import 'package:flutter/material.dart';
import 'package:flutter/services.dart'; // HapticFeedback
import 'dart:async';
import 'dart:math' as math;
import 'package:wakelock_plus/wakelock_plus.dart';
import 'package:flutter_overlay_window/flutter_overlay_window.dart';
import 'package:bg_launcher/bg_launcher.dart';
import '../config/speed_unit.dart';
import '../config/color_themes.dart';
import '../config/timing_constants.dart';
import '../config/overlay_constants.dart';
import '../models/overlay_message.dart';
import '../models/processed_gps_data.dart';
import '../services/gps_data_manager.dart';
import '../services/logger.dart';

class SpeedometerScreen extends StatefulWidget {
  final bool isOverlayMode;

  const SpeedometerScreen({super.key, this.isOverlayMode = false});

  @override
  State<SpeedometerScreen> createState() => _SpeedometerScreenState();
}

class _SpeedometerScreenState extends State<SpeedometerScreen> with WidgetsBindingObserver {
  SpeedUnit _currentUnit = SpeedUnit.kmh;
  int _currentThemeIndex = 0;
  StreamSubscription<ProcessedGpsData>? _gpsDataSubscription;
  StreamSubscription<dynamic>? _overlaySubscription;
  ProcessedGpsData _currentGpsData = const ProcessedGpsData(
    speed: 0.0,
    heading: -1.0,
    displaySpeed: '--',
    displayHeading: 'N/A',
    isSpeedValid: false,
    isHeadingValid: false,
  );
  String _errorMessage = '';
  bool _isInBackground = false;
  bool _isOverlayActive = false;
  bool _tapCloseRequested = false;
  Timer? _tapCloseTimer;

  // Single source of truth for overlay sizing
  Map<String, int> _getOverlaySize() {
    final window = WidgetsBinding.instance.platformDispatcher.views.first;
    final physicalSize = window.physicalSize;

    // Use actual physical pixels for overlay sizing
    final overlayWidth = (physicalSize.width * OverlayConfig.WIDTH_PERCENTAGE).round();
    final overlayHeight = (overlayWidth * OverlayConfig.ASPECT_RATIO).round();

    return {'width': overlayWidth, 'height': overlayHeight};
  }

  Timer? _backgroundHeartbeatTimer;
  Timer? _overlayStatusCheckTimer;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _initializeGpsManager();
    _enableWakelock();
    _ensureOverlayPermission();
    // Overlay listener will be created lazily when overlay is shown
    _startBackgroundHeartbeat();
  }

  void _startListeningToOverlayMessages() {
    // Only create listener when overlay is actually shown
    if (_overlaySubscription != null) {
      return;
    }
    _overlaySubscription = FlutterOverlayWindow.overlayListener.listen(
      (data) {
        try {
          if (data is Map) {
            final action = data['action'];
            switch (action) {
              case 'overlayClosed':
                _handleOverlayClose();
                break;
              case 'longPressClose':
                _tapCloseRequested = true; // Reusing the flag for long press
                // Set a timer to reset this flag if overlay doesn't close soon
                _tapCloseTimer?.cancel();
                _tapCloseTimer = Timer(TimingConfig.TAP_CLOSE_DELAY, () {
                  _tapCloseRequested = false;
                });
                break;
              // 'bringToFront' action handler removed per NOTES.txt (tap to bring front functionality disabled)
              default:
                Logger.warn('Unknown overlay action: "$action"', 'Main');
            }
          }
        } catch (e, stackTrace) {
          Logger.error('Error processing overlay message: $e', 'Main');
          Logger.error('Stack trace: $stackTrace', 'Main');
        }
      },
      onError: (error) {
        Logger.error('Overlay listener error: $error', 'Main');
      },
    );
  }

  void _stopListeningToOverlayMessages() {
    _overlaySubscription?.cancel();
    _overlaySubscription = null;
  }

  void _startOverlayStatusCheck() {
    // Cancel any existing timer first
    _overlayStatusCheckTimer?.cancel();

