subscription to clean up
      stream.listen(null).cancel();
      return true;
    } catch (e) {
      // Connection failed - disconnect and disable the relay
      try {
        nostrService.disconnectRelay(relayUrl);
        nostrService.setRelayEnabled(relayUrl, false);
        // Reload and notify to update UI
        _loadRelays();
        notifyListeners();
      } catch (_) {
        // Ignore disconnect errors
      }
      return false;
    }
  }

  /// Toggles a relay on/off (enables/disables it).
  /// 
  /// [relayUrl] - The URL of the relay to toggle.
  /// 
  /// When enabling, automatically attempts to connect to the relay.
  /// If connection fails, automatically disables the relay (toggle moves back to OFF).
  /// Always attempts to reconnect when toggling on, even if previously failed.
  /// 
  /// The toggle responds immediately for better UX, then reverts if connection fails.
  Future<void> toggleRelay(String relayUrl) async {
    try {
      _error = null;
      final relay = _relays.firstWhere((r) => r.url == relayUrl);
      final newEnabledState = !relay.isEnabled;
      
      // If disabling, just disconnect (no test needed) - update UI immediately
      if (!newEnabledState) {
        try {
          nostrService.setRelayEnabled(relayUrl, false);
          nostrService.disconnectRelay(relayUrl);
          _loadRelays();
        } catch (_) {
          // Ignore disconnect errors
        }
        return;
      }
      
      // If enabling, update UI immediately (optimistic update)
      // Disconnect first to ensure a fresh connection attempt
      Logger.debug('Disconnecting existing connection for relay: $relayUrl (if any)');
      try {
        nostrService.disconnectRelay(relayUrl);
      } catch (_) {
        // Ignore if not connected
      }
      
      // Enable the relay immediately and update UI (optimistic update)
      Logger.info('Toggling relay ON: $relayUrl - updating UI immediately');
      nostrService.setRelayEnabled(relayUrl, true);
      
      // Update UI immediately by updating the relay in our list directly
      // This bypasses the auto-disable logic in getRelays() during connection attempt
      final relayIndex = _relays.indexWhere((r) => r.url == relayUrl);
      if (relayIndex != -1) {
        _relays[relayIndex] = NostrRelay(
          url: relayUrl,
          isConnected: _relays[relayIndex].isConnected,
          isEnabled: true,
        );
        notifyListeners(); // Update UI immediately
      }
      
      // Now attempt to connect in the background
      // If connection fails, we'll toggle it back to OFF
      Logger.info('Attempting to connect to relay: $relayUrl (background)');
      try {
        final stream = await nostrService
            .connectRelay(relayUrl)
            .timeout(
              const Duration(seconds: 5),
              onTimeout: () {
                Logger.warning('Connection timeout for relay: $relayUrl (5 seconds)');
                throw Exception('Connection timeout');
              },
            );
        Logger.debug('WebSocket stream created for relay: $relayUrl');
        
        // Wait a short time to see if connection is established (no errors)
        // The service marks connection as established after 500ms if no errors occur
        Logger.debug('Waiting for connection confirmation for relay: $relayUrl (timeout: 1 second)');
        await Future.delayed(const Duration(seconds: 1));
        
        // Cancel the stream subscription to clean up
        stream.listen(null).cancel();
        
        // Check if connection was established (no errors occurred)
        _loadRelays();
        final updatedRelay = _relays.firstWhere(
          (r) => r.url == relayUrl,
          orElse: () => throw Exception('Relay not found'),
        );
        
        Logger.debug('Relay $relayUrl connection state: isConnected=${updatedRelay.isConnected}, isEnabled=${updatedRelay.isEnabled}');
        
        if (!updatedRelay.isConnected) {
          // Connection failed - toggle back to OFF
          Logger.warning('Connection failed for relay: $relayUrl - toggling back to OFF');
          nostrService.disconnectRelay(relayUrl);
          nostrService.setRelayEnabled(relayUrl, false);
          _loadRelays();
          _error = 'Failed to connect to relay';
          notifyListeners();
        } else {
          // Connection successful - keep it enabled and connected
          Logger.info('Connection successful for relay: $relayUrl - keeping enabled');
          _loadRelays();
        }
      } catch (e) {
        // Connection failed - toggle back to OFF
        Logger.error('Exception during toggle connection for relay: $relayUrl', e);
        try {
          nostrService.disconnectRelay(relayUrl);
          nostrService.setRelayEnabled(relayUrl, false);
      _loadRelays();
          _error = 'Failed to connect to relay: ${e.toString().replaceAll('Exception: ', '')}';
          notifyListeners();
        } catch (_) {
          // Ignore disconnect errors
        }
      }
    } catch (e) {
      _error = 'Failed to toggle relay: $e';
      notifyListeners();
    }
  }

  /// Turns all disabled relays ON.
  /// 
  /// Only affects relays that are currently disabled.
  /// Automatically attempts to connect to newly enabled relays.
  Future<void> turnAllOn() async {
    try {
      _error = null;
      
      // Find all disabled relays
      final disabledRelays = _relays.where((r) => !r.isEnabled).toList();
      if (disabledRelays.isEmpty) {
        Logger.info('No disabled relays to turn on');
        return;
      }
      
