import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../../core/api/api_error_mapper.dart';
import '../data/admin_repository.dart';
import '../domain/user_admin.dart';

class AdminScreen extends ConsumerStatefulWidget {
  const AdminScreen({super.key});

  @override
  ConsumerState<AdminScreen> createState() => _AdminScreenState();
}

class _AdminScreenState extends ConsumerState<AdminScreen> {
  bool _isLoading = true;
  String? _error;
  List<UserAdmin> _users = [];

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

  Future<void> _load() async {
    setState(() {
      _isLoading = true;
      _error = null;
    });
    try {
      final users = await ref.read(adminRepositoryProvider).listUsers();
      if (!mounted) return;
      setState(() => _users = users);
    } catch (e) {
      if (!mounted) return;
      setState(() => _error = mapErrorToUserMessage(e, context));
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _changeRole(UserAdmin user) async {
    final newRole = user.isAdmin ? 'user' : 'admin';
    final confirmed = await _confirm(
      context,
      'Ändra roll',
      'Ändra ${user.username} till $newRole?',
    );
    if (!confirmed || !mounted) return;
    try {
      await ref.read(adminRepositoryProvider).setRole(user.id, newRole);
      if (!mounted) return;
      _load();
    } catch (e) {
      if (!mounted) return;
      _showError(e);
    }
  }

  Future<void> _resetPassword(UserAdmin user) async {
    final confirmed = await _confirm(
      context,
      'Återställ lösenord',
      'Generera ett tillfälligt lösenord för ${user.username}?',
    );
    if (!confirmed || !mounted) return;
    try {
      final result = await ref.read(adminRepositoryProvider).resetPassword(user.id);
      if (!mounted) return;
      final tempPw = result['temporaryPassword'] as String? ?? '';
      await showDialog<void>(
        context: context,
        builder: (_) => AlertDialog(
          title: const Text('Tillfälligt lösenord'),
          content: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text('Lösenord för ${user.username}:'),
              const SizedBox(height: 8),
              Row(
                children: [
                  Expanded(
                    child: SelectableText(
                      tempPw,
                      style: const TextStyle(fontFamily: 'monospace', fontWeight: FontWeight.bold),
                    ),
                  ),
                  IconButton(
                    icon: const Icon(Icons.copy),
                    tooltip: 'Kopiera',
                    onPressed: () => Clipboard.setData(ClipboardData(text: tempPw)),
                  ),
                ],
              ),
              const SizedBox(height: 8),
              const Text('Användaren måste byta lösenord vid nästa inloggning.', style: TextStyle(fontSize: 12)),
            ],
          ),
          actions: [TextButton(onPressed: () => Navigator.pop(context), child: const Text('Stäng'))],
        ),
      );
    } catch (e) {
      if (!mounted) return;
      _showError(e);
    }
  }

  Future<void> _deleteUser(UserAdmin user) async {
    final confirmed = await _confirm(
      context,
      'Ta bort användare',
      'Ta bort ${user.username} permanent? Detta går inte att ångra.',
      destructive: true,
    );
    if (!confirmed || !mounted) return;
    try {
      await ref.read(adminRepositoryProvider).deleteUser(user.id);
      if (!mounted) return;
      _load();
    } catch (e) {
      if (!mounted) return;
      _showError(e);
    }
  }

  Future<void> _createUser() async {
    final result = await showDialog<Map<String, String>>(
      context: context,
      builder: (_) => const _CreateUserDialog(),
    );
    if (result == null || !mounted) return;
    try {
      await ref.read(adminRepositoryProvider).createUser(
            username: result['username']!,
            email: result['email']!,
            password: result['password']!,
            role: result['role'] ?? 'user',
          );
      if (!mounted) return;
      _load();
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('Användare ${result['username']} skapad.')),
      );
    } catch (e) {
      if (!mounted) return;
      _showError(e);
    }
  }

  void _showError(Object e) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(mapErrorToUserMessage(e, context)),
        backgroundColor: Theme.of(context).colorScheme.error,
      ),
    );
  }

  Future<bool> _confirm(BuildContext ctx, String title, String body, {bool destructive = false}) async {
    final result = await showDialog<bool>(
      context: ctx,
      builder: (_) => AlertDialog(
        title: Text(title),
        content: Text(body),
        actions: [
          TextButton(onPressed: () => Navigator.pop(_, false), child: const Text('Avbryt')),
          TextButton(
            onPressed: () => Navigator.pop(_, true),
            style: destructive
                ? TextButton.styleFrom(foregroundColor: Theme.of(ctx).colorScheme.error)
                : null,
            child: const Text('Bekräfta'),
          ),
        ],
      ),
    );
    return result ?? false;
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(
        title: const Text('Admin – Användare'),
        actions: [
          IconButton(
            icon: const Icon(Icons.refresh),
            tooltip: 'Uppdatera',
            onPressed: _isLoading ? null : _load,
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: _createUser,
        icon: const Icon(Icons.person_add_outlined),
        label: const Text('Ny användare'),
      ),
      body: _isLoading
          ? const Center(child: CircularProgressIndicator())
          : _error != null
              ? Center(
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Text(_error!, style: TextStyle(color: theme.colorScheme.error)),
                      const SizedBox(height: 16),
                      FilledButton(onPressed: _load, child: const Text('Försök igen')),
                    ],
                  ),
                )
              : _users.isEmpty
                  ? const Center(child: Text('Inga användare hittades.'))
                  : ListView.builder(
                      padding: const EdgeInsets.fromLTRB(16, 8, 16, 80),
                      itemCount: _users.length,
                      itemBuilder: (ctx, i) => _UserTile(
                        user: _users[i],
                        onChangeRole: () => _changeRole(_users[i]),
                        onResetPassword: () => _resetPassword(_users[i]),
                        onDelete: () => _deleteUser(_users[i]),
                      ),
                    ),
    );
  }
}

