...

6 files changed, 147 insertions, 125 deletions

diff --git a/BackEnd/Timeline/Helpers/Cache/CacheableDataDigest.cs b/BackEnd/Timeline/Helpers/Cache/CacheableDataDigest.cs
new file mode 100644
index 00000000..3b5bcf52
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Cache/CacheableDataDigest.cs
@@ -0,0 +1,16 @@
+using System;

+

+namespace Timeline.Helpers.Cache

+{

+    public class CacheableDataDigest

+    {

+        public CacheableDataDigest(string eTag, DateTime lastModified)

+        {

+            ETag = eTag;

+            LastModified = lastModified;

+        }

+

+        public string ETag { get; set; }

+        public DateTime LastModified { get; set; }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/Cache/DataCacheHelper.cs b/BackEnd/Timeline/Helpers/Cache/DataCacheHelper.cs
new file mode 100644
index 00000000..c26bdddc
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Cache/DataCacheHelper.cs
@@ -0,0 +1,82 @@
+using Microsoft.AspNetCore.Http;

+using Microsoft.AspNetCore.Mvc;

+using Microsoft.Net.Http.Headers;

+using System;

+using System.Linq;

+using System.Threading.Tasks;

+using Timeline.Models;

+using Timeline.Models.Http;

+

+namespace Timeline.Helpers.Cache

+{

+    public static class DataCacheHelper

+    {

+        public static async Task<ActionResult> GenerateActionResult(Controller controller, ICacheableDataProvider provider, TimeSpan? maxAge = null)

+        {

+            const string CacheControlHeaderKey = "Cache-Control";

+            const string IfNonMatchHeaderKey = "If-None-Match";

+            const string IfModifiedSinceHeaderKey = "If-Modified-Since";

+            const string ETagHeaderKey = "ETag";

+            const string LastModifiedHeaderKey = "Last-Modified";

+

+            string GenerateCacheControlHeaderValue()

+            {

+                var cacheControlHeader = new CacheControlHeaderValue()

+                {

+                    NoCache = true,

+                    NoStore = false,

+                    MaxAge = maxAge ?? TimeSpan.FromDays(14),

+                    Private = true,

+                    MustRevalidate = true

+                };

+                return cacheControlHeader.ToString();

+            }

+

+            var digest = await provider.GetDigest();

+            var eTagValue = '"' + digest.ETag + '"';

+            var eTag = new EntityTagHeaderValue(eTagValue);

+

+            ActionResult Generate304Result()

+            {

+                controller.Response.Headers.Add(ETagHeaderKey, eTagValue);

+                controller.Response.Headers.Add(LastModifiedHeaderKey, digest.LastModified.ToString("R"));

+                controller.Response.Headers.Add(CacheControlHeaderKey, GenerateCacheControlHeaderValue());

+                return controller.StatusCode(StatusCodes.Status304NotModified, null);

+            }

+

+            if (controller.Request.Headers.TryGetValue(IfNonMatchHeaderKey, out var ifNonMatchHeaderValue))

+            {

+                if (!EntityTagHeaderValue.TryParseList(ifNonMatchHeaderValue, out var eTagList))

+                {

+                    return controller.BadRequest(ErrorResponse.Common.Header.IfNonMatch_BadFormat());

+                }

+

+                if (eTagList.FirstOrDefault(e => e.Equals(eTag)) != null)

+                {

+                    return Generate304Result();

+                }

+            }

+            else if (controller.Request.Headers.TryGetValue(IfModifiedSinceHeaderKey, out var ifModifiedSinceHeaderValue))

+            {

+                if (!DateTime.TryParse(ifModifiedSinceHeaderValue, out var headerValue))

+                {

+                    return controller.BadRequest(new CommonResponse(ErrorCodes.Common.Header.IfModifiedSince_BadFormat, "Header If-Modified-Since is of bad format."));

+                }

+

+                if (headerValue > digest.LastModified)

+                {

+                    return Generate304Result();

