/*

 * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.beans.finder;

/**

 * This class is designed to be a key of a cache

 * of constructors or methods.

 *

 * @since 1.7

 *

 * @author Sergey A. Malenkov

 */

final class Signature {

    private final Class<?> type;

    private final String name;

    private final Class<?>[] args;

    private volatile int code;

    /**

     * Constructs signature for constructor.

     *

     * @param type  the class that contains constructor

     * @param args  the types of constructor's parameters

     */

    Signature(Class<?> type, Class<?>[] args) {

        this(type, null, args);

    }

    /**

     * Constructs signature for method.

     *

     * @param type  the class that contains method

     * @param name  the name of the method

     * @param args  the types of method's parameters

     */

    Signature(Class<?> type, String name, Class<?>[] args) {

        this.type = type;

        this.name = name;

        this.args = args;

    }

    /**

     * Indicates whether some other object is "equal to" this one.

     *

     * @param object  the reference object with which to compare

     * @return {@code true} if this object is the same as the

     *         {@code object} argument, {@code false} otherwise

     * @see #hashCode()

     */

    @Override

    public boolean equals(Object object) {

        if (this == object) {

            return true;

        }

        if (object instanceof Signature) {

            Signature signature = (Signature) object;

            return isEqual(signature.type, this.type)

                && isEqual(signature.name, this.name)

                && isEqual(signature.args, this.args);

        }

        return false;

    }

    /**

     * Indicates whether some object is "equal to" another one.

     * This method supports {@code null} values.

     *

     * @param obj1  the first reference object that will compared

     * @param obj2  the second reference object that will compared

     * @return {@code true} if first object is the same as the second object,

     *         {@code false} otherwise

     */

    private static boolean isEqual(Object obj1, Object obj2) {

        return (obj1 == null)

                ? obj2 == null

                : obj1.equals(obj2);

    }

    /**

     * Indicates whether some array is "equal to" another one.

     * This method supports {@code null} values.

     *

     * @param args1 the first reference array that will compared

     * @param args2 the second reference array that will compared

     * @return {@code true} if first array is the same as the second array,

     *         {@code false} otherwise

     */

    private static boolean isEqual(Class<?>[] args1, Class<?>[] args2) {

        if ((args1 == null) || (args2 == null)) {

            return args1 == args2;

        }

        if (args1.length != args2.length) {

            return false;

        }

        for (int i = 0; i < args1.length; i++) {

            if (!isEqual(args1[i], args2[i])) {

                return false;

            }

        }

        return true;

    }

    /**

     * Returns a hash code value for the object.

     * This method is supported for the benefit of hashtables

     * such as {@link java.util.HashMap} or {@link java.util.HashSet}.

     * Hash code computed using algorithm

     * suggested in Effective Java, Item 8.

     *

     * @return a hash code value for this object

     * @see #equals(Object)

     */

    @Override

    public int hashCode() {

        if (this.code == 0) {

            int code = 17;

            code = addHashCode(code, this.type);

            code = addHashCode(code, this.name);

            if (this.args != null) {

                for (Class<?> arg : this.args) {

                    code = addHashCode(code, arg);

                }

            }

            this.code = code;

        }

        return this.code;

    }

    /**

     * Adds hash code value if specified object.

     * This is a part of the algorithm

     * suggested in Effective Java, Item 8.

     *

     * @param code    current hash code value

     * @param object  object that updates hash code value

     * @return updated hash code value

     * @see #hashCode()

     */

    private static int addHashCode(int code, Object object) {

        code *= 37;

        return (object != null)

                ? code + object.hashCode()

                : code;

    }

}