import 'dart:io';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart';
import 'package:path/path.dart' as p;

import 'package:environment_monitoring_app/auth_provider.dart';
import 'package:environment_monitoring_app/services/api_service.dart';

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

  @override
  State<ProfileScreen> createState() => _ProfileScreenState();
}

class _ProfileScreenState extends State<ProfileScreen> {
  // FIX: Removed direct instantiation of ApiService
  bool _isLoading = false;
  String _errorMessage = '';
  File? _profileImageFile;

  // FIX: Use late initialization to retrieve the service instance.
  late ApiService _apiService;

  @override
  void initState() {
    super.initState();

    // FIX: Retrieve the ApiService instance after the context is fully available.
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _apiService = Provider.of<ApiService>(context, listen: false);
      _loadLocalProfileImage().then((_) {
        // If no profile data is available at all, trigger a refresh
        if (Provider.of<AuthProvider>(context, listen: false).profileData == null) {
          _refreshProfile();
        }
      });
    });
  }

  /// Refreshes only the profile data using the dedicated provider method.
  Future<void> _refreshProfile() async {
    setState(() {
      _isLoading = true;
      _errorMessage = '';
    });

    try {
      final auth = Provider.of<AuthProvider>(context, listen: false);
      // Call the efficient refreshProfile method instead of the full sync.
      await auth.refreshProfile();
      // After syncing, reload the potentially new profile image
      await _loadLocalProfileImage();
    } catch (e) {
      if (mounted) {
        setState(() {
          _errorMessage = 'An unexpected error occurred during sync: ${e.toString()}';
        });
      }
    } finally {
      if (mounted) {
        setState(() {
          _isLoading = false;
        });
      }
    }
  }

  /// Loads the profile image from the local cache or downloads it if not present.
  Future<void> _loadLocalProfileImage() async {
    final auth = Provider.of<AuthProvider>(context, listen: false);
    final String? serverImagePath = auth.profileData?['profile_picture'];

    if (serverImagePath != null && serverImagePath.isNotEmpty) {
      final String localFileName = p.basename(serverImagePath);
      final Directory appDocDir = await getApplicationDocumentsDirectory();
      final String localFilePath = p.join(appDocDir.path, 'profile_pictures', localFileName);
      final File localFile = File(localFilePath);

      if (await localFile.exists()) {
        if (mounted) setState(() => _profileImageFile = localFile);
      } else {
        final String fullImageUrl = ApiService.imageBaseUrl + serverImagePath;
        // FIX: Use the injected _apiService instance
        final downloadedFile = await _apiService.downloadProfilePicture(fullImageUrl, localFilePath);
        if (downloadedFile != null && mounted) {
          setState(() => _profileImageFile = downloadedFile);
        }
      }
    } else {
      if (mounted) setState(() => _profileImageFile = null);
    }
  }

  /// Shows a modal bottom sheet for selecting an image source.
  Future<void> _showImageSourceSelection() async {
    showModalBottomSheet(
      context: context,
      builder: (BuildContext context) {
        return SafeArea(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              ListTile(
                leading: const Icon(Icons.camera_alt),
                title: const Text('Take a photo'),
                onTap: () {
                  Navigator.pop(context);
                  _pickAndUploadImage(ImageSource.camera);
                },
              ),
              ListTile(
                leading: const Icon(Icons.photo_library),
                title: const Text('Choose from gallery'),
                onTap: () {
                  Navigator.pop(context);
                  _pickAndUploadImage(ImageSource.gallery);
                },
              ),
            ],
          ),
        );
      },
    );
  }

  /// Picks an image and initiates the upload process.
  Future<void> _pickAndUploadImage(ImageSource source) async {
    final ImagePicker picker = ImagePicker();
    final XFile? pickedFile = await picker.pickImage(source: source, imageQuality: 85, maxWidth: 1024);

    if (pickedFile != null) {
      setState(() => _isLoading = true);
      final File imageFile = File(pickedFile.path);

      // FIX: Use the injected _apiService instance
      final uploadResult = await _apiService.uploadProfilePicture(imageFile);

      if (mounted) {
        if (uploadResult['success']) {
          // After a successful upload, efficiently refresh only the profile data.
          await _refreshProfile();
          _showSnackBar("Profile picture updated successfully.", isError: false);
        } else {
          setState(() {
            _errorMessage = uploadResult['message'] ?? 'Failed to upload profile picture.';
          });
          _showSnackBar(_errorMessage, isError: true);
        }
        setState(() => _isLoading = false);
      }
    }
  }

  void _showSnackBar(String message, {bool isError = false}) {
    if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(message),
          backgroundColor: isError ? Theme.of(context).colorScheme.error : Colors.green,
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    final auth = Provider.of<AuthProvider>(context);
    final profileData = auth.profileData;

