package foundation.system;

import java.lang.reflect.Method;

import foundation.dao.preload.Bucket;
import foundation.engine.EngineState;
import foundation.util.MapList;

public class LoadMonitor {

	private static Object lock;
	private MapList<Class<?>, Bucket<?>> items;
	private EngineState state;
	
	static {
		lock = new Object();
	}
	
	public LoadMonitor() {
		items = new MapList<Class<?>, Bucket<?>>();
		state = EngineState.Idle;
	}
	
	public boolean lock() {
		if (state == EngineState.Idle) {
			synchronized (lock) {
				if (state != EngineState.Idle) {
					return false;
				}
				
				state = EngineState.Working;
				return true;
			}
		}
		else {
			return false;
		}
	}
	
	public void release() {
		if (state == EngineState.Idle) {
			return;
		}
		
		state = EngineState.Idle;
	}
	
	public void activate() {
		for (Bucket<?> item: items) {
			item.activate();
		}
	}
	
	@SuppressWarnings("unchecked")
	public <T> T register(Class<?> clazz) throws Exception {
		Method newInstance = null;
		try {
			newInstance = clazz.getDeclaredMethod("newInstance");
		} 
		catch (NoSuchMethodException e) {
		}		
		
		Bucket<?> bucket = (Bucket<?>)newInstance.invoke(null);
		items.add(clazz, bucket);
		
		return (T)bucket;
	}

	@SuppressWarnings("unchecked")
	public <T> T get(Class<?> clazz) throws Exception {
		Bucket<?> result = items.get(clazz);
		
		if (result == null) {
			Method getInstance = null;
			try {
				getInstance = clazz.getDeclaredMethod("getInstance");
			} 
			catch (NoSuchMethodException e) {
			}

			if (getInstance != null) {
				result = (Bucket<?>) getInstance.invoke(null);
			}
		}
		
		return (T) result;
	}

}