using Microsoft.Practices.EnterpriseLibrary.Caching;

namespace Website.Caching
{
    public class CachingSyndicatedFeedService : CacheBase<FeedItemCollection>, ISyndicatedFeedService
    {
        private const string CACHE_MANAGER_PREFIX = "SyndicatedFeedService";
        private static readonly object __CACHE_LOCK = new object();

        private readonly ISyndicatedFeedService service;

        public CachingSyndicatedFeedService(ISyndicatedFeedService service) : this(service, null)
        {
            
        }
        public CachingSyndicatedFeedService(ISyndicatedFeedService service, ICacheManager cache)
            : base(cache, CACHE_MANAGER_PREFIX)
        {
            this.service = service;
        }

        public FeedItemCollection GetFeedItems(string feedUrl, int count)
        {
            var items = this[feedUrl];

            if (items == null)
            {
                lock (__CACHE_LOCK)
                {
                    if (this[feedUrl] == null)
                        this[feedUrl] = service.GetFeedItems(feedUrl, count);
                }
                items = this[feedUrl];
            }

            return items;
        }
    }
}