FileCache.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.Storage.Streams;

namespace Microsoft.Toolkit.Uwp.UI
{
    /// <summary>
    /// Provides methods and tools to cache files in a folder
    /// </summary>
    public class FileCache : CacheBase<StorageFile>
    {
        /// <summary>
        /// Private singleton field.
        /// </summary>
        private static FileCache _instance;

        /// <summary>
        /// Gets public singleton property.
        /// </summary>
        public static FileCache Instance => _instance ?? (_instance = new FileCache());

        /// <summary>
        /// Cache specific hooks to process items from HTTP response
        /// </summary>
        /// <param name="stream">input stream</param>
        /// <param name="initializerKeyValues">key value pairs used when initializing instance of generic type</param>
        /// <returns>awaitable task</returns>
        protected override Task<StorageFile> InitializeTypeAsync(Stream stream, List<KeyValuePair<string, object>> initializerKeyValues = null)
        {
            // nothing to do in this instance;
            return null;
        }

        /// <summary>
        /// Cache specific hooks to process items from HTTP response
        /// </summary>
        /// <param name="baseFile">storage file</param>
        /// <param name="initializerKeyValues">key value pairs used when initializing instance of generic type</param>
        /// <returns>awaitable task</returns>
        protected override Task<StorageFile> InitializeTypeAsync(StorageFile baseFile, List<KeyValuePair<string, object>> initializerKeyValues = null)
        {
            return Task.Run(() => baseFile);
        }
    }
}