      Logger.info('Turning ${disabledRelays.length} relay(s) ON');
      
      // Disconnect disabled relays first to ensure fresh connection attempts
      for (final relay in disabledRelays) {
        try {
          nostrService.disconnectRelay(relay.url);
        } catch (_) {
          // Ignore if not connected
        }
      }
      
      // Enable disabled relays immediately and update UI (optimistic update)
      for (final relay in disabledRelays) {
        nostrService.setRelayEnabled(relay.url, true);
        
        // Update UI immediately
        final relayIndex = _relays.indexWhere((r) => r.url == relay.url);
        if (relayIndex != -1) {
          _relays[relayIndex] = NostrRelay(
            url: relay.url,
            isConnected: relay.isConnected,
            isEnabled: true,
          );
        }
      }
      notifyListeners(); // Update UI immediately
      
      // Capture relay URLs before starting connections (list might change)
      final relayUrls = disabledRelays.map((r) => r.url).toList();
      
      // Now attempt to connect to all newly enabled relays in parallel
      final futures = <Future<void>>[];
      for (final relayUrl in relayUrls) {
        futures.add(
          Future<void>(() async {
            try {
              Logger.info('Attempting to connect to relay: $relayUrl');
              final stream = await nostrService
                  .connectRelay(relayUrl)
                  .timeout(
                    const Duration(seconds: 5),
                    onTimeout: () {
                      Logger.warning('Connection timeout for relay: $relayUrl (5 seconds)');
                      throw Exception('Connection timeout');
                    },
                  );
              Logger.debug('WebSocket stream created for relay: $relayUrl');
              
              // Wait a short time to see if connection is established (no errors)
              // The service marks connection as established after 500ms if no errors occur
              Logger.debug('Waiting for connection confirmation for relay: $relayUrl (timeout: 1 second)');
              await Future.delayed(const Duration(seconds: 1));
              
              // Cancel the stream subscription to clean up
              stream.listen(null).cancel();
              
              // Check if connection was established
              _loadRelays();
              final updatedRelay = _relays.firstWhere(
                (r) => r.url == relayUrl,
                orElse: () => throw Exception('Relay not found'),
              );
              
              Logger.debug('Relay $relayUrl connection state: isConnected=${updatedRelay.isConnected}, isEnabled=${updatedRelay.isEnabled}');
              
              if (!updatedRelay.isConnected) {
                // Connection failed - disable the relay
                Logger.warning('Connection failed for relay: $relayUrl');
                throw Exception('Connection failed');
              }
              
              // Connection successful
              Logger.info('Connection successful for relay: $relayUrl');
            } catch (e) {
              // Connection failed - automatically disable the relay
              Logger.error('Exception during connection for relay: $relayUrl', e);
              try {
                nostrService.disconnectRelay(relayUrl);
                nostrService.setRelayEnabled(relayUrl, false);
                _loadRelays();
              } catch (_) {
                // Ignore disconnect errors
              }
            }
          }).catchError((error) {
            // Final safety net - ensure no exceptions escape
            Logger.error('Error in toggleAllRelays for relay: $relayUrl', error);
            try {
              nostrService.disconnectRelay(relayUrl);
              nostrService.setRelayEnabled(relayUrl, false);
              _loadRelays();
            } catch (_) {
              // Ignore all errors
            }
            return Future<void>.value();
          }),
        );
      }
      
      // Wait for all connection attempts to complete (or fail gracefully)
      Logger.info('Waiting for all ${futures.length} relay connection attempts to complete');
      await Future.wait(futures, eagerError: false);
      Logger.info('All relay connection attempts completed');
      _loadRelays();
    } catch (e) {
      Logger.error('Failed to turn all relays on', e);
      _error = 'Failed to turn all relays on: $e';
      notifyListeners();
    }
  }

  /// Turns all enabled relays OFF.
  /// 
  /// Only affects relays that are currently enabled.
  Future<void> turnAllOff() async {
    try {
      _error = null;
      
      // Find all enabled relays
      final enabledRelays = _relays.where((r) => r.isEnabled).toList();
      if (enabledRelays.isEmpty) {
        Logger.info('No enabled relays to turn off');
        return;
      }
      
      Logger.info('Turning ${enabledRelays.length} relay(s) OFF');
      
      // Disconnect and disable all enabled relays
      for (final relay in enabledRelays) {
        try {
          nostrService.setRelayEnabled(relay.url, false);
          nostrService.disconnectRelay(relay.url);
        } catch (_) {
          // Ignore disconnect errors
        }
      }
      
      _loadRelays();
    } catch (e) {
      Logger.error('Failed to turn all relays off', e);
      _error = 'Failed to turn all relays off: $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 and disable to mark as unhealthy
              try {
                nostrService.disconnectRelay(relay.url);
                nostrService.setRelayEnabled(relay.url, false);
                // Reload and notify to update UI
                _loadRelays();
                notifyListeners();
              } 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 and disable relay to mark as unhealthy
            try {
              nostrService.disconnectRelay(relay.url);
              nostrService.setRelayEnabled(relay.url, false);
              // Reload and notify to update UI
              _loadRelays();
              notifyListeners();
            } 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);
            nostrService.setRelayEnabled(relay.url, false);
            _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();
  }
}