import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import '../../../core/network/api_client.dart';
import '../../../core/network/signalr_service.dart';
import '../../../core/theme/app_theme.dart';
import '../../../core/widgets/glass_container.dart';
import '../../../core/widgets/status_badge.dart';
import '../models/admin_update_user_request_dto.dart';
import '../models/admin_user_model.dart';
import '../bloc/admin_bloc.dart';
import '../repositories/admin_repository.dart';
import '../widgets/admin_kpi_header.dart';
import '../widgets/create_user_dialog.dart';
import '../widgets/edit_user_dialog.dart';

import '../widgets/system_diagnostics_widget.dart';

/// Role-Restricted Admin Panel Screen managing users, service settings, and system health.
class AdminUsersScreen extends StatelessWidget {
  final ApiClient apiClient;
  final SignalRService? signalRService;

  const AdminUsersScreen({
    super.key,
    required this.apiClient,
    this.signalRService,
  });

  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (context) => AdminBloc(
        repository: AdminRepository(apiClient: apiClient),
      )..add(FetchAdminUsers()),
      child: _AdminUsersScreenContent(
        apiClient: apiClient,
        signalRService: signalRService,
      ),
    );
  }
}

class _AdminUsersScreenContent extends StatefulWidget {
  final ApiClient apiClient;
  final SignalRService? signalRService;

  const _AdminUsersScreenContent({
    required this.apiClient,
    this.signalRService,
  });

  @override
  State<_AdminUsersScreenContent> createState() => _AdminUsersScreenContentState();
}

class _AdminUsersScreenContentState extends State<_AdminUsersScreenContent> with SingleTickerProviderStateMixin {
  late TabController _tabController;
  String _searchQuery = '';
  String _roleFilter = 'Alle';

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 2, vsync: this);
  }

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

  void _openCreateUser(BuildContext context) async {
    final res = await showDialog(context: context, builder: (_) => const CreateUserDialog());
    if (res != null && context.mounted) {
      context.read<AdminBloc>().add(CreateAdminUser(res));
    }
  }

  void _openEditUser(BuildContext context, AdminUserModel user) async {
    final res = await showDialog(context: context, builder: (_) => EditUserDialog(user: user));
    if (res != null && context.mounted) {
      context.read<AdminBloc>().add(UpdateAdminUser(user.id, res as AdminUpdateUserRequestDto));
    }
  }

  void _toggleUserActiveStatus(BuildContext context, AdminUserModel user, bool newActive) {
    final dto = AdminUpdateUserRequestDto(role: user.role, isActive: newActive);
    context.read<AdminBloc>().add(UpdateAdminUser(user.id, dto));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.transparent,
      body: BlocBuilder<AdminBloc, AdminState>(
        builder: (context, state) {
          final users = state is AdminLoaded ? state.users : <AdminUserModel>[];

          return Padding(
            padding: const EdgeInsets.all(20),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                // Top Header Ribbon
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Row(
                          children: [
                            Container(
                              padding: const EdgeInsets.all(8),
                              decoration: BoxDecoration(
                                color: AppTheme.primaryEmerald.withValues(alpha: 0.15),
                                borderRadius: BorderRadius.circular(10),
                                border: Border.all(color: AppTheme.primaryEmerald.withValues(alpha: 0.3)),
                              ),
                              child: Icon(Icons.admin_panel_settings_rounded, color: AppTheme.primaryEmerald, size: 22),
                            ),
                            const SizedBox(width: 12),
                            const Text(
                              'Admin Control Panel',
                              style: TextStyle(fontSize: 22, fontWeight: FontWeight.bold, letterSpacing: -0.5),
                            ),
                          ],
                        ),
                        const SizedBox(height: 4),
                        Text(
                          'Zentrales Management für Nutzer, Mikrodienste & MQTT System-Bus',
                          style: TextStyle(fontSize: 12, color: AppTheme.textSecondary),
                        ),
                      ],
                    ),
                    ElevatedButton.icon(
                      onPressed: () => _openCreateUser(context),
                      icon: const Icon(Icons.person_add_outlined, size: 18),
                      label: const Text('Nutzer Anlegen', style: TextStyle(fontWeight: FontWeight.bold)),
                      style: ElevatedButton.styleFrom(
                        backgroundColor: AppTheme.primaryEmerald,
                        foregroundColor: Colors.black,
                        padding: const EdgeInsets.symmetric(horizontal: 18, vertical: 12),
                        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
                      ),
                    ),
                  ],
                ),
                const SizedBox(height: 16),

