From 8a1ecbf49673cb2bed538ac8bc4e82691b90d973 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Fri, 13 Mar 2020 17:05:03 +0800
Subject: Abstract out data cache helper.

---
 Timeline/Controllers/UserAvatarController.cs       |  31 +----
 Timeline/Helpers/DataCacheHelper.cs                | 108 +++++++++++++++++
 .../Controllers/UserAvatarController.Designer.cs   |  27 -----
 .../Controllers/UserAvatarController.resx          |   9 --
 .../Resources/Helper/DataCacheHelper.Designer.cs   |  90 ++++++++++++++
 Timeline/Resources/Helper/DataCacheHelper.resx     | 129 +++++++++++++++++++++
 Timeline/Services/UserAvatarService.cs             |   5 +
 Timeline/Timeline.csproj                           |   9 ++
 8 files changed, 345 insertions(+), 63 deletions(-)
 create mode 100644 Timeline/Helpers/DataCacheHelper.cs
 create mode 100644 Timeline/Resources/Helper/DataCacheHelper.Designer.cs
 create mode 100644 Timeline/Resources/Helper/DataCacheHelper.resx

diff --git a/Timeline/Controllers/UserAvatarController.cs b/Timeline/Controllers/UserAvatarController.cs
index f4f3db3e..f78dcb08 100644
--- a/Timeline/Controllers/UserAvatarController.cs
+++ b/Timeline/Controllers/UserAvatarController.cs
@@ -46,34 +46,11 @@ namespace Timeline.Controllers
                 return NotFound(ErrorResponse.UserCommon.NotExist());
             }
 
-            const string IfNonMatchHeaderKey = "If-None-Match";
-
-            var eTagValue = $"\"{await _service.GetAvatarETag(id)}\"";
-            var eTag = new EntityTagHeaderValue(eTagValue);
-
-            if (Request.Headers.TryGetValue(IfNonMatchHeaderKey, out var value))
+            return await DataCacheHelper.GenerateActionResult(this, () => _service.GetAvatarETag(id), async () =>
             {
-                if (!EntityTagHeaderValue.TryParseStrictList(value, out var eTagList))
-                {
-                    _logger.LogInformation(Log.Format(LogGetBadIfNoneMatch,
-                        ("Username", username), ("If-None-Match", value)));
-                    return BadRequest(ErrorResponse.Common.Header.IfNonMatch_BadFormat());
-                }
-
-                if (eTagList.FirstOrDefault(e => e.Equals(eTag)) != null)
-                {
-                    Response.Headers.Add("ETag", eTagValue);
-                    _logger.LogInformation(Log.Format(LogGetReturnNotModify, ("Username", username)));
-                    return StatusCode(StatusCodes.Status304NotModified);
-                }
-            }
-
-            var avatarInfo = await _service.GetAvatar(id);
-            var avatar = avatarInfo.Avatar;
-
-            _logger.LogInformation(Log.Format(LogGetReturnData, ("Username", username)));
-            return File(avatar.Data, avatar.Type, new DateTimeOffset(avatarInfo.LastModified), eTag);
-
+                var avatar = await _service.GetAvatar(id);
+                return avatar.ToCacheableData();
+            });
         }
 
