import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import '../../core/constants/app_colors.dart';
import '../../core/constants/app_text_styles.dart';
import '../../data/services/api_service.dart';
import '../widgets/teacher_panel_scaffold.dart';
import 'course_page.dart';
import 'dashboard_page.dart';
import 'license_builder_page.dart';
import 'new_license_page.dart';
import 'ticket_page.dart';
import 'transaction_page.dart';

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

  @override
  State<PanelLicensePage> createState() => _PanelLicensePageState();
}

class _PanelLicensePageState extends State<PanelLicensePage> {
  bool _isLoadingCourses = true;
  bool _isLoadingLicenses = false;
  String? _errorMessage;

  List<Map<String, dynamic>> _courses = <Map<String, dynamic>>[];
  List<Map<String, dynamic>> _licenses = <Map<String, dynamic>>[];
  List<Map<String, dynamic>> _filteredLicenses = <Map<String, dynamic>>[];

  int? _selectedCourseId;
  int _currentPage = 1;
  int _lastPage = 1;

  final TextEditingController _searchController = TextEditingController();

  @override
  void initState() {
    super.initState();
    _loadCoursesAndInitialLicenses();
    _searchController.addListener(_applySearchFilter);
  }

  @override
  void dispose() {
    _searchController.dispose();
    super.dispose();
  }

  Future<void> _loadCoursesAndInitialLicenses() async {
    setState(() {
      _isLoadingCourses = true;
      _errorMessage = null;
    });

    try {
      final apiService = Provider.of<ApiService>(context, listen: false);
      final response = await apiService.getCourses();
      final data = response['data'];

      final courses = data is List
          ? data
                .whereType<Map>()
                .map((e) => Map<String, dynamic>.from(e))
                .toList()
          : <Map<String, dynamic>>[];

      setState(() {
        _courses = courses;
        _selectedCourseId = _extractCourseId(courses.isNotEmpty ? courses.first : null);
        _isLoadingCourses = false;
      });

      if (_selectedCourseId != null) {
        await _loadLicensesForSelectedCourse(page: 1);
      }
    } catch (e) {
      setState(() {
        _isLoadingCourses = false;
        _errorMessage = e.toString();
      });
    }
  }

  Future<void> _loadLicensesForSelectedCourse({int page = 1}) async {
    if (_selectedCourseId == null) return;

    setState(() {
      _isLoadingLicenses = true;
      _errorMessage = null;
    });

    try {
      final apiService = Provider.of<ApiService>(context, listen: false);
      final response = await apiService.getCourseLicenses(
        courseId: _selectedCourseId!,
        page: page,
      );

      final data = response['data'];
      final meta = response['meta'];

      final licenses = data is List
          ? data
                .whereType<Map>()
                .map((e) => Map<String, dynamic>.from(e))
                .toList()
          : <Map<String, dynamic>>[];

      setState(() {
        _licenses = licenses;
        if (meta is Map<String, dynamic>) {
          _currentPage = (meta['current_page'] as num?)?.toInt() ?? page;
          _lastPage = (meta['last_page'] as num?)?.toInt() ?? 1;
        } else {
          _currentPage = page;
          _lastPage = 1;
        }
        _isLoadingLicenses = false;
      });

      _applySearchFilter();
    } catch (e) {
      setState(() {
        _isLoadingLicenses = false;
        _errorMessage = e.toString();
      });
    }
  }

  void _applySearchFilter() {
    final query = _searchController.text.trim().toLowerCase();
    if (query.isEmpty) {
      setState(() {
        _filteredLicenses = List<Map<String, dynamic>>.from(_licenses);
      });
      return;
    }

    setState(() {
      _filteredLicenses = _licenses.where((item) {
        final code = (item['activation_code'] ?? '').toString().toLowerCase();
        final status = (item['status'] ?? '').toString().toLowerCase();
        final userName = _extractUserName(item['user']).toLowerCase();
        return code.contains(query) || status.contains(query) || userName.contains(query);
      }).toList();
    });
  }

  int? _extractCourseId(Map<String, dynamic>? course) {
    if (course == null) return null;
    return (course['id'] as num?)?.toInt();
  }

  String _extractCourseTitle(Map<String, dynamic>? course) {
    if (course == null) return '-';
    final title = course['title'];
    if (title is String && title.trim().isNotEmpty) {
      return title;
    }
    return '-';
  }