    return Scaffold(
      appBar: AppBar(
        title: const Text("User Profile"),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            onPressed: _isLoading ? null : _refreshProfile,
          ),
        ],
      ),
      body: Column(
        children: [
          Expanded(
            child: _isLoading && profileData == null
                ? const Center(child: CircularProgressIndicator())
                : _errorMessage.isNotEmpty
                ? Center(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Icon(Icons.error_outline, color: Theme.of(context).colorScheme.error, size: 50),
                    const SizedBox(height: 16),
                    Text(
                      _errorMessage,
                      textAlign: TextAlign.center,
                      style: TextStyle(color: Theme.of(context).colorScheme.error, fontSize: 16),
                    ),
                    const SizedBox(height: 24),
                    ElevatedButton(
                      onPressed: _isLoading ? null : _refreshProfile,
                      child: const Text('Retry'),
                    ),
                  ],
                ),
              ),
            )
                : profileData == null
                ? const Center(child: Text('No profile data available.'))
                : RefreshIndicator(
              onRefresh: _refreshProfile,
              child: SingleChildScrollView(
                physics: const AlwaysScrollableScrollPhysics(),
                padding: const EdgeInsets.all(24.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Center(
                      child: GestureDetector(
                        onTap: _isLoading ? null : _showImageSourceSelection,
                        child: Stack(
                          alignment: Alignment.bottomRight,
                          children: [
                            CircleAvatar(
                              radius: 60,
                              backgroundColor: Theme.of(context).colorScheme.secondary,
                              backgroundImage: _profileImageFile != null ? FileImage(_profileImageFile!) : null,
                              child: _profileImageFile == null ? Icon(Icons.person, size: 80, color: Theme.of(context).colorScheme.onSecondary) : null,
                            ),
                            if (!_isLoading)
                              Positioned(
                                right: 0,
                                bottom: 0,
                                child: CircleAvatar(
                                  radius: 20,
                                  backgroundColor: Theme.of(context).primaryColor,
                                  child: Icon(Icons.edit, color: Theme.of(context).colorScheme.onPrimary, size: 20),
                                ),
                              ),
                          ],
                        ),
                      ),
                    ),
                    const SizedBox(height: 32),
                    _buildProfileSection(context, "Personal Information", [
                      _buildProfileDetail(context, "Username:", profileData['username']),
                      _buildProfileDetail(context, "Email:", profileData['email']),
                      _buildProfileDetail(context, "First Name:", profileData['first_name']),
                      _buildProfileDetail(context, "Last Name:", profileData['last_name']),
                      _buildProfileDetail(context, "Phone Number:", profileData['phone_number']),
                    ]),
                    const SizedBox(height: 24),
                    _buildProfileSection(context, "Organizational Details", [
                      _buildProfileDetail(context, "Role:", profileData['role_name']),
                      _buildProfileDetail(context, "Department:", profileData['department_name']),
                      _buildProfileDetail(context, "Company:", profileData['company_name']),
                      _buildProfileDetail(context, "Position:", profileData['position_name']),
                    ]),
                    const SizedBox(height: 24),
                    _buildProfileSection(context, "Account Status", [
                      _buildProfileDetail(context, "Account Status:", profileData['account_status']),
                      _buildProfileDetail(context, "Registered On:", profileData['date_registered']),
                    ]),
                  ],
                ),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.all(24.0),
            child: Center(
              child: ElevatedButton.icon(
                icon: const Icon(Icons.logout),
                label: const Text("Logout"),
                onPressed: () {
                  showDialog(
                    context: context,
                    barrierDismissible: false,
                    builder: (dialogContext) => AlertDialog(
                      title: const Text("Confirm Logout"),
                      content: const Text("Are you sure you want to log out?"),
                      actions: [
                        TextButton(
                          onPressed: () => Navigator.pop(dialogContext),
                          child: const Text("Cancel"),
                        ),
                        ElevatedButton(
                          onPressed: () {
                            Navigator.pop(dialogContext);
                            auth.logout();
                            Navigator.pushNamedAndRemoveUntil(context, '/', (route) => false);
                          },
                          style: ElevatedButton.styleFrom(
                            backgroundColor: Colors.red[700],
                            foregroundColor: Colors.white,
                          ),
                          child: const Text("Logout"),
                        ),
                      ],
                    ),
                  );
                },
                style: ElevatedButton.styleFrom(
                  backgroundColor: Colors.red[700],
                  foregroundColor: Colors.white,
                  padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 16),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildProfileSection(BuildContext context, String title, List<Widget> details) {
    return Card(
      elevation: 4,
      margin: const EdgeInsets.symmetric(vertical: 8.0),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: Theme.of(context).textTheme.headlineSmall?.copyWith(fontWeight: FontWeight.bold, color: Theme.of(context).primaryColor),
            ),
            const Divider(height: 20, thickness: 1.5),
            ...details,
          ],
        ),
      ),
    );
  }

  Widget _buildProfileDetail(BuildContext context, String label, dynamic value) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 8.0),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Expanded(
            flex: 2,
            child: Text(
              label,
              style: Theme.of(context).textTheme.titleMedium?.copyWith(fontWeight: FontWeight.bold),
            ),
          ),
          const SizedBox(width: 16),
          Expanded(
            flex: 3,
            child: Text(
              value?.toString() ?? 'N/A',
              style: Theme.of(context).textTheme.bodyLarge,
            ),
          ),
        ],
      ),
    );
  }
}