import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../domain/entities/create_todo_params.dart';
import '../../domain/entities/update_todo_params.dart';
import '../providers/todo_providers.dart';

class TodoDetailScreen extends ConsumerStatefulWidget {
  final String? todoId;

  const TodoDetailScreen({super.key, this.todoId});

  @override
  ConsumerState<TodoDetailScreen> createState() => _TodoDetailScreenState();
}

class _TodoDetailScreenState extends ConsumerState<TodoDetailScreen> {
  final _formKey = GlobalKey<FormState>();
  late final TextEditingController _titleController;
  late final TextEditingController _descriptionController;
  String _priority = 'medium';
  DateTime? _dueDate;
  bool _isLoading = false;

  bool get isEditing => widget.todoId != null;

  @override
  void initState() {
    super.initState();
    _titleController = TextEditingController();
    _descriptionController = TextEditingController();

    if (isEditing) {
      _loadTodo();
    }
  }

  Future<void> _loadTodo() async {
    final todoAsync = ref.read(todoDetailProvider(widget.todoId!));
    todoAsync.whenData((todo) {
      _titleController.text = todo.title;
      _descriptionController.text = todo.description ?? '';
      _priority = todo.priority;
      _dueDate = todo.dueDate;
    });
  }

  @override
  void dispose() {
    _titleController.dispose();
    _descriptionController.dispose();
    super.dispose();
  }

  Future<void> _save() async {
    if (!_formKey.currentState!.validate()) return;

    setState(() => _isLoading = true);

    try {
      if (isEditing) {
        await ref.read(todoListProvider.notifier).updateTodo(
              widget.todoId!,
              UpdateTodoParams(
                title: _titleController.text,
                description: _descriptionController.text.isEmpty
                    ? null
                    : _descriptionController.text,
                priority: _priority,
                dueDate: _dueDate,
              ),
            );
      } else {
        await ref.read(todoListProvider.notifier).createTodo(
              CreateTodoParams(
                title: _titleController.text,
                description: _descriptionController.text.isEmpty
                    ? null
                    : _descriptionController.text,
                priority: _priority,
                dueDate: _dueDate,
              ),
            );
      }

      if (mounted) context.pop();
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Failed to save: $e')),
        );
      }
    } finally {
      if (mounted) setState(() => _isLoading = false);
    }
  }

  Future<void> _pickDueDate() async {
    final date = await showDatePicker(
      context: context,
      initialDate: _dueDate ?? DateTime.now().add(const Duration(days: 1)),
      firstDate: DateTime.now(),
      lastDate: DateTime.now().add(const Duration(days: 365)),
    );
    if (date != null) {
      setState(() => _dueDate = date);
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Scaffold(
      appBar: AppBar(
        title: Text(isEditing ? 'Edit Todo' : 'New Todo'),
      ),
      body: Form(
        key: _formKey,
        child: ListView(
          padding: const EdgeInsets.all(16),
          children: [
            TextFormField(
              controller: _titleController,
              decoration: const InputDecoration(
                labelText: 'Title',
                border: OutlineInputBorder(),
              ),
              validator: (value) {
                if (value == null || value.trim().isEmpty) {
                  return 'Title is required';
                }
                return null;
              },
              autofocus: !isEditing,
            ),
            const SizedBox(height: 16),
            TextFormField(
              controller: _descriptionController,
              decoration: const InputDecoration(
                labelText: 'Description (optional)',
                border: OutlineInputBorder(),
              ),
              maxLines: 3,
            ),
            const SizedBox(height: 16),
            DropdownButtonFormField<String>(
              initialValue: _priority,
              decoration: const InputDecoration(
                labelText: 'Priority',
                border: OutlineInputBorder(),
              ),
              items: const [
                DropdownMenuItem(value: 'low', child: Text('Low')),
                DropdownMenuItem(value: 'medium', child: Text('Medium')),
                DropdownMenuItem(value: 'high', child: Text('High')),
              ],
              onChanged: (value) {
                if (value != null) setState(() => _priority = value);
              },
            ),
            const SizedBox(height: 16),
            InkWell(
              onTap: _pickDueDate,
              child: InputDecorator(
                decoration: const InputDecoration(
                  labelText: 'Due Date (optional)',
                  border: OutlineInputBorder(),
                  suffixIcon: Icon(Icons.calendar_today),
                ),
                child: Text(
                  _dueDate != null
                      ? '${_dueDate!.year}-${_dueDate!.month.toString().padLeft(2, '0')}-${_dueDate!.day.toString().padLeft(2, '0')}'
                      : 'No date selected',
                  style: theme.textTheme.bodyLarge?.copyWith(
                    color: _dueDate != null ? null : theme.colorScheme.onSurfaceVariant,
                  ),
                ),
              ),
            ),
            if (_dueDate != null)
              TextButton(
                onPressed: () => setState(() => _dueDate = null),
                child: const Text('Clear date'),
              ),
            const SizedBox(height: 24),
            FilledButton(
              onPressed: _isLoading ? null : _save,
              child: _isLoading
                  ? const SizedBox(
                      height: 20,
                      width: 20,
                      child: CircularProgressIndicator(strokeWidth: 2),
                    )
                  : Text(isEditing ? 'Save Changes' : 'Create Todo'),
            ),
          ],
        ),
      ),
    );
  }
}