add ReflectionUtil

lib/src/main/java/net/tomatentum/marinara/util/ReflectionUtil.java

@@ -0,0 +1,39 @@
+package net.tomatentum.marinara.util;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+
+import net.tomatentum.marinara.interaction.commands.annotation.ApplicationCommand;
+import net.tomatentum.marinara.interaction.commands.annotation.SubCommand;
+
+public final class ReflectionUtil {
+
+    public static <T extends Annotation> boolean isAnnotationPresent(Method method, Class<T> annotationClass) {
+        if (method.isAnnotationPresent(annotationClass) || method.getDeclaringClass().isAnnotationPresent(annotationClass))
+            return true;
+
+        return false;
+    }
+
+    public static <T extends Annotation> T getAnnotation(Method method, Class<T> annotationClass) {
+        return method.isAnnotationPresent(annotationClass) ? 
+            method.getAnnotation(annotationClass) : 
+            method.getDeclaringClass().getAnnotation(annotationClass);
+    }
+
+    public static void checkValidCommandMethod(Method method) {
+        if (method.isAnnotationPresent(ApplicationCommand.class) && 
+            method.getDeclaringClass().isAnnotationPresent(ApplicationCommand.class)) {
+            throw new RuntimeException(method.getName() + ": Can't have ApplicationCommand Annotation on Class and Method");
+        }
+
+        if (!isAnnotationPresent(method, ApplicationCommand.class))
+            throw new RuntimeException(method.getName() + ": Missing ApplicationCommand Annotation on either Class or Method");
+
+        if (!(method.isAnnotationPresent(SubCommand.class) && 
+            isAnnotationPresent(method, ApplicationCommand.class))) {
+            throw new RuntimeException(method.getName() + ": Missing ApplicationCommand Annotation on either Method or Class");
+        }
+    }
+    
+}