  String _extractUserName(dynamic userObj) {
    if (userObj is Map<String, dynamic>) {
      final value = userObj['user_name'];
      if (value is String && value.trim().isNotEmpty) {
        return value;
      }
    }
    return '-';
  }

  int _extractDeviceCount(dynamic limitsObj) {
    if (limitsObj is List) {
      int sum = 0;
      for (final item in limitsObj) {
        if (item is Map<String, dynamic>) {
          final count = item['count'] ?? item['device_count'] ?? item['limit'];
          if (count is num) {
            sum += count.toInt();
          }
        }
      }
      if (sum > 0) return sum;
      return limitsObj.length;
    }
    return 0;
  }

  @override
  Widget build(BuildContext context) {
    final isDesktop = MediaQuery.of(context).size.width > 900;

    return TeacherPanelScaffold(
      selectedMenu: PanelMenu.license,
      onDashboardTap: () {
        Navigator.of(context).pushReplacement(
          MaterialPageRoute(builder: (context) => const DashboardPage()),
        );
      },
      onCourseTap: () {
        Navigator.of(context).pushReplacement(
          MaterialPageRoute(builder: (context) => const CoursePage()),
        );
      },
      onLicenseTap: () {},
      onTransactionTap: () {
        Navigator.of(context).push(
          MaterialPageRoute(builder: (context) => const TransactionPage()),
        );
      },
      onTicketTap: () {
        Navigator.of(context).push(
          MaterialPageRoute(builder: (context) => const TicketPage()),
        );
      },
      child: Padding(
        padding: EdgeInsets.all(isDesktop ? 24 : 12),
        child: Container(
          decoration: BoxDecoration(
            color: Colors.white.withValues(alpha: 0.35),
            borderRadius: BorderRadius.circular(10),
          ),
          child: Column(
            children: [
              Padding(
                padding: EdgeInsets.all(isDesktop ? 14 : 10),
                child: _LicenseToolbar(
                  isDesktop: isDesktop,
                  searchController: _searchController,
                  courses: _courses,
                  selectedCourseId: _selectedCourseId,
                  onCreateNewLicense: () async {
                    if (_selectedCourseId == null) {
                      ScaffoldMessenger.of(context).showSnackBar(
                        const SnackBar(
                          content: Text('ابتدا یک دوره انتخاب کنید.'),
                        ),
                      );
                      return;
                    }

                    final selectedCourse = _courses.firstWhere(
                      (e) => _extractCourseId(e) == _selectedCourseId,
                      orElse: () => <String, dynamic>{},
                    );

                    final created = await Navigator.of(context).push<bool>(
                      MaterialPageRoute(
                        builder: (_) => NewLicensePage(
                          courseId: _selectedCourseId!,
                          courseTitle: _extractCourseTitle(selectedCourse),
                        ),
                      ),
                    );

                    if (created == true) {
                      await _loadLicensesForSelectedCourse(page: _currentPage);
                    }
                  },
                  onCourseChanged: (courseId) async {
                    setState(() {
                      _selectedCourseId = courseId;
                      _currentPage = 1;
                    });
                    await _loadLicensesForSelectedCourse(page: 1);
                  },
                ),
              ),
              Expanded(
                child: Container(
                  margin: EdgeInsets.fromLTRB(
                    isDesktop ? 14 : 8,
                    0,
                    isDesktop ? 14 : 8,
                    isDesktop ? 14 : 8,
                  ),
                  decoration: BoxDecoration(
                    color: Colors.white,
                    border: Border.all(color: Colors.black12),
                    borderRadius: BorderRadius.circular(8),
                  ),
                  child: Column(
                    children: [
                      Container(
                        height: 46,
                        decoration: const BoxDecoration(
                          color: Color(0xFFD5D5D5),
                          borderRadius: BorderRadius.only(
                            topLeft: Radius.circular(8),
                            topRight: Radius.circular(8),
                          ),
                        ),
                        child: const Row(
                          children: [
                            _HeaderCell(title: 'کد فعال‌سازی', flex: 4),
                            _HeaderCell(title: 'کاربر', flex: 3),
                            _HeaderCell(title: 'دوره', flex: 4),
                            _HeaderCell(title: 'دستگاه', flex: 2),
                            _HeaderCell(title: 'وضعیت', flex: 2),
                          ],
                        ),
                      ),
                      Expanded(child: _buildContent()),
                      _PaginationBar(
                        currentPage: _currentPage,
                        lastPage: _lastPage,
                        onPrevious: _currentPage > 1
                            ? () => _loadLicensesForSelectedCourse(page: _currentPage - 1)
                            : null,
                        onNext: _currentPage < _lastPage
                            ? () => _loadLicensesForSelectedCourse(page: _currentPage + 1)
                            : null,
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildContent() {
    if (_isLoadingCourses || _isLoadingLicenses) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_errorMessage != null) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text(
                _errorMessage!,
                style: AppTextStyles.bodyMedium.copyWith(color: Colors.red),
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 10),
              OutlinedButton(
                onPressed: _selectedCourseId == null
                    ? _loadCoursesAndInitialLicenses
                    : () => _loadLicensesForSelectedCourse(page: _currentPage),
                child: const Text('تلاش مجدد'),
              ),
            ],
          ),
        ),
      );
    }

