Split front and back end.

5 files changed, 198 insertions, 0 deletions

diff --git a/BackEnd/Timeline/Helpers/DataCacheHelper.cs b/BackEnd/Timeline/Helpers/DataCacheHelper.cs
new file mode 100644
index 00000000..1ad69708
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/DataCacheHelper.cs
@@ -0,0 +1,125 @@
+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);

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/DateTimeExtensions.cs b/BackEnd/Timeline/Helpers/DateTimeExtensions.cs
new file mode 100644
index 00000000..374f3bc9
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/DateTimeExtensions.cs
@@ -0,0 +1,14 @@
+using System;

+

+namespace Timeline.Helpers

+{

+    public static class DateTimeExtensions

+    {

+        public static DateTime MyToUtc(this DateTime dateTime)

+        {

+            if (dateTime.Kind == DateTimeKind.Utc) return dateTime;

+            if (dateTime.Kind == DateTimeKind.Local) return dateTime.ToUniversalTime();

+            return DateTime.SpecifyKind(dateTime, DateTimeKind.Utc);

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/InvalidModelResponseFactory.cs b/BackEnd/Timeline/Helpers/InvalidModelResponseFactory.cs
new file mode 100644
index 00000000..9b253e7d
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/InvalidModelResponseFactory.cs
@@ -0,0 +1,25 @@
+using Microsoft.AspNetCore.Mvc;

+using System.Text;

+using Timeline.Models.Http;

+

+namespace Timeline.Helpers

+{

+    public static class InvalidModelResponseFactory

+    {

+        public static IActionResult Factory(ActionContext context)

+        {

+            var modelState = context.ModelState;

+

+            var messageBuilder = new StringBuilder();

+            foreach (var model in modelState)

+                foreach (var error in model.Value.Errors)

+                {

+                    messageBuilder.Append(model.Key);

+                    messageBuilder.Append(" : ");

+                    messageBuilder.AppendLine(error.ErrorMessage);

+                }

+

+            return new BadRequestObjectResult(ErrorResponse.Common.CustomMessage_InvalidModel(messageBuilder.ToString()));

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/LanguageHelper.cs b/BackEnd/Timeline/Helpers/LanguageHelper.cs
new file mode 100644
index 00000000..b0156b8b
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/LanguageHelper.cs
@@ -0,0 +1,12 @@
+using System.Linq;

+

+namespace Timeline.Helpers

+{

+    public static class LanguageHelper

+    {

+        public static bool AreSame(this bool firstBool, params bool[] otherBools)

+        {

+            return otherBools.All(b => b == firstBool);

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Helpers/Log.cs b/BackEnd/Timeline/Helpers/Log.cs
new file mode 100644
index 00000000..af0b7e13
--- /dev/null
+++ b/BackEnd/Timeline/Helpers/Log.cs
@@ -0,0 +1,22 @@
+using System.Text;

+

+namespace Timeline.Helpers

+{

+    public static class Log

+    {

+        public static string Format(string summary, params (string, object?)[] properties)

+        {

+            var builder = new StringBuilder();

+            builder.Append(summary);

+            foreach (var property in properties)

+            {

+                var (key, value) = property;

+                builder.AppendLine();

+                builder.Append(key);

+                builder.Append(" : ");

+                builder.Append(value);

+            }

+            return builder.ToString();

+        }

+    }

+}