package net.sf.openrocket.plugin;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.google.inject.AbstractModule;
import com.google.inject.multibindings.Multibinder;

/**
 * Guice module definition that searches for plugins in a list of provided
 * JAR files and registers each found plugin to the corresponding plugin interface.
 * 
 * @author Sampo Niskanen <sampo.niskanen@iki.fi>
 */
public class PluginModule extends AbstractModule {
	
	
	private Map<Class<?>, Multibinder<?>> binders = new HashMap<Class<?>, Multibinder<?>>();
	private AnnotationFinder finder = new AnnotationFinderImpl();
	
	
	@SuppressWarnings("unchecked")
	@Override
	protected void configure() {
		
		List<Class<?>> classes = finder.findAnnotatedTypes(Plugin.class);
		List<Class<?>> interfaces = new ArrayList<Class<?>>();
		List<Class<?>> unusedInterfaces;
		
		// Find plugin interfaces
		for (Class<?> c : classes) {
			if (c.isInterface()) {
				interfaces.add(c);
			}
		}
		unusedInterfaces = new ArrayList<Class<?>>(interfaces);
		
		// Find plugin implementations
		for (Class<?> c : classes) {
			if (c.isInterface())
				continue;
			
			for (Class<?> intf : interfaces) {
				if (intf.isAssignableFrom(c)) {
					// Ugly hack to enable dynamic binding...  Can this be done type-safely?
					Multibinder<Object> binder = (Multibinder<Object>) findBinder(intf);
					binder.addBinding().to(c);
					unusedInterfaces.remove(intf);
				}
			}
		}
		
		// TODO: Unused plugin interfaces should be bound to an empty set - how?
	}
	
	private Multibinder<?> findBinder(Class<?> intf) {
		Multibinder<?> binder = binders.get(intf);
		if (binder == null) {
			binder = Multibinder.newSetBinder(binder(), intf);
			binders.put(intf, binder);
		}
		return binder;
	}
	
}