    if (_courses.isEmpty) {
      return const Center(child: _EmptyLicenseState(message: 'هیچ دوره‌ای یافت نشد.'));
    }

    if (_selectedCourseId == null) {
      return const Center(child: _EmptyLicenseState(message: 'دوره‌ای برای نمایش انتخاب نشده است.'));
    }

    if (_filteredLicenses.isEmpty) {
      return const Center(child: _EmptyLicenseState(message: 'برای این دوره لایسنسی ثبت نشده است.'));
    }

    return ListView.separated(
      itemCount: _filteredLicenses.length,
      separatorBuilder: (_, _) => const Divider(height: 1),
      itemBuilder: (context, index) {
        final item = _filteredLicenses[index];
        final activationCode = (item['activation_code'] ?? '-').toString();
        final userName = _extractUserName(item['user']);
        final courseTitle = item['course'] is Map<String, dynamic>
            ? _extractCourseTitle(item['course'] as Map<String, dynamic>)
            : _extractCourseTitle(
                _courses.firstWhere(
                  (e) => _extractCourseId(e) == _selectedCourseId,
                  orElse: () => <String, dynamic>{},
                ),
              );
        final deviceCount = _extractDeviceCount(item['device_limits']);
        final status = (item['status'] ?? '-').toString();

        return SizedBox(
          height: 62,
          child: Row(
            children: [
              _BodyCell(text: activationCode, flex: 4),
              _BodyCell(text: userName, flex: 3),
              _BodyCell(text: courseTitle, flex: 4),
              _BodyCell(text: deviceCount.toString(), flex: 2),
              _BodyCell(text: status, flex: 2),
            ],
          ),
        );
      },
    );
  }
}

class _LicenseToolbar extends StatelessWidget {
  final bool isDesktop;
  final TextEditingController searchController;
  final List<Map<String, dynamic>> courses;
  final int? selectedCourseId;
  final VoidCallback onCreateNewLicense;
  final ValueChanged<int?> onCourseChanged;

  const _LicenseToolbar({
    required this.isDesktop,
    required this.searchController,
    required this.courses,
    required this.selectedCourseId,
    required this.onCreateNewLicense,
    required this.onCourseChanged,
  });

  @override
  Widget build(BuildContext context) {
    if (!isDesktop) {
      return Column(
        children: [
          _searchBox(double.infinity),
          const SizedBox(height: 8),
          _courseDropdown(width: double.infinity),
          const SizedBox(height: 8),
          _staticDropdown('تاریخ ایجاد', width: double.infinity),
          const SizedBox(height: 8),
          _staticDropdown('تنظیمات', width: double.infinity),
          const SizedBox(height: 8),
          SizedBox(
            width: double.infinity,
            height: 36,
            child: _buildActionButton(context, 'تنظیمات پیش فرض'),
          ),
          const SizedBox(height: 8),
          SizedBox(
            width: double.infinity,
            height: 36,
            child: ElevatedButton(
              onPressed: () {},
              style: ElevatedButton.styleFrom(
                backgroundColor: AppColors.sidebarBg,
                foregroundColor: Colors.white,
              ),
              child: const Text('دانلود اکسل'),
            ),
          ),
          const SizedBox(height: 8),
          SizedBox(
            width: double.infinity,
            height: 36,
            child: ElevatedButton.icon(
              onPressed: onCreateNewLicense,
              icon: const Icon(Icons.add, size: 18),
              label: const Text('لایسنس جدید'),
              style: ElevatedButton.styleFrom(
                backgroundColor: const Color(0xFF56B33E),
                foregroundColor: Colors.white,
              ),
            ),
          ),
        ],
      );
    }

