SharpRSS/SharpRss/FeedCache.cs

using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using CodeHollow.FeedReader;
using Serilog;
using ToolQit.Extensions;

namespace SharpRss
{
    /// <summary>
    /// Global memory feed cache.
    /// </summary>
    public static class FeedCache
    {
        private static readonly Dictionary<string, Feed> CachedFeeds = new Dictionary<string, Feed>();

        public static async Task<Feed> GetFeed(string urlKey)
        {
            Log.Verbose("Fetching feed: {UrlKey}", urlKey);
            if (urlKey.IsNullEmptyWhiteSpace())
            {
                Log.Error("RSS Url is empty!");
                return new Feed();
            }
            
            if (CachedFeeds.TryGetValue(urlKey, out Feed? fModel))
                return fModel;
            string feedUrl;
            var urls = await FeedReader.GetFeedUrlsFromUrlAsync(urlKey);
            if (!urls.Any())
                feedUrl = urlKey;
            else
                feedUrl = urls.First().Url;
            
            Feed feed = await FeedReader.ReadAsync(feedUrl);
            if (feed == null)
                Log.Warning("Could not get feed: {FeedUrl}", feedUrl);
            CachedFeeds.Add(urlKey, feed);
            return feed;
        }
    }
}