import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:permission_handler/permission_handler.dart';
import 'bridge/location_bridge.dart';
import 'preferences.dart';
import 'main_screen.dart';

class PermissionScreen extends StatefulWidget {
  const PermissionScreen({super.key});

  @override
  State<PermissionScreen> createState() => _PermissionScreenState();
}

class _PermissionScreenState extends State<PermissionScreen> {
  bool _locationGranted = false;
  bool _notificationGranted = false;
  bool _batteryOptOut = false;

  @override
  void initState() {
    super.initState();
    SystemChrome.setSystemUIOverlayStyle(
      const SystemUiOverlayStyle(
        statusBarColor: Color(0xFF0d0d0d),
        statusBarIconBrightness: Brightness.light,
      ),
    );
    _checkPermissions();
  }

  Future<void> _checkPermissions() async {
    final location = await Permission.locationAlways.status;
    final notification = await Permission.notification.status;
    final batteryOptOut = await _isBatteryOptimizationDisabled();

    if (mounted) {
      setState(() {
        _locationGranted = location.isGranted;
        _notificationGranted = notification.isGranted;
        _batteryOptOut = batteryOptOut;
      });
    }
  }

  Future<bool> _isBatteryOptimizationDisabled() async {
    try {
      final result = await LocationBridge.isBatteryOptimizationDisabled();
      return result == true;
    } catch (_) {
      return false;
    }
  }

  bool get _allGranted =>
      _locationGranted && _notificationGranted && _batteryOptOut;

  Future<void> _requestLocation() async {
    // Check current status first
    var status = await Permission.locationAlways.status;
    if (status.isGranted) {
      if (mounted) setState(() => _locationGranted = true);
      return;
    }

    // On Android, request locationWhenInUse first before locationAlways
    var whenInUse = await Permission.locationWhenInUse.status;
    if (!whenInUse.isGranted) {
      whenInUse = await Permission.locationWhenInUse.request();
    }

    // Now request locationAlways (background permission)
    status = await Permission.locationAlways.request();

    if (!status.isGranted && status.isPermanentlyDenied) {
      await openAppSettings();
    }

    final finalStatus = await Permission.locationAlways.status;
    if (mounted) {
      setState(() => _locationGranted = finalStatus.isGranted);
    }
  }

  Future<void> _requestNotification() async {
    var status = await Permission.notification.status;
    if (status.isGranted) {
      if (mounted) setState(() => _notificationGranted = true);
      return;
    }

    status = await Permission.notification.request();

    if (!status.isGranted && status.isPermanentlyDenied) {
      await openAppSettings();
    }

    final finalStatus = await Permission.notification.status;
    if (mounted) {
      setState(() => _notificationGranted = finalStatus.isGranted);
    }
  }

  Future<void> _requestBatteryOptOut() async {
    final opened = await LocationBridge.openBatteryOptimizationSettings();
    if (mounted) {
      _showBatteryOptDialog(opened);
    }
  }

