using AngleSharp;
using AngleSharp.Dom;
using AngleSharp.Html.Dom;

public class YoutubeValidator : UriBasedSongValidatorBase
{
    public override string UriValidatorRegex => @"^(https?://)?(www\.)?(youtube\.com/watch\?v=|youtu\.be/)([a-zA-Z0-9_-]{11})";

    public override async Task<bool> CanExtractSongMetadataAsync(Uri songUri)
    {
        using(HttpClient httpClient = new HttpClient())
        {
            var response = await httpClient.GetAsync(songUri);
            var config = Configuration.Default.WithDefaultLoader();
            var context = BrowsingContext.New(config);
            using(var document = await context.OpenAsync(async req => req.Content(await response.Content.ReadAsStringAsync())))
            {
                var documentContents = (document.ChildNodes[1] as HtmlElement).InnerHtml;
                var titleElement = document.QuerySelectorAll(".yt-video-attribute-view-model__title")[0];
                var artistParentElement = document.QuerySelectorAll(".yt-video-attribute-view-model__secondary-subtitle")[0];

                return titleElement != null && artistParentElement != null && artistParentElement.Children.Length > 0;
            }
        }
    }

    public override async Task<Song> ValidateAsync(Uri songUri)
    {
        var title = string.Empty;
        var artist = string.Empty;

        using(HttpClient httpClient = new HttpClient())
        {
            var response = await httpClient.GetAsync(songUri);
            var config = Configuration.Default.WithDefaultLoader();
            var context = BrowsingContext.New(config);
            using(var document = await context.OpenAsync(async req => req.Content(await response.Content.ReadAsStringAsync())))
            {
                title = document.QuerySelectorAll(".yt-video-attribute-view-model__title")[0]?.InnerHtml;
                artist = document.QuerySelectorAll(".yt-video-attribute-view-model__secondary-subtitle")[0]?.Children[0]?.InnerHtml;
            }
        }
        
        var song = new Song
        {
            Name = title,
            Artist = artist,
            Url = songUri.ToString(),
            Provider = SongProvider.YouTube,
            SpotifyId = this.LookupSpotifyId(title, artist)
        };

        return song;
    }
}