class _UserTile extends StatelessWidget {
  final UserAdmin user;
  final VoidCallback onChangeRole;
  final VoidCallback onResetPassword;
  final VoidCallback onDelete;

  const _UserTile({
    required this.user,
    required this.onChangeRole,
    required this.onResetPassword,
    required this.onDelete,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Card(
      margin: const EdgeInsets.symmetric(vertical: 4),
      child: ListTile(
        leading: CircleAvatar(
          backgroundColor: user.isAdmin
              ? theme.colorScheme.primaryContainer
              : theme.colorScheme.secondaryContainer,
          child: Icon(
            user.isAdmin ? Icons.shield_outlined : Icons.person_outline,
            color: user.isAdmin
                ? theme.colorScheme.onPrimaryContainer
                : theme.colorScheme.onSecondaryContainer,
            size: 20,
          ),
        ),
        title: Text(user.displayName),
        subtitle: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(user.email, style: theme.textTheme.bodySmall),
            Row(
              children: [
                Chip(
                  label: Text(user.role),
                  padding: EdgeInsets.zero,
                  visualDensity: VisualDensity.compact,
                  labelStyle: theme.textTheme.labelSmall,
                ),
                if (user.isPremium) ...[
                  const SizedBox(width: 4),
                  Chip(
                    label: const Text('Premium'),
                    padding: EdgeInsets.zero,
                    visualDensity: VisualDensity.compact,
                    labelStyle: theme.textTheme.labelSmall,
                    backgroundColor: theme.colorScheme.tertiaryContainer,
                  ),
                ],
              ],
            ),
          ],
        ),
        isThreeLine: true,
        trailing: PopupMenuButton<String>(
          onSelected: (action) {
            switch (action) {
              case 'role':
                onChangeRole();
              case 'reset':
                onResetPassword();
              case 'delete':
                onDelete();
            }
          },
          itemBuilder: (_) => [
            PopupMenuItem(
              value: 'role',
              child: Text(user.isAdmin ? 'Nedgradera till user' : 'Uppgradera till admin'),
            ),
            const PopupMenuItem(value: 'reset', child: Text('Återställ lösenord')),
            const PopupMenuDivider(),
            PopupMenuItem(
              value: 'delete',
              child: Text('Ta bort', style: TextStyle(color: Theme.of(context).colorScheme.error)),
            ),
          ],
        ),
      ),
    );
  }
}

class _CreateUserDialog extends StatefulWidget {
  const _CreateUserDialog();

  @override
  State<_CreateUserDialog> createState() => _CreateUserDialogState();
}

class _CreateUserDialogState extends State<_CreateUserDialog> {
  final _formKey = GlobalKey<FormState>();
  final _usernameCtrl = TextEditingController();
  final _emailCtrl = TextEditingController();
  final _passwordCtrl = TextEditingController();
  String _role = 'user';
  bool _obscure = true;

  @override
  void dispose() {
    _usernameCtrl.dispose();
    _emailCtrl.dispose();
    _passwordCtrl.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Skapa användare'),
      content: Form(
        key: _formKey,
        child: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              TextFormField(
                controller: _usernameCtrl,
                decoration: const InputDecoration(labelText: 'Användarnamn'),
                validator: (v) => (v == null || v.length < 2) ? 'Minst 2 tecken' : null,
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _emailCtrl,
                decoration: const InputDecoration(labelText: 'E-post'),
                keyboardType: TextInputType.emailAddress,
                validator: (v) {
                  if (v == null || v.isEmpty) return 'Obligatoriskt';
                  if (!RegExp(r'^[^@]+@[^@]+\.[^@]+').hasMatch(v)) return 'Ogiltig e-post';
                  return null;
                },
              ),
              const SizedBox(height: 12),
              TextFormField(
                controller: _passwordCtrl,
                decoration: InputDecoration(
                  labelText: 'Lösenord',
                  suffixIcon: IconButton(
                    icon: Icon(_obscure ? Icons.visibility_off_outlined : Icons.visibility_outlined),
                    onPressed: () => setState(() => _obscure = !_obscure),
                  ),
                ),
                obscureText: _obscure,
                validator: (v) => (v == null || v.length < 8) ? 'Minst 8 tecken' : null,
              ),
              const SizedBox(height: 12),
              DropdownButtonFormField<String>(
                initialValue: _role,
                decoration: const InputDecoration(labelText: 'Roll'),
                items: const [
                  DropdownMenuItem(value: 'user', child: Text('Användare')),
                  DropdownMenuItem(value: 'admin', child: Text('Admin')),
                ],
                onChanged: (v) => setState(() => _role = v ?? 'user'),
              ),
            ],
          ),
        ),
      ),
      actions: [
        TextButton(onPressed: () => Navigator.pop(context), child: const Text('Avbryt')),
        FilledButton(
          onPressed: () {
            if (_formKey.currentState!.validate()) {
              Navigator.pop(context, {
                'username': _usernameCtrl.text.trim(),
                'email': _emailCtrl.text.trim(),
                'password': _passwordCtrl.text,
                'role': _role,
              });
            }
          },
          child: const Text('Skapa'),
        ),
      ],
    );
  }
}