router.post('/playlist', (req, res) => {

    // Find all playlists that match your answers
    Playlist.find({
        answers: req.body.answers,
        genre: req.body.genre
    }).then(playlists => {
        // Choose a random playlist from the perfect matches, or a less-than-perfect match if there's no perfect match
        if (playlists.length > 0){
            return res.json(playlists[Math.floor((Math.random() * playlists.length-1))])
        } else{
            Playlist.find({ genre: req.body.genre })
                .then(playlists => res.json(playlists[Math.floor((Math.random() * playlists.length-1))]))
                .catch(err => console.log(err))
        }
    })
}

class FeedIndex extends React.Component {
    constructor(props) {
        super(props);
        
        // Component state stores information about whether an initial search has been performed,
        // whether there are remaining posts left to fetch,
        // and what offset to use in the DB query
        this.state = {
            offset: 0,
            didSearch: false,
            morePlaylists: true
        };

        this.observer = React.createRef();
    }

    // This function defines the infinite scroll
    lastPlaylistRef(node) {
            this.observer.current = new IntersectionObserver(entries => {
                if (entries[0].isIntersecting && this.state.morePosts) {
                    props.fetchAddlFeedPlaylists(props.currentUser.username, this.state.offset + 5)
                    .then((res) => {
                        // If there aren't enough playlists, change state to prevent additional queries
                        if (res.playlists.length < 5) {
                            this.setState({morePlaylists: false})
                        }
                    });
                    // Adjust the offset for future queries
                    this.incrementOffset();
                }
            });

            if (node) this.observer.current.observe(node);
    }
}