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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.microsphere.util;

import java.util.Comparator;
import java.util.Objects;

import static io.microsphere.reflect.MethodUtils.invokeMethod;
import static io.microsphere.util.AnnotationUtils.findAnnotation;

/**
 * The {@link Comparator} for the annotation {@link javax.annotation.Priority}
 * 

 * The less value of {@link javax.annotation.Priority}, the more priority
 *
 * @author Mercy
 * @see javax.annotation.Priority
 * @since 1.0.0
 */
public class PriorityComparator implements Comparator {

    private static final Class PRIORITY_CLASS = ClassLoaderUtils.resolveClass("javax.annotation.Priority");

    private static final int UNDEFINED_VALUE = -1;

    /**
     * Singleton instance of {@link PriorityComparator}
     */
    public static final PriorityComparator INSTANCE = new PriorityComparator();

    @Override
    public int compare(Object o1, Object o2) {
        return compare(resolveClass(o1), resolveClass(o2));
    }

    public static int compare(Class type1, Class type2) {
        if (Objects.equals(type1, type2) || PRIORITY_CLASS == null) {
            return 0;
        }

        Object priority1 = findAnnotation(type1, PRIORITY_CLASS);
        Object priority2 = findAnnotation(type2, PRIORITY_CLASS);

        int priorityValue1 = getValue(priority1);
        int priorityValue2 = getValue(priority2);

        return Integer.compare(priorityValue1, priorityValue2);
    }

    private static Class resolveClass(Object object) {
        return object instanceof Class ? (Class) object : object.getClass();
    }

    private static int getValue(Object priority) {
        int value = priority == null ? UNDEFINED_VALUE : invokeMethod(priority, "value");
        return value < 0 ? UNDEFINED_VALUE : value;
    }

}
    

    

    

            

    

            



    
    






    
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