    return LayoutBuilder(
      builder: (context, constraints) {
        const fixedWidth = 160 + 120 + 100 + 146 + 146 + 146;
        const gaps = 10.0 * 6;
        const minSearch = 170.0;
        final canExpandSearch = constraints.maxWidth >= (fixedWidth + gaps + minSearch);

        if (canExpandSearch) {
          return Row(
            textDirection: TextDirection.rtl,
            children: [
              Expanded(child: _searchBox(double.infinity)),
              const SizedBox(width: 10),
              _courseDropdown(width: 160),
              const SizedBox(width: 10),
              _staticDropdown('تاریخ ایجاد', width: 120),
              const SizedBox(width: 10),
              _staticDropdown('تنظیمات', width: 100),
              const SizedBox(width: 10),
              SizedBox(
                width: 146,
                height: 36,
                child: _buildActionButton(context, 'تنظیمات پیش فرض'),
              ),
              const SizedBox(width: 10),
              SizedBox(
                height: 36,
                width: 146,
                child: ElevatedButton(
                  onPressed: () {},
                  style: ElevatedButton.styleFrom(
                    backgroundColor: AppColors.sidebarBg,
                    foregroundColor: Colors.white,
                    textStyle: AppTextStyles.bodyMedium.copyWith(color: Colors.white),
                    padding: const EdgeInsets.symmetric(horizontal: 10),
                  ),
                  child: const Text('دانلود اکسل'),
                ),
              ),
              const SizedBox(width: 10),
              SizedBox(
                height: 36,
                width: 146,
                child: ElevatedButton.icon(
                  onPressed: onCreateNewLicense,
                  icon: const Icon(Icons.add, size: 18),
                  label: const Text('لایسنس جدید'),
                  style: ElevatedButton.styleFrom(
                    backgroundColor: const Color(0xFF56B33E),
                    foregroundColor: Colors.white,
                  ),
                ),
              ),
            ],
          );
        }

        return Align(
          alignment: Alignment.centerRight,
          child: SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            child: Row(
              textDirection: TextDirection.rtl,
              children: [
                _searchBox(170),
                const SizedBox(width: 10),
                _courseDropdown(width: 160),
                const SizedBox(width: 10),
                _staticDropdown('تاریخ ایجاد', width: 120),
                const SizedBox(width: 10),
                _staticDropdown('تنظیمات', width: 100),
                const SizedBox(width: 10),
                SizedBox(
                  width: 146,
                  height: 36,
                  child: _buildActionButton(context, 'تنظیمات پیش فرض'),
                ),
                const SizedBox(width: 10),
                SizedBox(
                  height: 36,
                  width: 146,
                  child: ElevatedButton(
                    onPressed: () {},
                    style: ElevatedButton.styleFrom(
                      backgroundColor: AppColors.sidebarBg,
                      foregroundColor: Colors.white,
                    ),
                    child: const Text('دانلود اکسل'),
                  ),
                ),
                const SizedBox(width: 10),
                SizedBox(
                  height: 36,
                  width: 146,
                  child: ElevatedButton.icon(
                    onPressed: onCreateNewLicense,
                    icon: const Icon(Icons.add, size: 18),
                    label: const Text('لایسنس جدید'),
                    style: ElevatedButton.styleFrom(
                      backgroundColor: const Color(0xFF56B33E),
                      foregroundColor: Colors.white,
                    ),
                  ),
                ),
              ],
            ),
          ),
        );
      },
    );
  }

  Widget _courseDropdown({required double width}) {
    final items = courses
        .where((c) => (c['id'] as num?) != null)
        .map(
          (c) => DropdownMenuItem<int>(
            value: (c['id'] as num).toInt(),
            child: Text((c['title'] ?? 'بدون عنوان').toString()),
          ),
        )
        .toList();

    final hasSelected = selectedCourseId != null && items.any((e) => e.value == selectedCourseId);

    return SizedBox(
      width: width,
      height: 36,
      child: DropdownButtonFormField<int>(
        initialValue: hasSelected ? selectedCourseId : null,
        isExpanded: true,
        hint: const Text('فیلتر دوره'),
        decoration: InputDecoration(
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(6),
            borderSide: BorderSide(color: Colors.grey.shade400),
          ),
          contentPadding: const EdgeInsets.symmetric(horizontal: 8, vertical: 6),
        ),
        items: items,
        onChanged: onCourseChanged,
      ),
    );
  }

