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package org.glassfish.jersey.process.internal;

import java.util.Comparator;

import javax.ws.rs.BindingPriority;

/**
 * Comparator used to sort types by their priorities defined by {@link BindingPriority
 * annotations BindingPriority}.
 * @author Miroslav Fuksa (miroslav.fuksa at oracle.com)
 *
 * @param  Type of the elements to be sorted.
 */
public class PriorityComparator implements Comparator {

    /**
     * Defines which ordering should be used for sorting.
     */
    public enum Order {
        /**
         * Ascending order. The lowest priority first, the highest priority last.
         */
        ASCENDING(1),
        /**
         * Ascending order. The highest priority first, the lowest priority last.
         */
        DESCENDING(-1);

        private int ordering;

        private Order(int ordering) {
            this.ordering = ordering;
        }
    }

    private Order order;

    public PriorityComparator(Order order) {
        this.order = order;
    }

    @Override
    public int compare(T o1, T o2) {
        return (getPriority(o1) - getPriority(o2)) * order.ordering;
    }

    private int getPriority(T o) {
        if (o.getClass().isAnnotationPresent(BindingPriority.class)) {
            return o.getClass().getAnnotation(BindingPriority.class).value();
        } else {
            return BindingPriority.USER;
        }
    }
}