/*
 * Copyright 2013 Nicolas Morel
 *
 * Licensed 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 java.util;

import java.io.Serializable;

/**
 * A simplified implementation of {@link java.util.UUID} as a translatable class
 * for GWT. Only methods implemented here can be used in client-side code. Also
 * note that while the equality and hashcode should operate as expected, the
 * hash codes would not translate between client and server; also note that
 * natural ordering of these objects on the client side would likely be
 * different.
 *
 * @author Ross M. Lodge
 */
public class UUID implements Serializable, Comparable<UUID> {

    private String uuidValue;

    /**
     * Default constructor to make this work for GWT serialization.
     */
    private UUID() {
        // Intentionally blank
    }

    /**
     * Constructs a new UUID from a string representation.
     *
     * @param name
     *
     * @return
     */
    public static UUID fromString( String name ) {
        UUID newUUID = new UUID();
        newUUID.uuidValue = name;
        return newUUID;
    }

    /**
     * Generates a random UUID that <em>should</em> be RFC-4122 Version 4 compliant,
     * although we can't really guarantee much about it's randomness.
     *
     * @return
     */
    public static UUID randomUUID() {
        return fromString( generateUUIDString() );
    }

    /**
     * {@inheritDoc}
     *
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    @Override
    public int compareTo( UUID o ) {
        return uuidValue.compareTo( o.toString() );
    }

    /**
     * {@inheritDoc}
     *
     * @see java.lang.Object#hashCode()
     */
    @Override
    public int hashCode() {
        return uuidValue.hashCode();
    }

    /**
     * {@inheritDoc}
     *
     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals( Object obj ) {
        if ( this == obj ) {
            return true;
        }
        if ( obj == null || getClass() != obj.getClass() ) {
            return false;
        }
        return uuidValue.equals( obj.toString() );
    }

    /**
     * {@inheritDoc}
     *
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return uuidValue;
    }

    /**
     * Generates an RFC-4122, version 4, random UUID as a formatted string.  Code altered
     * from http://www.broofa.com/Tools/Math.uuid.js under the MIT license.
     *
     * @return
     */
    private static native String generateUUIDString() /*-{
        var chars = '0123456789ABCDEF'.split(''), uuid = [];
        radix = chars.length;

        var r;

        // rfc4122 requires these characters
        uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-';
        uuid[14] = '4';

        // Fill in random data.  At i==19 set the high bits of clock sequence as per rfc4122, sec. 4.1.5
        for (var i = 0; i < 36; i++) {
            if (!uuid[i]) {
                r = 0 | Math.random() * 16;
                uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];
            }
        }

        return uuid.join('');
    }-*/;

}