  Widget _staticDropdown(String hint, {required double width}) {
    return SizedBox(
      width: width,
      height: 36,
      child: DropdownButtonFormField<String>(
        initialValue: hint,
        isExpanded: true,
        decoration: InputDecoration(
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(6),
            borderSide: BorderSide(color: Colors.grey.shade400),
          ),
          contentPadding: const EdgeInsets.symmetric(horizontal: 8, vertical: 6),
        ),
        items: [
          DropdownMenuItem(value: hint, child: Text(hint)),
          const DropdownMenuItem(value: 'همه', child: Text('همه')),
        ],
        onChanged: (_) {},
      ),
    );
  }

  Widget _buildActionButton(BuildContext context, String text) {
    return OutlinedButton(
      onPressed: () {
        Navigator.of(context).push(
          MaterialPageRoute(builder: (context) => const LicenseBuilderPage()),
        );
      },
      style: OutlinedButton.styleFrom(
        side: const BorderSide(color: AppColors.sidebarBg),
        foregroundColor: AppColors.sidebarBg,
      ),
      child: Text(text, maxLines: 1, overflow: TextOverflow.ellipsis),
    );
  }

  Widget _searchBox(double width) {
    return SizedBox(
      width: width,
      height: 36,
      child: TextField(
        controller: searchController,
        decoration: InputDecoration(
          hintText: 'جست و جو',
          prefixIcon: const Icon(Icons.search, size: 18),
          border: OutlineInputBorder(
            borderRadius: BorderRadius.circular(6),
            borderSide: BorderSide(color: Colors.grey.shade400),
          ),
          contentPadding: const EdgeInsets.symmetric(vertical: 8),
        ),
      ),
    );
  }
}

class _HeaderCell extends StatelessWidget {
  final String title;
  final int flex;

  const _HeaderCell({required this.title, required this.flex});

  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: flex,
      child: Center(
        child: Text(
          title,
          style: AppTextStyles.bodyLarge.copyWith(fontWeight: FontWeight.w700),
        ),
      ),
    );
  }
}

class _BodyCell extends StatelessWidget {
  final String text;
  final int flex;

  const _BodyCell({required this.text, required this.flex});

  @override
  Widget build(BuildContext context) {
    return Expanded(
      flex: flex,
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 8),
        child: Text(
          text,
          maxLines: 2,
          overflow: TextOverflow.ellipsis,
          style: AppTextStyles.bodyMedium,
          textAlign: TextAlign.center,
        ),
      ),
    );
  }
}

class _PaginationBar extends StatelessWidget {
  final int currentPage;
  final int lastPage;
  final VoidCallback? onPrevious;
  final VoidCallback? onNext;

  const _PaginationBar({
    required this.currentPage,
    required this.lastPage,
    this.onPrevious,
    this.onNext,
  });

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 52,
      padding: const EdgeInsets.symmetric(horizontal: 12),
      decoration: const BoxDecoration(
        border: Border(top: BorderSide(color: Colors.black12)),
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text('صفحه $currentPage از $lastPage', style: AppTextStyles.bodyMedium),
          Row(
            children: [
              TextButton(onPressed: onPrevious, child: const Text('قبلی')),
              const SizedBox(width: 8),
              TextButton(onPressed: onNext, child: const Text('بعدی')),
            ],
          ),
        ],
      ),
    );
  }
}

class _EmptyLicenseState extends StatelessWidget {
  final String message;

  const _EmptyLicenseState({required this.message});

  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        Container(
          width: 340,
          constraints: const BoxConstraints(maxWidth: 340),
          padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 20),
          decoration: BoxDecoration(
            color: Colors.grey.shade50,
            borderRadius: BorderRadius.circular(12),
            border: Border.all(color: Colors.grey.shade200),
          ),
          child: Column(
            children: [
              Icon(
                Icons.desktop_windows_outlined,
                size: 120,
                color: AppColors.sidebarBg.withValues(alpha: 0.7),
              ),
              const SizedBox(height: 6),
              Text(
                'NO DATA',
                style: AppTextStyles.headlineMedium.copyWith(
                  color: AppColors.sidebarBg,
                  fontSize: 18,
                ),
              ),
            ],
          ),
        ),
        const SizedBox(height: 22),
        Text(
          message,
          style: AppTextStyles.bodyMedium.copyWith(color: AppColors.sidebarBg),
        ),
      ],
    );
  }
}