VeloeKemonoPartyFlutter/lib/pages/posts_screen.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:veloe_kemono_party_flutter/app_layout.dart';
import 'package:veloe_kemono_party_flutter/main.dart';
import 'package:veloe_kemono_party_flutter/pages/widgets/post_container.dart';

final searchQueryProvider = StateProvider.autoDispose<String>((ref) => '');
final debouncedSearchQueryProvider = Provider.autoDispose<String>((ref) {
  final query = ref.watch(searchQueryProvider);
  final debouncer = Debouncer(delay: const Duration(milliseconds: 500));
  debouncer.run(() {});
  return query;
});

// Add Debouncer class
class Debouncer {
  final Duration delay;
  Timer? _timer;

  Debouncer({required this.delay});

  void run(VoidCallback action) {
    _timer?.cancel();
    _timer = Timer(delay, action);
  }
}

class PostsScreen extends ConsumerStatefulWidget {
  final String creatorId;
  final String service;
  final bool withAppBar;

  const PostsScreen({
    super.key,
    required this.creatorId,
    required this.service,
    this.withAppBar = true
  });

  @override
  ConsumerState<PostsScreen> createState() => _PostsScreenState();
}

class _PostsScreenState extends ConsumerState<PostsScreen> with PaginationMixin {
 late final TextEditingController _searchController;

  @override
  void initState() {
    super.initState();
    _searchController = TextEditingController();
    Future.microtask(() => ref.read(postsProvider((
      widget.creatorId,
      widget.service,
      ref.read(searchQueryProvider) // Initial query
    )).notifier).loadInitial());
  }

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

  @override
  Widget build(BuildContext context) {
    final currentQuery = ref.watch(debouncedSearchQueryProvider);
    final postsAsync = ref.watch(postsProvider((
      widget.creatorId,
      widget.service,
      currentQuery
    )));
    return Scaffold(
      appBar:  AppBar(
        title: _buildSearchField(),
        leading: widget.withAppBar ? 
        IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () => Navigator.pop(context),
        ) : 
        Builder(
          builder: (context) => IconButton(
            icon: const Icon(Icons.menu),
            onPressed: () => AppLayout.openDrawer(context),
          ),
        ),
      ),
      body: postsAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (error, _) => Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('Error: ${error.toString()}'),
              ElevatedButton(
                onPressed: () => ref.invalidate(postsProvider((widget.creatorId, widget.service,ref.read(searchQueryProvider)))),
                child: const Text('Retry'),
              )
            ],
          ),
        ),
        data: (allPosts) => NotificationListener<ScrollNotification>(
          onNotification: (notification) {
            if (notification is ScrollUpdateNotification) {
              _scrollListener();
            }
            return false;
          },
          child: CustomScrollView(
            controller: _scrollController,
            slivers: [
              SliverList(
                delegate: SliverChildBuilderDelegate(
                  (context, index) => PostContainer(
                    key: ValueKey(allPosts[index].id),
                    post: allPosts[index],
                    postIndex: index,
                    allPosts: allPosts,
                    loadMorePosts: () async { _loadNextPage(); },
                  ),
                  childCount: allPosts.length,
                ),
              ),
              SliverToBoxAdapter(
                child: _buildLoadMoreIndicator(),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildSearchField() {
    return TextField(
      controller: _searchController,
      decoration: InputDecoration(
        hintText: 'Search posts...',
        suffixIcon: IconButton(
          icon: const Icon(Icons.clear),
          onPressed: () {
            _searchController.clear();
            ref.read(searchQueryProvider.notifier).state = '';
          },
        ),
      ),
      onChanged: (value) => ref.read(searchQueryProvider.notifier).state = value,
    );
  }

  Widget _buildLoadMoreIndicator() {
    return ref.watch(postsProvider((widget.creatorId, widget.service,ref.read(searchQueryProvider)))).maybeWhen(
          loading: () => const Padding(
            padding: EdgeInsets.all(16),
            child: Center(child: CircularProgressIndicator()),
          ),
          error: (error, _) => Column(
            children: [
              Text('Load more failed: ${error.toString()}'),
              ElevatedButton(
                onPressed: () => ref.read(postsProvider((widget.creatorId, widget.service,ref.read(searchQueryProvider))).notifier).loadNext(),
                child: const Text('Retry'),
              )
            ],
          ),
          orElse: () => const SizedBox.shrink(),
        );
  }
}

mixin PaginationMixin<T extends ConsumerStatefulWidget> on ConsumerState<T> {
  final ScrollController _scrollController = ScrollController();
  bool _isLoading = false;

  @override
  void initState() {
    super.initState();
    _scrollController.addListener(_scrollListener);
  }

  void _scrollListener() {
    if (_scrollController.position.pixels >= 
        _scrollController.position.maxScrollExtent * 0.8) {
      _loadNextPage();
    }
  }

  PostsScreen get postsWidget => widget as PostsScreen;

  Future<void> _loadNextPage() async {
    if (_isLoading || !mounted) return;
    _isLoading = true;
    
    final notifier = ref.read(postsProvider((
      postsWidget.creatorId,
      postsWidget.service,
      ref.read(searchQueryProvider)
    )).notifier);

    if (!notifier.mounted) return;

    await notifier.loadNext();
    _isLoading = false;
  }

  @override
  void dispose() {
    _scrollController.removeListener(_scrollListener);
    _scrollController.dispose();
    super.dispose();
  }
}