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

import '../../core/constants.dart';
import '../../providers/chat_provider.dart';

class ConversationsListScreen extends ConsumerWidget {
  const ConversationsListScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final convsAsync = ref.watch(conversationsProvider);

    return Scaffold(
      appBar: AppBar(title: const Text('Chat')),
      body: convsAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (e, _) => Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('Error: $e'),
              TextButton(
                onPressed: () => ref.invalidate(conversationsProvider),
                child: const Text('Retry'),
              ),
            ],
          ),
        ),
        data: (convs) {
          if (convs.isEmpty) {
            return const Center(
                child: Text('No conversations yet. Tap + to start one.'));
          }
          return RefreshIndicator(
            onRefresh: () => ref.refresh(conversationsProvider.future),
            child: ListView.separated(
              itemCount: convs.length,
              separatorBuilder: (_, _) => const Divider(height: 1),
              itemBuilder: (context, i) {
                final conv = convs[i];
                return ListTile(
                  leading: const Icon(Icons.chat_bubble_outline),
                  title: Text(conv.title),
                  subtitle: Text(
                    conv.updatedAt.toLocal().toString().substring(0, 16),
                    style: Theme.of(context).textTheme.bodySmall,
                  ),
                  onTap: () => context.push(
                    Routes.chat.replaceFirst(':id', '${conv.id}'),
                  ),
                  onLongPress: () async {
                    final confirm = await showDialog<bool>(
                      context: context,
                      builder: (_) => AlertDialog(
                        title: const Text('Delete conversation?'),
                        content: Text(conv.title),
                        actions: [
                          TextButton(
                            onPressed: () => Navigator.pop(context, false),
                            child: const Text('Cancel'),
                          ),
                          TextButton(
                            onPressed: () => Navigator.pop(context, true),
                            child: const Text('Delete'),
                          ),
                        ],
                      ),
                    );
                    if (confirm == true) {
                      await ref
                          .read(conversationsProvider.notifier)
                          .delete(conv.id);
                    }
                  },
                );
              },
            ),
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        heroTag: 'chat_fab',
        onPressed: () => _newConversation(context, ref),
        child: const Icon(Icons.add),
      ),
    );
  }

  Future<void> _newConversation(BuildContext context, WidgetRef ref) async {
    final controller = TextEditingController();
    final title = await showDialog<String>(
      context: context,
      builder: (_) => AlertDialog(
        title: const Text('New Conversation'),
        content: TextField(
          controller: controller,
          decoration: const InputDecoration(hintText: 'Title'),
          autofocus: true,
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(context, controller.text.trim()),
            child: const Text('Create'),
          ),
        ],
      ),
    );
    if (title != null && title.isNotEmpty) {
      final conv =
          await ref.read(conversationsProvider.notifier).create(title);
      if (context.mounted) {
        context.push(Routes.chat.replaceFirst(':id', '${conv.id}'));
      }
    }
  }
}