                // KPI Header Metrics
                AdminKpiHeader(
                  users: users,
                  signalRService: widget.signalRService,
                ),
                const SizedBox(height: 16),

                // Tab Selector Ribbon
                Container(
                  decoration: BoxDecoration(
                    color: AppTheme.glassSurface,
                    borderRadius: BorderRadius.circular(14),
                    border: Border.all(color: AppTheme.glassBorder),
                  ),
                  child: TabBar(
                    controller: _tabController,
                    indicatorColor: AppTheme.primaryEmerald,
                    indicatorSize: TabBarIndicatorSize.tab,
                    labelColor: AppTheme.primaryEmerald,
                    unselectedLabelColor: AppTheme.textMuted,
                    labelStyle: const TextStyle(fontWeight: FontWeight.bold, fontSize: 13),
                    indicator: BoxDecoration(
                      color: AppTheme.primaryEmerald.withValues(alpha: 0.15),
                      borderRadius: BorderRadius.circular(12),
                      border: Border.all(color: AppTheme.primaryEmerald.withValues(alpha: 0.4)),
                    ),
                    tabs: const [
                      Tab(icon: Icon(Icons.people_alt_outlined, size: 18), text: 'Nutzerverwaltung'),
                      Tab(icon: Icon(Icons.monitor_heart_outlined, size: 18), text: 'System-Diagnose & MQTT'),
                    ],
                  ),
                ),
                const SizedBox(height: 16),

                // Tab Content View
                Expanded(
                  child: TabBarView(
                    controller: _tabController,
                    children: [
                      // Tab 1: User Management with Filter & Actions
                      _buildUserManagementTab(context, state, users),

                      // Tab 2: System Diagnostics & Microservices Health
                      SystemDiagnosticsWidget(
                        signalRService: widget.signalRService,
                      ),
                    ],
                  ),
                ),
              ],
            ),
          );
        },
      ),
    );
  }

  Widget _buildUserManagementTab(BuildContext context, AdminState state, List<AdminUserModel> allUsers) {
    if (state is AdminLoading) {
      return Center(child: CircularProgressIndicator(color: AppTheme.primaryEmerald));
    }

    if (state is AdminError) {
      return Center(
        child: GlassContainer(
          padding: const EdgeInsets.all(24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Icon(Icons.error_outline_rounded, color: AppTheme.accentRed, size: 40),
              const SizedBox(height: 12),
              Text(state.message, style: TextStyle(color: AppTheme.textPrimary, fontWeight: FontWeight.bold)),
              const SizedBox(height: 16),
              ElevatedButton(
                onPressed: () => context.read<AdminBloc>().add(FetchAdminUsers()),
                style: ElevatedButton.styleFrom(backgroundColor: AppTheme.primaryEmerald, foregroundColor: Colors.black),
                child: const Text('Erneut versuchen'),
              ),
            ],
          ),
        ),
      );
    }

    // Apply Search Query & Role Filter
    final filteredUsers = allUsers.where((u) {
      final matchesSearch = u.fullName.toLowerCase().contains(_searchQuery.toLowerCase()) ||
          u.email.toLowerCase().contains(_searchQuery.toLowerCase());
      final matchesRole = _roleFilter == 'Alle' || u.role.toLowerCase() == _roleFilter.toLowerCase();
      return matchesSearch && matchesRole;
    }).toList();

    return Column(
      children: [
        // Filter Bar (Search Field & Role Filter Chips)
        Row(
          children: [
            Expanded(
              child: TextField(
                onChanged: (val) => setState(() => _searchQuery = val),
                decoration: InputDecoration(
                  hintText: 'Benutzer nach Name oder E-Mail suchen...',
                  prefixIcon: Icon(Icons.search_rounded, color: AppTheme.textMuted),
                  suffixIcon: _searchQuery.isNotEmpty
                      ? IconButton(
                          icon: const Icon(Icons.clear, size: 18),
                          onPressed: () => setState(() => _searchQuery = ''),
                        )
                      : null,
                ),
              ),
            ),
            const SizedBox(width: 12),
            SingleChildScrollView(
              scrollDirection: Axis.horizontal,
              child: Row(
                children: ['Alle', 'Admin', 'Premium', 'User'].map((role) {
                  final isSelected = _roleFilter == role;
                  return Padding(
                    padding: const EdgeInsets.only(right: 6),
                    child: ChoiceChip(
                      label: Text(role),
                      selected: isSelected,
                      selectedColor: AppTheme.primaryEmerald,
                      backgroundColor: AppTheme.glassSurface,
                      labelStyle: TextStyle(
                        color: isSelected ? Colors.black : AppTheme.textSecondary,
                        fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
                        fontSize: 12,
                      ),
                      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
                      side: BorderSide(color: isSelected ? AppTheme.primaryEmerald : AppTheme.glassBorder),
                      onSelected: (val) {
                        if (val) setState(() => _roleFilter = role);
                      },
                    ),
                  );
                }).toList(),
              ),
            ),
          ],
        ),
        const SizedBox(height: 14),

