Essentials middleware first addition, websocket feature and generics

4 files changed, 239 insertions, 0 deletions

diff --git a/lib/Plugins.Essentials/src/Middleware/HttpMiddlewareResult.cs b/lib/Plugins.Essentials/src/Middleware/HttpMiddlewareResult.cs
new file mode 100644
index 0000000..6054a6e
--- /dev/null
+++ b/lib/Plugins.Essentials/src/Middleware/HttpMiddlewareResult.cs
@@ -0,0 +1,42 @@
+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials
+* File: HttpMiddlewareResult.cs 
+*
+* HttpMiddlewareResult.cs is part of VNLib.Plugins.Essentials which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+namespace VNLib.Plugins.Essentials.Middleware
+{
+    /// <summary>
+    /// The result of a <see cref="IHttpMiddleware"/> process.
+    /// </summary>
+    public enum HttpMiddlewareResult
+    {
+        /// <summary>
+        /// The request has not been completed and should continue to be processed.
+        /// </summary>
+        Continue,
+
+        /// <summary>
+        /// The request has been handled and no further processing should occur.
+        /// </summary>
+        Complete
+    }
+}
diff --git a/lib/Plugins.Essentials/src/Middleware/IHttpMiddleware.cs b/lib/Plugins.Essentials/src/Middleware/IHttpMiddleware.cs
new file mode 100644
index 0000000..a5a3949
--- /dev/null
+++ b/lib/Plugins.Essentials/src/Middleware/IHttpMiddleware.cs
@@ -0,0 +1,44 @@
+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials
+* File: IHttpMiddleware.cs 
+*
+* IHttpMiddleware.cs is part of VNLib.Plugins.Essentials which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System.Threading.Tasks;
+
+
+namespace VNLib.Plugins.Essentials.Middleware
+{
+    /// <summary>
+    /// Represents a low level intermediate request processor with high privilages, meant to add 
+    /// functionality to entity processing.
+    /// </summary>
+    public interface IHttpMiddleware
+    {
+        /// <summary>
+        /// Processes the <see cref="HttpEntity"/> and returns a <see cref="HttpMiddlewareResult"/> 
+        /// indicating whether the request should continue to be processed.
+        /// </summary>
+        /// <param name="entity">The entity to process</param>
+        /// <returns>The result of the operation</returns>
+        ValueTask<HttpMiddlewareResult> ProcessAsync(HttpEntity entity);
+    }
+}
diff --git a/lib/Plugins.Essentials/src/Middleware/IHttpMiddlewareChain.cs b/lib/Plugins.Essentials/src/Middleware/IHttpMiddlewareChain.cs
new file mode 100644
index 0000000..54da6c1
--- /dev/null
+++ b/lib/Plugins.Essentials/src/Middleware/IHttpMiddlewareChain.cs
@@ -0,0 +1,67 @@
+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials
+* File: IHttpMiddlewareChain.cs 
+*
+* IHttpMiddlewareChain.cs is part of VNLib.Plugins.Essentials which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace VNLib.Plugins.Essentials.Middleware
+{
+    /// <summary>
+    /// Represents a chain of <see cref="IHttpMiddleware"/> instances that 
+    /// will be called by an <see cref="EventProcessor"/> during 
+    /// entity processing.
+    /// </summary>
+    public interface IHttpMiddlewareChain
+    {
+        /// <summary>
+        /// Gets the current head of the middleware chain
+        /// </summary>
+        /// <returns>A <see cref="LinkedListNode{T}"/> that points to the head of the current chain</returns>
+        LinkedListNode<IHttpMiddleware>? GetCurrentHead();
+
+        /// <summary>
+        /// Adds a middleware handler to the end of the chain
+        /// </summary>
+        /// <param name="middleware">The middleware processor to add</param>
+        void AddLast(IHttpMiddleware middleware);
+
+        /// <summary>
+        /// Adds a middleware handler to the beginning of the chain
+        /// </summary>
+        /// <param name="middleware">The middleware processor to add</param>
+        void AddFirst(IHttpMiddleware middleware);
+
+        /// <summary>
+        /// Removes a middleware handler from the chain
+        /// </summary>
+        /// <param name="middleware">The middleware instance to remove</param>
+        void RemoveMiddleware(IHttpMiddleware middleware);
+
+        /// <summary>
+        /// Removes all middleware handlers from the chain
+        /// </summary>
+        void Clear();
+    }
+}
\ No newline at end of file
diff --git a/lib/Plugins.Essentials/src/Middleware/SemiConistentMiddlewareChain.cs b/lib/Plugins.Essentials/src/Middleware/SemiConistentMiddlewareChain.cs
new file mode 100644
index 0000000..197ba12
--- /dev/null
+++ b/lib/Plugins.Essentials/src/Middleware/SemiConistentMiddlewareChain.cs
@@ -0,0 +1,86 @@
+/*
+* Copyright (c) 2023 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials
+* File: SemiConistentMiddlewareChain.cs 
+*
+* SemiConistentMiddlewareChain.cs is part of VNLib.Plugins.Essentials which 
+* is part of the larger VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace VNLib.Plugins.Essentials.Middleware
+{
+    /// <summary>
+    /// A default implementation of <see cref="IHttpMiddlewareChain"/> that
+    /// maintains a semi-conistant chain of middleware handlers, for infrequent 
+    /// chain updates
+    /// </summary>
+    internal sealed class SemiConistentMiddlewareChain : IHttpMiddlewareChain
+    {
+        private LinkedList<IHttpMiddleware> _middlewares = new();
+
+        ///<inheritdoc/>
+        public void AddFirst(IHttpMiddleware middleware)
+        {
+            lock (_middlewares)
+            {
+                _middlewares.AddFirst(middleware);
+            }
+        }
+
+        ///<inheritdoc/>
+        public void AddLast(IHttpMiddleware middleware)
+        {
+            lock (_middlewares)
+            {
+                _middlewares.AddLast(middleware);
+            }
+        }
+
+        ///<inheritdoc/>
+        public void Clear()
+        {
+            lock (_middlewares)
+            {
+                _middlewares.Clear();
+            }
+        }
+
+        ///<inheritdoc/>
+        public LinkedListNode<IHttpMiddleware>? GetCurrentHead() => _middlewares.First;
+
+        ///<inheritdoc/>
+        public void RemoveMiddleware(IHttpMiddleware middleware)
+        {
+            lock (_middlewares)
+            {
+                //Clone current table
+                LinkedList<IHttpMiddleware> newTable = new(_middlewares);
+
+                //Remove the middleware
+                newTable.Remove(middleware);
+
+                //Replace the current table with the new one
+                _middlewares = newTable;
+            }
+        }
+    }
+}
\ No newline at end of file