    _overlayStatusCheckTimer = Timer.periodic(TimingConfig.OVERLAY_STATUS_CHECK_INTERVAL, (timer) async {
      if (_isOverlayActive) {
        try {
          final isActive = await FlutterOverlayWindow.isActive();
          if (!isActive) {
            timer.cancel(); // Cancel the timer before handling close
            _handleOverlayClose();
          }
        } catch (e) {
          Logger.error('Overlay status check failed: $e', 'Main');
        }
      } else {
        // If overlay is not supposed to be active, cancel the timer
        timer.cancel();
      }
    });
    Logger.debug('Started overlay status monitoring', 'Main');
  }

  void _handleOverlayClose({bool bringToForeground = false}) {
    // Check if this was a long-press close based on recent signal
    final shouldBringToFront = bringToForeground || _tapCloseRequested;

    // Cancel timers and reset flag
    _tapCloseTimer?.cancel();
    _overlayStatusCheckTimer?.cancel();
    _tapCloseRequested = false;

    setState(() {
      _isOverlayActive = false;
    });
    _stopListeningToOverlayMessages(); // Clean up listener when overlay closes

    // Bring app to foreground on long press close, otherwise quiet close
    if (shouldBringToFront) {
      _bringAppToFront();
    }
  }


  void _startBackgroundHeartbeat() {
    // Aggressive heartbeat to keep main app process active for overlay communication
    _backgroundHeartbeatTimer = Timer.periodic(TimingConfig.HEARTBEAT_INTERVAL, (timer) {
      if (_isInBackground && _isOverlayActive) {
        // Minimal activity to prevent hibernation
        if (mounted) {
          // Force data push to overlay to maintain communication
          _pushDataToOverlay();
          // Small state update to keep Flutter engine active
          setState(() {
            // Tiny update that doesn't affect UI but keeps engine alive
            _isInBackground = _isInBackground;
          });
        }
      } else if (_isInBackground) {
        if (mounted) {
          // Lighter heartbeat when no overlay is active
          setState(() {
            _isInBackground = _isInBackground;
          });
        }
      }
    });
  }

  void _bringAppToFront() async {
    try {
      // Use proper Android method to bring app to foreground
      BgLauncher.bringAppToForeground();

      // Update app state to reflect foreground status
      if (mounted) {
        setState(() {
          _isInBackground = false;
        });
      }
    } catch (e) {
      Logger.error('BgLauncher failed to bring app to front: $e', 'Main');

      // Enhanced fallback: try alternative approach
      try {
        if (mounted) {
          setState(() {
            _isInBackground = false;
          });
        }
      } catch (fallbackError) {
        Logger.error('Fallback method also failed: $fallbackError', 'Main');
      }
    }
  }

  Future<void> _enableWakelock() async {
    try {
      // Force enable wake lock even if already enabled for robustness
      await WakelockPlus.enable();
      final isEnabled = await WakelockPlus.enabled;

      // Double-check wake lock status for debugging
      if (!isEnabled) {
        Logger.warn('Wake lock not properly enabled, retrying...', 'Main');
        await WakelockPlus.enable();
      }
    } catch (e) {
      Logger.error('Wake lock failed: $e', 'Main');
      // Wake lock not supported on this platform, continue normally
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    _gpsDataSubscription?.cancel();
    _overlaySubscription?.cancel();
    _backgroundHeartbeatTimer?.cancel();
    _overlayStatusCheckTimer?.cancel();
    _tapCloseTimer?.cancel();
    WakelockPlus.disable();
    Logger.info('Main app disposed - all subscriptions and timers canceled', 'Main');
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);

    switch (state) {
      case AppLifecycleState.paused:
        // App went to background (home key pressed or task switch)
        if (!_isInBackground) {
          _isInBackground = true;
          _handleBackgroundTransition();
        }
        break;
      case AppLifecycleState.resumed:
        // App came back to foreground
        _isInBackground = false;
        break;
      case AppLifecycleState.inactive:
      case AppLifecycleState.detached:
      case AppLifecycleState.hidden:
        break;
    }
  }

  void _handleBackgroundTransition() {
    // Enhanced background persistence - keep GPS stream active
    _enableWakelock();
    _requestBatteryOptimizationExemption();

