spotube/lib/components/Library/UserArtists.dart

import 'package:flutter/material.dart';
import 'package:infinite_scroll_pagination/infinite_scroll_pagination.dart';
import 'package:provider/provider.dart';
import 'package:spotify/spotify.dart';
import 'package:spotube/components/Artist/ArtistCard.dart';
import 'package:spotube/provider/SpotifyDI.dart';

class UserArtists extends StatefulWidget {
  const UserArtists({Key? key}) : super(key: key);

  @override
  State<UserArtists> createState() => _UserArtistsState();
}

class _UserArtistsState extends State<UserArtists> {
  final PagingController<int, Artist> _pagingController =
      PagingController(firstPageKey: 0);

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance?.addPostFrameCallback((timestamp) {
      _pagingController.addPageRequestListener((pageKey) async {
        try {
          SpotifyDI data = context.read<SpotifyDI>();
          var offset =
              _pagingController.value.itemList?.elementAt(pageKey).id ?? "";
          CursorPage<Artist> artists = await data.spotifyApi.me
              .following(FollowingType.artist)
              .getPage(15, offset);

          var items = artists.items!.toList();

          if (artists.items != null && items.length < 15) {
            _pagingController.appendLastPage(items);
          } else if (artists.items != null) {
            var yetToBe = [
              ...(_pagingController.value.itemList ?? []),
              ...items
            ];
            _pagingController.appendPage(items, yetToBe.length - 1);
          }
        } catch (e, stack) {
          _pagingController.error = e;
          print("[UserArtists.pagingController]: $e");
          print(stack);
        }
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    SpotifyDI data = context.watch<SpotifyDI>();

    return FutureBuilder<CursorPage<Artist>>(
      future: data.spotifyApi.me.following(FollowingType.artist).first(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return const Center(child: CircularProgressIndicator.adaptive());
        }

        return PagedGridView(
          gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
            maxCrossAxisExtent: 250,
            childAspectRatio: 9 / 11,
            crossAxisSpacing: 20,
            mainAxisSpacing: 20,
          ),
          padding: const EdgeInsets.all(10),
          pagingController: _pagingController,
          builderDelegate: PagedChildBuilderDelegate<Artist>(
            itemBuilder: (context, item, index) {
              return ArtistCard(item);
            },
          ),
        );
      },
    );
  }
}