implement AnnotationParser system

lib/src/main/java/net/tomatentum/marinara/parser/SlashCommandParser.java

@@ -0,0 +1,63 @@
+package net.tomatentum.marinara.parser;
+
+import java.lang.reflect.Method;
+import java.util.function.Consumer;
+
+import net.tomatentum.marinara.interaction.commands.ExecutableSlashCommandDefinition;
+import net.tomatentum.marinara.interaction.commands.annotation.SlashCommand;
+import net.tomatentum.marinara.interaction.commands.annotation.SubCommand;
+import net.tomatentum.marinara.interaction.commands.annotation.SubCommandGroup;
+import net.tomatentum.marinara.util.ReflectionUtil;
+
+public class SlashCommandParser implements AnnotationParser {
+
+    private Method method;
+    private Consumer<ExecutableSlashCommandDefinition> consumer;
+
+    public SlashCommandParser(Method method, Consumer<ExecutableSlashCommandDefinition> consumer) {
+        this.method = method;
+        this.consumer = consumer;
+    }
+
+    @Override
+    public void parse() {
+        this.checkValidCommandMethod(method);
+
+        SlashCommand cmd = ReflectionUtil.getAnnotation(method, SlashCommand.class);
+        ExecutableSlashCommandDefinition.Builder builder = new ExecutableSlashCommandDefinition.Builder();
+        builder.setApplicationCommand(cmd);
+
+        if (ReflectionUtil.isAnnotationPresent(method, SubCommandGroup.class)) {
+            SubCommandGroup cmdGroup = ReflectionUtil.getAnnotation(method, SubCommandGroup.class);
+            builder.setSubCommandGroup(cmdGroup);
+        }
+
+        if (ReflectionUtil.isAnnotationPresent(method, SubCommand.class)) {
+            SubCommand subCmd = ReflectionUtil.getAnnotation(method, SubCommand.class);
+            builder.setSubCommand(subCmd);
+        }
+
+        consumer.accept(builder.build());
+    }
+
+    @Override
+    public Method getMethod() {
+       return this.method;
+    }
+
+    private void checkValidCommandMethod(Method method) {
+        if (method.isAnnotationPresent(SlashCommand.class) && 
+            method.getDeclaringClass().isAnnotationPresent(SlashCommand.class)) {
+            throw new RuntimeException(method.getName() + ": Can't have ApplicationCommand Annotation on Class and Method");
+        }
+
+        if (!ReflectionUtil.isAnnotationPresent(method, SlashCommand.class))
+            throw new RuntimeException(method.getName() + ": Missing ApplicationCommand Annotation on either Class or Method");
+
+        if ((method.isAnnotationPresent(SubCommand.class) && 
+            !ReflectionUtil.isAnnotationPresent(method, SlashCommand.class))) {
+            throw new RuntimeException(method.getName() + ": Missing ApplicationCommand Annotation on either Method or Class");
+        }
+    }
+    
+}