1 files changed, 199 insertions, 0 deletions
diff --git a/lib/VNLib.Plugins.Extensions.Loading/src/ConfigurationExtensions.cs b/lib/VNLib.Plugins.Extensions.Loading/src/ConfigurationExtensions.cs
new file mode 100644
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+++ b/lib/VNLib.Plugins.Extensions.Loading/src/ConfigurationExtensions.cs
@@ -0,0 +1,199 @@
+/*
+* Copyright (c) 2022 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Extensions.Loading
+* File: ConfigurationExtensions.cs 
+*
+* ConfigurationExtensions.cs is part of VNLib.Plugins.Extensions.Loading which is part of the larger 
+* VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Extensions.Loading is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU General Public License as published
+* by the Free Software Foundation, either version 2 of the License,
+* or (at your option) any later version.
+*
+* VNLib.Plugins.Extensions.Loading 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 
+* General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License 
+* along with VNLib.Plugins.Extensions.Loading. If not, see http://www.gnu.org/licenses/.
+*/
+
+using System;
+using System.Linq;
+using System.Text.Json;
+using System.Reflection;
+using System.Collections.Generic;
+
+using VNLib.Utils.Extensions;
+
+namespace VNLib.Plugins.Extensions.Loading
+{
+    /// <summary>
+    /// Specifies a configuration variable name in the plugin's configuration 
+    /// containing data specific to the type
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Class)]
+    public sealed class ConfigurationNameAttribute : Attribute
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        public string ConfigVarName { get; }
+
+        /// <summary>
+        /// Initializes a new <see cref="ConfigurationNameAttribute"/>
+        /// </summary>
+        /// <param name="configVarName">The name of the configuration variable for the class</param>
+        public ConfigurationNameAttribute(string configVarName)
+        {
+            ConfigVarName = configVarName;
+        }
+    }
+    
+    /// <summary>
+    /// Contains extensions for plugin configuration specifc extensions
+    /// </summary>
+    public static class ConfigurationExtensions
+    {
+        public const string S3_CONFIG = "s3_config";
+        public const string S3_SECRET_KEY = "s3_secret";
+
+        /// <summary>
+        /// Retrieves a top level configuration dictionary of elements for the specified type.
+        /// The type must contain a <see cref="ConfigurationNameAttribute"/>
+        /// </summary>
+        /// <typeparam name="T">The type to get the configuration of</typeparam>
+        /// <param name="plugin"></param>
+        /// <returns>A <see cref="Dictionary{TKey, TValue}"/> of top level configuration elements for the type</returns>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IReadOnlyDictionary<string, JsonElement> GetConfigForType<T>(this PluginBase plugin)
+        {
+            Type t = typeof(T);
+            return plugin.GetConfigForType(t);
+        }
+        /// <summary>
+        /// Retrieves a top level configuration dictionary of elements with the specified property name,
+        /// from the plugin config first, or falls back to the host config file
+        /// </summary>
+        /// <param name="plugin"></param>
+        /// <param name="propName">The config property name to retrieve</param>
+        /// <returns>A <see cref="Dictionary{TKey, TValue}"/> of top level configuration elements for the type</returns>
+        /// <exception cref="KeyNotFoundException"></exception>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IReadOnlyDictionary<string, JsonElement> GetConfig(this PluginBase plugin, string propName)
+        {
+            plugin.ThrowIfUnloaded();
+            try
+            {
+                //Try to get the element from the plugin config first
+                if (!plugin.PluginConfig.TryGetProperty(propName, out JsonElement el))
+                {
+                    //Fallback to the host config
+                    el = plugin.HostConfig.GetProperty(propName);
+                }
+                //Get the top level config as a dictionary
+                return el.EnumerateObject().ToDictionary(static k => k.Name, static k => k.Value);
+            }
+            catch(KeyNotFoundException)
+            {
+                throw new KeyNotFoundException($"Missing required top level configuration object '{propName}', in host/plugin configuration files");
+            }
+        }
+        /// <summary>
+        /// Retrieves a top level configuration dictionary of elements with the specified property name,
+        /// from the plugin config first, or falls back to the host config file
+        /// </summary>
+        /// <param name="plugin"></param>
+        /// <param name="propName">The config property name to retrieve</param>
+        /// <returns>A <see cref="Dictionary{TKey, TValue}"/> of top level configuration elements for the type</returns>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IReadOnlyDictionary<string, JsonElement>? TryGetConfig(this PluginBase plugin, string propName)
+        {
+            plugin.ThrowIfUnloaded();
+            //Try to get the element from the plugin config first, or fallback to host
+            if (plugin.PluginConfig.TryGetProperty(propName, out JsonElement el) || plugin.HostConfig.TryGetProperty(propName, out el))
+            {
+                //Get the top level config as a dictionary
+                return el.EnumerateObject().ToDictionary(static k => k.Name, static k => k.Value);
+            }
+            //No config found
+            return null;
+        }
+
+        /// <summary>
+        /// Retrieves a top level configuration dictionary of elements for the specified type.
