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package com.artemis.io;

import com.artemis.utils.reflect.ClassReflection;
import com.artemis.utils.reflect.Field;
import com.artemis.utils.reflect.ReflectionException;

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

/**
 * This class is only public in order to keep GWT happy.
 * Nothing to see here (API can change without prior notice)
 */
public class DefaultObjectStore {

	private HashMap defaultValues = new HashMap();
	private boolean usePrototypes = true;

	public boolean hasDefaultValues(Object object) {
		if (!usePrototypes)
			return false;

		TypeData typeData = defaultValues.get(object.getClass());
		if (typeData == null) {
			typeData = new TypeData(newInstance(object.getClass()));
			defaultValues.put(object.getClass(), typeData);
		}

		return typeData.hasDefaultValues(object);
	}

	private Object newInstance(Class type) {
		try {
			return ClassReflection.newInstance(type);
		} catch (ReflectionException e) {
			throw new RuntimeException(e);
		}
	}

	public void setUsePrototypes(boolean usePrototypes) {
		this.usePrototypes = usePrototypes;
	}

	static class TypeData {
		private final Object object;
		private final Class type;
		private final Field[] fields;

		TypeData(Object object) {
			this.object = object;
			this.type = object.getClass();

			Field[] fields = ClassReflection.getDeclaredFields(type);
			List filtered = new ArrayList();
			for (int i = 0; i < fields.length; i++) {
				Field f = fields[i];
				if (!f.isStatic()) {
					f.setAccessible(true);
					filtered.add(f);
				}
			}

			this.fields = filtered.toArray(new Field[0]);
		}

		boolean hasDefaultValues(Object other) {
			assert (other.getClass() == type);

			try {
				for (int i = 0; i < fields.length; i++) {
					Field f = fields[i];
					if (!equals(f.get(object), f.get(other)))
						return false;
				}

				return true;
			} catch (ReflectionException e) {
				throw new RuntimeException(e);
			}
		}

		private static boolean equals(Object a, Object b) {
			return (a != null) ? a.equals(b) : b == null;
		}
	}
}