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

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

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

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

class _PostsScreenState extends ConsumerState<PostsScreen> with PaginationMixin {
  @override
  void initState() {
    super.initState();
    Future.microtask(() => ref.read(postsProvider((
      widget.creatorId, // Direct access now valid
      widget.service
    )).notifier).loadInitial());
  }

  @override
  Widget build(BuildContext context) {
    final postsAsync = ref.watch(postsProvider((widget.creatorId, widget.service)));

    return Scaffold(
      appBar: AppBar(
        title: const Text('Posts'),
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () => Navigator.pop(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))),
                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],
                  ),
                  childCount: allPosts.length,
                ),
              ),
              SliverToBoxAdapter(
                child: _buildLoadMoreIndicator(),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildLoadMoreIndicator() {
    return ref.watch(postsProvider((widget.creatorId, widget.service))).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)).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) return;
    _isLoading = true;
    
    final notifier = ref.read(postsProvider((
      postsWidget.creatorId, // Use converted widget reference
      postsWidget.service
    )).notifier);
    
    await notifier.loadNext();
    _isLoading = false;
  }

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