    // If overlay is active, ensure more frequent data pushing
    if (_isOverlayActive) {
      _pushDataToOverlay();
    }
  }

  Future<void> _requestBatteryOptimizationExemption() async {
    try {
      // This would show Android's battery optimization whitelist dialog
      // Note: This requires platform-specific implementation which we'd need to add via method channel
      // For now, we'll rely on other persistence mechanisms
    } catch (e) {
      Logger.warn('Battery optimization exemption not available: $e', 'Main');
    }
  }

  Future<void> _ensureOverlayPermission() async {
    try {
      // Check if overlay permission is granted (required for bg_launcher to work properly)
      final isGranted = await FlutterOverlayWindow.isPermissionGranted();

      if (!isGranted) {
        await FlutterOverlayWindow.requestPermission();
      }
    } catch (e) {
      Logger.error('Error checking overlay permission: $e', 'Main');
    }
  }

  Future<void> _initializeGpsManager() async {
    Logger.info('Starting GPS manager initialization...', 'Main');
    try {
      // Initialize the GPS manager
      Logger.debug('Calling GpsDataManager.instance.initialize()...', 'Main');
      await GpsDataManager.instance.initialize();
      Logger.info('GPS manager initialization completed', 'Main');

      // Subscribe to processed GPS data
      Logger.debug('Setting up data stream subscription...', 'Main');
      _gpsDataSubscription = GpsDataManager.instance.dataStream.listen(
        _onGpsDataUpdate,
        onError: (error) {
          Logger.error('GPS data stream error: $error', 'Main');
          setState(() => _errorMessage = 'GPS manager error: $error');
        },
      );
      Logger.info('GPS data stream subscription active', 'Main');

      Logger.info('GPS manager initialized and subscribed', 'Main');
    } catch (e) {
      Logger.error('GPS manager initialization exception: $e', 'Main');
      setState(() => _errorMessage = 'Failed to initialize GPS manager');
      Logger.error('GPS manager initialization failed: $e', 'Main');
    }
  }

  void _onGpsDataUpdate(ProcessedGpsData gpsData) {
    Logger.debug('Received GPS data: ${gpsData.speed.toStringAsFixed(1)} m/s, ${gpsData.displayHeading}', 'Main');

    setState(() {
      _currentGpsData = gpsData;
      _errorMessage = '';
    });

    Logger.debug('State updated with GPS data', 'Main');
    final convertedSpeed = _currentUnit.convert(gpsData.speed);
    Logger.debug('Converted for display: ${convertedSpeed.toStringAsFixed(1)} ${_currentUnit.label}, ${gpsData.displayHeading}', 'Main');

    // Always push display data to overlay if active - critical for background communication
    if (_isOverlayActive) {
      _pushDataToOverlay();
      Logger.debug('Data pushed to overlay from GPS update', 'Main');
    }
  }


  void _pushDataToOverlay() {
    // Only push data if overlay is actually active (listener check was causing race conditions)
    if (!_isOverlayActive) {
      Logger.debug('Skipping data push - no active overlay (active: $_isOverlayActive, subscription: ${_overlaySubscription != null})', 'Main');
      return;
    }

    Logger.debug('Overlay guard passed - pushing data (active: $_isOverlayActive, subscription: ${_overlaySubscription != null})', 'Main');

    // Get formatted speed for current unit from GPS manager
    final speedText = GpsDataManager.instance.getFormattedSpeed(_currentUnit);
    final unitText = _currentUnit.label.toString();
    final headingText = _currentGpsData.displayHeading;