+                }

+            }

+

+            var data = await provider.GetData();

+            controller.Response.Headers.Add(CacheControlHeaderKey, GenerateCacheControlHeaderValue());

+            return controller.File(data.Data, data.ContentType, digest.LastModified, eTag);

+        }

+

+        public static Task<ActionResult> GenerateActionResult(Controller controller, Func<Task<ICacheableDataDigest>> getDigestDelegate, Func<Task<ByteData>> getDataDelegate, TimeSpan? maxAge = null)

+        {

+            return GenerateActionResult(controller, new DelegateCacheableDataProvider(getDigestDelegate, getDataDelegate), maxAge);

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/Cache/DelegateCacheableDataProvider.cs b/BackEnd/Timeline/Helpers/Cache/DelegateCacheableDataProvider.cs
new file mode 100644
index 00000000..80cb66c7
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Cache/DelegateCacheableDataProvider.cs
@@ -0,0 +1,28 @@
+using System;

+using System.Threading.Tasks;

+using Timeline.Models;

+

+namespace Timeline.Helpers.Cache

+{

+    public class DelegateCacheableDataProvider : ICacheableDataProvider

+    {

+        private readonly Func<Task<ICacheableDataDigest>> _getDigestDelegate;

+        private readonly Func<Task<ByteData>> _getDataDelegate;

+

+        public DelegateCacheableDataProvider(Func<Task<ICacheableDataDigest>> getDigestDelegate, Func<Task<ByteData>> getDataDelegate)

+        {

+            _getDigestDelegate = getDigestDelegate;

+            _getDataDelegate = getDataDelegate;

+        }

+

+        public Task<ICacheableDataDigest> GetDigest()

+        {

+            return _getDigestDelegate();

+        }

+

+        public Task<ByteData> GetData()

+        {

+            return _getDataDelegate();

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/Cache/ICacheableDataDigest.cs b/BackEnd/Timeline/Helpers/Cache/ICacheableDataDigest.cs
new file mode 100644
index 00000000..32519d7e
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Cache/ICacheableDataDigest.cs
@@ -0,0 +1,10 @@
+using System;

+

+namespace Timeline.Helpers.Cache

+{

+    public interface ICacheableDataDigest

+    {

+        string ETag { get; }

+        DateTime LastModified { get; }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/Cache/ICacheableDataProvider.cs b/BackEnd/Timeline/Helpers/Cache/ICacheableDataProvider.cs
new file mode 100644
index 00000000..b270fb1d
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Cache/ICacheableDataProvider.cs
@@ -0,0 +1,11 @@
+using System.Threading.Tasks;

+using Timeline.Models;

+

+namespace Timeline.Helpers.Cache

+{

+    public interface ICacheableDataProvider

+    {

+        Task<ICacheableDataDigest> GetDigest();

+        Task<ByteData> GetData();

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/DataCacheHelper.cs b/BackEnd/Timeline/Helpers/DataCacheHelper.cs
deleted file mode 100644
index 1ad69708..00000000
--- a/BackEnd/Timeline/Helpers/DataCacheHelper.cs
+++ /dev/null
@@ -1,125 +0,0 @@
-using Microsoft.AspNetCore.Http;

-using Microsoft.AspNetCore.Mvc;

-using Microsoft.Extensions.DependencyInjection;

-using Microsoft.Extensions.Logging;

-using Microsoft.Net.Http.Headers;

-using System;

-using System.Linq;

-using System.Threading.Tasks;

-using Timeline.Models.Http;

-using static Timeline.Resources.Helper.DataCacheHelper;

-

-namespace Timeline.Helpers

-{

-    public interface ICacheableData

-    {

-        string Type { get; }

-#pragma warning disable CA1819 // Properties should not return arrays

-        byte[] Data { get; }

-#pragma warning restore CA1819 // Properties should not return arrays

-        DateTime? LastModified { get; }

-    }

-

-    public class CacheableData : ICacheableData

-    {

-        public CacheableData(string type, byte[] data, DateTime? lastModified)