+        /// The type must contain a <see cref="ConfigurationNameAttribute"/>
+        /// </summary>
+        /// <param name="plugin"></param>
+        /// <param name="type">The type to get configuration data for</param>
+        /// <returns>A <see cref="Dictionary{TKey, TValue}"/> of top level configuration elements for the type</returns>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IReadOnlyDictionary<string, JsonElement> GetConfigForType(this PluginBase plugin, Type type)
+        {
+            //Get config name attribute from plugin type
+            ConfigurationNameAttribute? configName = type.GetCustomAttribute<ConfigurationNameAttribute>();
+            return configName?.ConfigVarName == null
+                ? throw new KeyNotFoundException("No configuration attribute set")
+                : plugin.GetConfig(configName.ConfigVarName);
+        }
+
+        /// <summary>
+        /// Shortcut extension for <see cref="GetConfigForType{T}(PluginBase)"/> to get 
+        /// config of current class
+        /// </summary>
+        /// <param name="obj">The object that a configuration can be retrieved for</param>
+        /// <param name="plugin">The plugin containing configuration variables</param>
+        /// <returns>A <see cref="Dictionary{TKey, TValue}"/> of top level configuration elements for the type</returns>
+        /// <exception cref="ObjectDisposedException"></exception>
+        public static IReadOnlyDictionary<string, JsonElement> GetConfig(this PluginBase plugin, object obj)
+        {
+            Type t = obj.GetType();
+            return plugin.GetConfigForType(t);
+        }
+
+        /// <summary>
+        /// Determines if the current plugin configuration contains the require properties to initialize 
+        /// the type
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="plugin"></param>
+        /// <returns>True if the plugin config contains the require configuration property</returns>
+        public static bool HasConfigForType<T>(this PluginBase plugin) 
+        {
+            Type type = typeof(T);
+            ConfigurationNameAttribute? configName = type.GetCustomAttribute<ConfigurationNameAttribute>();
+            //See if the plugin contains a configuration varables
+            return configName != null && plugin.PluginConfig.TryGetProperty(configName.ConfigVarName, out _);
+        }
+
+        /// <summary>
+        /// Attempts to load the basic S3 configuration variables required
+        /// for S3 client access
+        /// </summary>
+        /// <param name="plugin"></param>
+        /// <returns>The S3 configuration object found in the plugin/host configuration</returns>
+        public static S3Config? TryGetS3Config(this PluginBase plugin)
+        {
+            //Try get the config
+            IReadOnlyDictionary<string, JsonElement>? s3conf = plugin.TryGetConfig(S3_CONFIG);
+            if(s3conf == null)
+            {
+                return null;
+            }
+
+            //Try get the elements
+            return new()
+            {
+                BaseBucket = s3conf.GetPropString("bucket"),
+                ClientId = s3conf.GetPropString("access_key"),
+                ServerAddress = s3conf.GetPropString("server_address"),
+                UseSsl = s3conf.TryGetValue("use_ssl", out JsonElement el) && el.GetBoolean(),
+                Region = s3conf.GetPropString("region"),
+            };
+        }
+    }
+}