    Logger.debug('SENDING to overlay:', 'Main');
    Logger.debug('  speedText: "$speedText"', 'Main');
    Logger.debug('  headingText: "$headingText"', 'Main');
    Logger.debug('  direction: ${_currentGpsData.heading.toStringAsFixed(1)}°', 'Main');
    Logger.debug('  unit: $unitText, theme: $_currentThemeIndex', 'Main');

    FlutterOverlayWindow.shareData(OverlayMessage.updateDisplay(
      speedText: speedText,
      unitText: unitText,
      headingText: headingText,
      heading: _currentGpsData.heading,
      unitIndex: _currentUnit.index,
      themeIndex: _currentThemeIndex,
    ).toMap());
  }

  void _cycleUnit() {
    HapticFeedback.lightImpact();
    setState(() {
      _currentUnit = _currentUnit.next;
    });
    // Push updated display data to overlay
    _pushDataToOverlay();
  }

  void _cycleTheme() {
    HapticFeedback.lightImpact();
    setState(() {
      _currentThemeIndex = ColorThemes.getNextThemeIndex(_currentThemeIndex);
    });
    // Push updated display data to overlay
    _pushDataToOverlay();
  }

  Future<void> _showFloatingWindow() async {
    try {
      // Use centralized sizing function
      final overlaySize = _getOverlaySize();

      // Send initial display data WITH size info (only needed on creation)
      final speedText = GpsDataManager.instance.getFormattedSpeed(_currentUnit);
      final headingText = _currentGpsData.displayHeading;
      final unitText = _currentUnit.label.toString();

      await FlutterOverlayWindow.shareData(OverlayMessage.updateDisplay(
        speedText: speedText,
        unitText: unitText,
        headingText: headingText,
        heading: _currentGpsData.heading,
        unitIndex: _currentUnit.index,
        themeIndex: _currentThemeIndex,
        overlayWidth: overlaySize['width']!.toDouble(),
        overlayHeight: overlaySize['height']!.toDouble(),
      ).toMap());

      // Show the overlay with proportional sizing based on system resolution
      await FlutterOverlayWindow.showOverlay(
        enableDrag: true,
        overlayTitle: "Speedometer",
        overlayContent: 'Speedo overlay active',
        flag: OverlayFlag.defaultFlag,
        visibility: NotificationVisibility.visibilityPublic,
        positionGravity: PositionGravity.none,
        // Use consistent sizing from centralized function
        width: overlaySize['width']!,
        height: overlaySize['height']!,
      );

      Logger.info('OVERLAY LAUNCHED - Size: ${overlaySize['width']}x${overlaySize['height']}', 'Main');

      // Set overlay active immediately and synchronously
      _isOverlayActive = true;
      Logger.debug('_isOverlayActive set to: $_isOverlayActive', 'Main');

      // Start listening to overlay messages after state is set
      _startListeningToOverlayMessages();

      // Start periodic overlay status check since message-based detection is unreliable
      _startOverlayStatusCheck();

      // Force UI update
      if (mounted) setState(() {});
    } catch (e) {
      // Silent error handling - floating window issues shouldn't crash main app
    }
  }

  Future<void> _closeFloatingWindow() async {
    if (!_isOverlayActive) {
      Logger.warn('No overlay to close', 'Main');
      return;
    }

    try {
      await FlutterOverlayWindow.closeOverlay();
      Logger.info('OVERLAY CLOSED - Requested from main app', 'Main');
      _handleOverlayClose(); // This will set _isOverlayActive = false and stop listener
    } catch (e) {
      Logger.error('Error closing overlay: $e', 'Main');
    }
  }

  String _getSpeedDisplayText(double displaySpeed) {
    // TEMPORARILY disabled for indoor testing - show all speeds
    // TODO: Re-enable: if (_currentGpsData.speed < 1.0 && (_currentGpsData.heading < 0.0 || _currentGpsData.heading >= 360.0)) return '--';
    return displaySpeed.toStringAsFixed(1);
  }

