Solian/lib/screens/explore.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:solian/models/pagination.dart';
import 'package:solian/models/post.dart';
import 'package:solian/providers/auth.dart';
import 'package:solian/providers/realm.dart';
import 'package:solian/router.dart';
import 'package:solian/utils/service_url.dart';
import 'package:infinite_scroll_pagination/infinite_scroll_pagination.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';
import 'package:http/http.dart' as http;
import 'package:solian/utils/theme.dart';
import 'package:solian/widgets/realms/realm_shortcuts.dart';
import 'package:solian/widgets/scaffold.dart';
import 'package:solian/widgets/notification_notifier.dart';
import 'package:solian/widgets/posts/post.dart';

class ExplorePostScreen extends StatelessWidget {
  const ExplorePostScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return IndentScaffold(
      noSafeArea: true,
      fixedAppBarColor: SolianTheme.isLargeScreen(context),
      appBarActions: const [NotificationButton()],
      title: AppLocalizations.of(context)!.explore,
      child: const ExplorePostWidget(showRealmShortcuts: true),
    );
  }
}

class ExplorePostWidget extends StatefulWidget {
  final String? realm;
  final bool showRealmShortcuts;

  const ExplorePostWidget({
    super.key,
    this.realm,
    this.showRealmShortcuts = false,
  });

  @override
  State<ExplorePostWidget> createState() => _ExplorePostWidgetState();
}

class _ExplorePostWidgetState extends State<ExplorePostWidget> {
  final PagingController<int, Post> _pagingController = PagingController(firstPageKey: 0);

  final http.Client _client = http.Client();

  Future<void> fetchFeed(int pageKey) async {
    final offset = pageKey;
    const take = 5;

    Uri uri;
    if (widget.realm == null) {
      uri = getRequestUri('interactive', '/api/feed?take=$take&offset=$offset');
    } else {
      uri = getRequestUri('interactive', '/api/feed?realm=${widget.realm}&take=$take&offset=$offset');
    }

    var res = await _client.get(uri);
    if (res.statusCode == 200) {
      final result = PaginationResult.fromJson(jsonDecode(utf8.decode(res.bodyBytes)));
      final items = result.data?.map((x) => Post.fromJson(x)).toList() ?? List.empty();
      final isLastPage = (result.count - pageKey) < take;
      if (isLastPage || result.data == null) {
        _pagingController.appendLastPage(items);
      } else {
        final nextPageKey = pageKey + items.length;
        _pagingController.appendPage(items, nextPageKey);
      }
    } else {
      _pagingController.error = utf8.decode(res.bodyBytes);
    }
  }

  @override
  void initState() {
    super.initState();

    Future.delayed(Duration.zero, () async {
      if (widget.showRealmShortcuts) {
        final auth = context.read<AuthProvider>();
        if (auth.client == null) {
          await auth.loadClient();
        }
        context.read<RealmProvider>().fetch(auth);
      }
    });

    _pagingController.addPageRequestListener((pageKey) => fetchFeed(pageKey));
  }

  @override
  Widget build(BuildContext context) {
    final auth = context.read<AuthProvider>();

    return Scaffold(
      floatingActionButton: FutureBuilder(
        future: auth.isAuthorized(),
        builder: (context, snapshot) {
          if (snapshot.hasData && snapshot.data!) {
            return FloatingActionButton(
              child: const Icon(Icons.edit),
              onPressed: () async {
                final did = await SolianRouter.router.pushNamed(
                  widget.realm == null ? 'posts.moments.editor' : 'realms.posts.moments.editor',
                  pathParameters: widget.realm == null ? {} : {'realm': widget.realm!},
                );
                if (did == true) _pagingController.refresh();
              },
            );
          } else {
            return Container();
          }
        },
      ),
      body: RefreshIndicator(
        onRefresh: () => Future.sync(
          () => _pagingController.refresh(),
        ),
        child: CustomScrollView(
          slivers: [
            widget.showRealmShortcuts
                ? SliverToBoxAdapter(
                    child: FutureBuilder(
                      future: auth.isAuthorized(),
                      builder: (context, snapshot) {
                        if (!snapshot.hasData || snapshot.data != true) {
                          return Container();
                        }

                        return Container(
                          height: 120,
                          decoration: BoxDecoration(
                            border: Border(
                              bottom: BorderSide(width: 0.3, color: Theme.of(context).dividerColor),
                            ),
                          ),
                          child: const RealmShortcuts(),
                        );
                      },
                    ),
                  )
                : SliverToBoxAdapter(child: Container()),
            PagedSliverList<int, Post>(
              pagingController: _pagingController,
              builderDelegate: PagedChildBuilderDelegate<Post>(
                itemBuilder: (context, item, index) => PostItem(
                  item: item,
                  onUpdate: () => _pagingController.refresh(),
                  onTap: () {
                    SolianRouter.router.pushNamed(
                      widget.realm == null ? 'posts.details' : 'realms.posts.details',
                      pathParameters: {
                        'alias': item.alias,
                        'dataset': item.dataset,
                        ...(widget.realm == null ? {} : {'realm': widget.realm!}),
                      },
                    );
                  },
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

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