Add Dependency Map, Update Assembly Crawler

[Untested] Assembly Crawler will now accept constructors matching: new(), new(CommandService), new(IDependencyMap).

Add IDependencyMap

Add DependencyMap

src/Discord.Net.Commands/CommandService.cs

@@ -164,7 +164,7 @@ namespace Discord.Commands
 
             return loadedModule;
         }
-        public async Task<IEnumerable<Module>> LoadAssembly(Assembly assembly)
+        public async Task<IEnumerable<Module>> LoadAssembly(Assembly assembly, IDependencyMap dependencyMap = null)
         {
             var modules = ImmutableArray.CreateBuilder<Module>();
             await _moduleLock.WaitAsync().ConfigureAwait(false);
@@ -176,7 +176,7 @@ namespace Discord.Commands
                     var moduleAttr = typeInfo.GetCustomAttribute<ModuleAttribute>();
                     if (moduleAttr != null && moduleAttr.Autoload)
                     {
-                        var moduleInstance = ReflectionUtils.CreateObject(typeInfo);
+                        var moduleInstance = ReflectionUtils.CreateObject(typeInfo, this, dependencyMap);
                         modules.Add(LoadInternal(moduleInstance, moduleAttr, typeInfo));
                     }
                 }

src/Discord.Net.Commands/Dependencies/DependencyMap.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace Discord.Commands
+{
+    public class DependencyMap : IDependencyMap
+    {
+        private Dictionary<Type, object> map;
+
+        public T Get<T>() where T : class
+        {
+            var t = typeof(T);
+            if (!map.ContainsKey(t))
+                throw new KeyNotFoundException($"The dependency map does not contain \"{t.FullName}\"");
+            return map[t] as T;
+        }
+
+        public void Add<T>(T obj)
+        {
+            var t = typeof(T);
+            if (map.ContainsKey(t))
+                throw new InvalidOperationException($"The dependency map already contains \"{t.FullName}\"");
+            map.Add(t, obj);
+        }
+    }
+}

src/Discord.Net.Commands/Dependencies/IDependencyMap.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Discord.Commands
+{
+    public interface IDependencyMap
+    {
+        T Get<T>() where T : class;
+        void Add<T>(T obj);
+    }
+}

src/Discord.Net.Commands/Module.cs

@@ -43,7 +43,7 @@ namespace Discord.Commands
                         nextGroupPrefix = groupPrefix + groupAttrib.Prefix ?? type.Name;
                     else
                         nextGroupPrefix = groupPrefix;
-                    SearchClass(ReflectionUtils.CreateObject(type), commands, type, nextGroupPrefix);
+                    SearchClass(ReflectionUtils.CreateObject(type, Service), commands, type, nextGroupPrefix);
                 }
             }
         }

src/Discord.Net.Commands/ReflectionUtils.cs

@@ -6,18 +6,33 @@ namespace Discord.Commands
 {
     internal class ReflectionUtils
     {
-        internal static object CreateObject(TypeInfo typeInfo)
+        internal static object CreateObject(TypeInfo typeInfo, CommandService commands, IDependencyMap map = null)
         {
-            var constructor = typeInfo.DeclaredConstructors.Where(x => x.GetParameters().Length == 0).FirstOrDefault();
-            if (constructor == null)
-                throw new InvalidOperationException($"Failed to find a valid constructor for \"{typeInfo.FullName}\"");
+            if (typeInfo.DeclaredConstructors.Count() > 1)
+                throw new InvalidOperationException($"Found too many constructors for \"{typeInfo.FullName}\"");
+            var constructor = typeInfo.DeclaredConstructors.FirstOrDefault();
             try
             {
-                return constructor.Invoke(null);
+                if (constructor.GetParameters().Length == 0)
+                    return constructor.Invoke(null);
+                else if (constructor.GetParameters().Length > 1)
+                    throw new InvalidOperationException($"Could not find a valid constructor for \"{typeInfo.FullName}\"");
+                var parameter = constructor.GetParameters().FirstOrDefault();
+                if (parameter == null)
+                    throw new InvalidOperationException($"Could not find a valid constructor for \"{typeInfo.FullName}\"");
+                if (parameter.GetType() == typeof(CommandService))
+                    return constructor.Invoke(new object[1] { commands });
+                else if (parameter is IDependencyMap)
+                {
+                    if (map == null) throw new InvalidOperationException($"The constructor for \"{typeInfo.FullName}\" requires a Dependency Map.");
+                    return constructor.Invoke(new object[1] { map });
+                }
+                else
+                    throw new InvalidOperationException($"Could not find a valid constructor for \"{typeInfo.FullName}\"");
             }
-            catch (Exception ex)
+            catch
             {
-                throw new InvalidOperationException($"Failed to create \"{typeInfo.FullName}\"", ex);
+                throw new InvalidOperationException($"Could not find a valid constructor for \"{typeInfo.FullName}\"");
             }
         }
     }