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 ConversationsTabScreen extends ConsumerWidget {
  const ConversationsTabScreen({super.key});

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

    return Scaffold(
      appBar: AppBar(
        title: Text('Chat', style: theme.textTheme.titleLarge),
        actions: [
          IconButton(
            icon: const Icon(Icons.add),
            tooltip: 'New conversation',
            onPressed: () async {
              final conv = await ref
                  .read(conversationsProvider.notifier)
                  .create('');
              if (context.mounted) {
                context.push(Routes.chat.replaceFirst(':id', '${conv.id}'));
              }
            },
          ),
        ],
      ),
      body: convsAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (e, _) => Center(child: Text('Error: $e')),
        data: (convs) {
          if (convs.isEmpty) {
            return Center(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Icon(Icons.chat_bubble_outline,
                      size: 48, color: theme.colorScheme.onSurfaceVariant),
                  const SizedBox(height: 16),
                  Text('No conversations yet',
                      style: theme.textTheme.titleMedium),
                  const SizedBox(height: 8),
                  FilledButton.icon(
                    icon: const Icon(Icons.add),
                    label: const Text('Start a conversation'),
                    onPressed: () async {
                      final conv = await ref
                          .read(conversationsProvider.notifier)
                          .create('');
                      if (context.mounted) {
                        context.push(
                            Routes.chat.replaceFirst(':id', '${conv.id}'));
                      }
                    },
                  ),
                ],
              ),
            );
          }
          return RefreshIndicator(
            onRefresh: () => ref.read(conversationsProvider.notifier).refresh(),
            child: ListView.builder(
              itemCount: convs.length,
              itemBuilder: (ctx, i) {
                final c = convs[i];
                return ListTile(
                  leading: const Icon(Icons.chat_bubble_outline),
                  title: Text(
                      c.title.isEmpty ? 'New conversation' : c.title,
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis),
                  subtitle: Text(
                    _relativeTime(c.updatedAt),
                    style: theme.textTheme.labelSmall,
                  ),
                  trailing: IconButton(
                    icon: const Icon(Icons.delete_outline),
                    onPressed: () =>
                        _confirmDelete(context, ref, c.id, c.title),
                  ),
                  onTap: () =>
                      ctx.push(Routes.chat.replaceFirst(':id', '${c.id}')),
                );
              },
            ),
          );
        },
      ),
    );
  }

  Future<void> _confirmDelete(
      BuildContext context, WidgetRef ref, int id, String title) async {
    final ok = await showDialog<bool>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: const Text('Delete conversation?'),
        content: Text('"$title" will be permanently deleted.'),
        actions: [
          TextButton(
              onPressed: () => Navigator.pop(dialogContext, false),
              child: const Text('Cancel')),
          FilledButton(
              onPressed: () => Navigator.pop(dialogContext, true),
              child: const Text('Delete')),
        ],
      ),
    );
    if (ok == true) {
      await ref.read(conversationsProvider.notifier).delete(id);
    }
  }
}

String _relativeTime(DateTime dt) {
  final diff = DateTime.now().difference(dt);
  if (diff.inMinutes < 1) return 'just now';
  if (diff.inHours < 1) return '${diff.inMinutes}m ago';
  if (diff.inDays < 1) return '${diff.inHours}h ago';
  if (diff.inDays < 7) return '${diff.inDays}d ago';
  return '${dt.day}/${dt.month}/${dt.year}';
}