Chain content instead of replacing it

API/Content/ContentElement.cs

@@ -59,6 +59,34 @@ public ContentElement(string path, ContentInfo details, FlexibleContentType cont
 
         #endregion
 
+        #region Functionality
+
+        public ulong CalculateChecksum() => CalculateChecksum(this);
+
+        private static ulong CalculateChecksum(ContentElement element)
+        {
+            unchecked
+            {
+                ulong hash = 17;
+
+                hash = hash * 23 + (uint)element.Path.GetHashCode();
+                hash = hash * 23 + (uint)element.Details.GetHashCode();
+                hash = hash * 23 + (uint)element.ContentType.GetHashCode();
+
+                if (element.Children != null)
+                {
+                    foreach (var child in element.Children)
+                    {
+                        hash = hash * 23 + CalculateChecksum(child);
+                    }
+                }
+
+                return hash;
+            }
+        }
+
+        #endregion
+
     }
 
 }

API/Content/IErrorHandler.cs

@@ -1,26 +1,15 @@
 using GenHTTP.Api.Content.Templating;
 
-using System.Threading.Tasks;
-
 namespace GenHTTP.Api.Content
 {
 
     /// <summary>
     /// Handlers implementing this interface will be queried to render
     /// errors that occur when handling requests.
     /// </summary>
-    public interface IErrorHandler
+    public interface IErrorHandler : IRenderer<ErrorModel>
     {
 
-        /// <summary>
-        /// Renders the given error into a web page that can be rendered
-        /// using a template.
-        /// </summary>
-        /// <param name="error">The error to be handled</param>
-        /// <param name="details">Additional details about the error</param>
-        /// <returns>The page to be rendered into the template</returns>
-        ValueTask<TemplateModel> RenderAsync(ErrorModel error, ContentInfo details);
-
     }
 
 }

API/Content/IPageRenderer.cs

@@ -1,7 +1,4 @@
-using System.Threading.Tasks;
-
-using GenHTTP.Api.Content.Templating;
-using GenHTTP.Api.Protocol;
+using GenHTTP.Api.Content.Templating;
 
 namespace GenHTTP.Api.Content
 {
@@ -10,15 +7,9 @@ namespace GenHTTP.Api.Content
     /// Handlers implementing this interface will be queried to render
     /// pages into a template.
     /// </summary>
-    public interface IPageRenderer
+    public interface IPageRenderer : IRenderer<TemplateModel>
     {
 
-        /// <summary>
-        /// Renders the given model into a web page to be served to the client.
-        /// </summary>
-        /// <param name="model">The model to be rendered</param>
-        /// <returns>The response to be returned to the client</returns>
-        ValueTask<IResponseBuilder> RenderAsync(TemplateModel model);
 
     }
 

API/Content/Templating/PageModel.cs → API/Content/Templating/AbstractModel.cs

@@ -1,4 +1,6 @@
-using GenHTTP.Api.Protocol;
+using System.Threading.Tasks;
+
+using GenHTTP.Api.Protocol;
 
 namespace GenHTTP.Api.Content.Templating
 {
@@ -7,7 +9,7 @@ namespace GenHTTP.Api.Content.Templating
     /// Model for pages which can be served by an application
     /// to the clients.
     /// </summary>
-    public class PageModel : IBaseModel
+    public abstract class AbstractModel : IModel
     {
 
         #region Get-/Setters
@@ -24,21 +26,27 @@ public class PageModel : IBaseModel
 
         #endregion
 
-        #region Functionality
+        #region Initialization
 
         /// <summary>
         /// Creates a new page model for the given request.
         /// </summary>
         /// <param name="request">The request which caused this rendering call</param>
         /// <param name="handler">The handler responsible to render the response</param>
-        public PageModel(IRequest request, IHandler handler)
+        public AbstractModel(IRequest request, IHandler handler)
         {
             Request = request;
             Handler = handler;
         }
 
         #endregion
 
+        #region Functionality
+
+        public abstract ValueTask<ulong> CalculateChecksumAsync();
+
+        #endregion
+
     }
 
 }

API/Content/Templating/BasicModel.cs

@@ -0,0 +1,32 @@
+using System.Threading.Tasks;
+
+using GenHTTP.Api.Protocol;
+
+namespace GenHTTP.Api.Content.Templating
+{
+
+    /// <summary>
+    /// Simple page model with no further information than the mandatory request
+    /// and handler values.
+    /// </summary>
+    public class BasicModel : AbstractModel
+    {
+
+        #region Initialization
+
+        public BasicModel(IRequest request, IHandler handler) : base(request, handler)
+        {
+
+        }
+
+        #endregion
+
+        #region Functionality
+
+        public override ValueTask<ulong> CalculateChecksumAsync() => new(17);
+
+        #endregion
+
+    }
+
+}

API/Content/Templating/ErrorModel.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading.Tasks;
 
 using GenHTTP.Api.Protocol;
 
@@ -8,7 +9,7 @@ namespace GenHTTP.Api.Content.Templating
     /// <summary>
     /// Model for errors that occur when handling requests.
     /// </summary>
-    public sealed class ErrorModel : PageModel
+    public sealed class ErrorModel : AbstractModel
     {
 
         #region Get-/Setters
@@ -48,6 +49,27 @@ public ErrorModel(IRequest request, IHandler handler, ResponseStatus status, str
 