  void _showBatteryOptDialog(bool settingsOpened) {
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (ctx) => AlertDialog(
        backgroundColor: const Color(0xFF1a1a1a),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(4),
          side: const BorderSide(color: Color(0xFF2a2a2a)),
        ),
        title: const Text(
          'BATTERY OPTIMIZATION',
          style: TextStyle(
            fontFamily: 'monospace',
            fontSize: 14,
            fontWeight: FontWeight.w700,
            letterSpacing: 2,
            color: Color(0xFFe0e0e0),
          ),
        ),
        content: Text(
          settingsOpened
              ? 'A settings screen has opened.\n\n'
                    'Find "TracPulse" and set it to "Don\'t optimize" or "Unrestricted", then come back and tap CHECK & DONE.'
              : 'Open Settings → Apps → TracPulse → Battery and select "Don\'t optimize" or "Unrestricted", then come back and tap CHECK & DONE.',
          style: const TextStyle(
            fontFamily: 'monospace',
            fontSize: 12,
            color: Color(0xFF9e9e9e),
          ),
        ),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.pop(ctx);
              openAppSettings();
            },
            child: const Text(
              'OPEN APP SETTINGS',
              style: TextStyle(
                fontFamily: 'monospace',
                fontSize: 11,
                fontWeight: FontWeight.w700,
                letterSpacing: 1,
                color: Color(0xFF00bcd4),
              ),
            ),
          ),
          TextButton(
            onPressed: () async {
              Navigator.pop(ctx);
              final disabled = await _isBatteryOptimizationDisabled();
              if (mounted) {
                setState(() => _batteryOptOut = disabled);
              }
            },
            child: const Text(
              'CHECK & DONE',
              style: TextStyle(
                fontFamily: 'monospace',
                fontSize: 11,
                fontWeight: FontWeight.w700,
                letterSpacing: 1,
                color: Color(0xFF00e676),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Future<void> _complete() async {
    await Preferences.setPermissionsGranted(true);
    if (mounted) {
      Navigator.pushReplacement(
        context,
        MaterialPageRoute(builder: (_) => const MainScreen()),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFF0d0d0d),
      body: SafeArea(
        child: Column(
          children: [
            _buildHeader(),
            Expanded(
              child: SingleChildScrollView(
                padding: const EdgeInsets.all(20),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    _buildIntroCard(),
                    const SizedBox(height: 20),
                    _buildPermissionItem(
                      icon: Icons.location_on,
                      title: 'LOCATION',
                      subtitle: 'All the time access',
                      granted: _locationGranted,
                      onRequest: _requestLocation,
                    ),
                    const SizedBox(height: 12),
                    _buildPermissionItem(
                      icon: Icons.notifications,
                      title: 'NOTIFICATION',
                      subtitle: 'Show sync & tracking alerts',
                      granted: _notificationGranted,
                      onRequest: _requestNotification,
                    ),
                    const SizedBox(height: 12),
                    _buildPermissionItem(
                      icon: Icons.battery_full,
                      title: 'BATTERY',
                      subtitle: 'Disable optimization for reliability',
                      granted: _batteryOptOut,
                      onRequest: _requestBatteryOptOut,
                    ),
                    const SizedBox(height: 32),
                    _buildStatusSummary(),
                    const SizedBox(height: 24),
                    _buildContinueButton(),
                    const SizedBox(height: 20),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 16),
      decoration: const BoxDecoration(
        color: Color(0xFF161616),
        border: Border(bottom: BorderSide(color: Color(0xFF2a2a2a), width: 1)),
      ),
      child: const Row(
        children: [
          Icon(Icons.shield, color: Color(0xFF00bcd4), size: 20),
          SizedBox(width: 12),
          Text(
            'PERMISSIONS',
            style: TextStyle(
              fontFamily: 'monospace',
              fontSize: 16,
              fontWeight: FontWeight.w700,
              letterSpacing: 3,
              color: Color(0xFFe0e0e0),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildIntroCard() {
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: const Color(0xFF161616),
        borderRadius: BorderRadius.circular(4),
        border: Border.all(color: const Color(0xFF2a2a2a), width: 1),
      ),
      child: Row(
        children: [
          Container(
            width: 40,
            height: 40,
            decoration: const BoxDecoration(
              color: Color(0xFF00bcd4),
              borderRadius: BorderRadius.all(Radius.circular(4)),
            ),
            child: const Icon(
              Icons.info_outline,
              color: Colors.white,
              size: 20,
            ),
          ),
          const SizedBox(width: 14),
          const Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'Required Permissions',
                  style: TextStyle(
                    fontFamily: 'monospace',
                    fontSize: 13,
                    fontWeight: FontWeight.w700,
                    letterSpacing: 1,
                    color: Color(0xFFe0e0e0),
                  ),
                ),
                SizedBox(height: 4),
                Text(
                  'TracPulse needs these permissions to track your location reliably in the background.',
                  style: TextStyle(
                    fontFamily: 'monospace',
                    fontSize: 11,
                    color: Color(0xFF757575),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildPermissionItem({
    required IconData icon,
    required String title,
    required String subtitle,
    required bool granted,
    required VoidCallback onRequest,
  }) {
    return Material(
      color: const Color(0xFF161616),
      borderRadius: BorderRadius.circular(4),
      child: InkWell(