         [HttpPut("users/{username}/avatar")]
diff --git a/Timeline/Helpers/DataCacheHelper.cs b/Timeline/Helpers/DataCacheHelper.cs
new file mode 100644
index 00000000..c13aaddb
--- /dev/null
+++ b/Timeline/Helpers/DataCacheHelper.cs
@@ -0,0 +1,108 @@
+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)
+        {
+            const string IfNonMatchHeaderKey = "If-None-Match";
+            const string ETagHeaderKey = "ETag";
+
+            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)
+                {
+                    controller.Response.Headers.Add(ETagHeaderKey, eTagValue);
+                    logger.LogInformation(LogResultNotModified);
+                    return controller.StatusCode(StatusCodes.Status304NotModified);
+                }
+            }
+
+            var data = await provider.GetData();
+            logger.LogInformation(LogResultData);
+            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)
+        {
+            return GenerateActionResult(controller, new DelegateCacheableDataProvider(getDataETagDelegate, getDataDelegate));
+        }
+    }
+}
diff --git a/Timeline/Resources/Controllers/UserAvatarController.Designer.cs b/Timeline/Resources/Controllers/UserAvatarController.Designer.cs
index e6eeb1e8..b0c35ff9 100644
--- a/Timeline/Resources/Controllers/UserAvatarController.Designer.cs
+++ b/Timeline/Resources/Controllers/UserAvatarController.Designer.cs
@@ -96,33 +96,6 @@ namespace Timeline.Resources.Controllers {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to Attempt to get a avatar with If-None-Match in bad format..
-        /// </summary>
-        internal static string LogGetBadIfNoneMatch {
-            get {
-                return ResourceManager.GetString("LogGetBadIfNoneMatch", resourceCulture);
-            }
-        }
-        
-        /// <summary>
-        ///   Looks up a localized string similar to Returned full data for a get avatar attempt..
-        /// </summary>
-        internal static string LogGetReturnData {
-            get {
-                return ResourceManager.GetString("LogGetReturnData", resourceCulture);
-            }
-        }
-        
-        /// <summary>
-        ///   Looks up a localized string similar to Returned NotModify for a get avatar attempt..
-        /// </summary>
-        internal static string LogGetReturnNotModify {
-            get {
-                return ResourceManager.GetString("LogGetReturnNotModify", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to Attempt to get a avatar of a non-existent user failed..
         /// </summary>
diff --git a/Timeline/Resources/Controllers/UserAvatarController.resx b/Timeline/Resources/Controllers/UserAvatarController.resx
index 58860c83..864d96c0 100644
--- a/Timeline/Resources/Controllers/UserAvatarController.resx
+++ b/Timeline/Resources/Controllers/UserAvatarController.resx
@@ -129,15 +129,6 @@
   <data name="LogDeleteSuccess" xml:space="preserve">
     <value>Succeed to delete a avatar of a user.</value>
   </data>
-  <data name="LogGetBadIfNoneMatch" xml:space="preserve">
-    <value>Attempt to get a avatar with If-None-Match in bad format.</value>
-  </data>
-  <data name="LogGetReturnData" xml:space="preserve">
-    <value>Returned full data for a get avatar attempt.</value>
-  </data>
-  <data name="LogGetReturnNotModify" xml:space="preserve">
-    <value>Returned NotModify for a get avatar attempt.</value>
-  </data>
   <data name="LogGetUserNotExist" xml:space="preserve">
     <value>Attempt to get a avatar of a non-existent user failed.</value>
   </data>
diff --git a/Timeline/Resources/Helper/DataCacheHelper.Designer.cs b/Timeline/Resources/Helper/DataCacheHelper.Designer.cs
new file mode 100644
index 00000000..acf56d13
--- /dev/null
+++ b/Timeline/Resources/Helper/DataCacheHelper.Designer.cs
@@ -0,0 +1,90 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace Timeline.Resources.Helper {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class DataCacheHelper {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal DataCacheHelper() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Timeline.Resources.Helper.DataCacheHelper", typeof(DataCacheHelper).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Header If-None-Match is of bad format..
+        /// </summary>
+        internal static string LogBadIfNoneMatch {
+            get {
+                return ResourceManager.GetString("LogBadIfNoneMatch", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cache is invalid and data is returned..
+        /// </summary>
+        internal static string LogResultData {
+            get {
+                return ResourceManager.GetString("LogResultData", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cache is valid and 304 Not Modified is returned..
+        /// </summary>
+        internal static string LogResultNotModified {
+            get {
+                return ResourceManager.GetString("LogResultNotModified", resourceCulture);
+            }
+        }
+    }
+}
diff --git a/Timeline/Resources/Helper/DataCacheHelper.resx b/Timeline/Resources/Helper/DataCacheHelper.resx
new file mode 100644
index 00000000..515cfa9b
--- /dev/null
+++ b/Timeline/Resources/Helper/DataCacheHelper.resx
@@ -0,0 +1,129 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="LogBadIfNoneMatch" xml:space="preserve">
+    <value>Header If-None-Match is of bad format.</value>
+  </data>
+  <data name="LogResultData" xml:space="preserve">
+    <value>Cache is invalid and data is returned.</value>
+  </data>
+  <data name="LogResultNotModified" xml:space="preserve">
+    <value>Cache is valid and 304 Not Modified is returned.</value>
+  </data>
+</root>
\ No newline at end of file
diff --git a/Timeline/Services/UserAvatarService.cs b/Timeline/Services/UserAvatarService.cs
index 1b1be698..3ab8f14d 100644
--- a/Timeline/Services/UserAvatarService.cs
+++ b/Timeline/Services/UserAvatarService.cs
@@ -22,6 +22,11 @@ namespace Timeline.Services
     {
         public Avatar Avatar { get; set; } = default!;
         public DateTime LastModified { get; set; }
+
+        public CacheableData ToCacheableData()
+        {
+            return new CacheableData(Avatar.Type, Avatar.Data, LastModified);
+        }
     }
 
     /// <summary>
diff --git a/Timeline/Timeline.csproj b/Timeline/Timeline.csproj
index 245ff3e7..739f79dd 100644
--- a/Timeline/Timeline.csproj
+++ b/Timeline/Timeline.csproj
@@ -72,6 +72,11 @@
             <AutoGen>True</AutoGen>
             <DependentUpon>Filters.resx</DependentUpon>
         </Compile>
+        <Compile Update="Resources\Helper\DataCacheHelper.Designer.cs">
+          <DesignTime>True</DesignTime>
+          <AutoGen>True</AutoGen>
+          <DependentUpon>DataCacheHelper.resx</DependentUpon>
+        </Compile>
         <Compile Update="Resources\Messages.Designer.cs">
             <DesignTime>True</DesignTime>
             <AutoGen>True</AutoGen>
@@ -159,6 +164,10 @@
             <Generator>ResXFileCodeGenerator</Generator>
             <LastGenOutput>Filters.Designer.cs</LastGenOutput>
         </EmbeddedResource>
+        <EmbeddedResource Update="Resources\Helper\DataCacheHelper.resx">
+          <Generator>ResXFileCodeGenerator</Generator>
+          <LastGenOutput>DataCacheHelper.Designer.cs</LastGenOutput>
+        </EmbeddedResource>
         <EmbeddedResource Update="Resources\Messages.resx">
             <Generator>ResXFileCodeGenerator</Generator>
             <LastGenOutput>Messages.Designer.cs</LastGenOutput>
-- 
cgit v1.2.3