         #endregion
 
+        #region Functionality
+
+        public override ValueTask<ulong> CalculateChecksumAsync()
+        {
+            unchecked
+            {
+                ulong hash = 17;
+
+                hash = hash * 23 + (uint)Status;
+
+                hash = hash * 23 + (uint)Message.GetHashCode();
+
+                hash = hash * 23 + (uint)(DevelopmentMode ? 1 : 0);
+                hash = hash * 23 + (uint)(Cause?.GetHashCode() ?? 0);
+
+                return new(hash);
+            }
+        }
+
+        #endregion
+
     }
 
 }

API/Content/Templating/IBaseModel.cs → API/Content/Templating/IModel.cs

@@ -1,4 +1,6 @@
-using GenHTTP.Api.Protocol;
+using System.Threading.Tasks;
+
+using GenHTTP.Api.Protocol;
 
 namespace GenHTTP.Api.Content.Templating
 {
@@ -7,7 +9,7 @@ namespace GenHTTP.Api.Content.Templating
     /// Interface which needs to be implemented by all models
     /// used to render pages or templates.
     /// </summary>
-    public interface IBaseModel
+    public interface IModel
     {
 
         /// <summary>
@@ -20,6 +22,16 @@ public interface IBaseModel
         /// </summary>
         IHandler Handler { get; }
 
+        /// <summary>
+        /// Calculates the checksum of this model.
+        /// </summary>
+        /// <returns>The checksum of this model</returns>
+        /// <remarks>
+        /// Required to determine, whether an already cached page
+        /// needs to be refreshed or not.
+        /// </remarks>
+        ValueTask<ulong> CalculateChecksumAsync();
+
     }
 
 }

API/Content/Templating/IRenderer.cs

@@ -8,7 +8,7 @@ namespace GenHTTP.Api.Content.Templating
     /// Allows to render models of the given type.
     /// </summary>
     /// <typeparam name="T">The type of the model to be rendered</typeparam>
-    public interface IRenderer<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] in T> where T : class, IBaseModel
+    public interface IRenderer<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] in T> where T : class, IModel
     {
 
         /// <summary>
@@ -18,6 +18,12 @@ public interface IRenderer<[DynamicallyAccessedMembers(DynamicallyAccessedMember
         /// </summary>
         ValueTask PrepareAsync();
 
+        /// <summary>
+        /// Returns a checksum for the template used by this renderer instance.
+        /// </summary>
+        /// <returns>The checksum of the template used by this renderer</returns>
+        ValueTask<ulong> CalculateChecksumAsync();
+
         /// <summary>
         /// Renders the given model.
         /// </summary>

API/Content/Templating/TemplateModel.cs

@@ -1,4 +1,6 @@
-using GenHTTP.Api.Protocol;
+using System.Threading.Tasks;
+
+using GenHTTP.Api.Protocol;
 
 namespace GenHTTP.Api.Content.Templating
 {
@@ -7,7 +9,7 @@ namespace GenHTTP.Api.Content.Templating
     /// Model used by templates to render the actual HTML returned
     /// to the client.
     /// </summary>
-    public sealed class TemplateModel : IBaseModel
+    public sealed class TemplateModel : AbstractModel
     {
 
         #region Get-/Setters
@@ -22,16 +24,6 @@ public sealed class TemplateModel : IBaseModel
         /// </summary>
         public string Content { get; }
 
-        /// <summary>
-        /// The request which caused this call.
-        /// </summary>
-        public IRequest Request { get; }
-
-        /// <summary>
-        /// The handler responsible to render the response.
-        /// </summary>
-        public IHandler Handler { get; }
-
         #endregion
 
         #region Initialization
@@ -43,7 +35,7 @@ public sealed class TemplateModel : IBaseModel
         /// <param name="handler">The handler responsible to render the response</param>
         /// <param name="pageInfo">Information about the page to be rendered</param>
         /// <param name="content">The content to be rendered within the template</param>
-        public TemplateModel(IRequest request, IHandler handler, ContentInfo pageInfo, string content)
+        public TemplateModel(IRequest request, IHandler handler, ContentInfo pageInfo, string content) : base(request, handler)
         {
             Content = content;
 
@@ -53,9 +45,23 @@ public TemplateModel(IRequest request, IHandler handler, ContentInfo pageInfo, s
             {
                 Meta = Meta with { Title = "Untitled Page" };
             }
+        }
 
-            Request = request;
-            Handler = handler;
+        #endregion
+
+        #region Functionality
+
+        public override ValueTask<ulong> CalculateChecksumAsync()
+        {
+            unchecked
+            {
+                ulong hash = 17;
+
+                hash = hash * 23 + (uint)Content.GetHashCode();
+                hash = hash * 23 + (uint)Meta.GetHashCode();
+
+                return new(hash);
+            }
         }
 
         #endregion

API/Content/Templating/ViewModel.cs

@@ -1,4 +1,5 @@
 using GenHTTP.Api.Protocol;
+using System.Threading.Tasks;
 
 namespace GenHTTP.Api.Content.Templating
 {
@@ -22,7 +23,7 @@ public ViewModel(IRequest request, IHandler handler) : base(request, handler, nu
 
     }
 
-    public class ViewModel<T> : PageModel where T : class
+    public class ViewModel<T> : AbstractModel where T : class
     {
 
         #region Get-/Setters
@@ -40,6 +41,12 @@ public ViewModel(IRequest request, IHandler handler, T? data) : base(request, ha
 
         #endregion
 
+        #region Functionality
+
+        public override ValueTask<ulong> CalculateChecksumAsync() => new((ulong)(Data?.GetHashCode() ?? 17));
+
+        #endregion
+
     }
 
 }