  Widget _buildSpeedDisplay(String speedText, ColorTheme currentTheme, double fontSize, {bool isLandscape = false}) {
    if (speedText == '--') {
      return Text(
        speedText,
        style: TextStyle(
          fontSize: fontSize,
          fontWeight: FontWeight.w300,
          color: currentTheme.speedText,
          fontFamily: 'DIN1451Alt',
        ),
      );
    }

    // Split speed into integral and decimal parts
    final parts = speedText.split('.');
    final integralPart = parts[0];
    final decimalPart = parts.length > 1 ? '.${parts[1]}' : '.0';

    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      crossAxisAlignment: CrossAxisAlignment.baseline,
      textBaseline: TextBaseline.alphabetic,
      children: [
        Text(
          integralPart,
          style: TextStyle(
            fontSize: fontSize,
            fontWeight: FontWeight.w300,
            color: currentTheme.speedText,
            fontFamily: 'DIN1451Alt',
          ),
        ),
        Text(
          decimalPart,
          style: TextStyle(
            fontSize: fontSize * 0.5, // 60% of main font size
            fontWeight: FontWeight.w300,
            color: currentTheme.speedTextSub,
            fontFamily: 'DIN1451Alt',
          ),
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    final displaySpeed = _currentUnit.convert(_currentGpsData.speed);
    final speedText = _getSpeedDisplayText(displaySpeed);
    final currentTheme = ColorThemes.getTheme(_currentThemeIndex);

    return Scaffold(
      backgroundColor: currentTheme.background,
      body: SafeArea(
        child: LayoutBuilder(
          builder: (context, constraints) {
            final isLandscape = constraints.maxWidth > constraints.maxHeight;

            if (isLandscape) {
              return _buildLandscapeLayout(speedText, currentTheme);
            } else {
              return _buildPortraitLayout(speedText, currentTheme);
            }
          },
        ),
      ),
    );
  }