        onTap: granted ? null : onRequest,
        borderRadius: BorderRadius.circular(4),
        child: Container(
          padding: const EdgeInsets.all(14),
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(4),
            border: Border.all(
              color: granted
                  ? const Color(0xFF00e676).withValues(alpha: 0.3)
                  : const Color(0xFF2a2a2a),
              width: 1,
            ),
          ),
          child: Row(
            children: [
              Container(
                width: 36,
                height: 36,
                decoration: BoxDecoration(
                  color: granted
                      ? const Color(0xFF00e676).withValues(alpha: 0.15)
                      : const Color(0xFF2a2a2a),
                  borderRadius: BorderRadius.circular(4),
                ),
                child: Icon(
                  icon,
                  color: granted
                      ? const Color(0xFF00e676)
                      : const Color(0xFF616161),
                  size: 18,
                ),
              ),
              const SizedBox(width: 14),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      title,
                      style: const TextStyle(
                        fontFamily: 'monospace',
                        fontSize: 12,
                        fontWeight: FontWeight.w700,
                        letterSpacing: 1,
                        color: Color(0xFFe0e0e0),
                      ),
                    ),
                    const SizedBox(height: 2),
                    Text(
                      subtitle,
                      style: const TextStyle(
                        fontFamily: 'monospace',
                        fontSize: 10,
                        color: Color(0xFF616161),
                      ),
                    ),
                  ],
                ),
              ),
              if (granted)
                Container(
                  padding: const EdgeInsets.symmetric(
                    horizontal: 8,
                    vertical: 4,
                  ),
                  decoration: BoxDecoration(
                    color: const Color(0xFF00e676).withValues(alpha: 0.15),
                    borderRadius: BorderRadius.circular(3),
                    border: Border.all(
                      color: const Color(0xFF00e676).withValues(alpha: 0.4),
                      width: 1,
                    ),
                  ),
                  child: const Text(
                    'GRANTED',
                    style: TextStyle(
                      fontFamily: 'monospace',
                      fontSize: 9,
                      fontWeight: FontWeight.w700,
                      letterSpacing: 1,
                      color: Color(0xFF00e676),
                    ),
                  ),
                )
              else
                Container(
                  padding: const EdgeInsets.symmetric(
                    horizontal: 8,
                    vertical: 4,
                  ),
                  decoration: BoxDecoration(
                    color: const Color(0xFF00bcd4).withValues(alpha: 0.1),
                    borderRadius: BorderRadius.circular(3),
                    border: Border.all(
                      color: const Color(0xFF00bcd4).withValues(alpha: 0.4),
                      width: 1,
                    ),
                  ),
                  child: const Text(
                    'TAP TO GRANT',
                    style: TextStyle(
                      fontFamily: 'monospace',
                      fontSize: 9,
                      fontWeight: FontWeight.w700,
                      letterSpacing: 1,
                      color: Color(0xFF00bcd4),
                    ),
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildStatusSummary() {
    final granted = [
      _locationGranted,
      _notificationGranted,
      _batteryOptOut,
    ].where((x) => x).length;
    const total = 3;
    final progress = granted / total;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            Icon(
              granted == total
                  ? Icons.check_circle
                  : Icons.check_circle_outline,
              color: const Color(0xFF00e676),
              size: 14,
            ),
            const SizedBox(width: 8),
            Text(
              '$granted / $total GRANTED',
              style: const TextStyle(
                fontFamily: 'monospace',
                fontSize: 11,
                fontWeight: FontWeight.w700,
                letterSpacing: 1,
                color: Color(0xFF00e676),
              ),
            ),
          ],
        ),
        const SizedBox(height: 10),
        Container(
          height: 4,
          decoration: BoxDecoration(
            color: const Color(0xFF2a2a2a),
            borderRadius: BorderRadius.circular(2),
          ),
          child: FractionallySizedBox(
            alignment: Alignment.centerLeft,
            widthFactor: progress,
            child: Container(
              decoration: BoxDecoration(
                color: const Color(0xFF00e676),
                borderRadius: BorderRadius.circular(2),
              ),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildContinueButton() {
    return Material(
      color: _allGranted
          ? const Color(0xFF00e676).withValues(alpha: 0.15)
          : const Color(0xFF2a2a2a),
      borderRadius: BorderRadius.circular(4),
      child: InkWell(
        onTap: _allGranted ? _complete : null,
        borderRadius: BorderRadius.circular(4),
        child: Container(
          width: double.infinity,
          padding: const EdgeInsets.symmetric(vertical: 16),
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(4),
            border: Border.all(
              color: _allGranted
                  ? const Color(0xFF00e676).withValues(alpha: 0.4)
                  : const Color(0xFF2a2a2a),
              width: 1,
            ),
          ),
          child: Center(
            child: Text(
              _allGranted ? 'CONTINUE' : 'GRANT ALL PERMISSIONS',
              style: TextStyle(
                fontFamily: 'monospace',
                fontSize: 13,
                fontWeight: FontWeight.w700,
                letterSpacing: 2,
                color: _allGranted
                    ? const Color(0xFF00e676)
                    : const Color(0xFF616161),
              ),
            ),
          ),
        ),
      ),
    );
  }
}