Namespace changes and dynamic user lib loading

1 files changed, 84 insertions, 0 deletions

diff --git a/VNLib.Plugins.Extensions.Loading/UserLoading.cs b/VNLib.Plugins.Extensions.Loading/UserLoading.cs
new file mode 100644
index 0000000..ae55094
--- /dev/null
+++ b/VNLib.Plugins.Extensions.Loading/UserLoading.cs
@@ -0,0 +1,84 @@
+using System;
+using System.Linq;
+using System.Threading;
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+
+using VNLib.Utils.Logging;
+using VNLib.Utils.Extensions;
+using VNLib.Plugins.Essentials.Users;
+
+namespace VNLib.Plugins.Extensions.Loading.Users
+{
+    /// <summary>
+    /// Contains extension methods for plugins to load the "users" system
+    /// </summary>
+    public static class UserLoading
+    {
+        public const string USER_CUSTOM_ASSEMBLY = "user_custom_asm";
+        public const string DEFAULT_USER_ASM = "VNLib.Plugins.Essentials.Users.dll";
+        public const string ONLOAD_METHOD_NAME = "OnPluginLoading";
+
+        private static readonly ConditionalWeakTable<PluginBase, Lazy<IUserManager>> UsersTable = new();
+
+        /// <summary>
+        /// Gets or loads the plugin's ambient <see cref="IUserManager"/>, with the specified user-table name,
+        /// or the default table name
+        /// </summary>
+        /// <param name="plugin"></param>
+        /// <returns>The ambient <see cref="IUserManager"/> for the current plugin</returns>
+        /// <exception cref="KeyNotFoundException"></exception>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IUserManager GetUserManager(this PluginBase plugin)
+        {
+            plugin.ThrowIfUnloaded();
+            //Get stored or load
+            return UsersTable.GetValue(plugin, LoadUsers).Value;
+        }
+
+        private static Lazy<IUserManager> LoadUsers(PluginBase pbase)
+        {
+            //lazy callack
+            IUserManager LoadManager()
+            {
+                //Try to load a custom user assembly for exporting IUserManager
+                string? customAsm = pbase.PluginConfig.GetPropString(USER_CUSTOM_ASSEMBLY);
+                //See if host config defined the path
+                customAsm ??= pbase.HostConfig.GetPropString(USER_CUSTOM_ASSEMBLY);
+                //Finally default
+                customAsm ??= DEFAULT_USER_ASM;
+
+                //Try to load a custom assembly
+                AssemblyLoader<IUserManager> loader = pbase.LoadAssembly<IUserManager>(customAsm);
+                try
+                {
+                    //Get the runtime type
+                    Type runtimeType = loader.Resource.GetType();
+
+                    //Get the onplugin load method
+                    Action<object>? onLoadMethod = runtimeType.GetMethods()
+                        .Where(static p => p.IsPublic && !p.IsAbstract && ONLOAD_METHOD_NAME.Equals(p.Name))
+                        .Select(p => p.CreateDelegate<Action<object>>(loader.Resource))
+                        .FirstOrDefault();
+
+                    //Call the onplugin load method
+                    onLoadMethod?.Invoke(pbase);
+
+                    if (pbase.IsDebug())
+                    {
+                        pbase.Log.Verbose("Loading user manager from assembly {name}", runtimeType.AssemblyQualifiedName);
+                    }
+
+                    //Return the loaded instance (may raise exception)
+                    return loader.Resource;
+                }
+                catch
+                {
+                    loader.Dispose();
+                    throw;
+                }
+            }
+            return new Lazy<IUserManager>(LoadManager, LazyThreadSafetyMode.PublicationOnly);
+        }
+    }
+}
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