Create module subsystem under TShockAPI.Modules

This should allow for TShock.cs to be split up to mini-modules, or "micro-plugins"

TShockAPI/Modules/ModuleManager.cs

@@ -0,0 +1,101 @@
+/*
+TShock, a server mod for Terraria
+Copyright (C) 2011-2019 Pryaxis & TShock Contributors
+
+This program 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 3 of the License, or
+(at your option) any later version.
+
+This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace TShockAPI.Modules
+{
+	public class ModuleManager : IDisposable
+	{
+		private List<Module> _modules = new();
+
+		/// <summary>
+		/// Discovers <see cref="Module"/> derived classes from across the assembly
+		/// </summary>
+		/// <returns>Type definitions of the modules that can be created</returns>
+		IEnumerable<Type> CollectModules() => Assembly.GetExecutingAssembly()
+				.GetTypes()
+				.Where(t => typeof(Module).IsAssignableFrom(t) && !t.IsAbstract)
+		;
+
+		/// <summary>
+		/// Initialises <see cref="Module"/> derived classes defined across the assembly
+		/// </summary>
+		/// <param name="parameters">Additional constructor arguments allowed for modules</param>
+		public void Initialise(object[] parameters)
+		{
+			foreach (var moduleType in CollectModules())
+				InitialiseModule(moduleType, parameters);
+		}
+
+		/// <summary>
+		/// Initialises a module by its type definition
+		/// </summary>
+		/// <param name="moduleType">The type of the module</param>
+		/// <param name="parameters">Additional constructor arguments allowed for modules</param>
+		public void InitialiseModule(Type moduleType, object[] parameters)
+		{
+			if (!typeof(Module).IsAssignableFrom(moduleType))
+				throw new NotSupportedException($"Cannot load module {moduleType.FullName} as it does not derive from {typeof(Module).FullName}");
+
+			var args = new List<object>();
+			ConstructorInfo constructor = null;
+
+			foreach (var ctor in moduleType.GetConstructors())
+			{
+				args.Clear();
+				var ctorParams = ctor.GetParameters();
+
+				foreach (var prm in ctorParams)
+				{
+					var matching_objects = parameters.Where(p => prm.ParameterType.IsAssignableFrom(p.GetType()));
+					if (matching_objects.Count() == 1)
+						args.Add(matching_objects.Single());
+					else
+					{
+						// skip this ctor since we cannot find a suitable parameter for it.
+						break;
+					}
+				}
+
+				if (args.Count() == ctorParams.Length)
+					constructor = ctor;
+			}
+
+			if (constructor is not null)
+			{
+				var module = (Module)constructor.Invoke(args.ToArray());
+				_modules.Add(module);
+				module.Initialise();
+			}
+		}
+
+		/// <summary>
+		/// Disposes of the module and the manager instance
+		/// </summary>
+		public void Dispose()
+		{
+			foreach (var module in _modules)
+				module.Dispose();
+			_modules.Clear();
+		}
+	}
+}
+