  Widget _buildPortraitLayout(String speedText, ColorTheme currentTheme) {
    return Column(
      children: [
        // Speed area - takes most space, precise tap targets on text only
        Expanded(
          flex: 65,
          child: Container(
            width: double.infinity,
            color: Colors.transparent,
            padding: const EdgeInsets.all(4),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                if (_errorMessage.isNotEmpty)
                  Flexible(
                    child: Text(
                      _errorMessage,
                      style: TextStyle(
                        color: currentTheme.speedText,
                        fontSize: 18,
                        fontFamily: 'DIN1451Alt',
                      ),
                      textAlign: TextAlign.center,
                    ),
                  )
                else ...[
                  Flexible(
                    flex: 7,
                    child: GestureDetector(
                      onTap: _cycleTheme, // Tap speed to cycle theme
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: _buildSpeedDisplay(speedText, currentTheme, 200),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 1,
                    child: FittedBox(
                      fit: BoxFit.contain,
                    ),
                  ),
                  Flexible(
                    flex: 2,
                    child: GestureDetector(
                      onTap: _cycleUnit, // clicking on unit to cycle unit is more intuitive
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: Text(
                          _currentUnit.label,
                          style: TextStyle(
                            fontSize: 80,
                            color: currentTheme.unitText,
                            fontFamily: 'DIN1451Alt',
                          ),
                        ),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 1,
                    child: FittedBox(
                      fit: BoxFit.contain,
                    ),
                  ),
                ],
              ],
            ),
          ),
        ),
        // Compass area - compact but fully tappable for floating window
        Expanded(
          flex: 32,
          child: GestureDetector(
            onTap: () {
              HapticFeedback.lightImpact();
              Logger.debug('Navigation area tapped - overlay active: $_isOverlayActive', 'Main');
              if (_isOverlayActive) {
                _closeFloatingWindow();
              } else {
                _showFloatingWindow();
              }
            },
            onLongPress: () {
              Logger.debug('Navigation area long-pressed - overlay active: $_isOverlayActive', 'Main');
              _closeFloatingWindow();
            },
            child: Container(
              width: double.infinity,
              color: Colors.transparent,
              padding: const EdgeInsets.all(2),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Flexible(
                    flex: 3,
                    child: Transform.rotate(
                      angle: (_currentGpsData.heading >= 0 && _currentGpsData.heading < 360) ? (_currentGpsData.heading * math.pi / 180.0) : 0,
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: Icon(
                          Icons.navigation,
                          size: 80,
                          color: currentTheme.headingText,
                        ),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 1,
                    child: FittedBox(
                      fit: BoxFit.contain,
                      child: Text(
                        _currentGpsData.displayHeading,
                        style: TextStyle(
                          fontSize: 50,
                          color: currentTheme.headingText,
                          fontFamily: 'DIN1451Alt',
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildLandscapeLayout(String speedText, ColorTheme currentTheme) {
    return Row(
      children: [
        // Speed area - takes majority of space, precise tap targets on text only
        Expanded(
          flex: 60,
          child: Container(
            height: double.infinity,
            color: Colors.transparent,
            padding: const EdgeInsets.all(3),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                if (_errorMessage.isNotEmpty)
                  Flexible(
                    child: Text(
                      _errorMessage,
                      style: TextStyle(
                        color: currentTheme.speedText,
                        fontSize: 16,
                        fontFamily: 'DIN1451Alt',
                      ),
                      textAlign: TextAlign.center,
                    ),
                  )
                else ...[
                  Flexible(
                    flex: 1,
                    child: FittedBox(),
                  ),
                  Flexible(
                    flex: 20,
                    child: GestureDetector(
                      onTap: _cycleTheme,
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: _buildSpeedDisplay(speedText, currentTheme, 160, isLandscape: true),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 7,
                    child: GestureDetector(
                      onTap: _cycleUnit,
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: Text(
                          _currentUnit.label,
                          style: TextStyle(
                            fontSize: 50,
                            color: currentTheme.unitText,
                            fontFamily: 'DIN1451Alt',
                          ),
                        ),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 5,
                    child: FittedBox(),
                  ),
                ],
              ],
            ),
          ),
        ),
        // Compass area - smaller but fully tappable for floating window
        Expanded(
          flex: 35,
          child: GestureDetector(
            onTap: () {
              HapticFeedback.lightImpact();
              Logger.debug('Navigation area tapped (landscape) - overlay active: $_isOverlayActive', 'Main');
              if (_isOverlayActive) {
                _closeFloatingWindow();
              } else {
                _showFloatingWindow();
              }
            },
            onLongPress: () {
              Logger.debug('Navigation area long-pressed (landscape) - overlay active: $_isOverlayActive', 'Main');
              _closeFloatingWindow();
            },
            child: Container(
              height: double.infinity,
              color: Colors.transparent,
              padding: const EdgeInsets.all(2),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Flexible(
                    flex: 3,
                    child: Transform.rotate(
                      angle: (_currentGpsData.heading >= 0 && _currentGpsData.heading < 360) ? (_currentGpsData.heading * math.pi / 180.0) : 0,
                      child: FittedBox(
                        fit: BoxFit.contain,
                        child: Icon(
                          Icons.navigation,
                          size: 60,
                          color: currentTheme.headingText,
                        ),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: 1,
                    child: FittedBox(
                      fit: BoxFit.contain,
                      child: Text(
                        _currentGpsData.displayHeading,
                        style: TextStyle(
                          fontSize: 30,
                          color: currentTheme.headingText,
                          fontFamily: 'DIN1451Alt',
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
        Expanded(
          flex: 1,
          child: FittedBox(
            fit: BoxFit.contain,
          ),
        ),
      ],
    );
  }
}