-        {

-            Type = type;

-            Data = data;

-            LastModified = lastModified;

-        }

-

-        public string Type { get; set; }

-#pragma warning disable CA1819 // Properties should not return arrays

-        public byte[] Data { get; set; }

-#pragma warning restore CA1819 // Properties should not return arrays

-        public DateTime? LastModified { get; set; }

-    }

-

-    public interface ICacheableDataProvider

-    {

-        Task<string> GetDataETag();

-        Task<ICacheableData> GetData();

-    }

-

-    public class DelegateCacheableDataProvider : ICacheableDataProvider

-    {

-        private readonly Func<Task<string>> _getDataETagDelegate;

-        private readonly Func<Task<ICacheableData>> _getDataDelegate;

-

-        public DelegateCacheableDataProvider(Func<Task<string>> getDataETagDelegate, Func<Task<ICacheableData>> getDataDelegate)

-        {

-            _getDataETagDelegate = getDataETagDelegate;

-            _getDataDelegate = getDataDelegate;

-        }

-

-        public Task<ICacheableData> GetData()

-        {

-            return _getDataDelegate();

-        }

-

-        public Task<string> GetDataETag()

-        {

-            return _getDataETagDelegate();

-        }

-    }

-

-    public static class DataCacheHelper

-    {

-        public static async Task<ActionResult> GenerateActionResult(Controller controller, ICacheableDataProvider provider, TimeSpan? maxAge = null)

-        {

-            const string CacheControlHeaderKey = "Cache-Control";

-            const string IfNonMatchHeaderKey = "If-None-Match";

-            const string ETagHeaderKey = "ETag";

-

-            string GenerateCacheControlHeaderValue()

-            {

-                var cacheControlHeader = new CacheControlHeaderValue()

-                {

-                    NoCache = true,

-                    NoStore = false,

-                    MaxAge = maxAge ?? TimeSpan.FromDays(14),

-                    Private = true,

-                    MustRevalidate = true

-                };

-                return cacheControlHeader.ToString();

-            }

-

-            var loggerFactory = controller.HttpContext.RequestServices.GetRequiredService<ILoggerFactory>();

-            var logger = loggerFactory.CreateLogger(typeof(DataCacheHelper));

-

-            var eTagValue = await provider.GetDataETag();

-            eTagValue = '"' + eTagValue + '"';

-            var eTag = new EntityTagHeaderValue(eTagValue);

-

-

-            if (controller.Request.Headers.TryGetValue(IfNonMatchHeaderKey, out var value))

-            {

-                if (!EntityTagHeaderValue.TryParseStrictList(value, out var eTagList))

-                {

-                    logger.LogInformation(Log.Format(LogBadIfNoneMatch, ("Header Value", value)));

-                    return controller.BadRequest(ErrorResponse.Common.Header.IfNonMatch_BadFormat());

-                }

-

-                if (eTagList.FirstOrDefault(e => e.Equals(eTag)) != null)

-                {

-                    logger.LogInformation(LogResultNotModified);

-                    controller.Response.Headers.Add(ETagHeaderKey, eTagValue);

-                    controller.Response.Headers.Add(CacheControlHeaderKey, GenerateCacheControlHeaderValue());

-

-                    return controller.StatusCode(StatusCodes.Status304NotModified, null);

-                }

-            }

-

-            var data = await provider.GetData();

-            logger.LogInformation(LogResultData);

-            controller.Response.Headers.Add(CacheControlHeaderKey, GenerateCacheControlHeaderValue());

-            return controller.File(data.Data, data.Type, data.LastModified, eTag);

-        }

-

-        public static Task<ActionResult> GenerateActionResult(Controller controller, Func<Task<string>> getDataETagDelegate, Func<Task<ICacheableData>> getDataDelegate, TimeSpan? maxAge = null)

-        {

-            return GenerateActionResult(controller, new DelegateCacheableDataProvider(getDataETagDelegate, getDataDelegate), maxAge);

-        }

-    }

-}