        // User Cards List
        Expanded(
          child: filteredUsers.isEmpty
              ? Center(
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Icon(Icons.person_search_outlined, size: 48, color: AppTheme.textMuted),
                      const SizedBox(height: 12),
                      Text(
                        'Keine passenden Benutzer gefunden.',
                        style: TextStyle(color: AppTheme.textMuted, fontSize: 14),
                      ),
                    ],
                  ),
                )
              : ListView.builder(
                  itemCount: filteredUsers.length,
                  itemBuilder: (context, index) {
                    final u = filteredUsers[index];
                    final String role = u.role;
                    final bool isActive = u.isActive;

                    final Color roleColor = role == 'Admin'
                        ? const Color(0xFFA855F7)
                        : role == 'Premium'
                            ? AppTheme.primaryEmerald
                            : AppTheme.accentCyan;

                    final String initials = _getInitials(u.fullName.isNotEmpty ? u.fullName : u.email);

                    return GlassContainer(
                      margin: const EdgeInsets.only(bottom: 10),
                      padding: const EdgeInsets.all(14),
                      child: Row(
                        children: [
                          // Avatar Initials Circle
                          Container(
                            width: 42,
                            height: 42,
                            alignment: Alignment.center,
                            decoration: BoxDecoration(
                              color: roleColor.withValues(alpha: 0.2),
                              shape: BoxShape.circle,
                              border: Border.all(color: roleColor, width: 1.5),
                            ),
                            child: Text(
                              initials,
                              style: TextStyle(fontWeight: FontWeight.bold, color: roleColor, fontSize: 14),
                            ),
                          ),
                          const SizedBox(width: 14),

                          // User Name & Email
                          Expanded(
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Row(
                                  children: [
                                    Text(
                                      u.fullName.isNotEmpty ? u.fullName : u.email,
                                      style: const TextStyle(fontWeight: FontWeight.bold, fontSize: 15),
                                    ),
                                    const SizedBox(width: 8),
                                    StatusBadge(label: role, color: roleColor),
                                  ],
                                ),
                                const SizedBox(height: 2),
                                Text(
                                  u.email,
                                  style: TextStyle(fontSize: 12, color: AppTheme.textSecondary),
                                ),
                              ],
                            ),
                          ),

                          // Active/Inactive Quick Switch Toggle
                          Row(
                            children: [
                              Column(
                                crossAxisAlignment: CrossAxisAlignment.end,
                                children: [
                                  Text(
                                    isActive ? 'Aktiv' : 'Gesperrt',
                                    style: TextStyle(
                                      fontSize: 12,
                                      fontWeight: FontWeight.bold,
                                      color: isActive ? AppTheme.primaryEmerald : AppTheme.accentRed,
                                    ),
                                  ),
                                ],
                              ),
                              const SizedBox(width: 8),
                              Switch(
                                value: isActive,
                                activeThumbColor: AppTheme.primaryEmerald,
                                onChanged: (val) => _toggleUserActiveStatus(context, u, val),
                              ),
                              const SizedBox(width: 8),
                              IconButton.filledTonal(
                                icon: const Icon(Icons.edit_outlined, size: 18),
                                tooltip: 'Benutzer Bearbeiten',
                                onPressed: () => _openEditUser(context, u),
                              ),
                            ],
                          ),
                        ],
                      ),
                    );
                  },
                ),
        ),
      ],
    );
  }

  String _getInitials(String name) {
    if (name.isEmpty) return 'U';
    final parts = name.trim().split(' ');
    if (parts.length >= 2) {
      return '${parts[0][0]}${parts[1][0]}'.toUpperCase();
    }
    return name.substring(0, name.length >= 2 ? 2 : 1).toUpperCase();
  }
}