package com.eactive.eai.common.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.StringTokenizer;
import java.util.Vector;

public final class UUID implements java.io.Serializable {
    /**
     * Explicit serialVersionUID for interoperability.
     */
    private static final long serialVersionUID = 1L;

    /*
     * The random number generator used by this class to create random based
     * UUIDs.
     */
    private static volatile SecureRandom numberGenerator = null;

    /*
     * The most significant 64 bits of this UUID.
     *
     * @serial
     */
    private final long mostSigBits;

    /*
     * The least significant 64 bits of this UUID.
     *
     * @serial
     */
    private final long leastSigBits;

    /*
     * The version number associated with this UUID. Computed on demand.
     */
    private transient int version = -1;

    /*
     * The variant number associated with this UUID. Computed on demand.
     */
    private transient int variant = -1;

    /*
     * The timestamp associated with this UUID. Computed on demand.
     */
    private transient volatile long timestamp = -1;

    /*
     * The clock sequence associated with this UUID. Computed on demand.
     */
    private transient int sequence = -1;

    /*
     * The node number associated with this UUID. Computed on demand.
     */
    private transient long node = -1;

    /*
     * The hashcode of this UUID. Computed on demand.
     */
    private transient int hashCode = -1;

    // Constructors and Factories

    /*
     * Private constructor which uses a byte array to construct the new UUID.
     */
    private UUID(byte[] data) {
        long msb = 0;
        long lsb = 0;

        for (int i = 0; i < 8; i++)
            msb = (msb << 8) | (data[i] & 0xff);

        for (int i = 8; i < 16; i++)
            lsb = (lsb << 8) | (data[i] & 0xff);

        this.mostSigBits = msb;
        this.leastSigBits = lsb;
    }

    /**
     * Constructs a new <tt>UUID</tt> using the specified data.
     * <tt>mostSigBits</tt> is used for the most significant 64 bits of the
     * <tt>UUID</tt> and <tt>leastSigBits</tt> becomes the least significant
     * 64 bits of the <tt>UUID</tt>.
     *
     * @param mostSigBits
     * @param leastSigBits
     */
    public UUID(long mostSigBits, long leastSigBits) {
        this.mostSigBits = mostSigBits;
        this.leastSigBits = leastSigBits;
    }

    /**
     * Static factory to retrieve a type 4 (pseudo randomly generated) UUID.
     *
     * The <code>UUID</code> is generated using a cryptographically strong
     * pseudo random number generator.
     *
     * @return a randomly generated <tt>UUID</tt>.
     */
    public static UUID randomUUID() {
        SecureRandom ng = numberGenerator;

        if (ng == null) {
            numberGenerator = ng = new SecureRandom();
        }

        byte[] randomBytes = new byte[16];
        ng.nextBytes(randomBytes);
        randomBytes[6] &= 0x0f; /* clear version */
        randomBytes[6] |= 0x40; /* set to version 4 */
        randomBytes[8] &= 0x3f; /* clear variant */
        randomBytes[8] |= 0x80; /* set to IETF variant */

        //UUID result = new UUID(randomBytes);

        return new UUID(randomBytes);
    }

    /**
     * Static factory to retrieve a type 3 (name based) <tt>UUID</tt> based on
     * the specified byte array.
     *
     * @param name
     *            a byte array to be used to construct a <tt>UUID</tt>.
     * @return a <tt>UUID</tt> generated from the specified array.
     */
    public static UUID nameUUIDFromBytes(byte[] name) {
        MessageDigest md;

        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException nsae) {
            throw new InternalError("MD5 not supported");
        }

        byte[] md5Bytes = md.digest(name);
        md5Bytes[6] &= 0x0f; /* clear version */
        md5Bytes[6] |= 0x30; /* set to version 3 */
        md5Bytes[8] &= 0x3f; /* clear variant */
        md5Bytes[8] |= 0x80; /* set to IETF variant */

        return new UUID(md5Bytes);
    }

    /**
     * Creates a <tt>UUID</tt> from the string standard representation as
     * described in the {@link #toString}method.
     *
     * @param name
     *            a string that specifies a <tt>UUID</tt>.
     * @return a <tt>UUID</tt> with the specified value.
     * @throws IllegalArgumentException
     *             if name does not conform to the string representation as
     *             described in {@link #toString}.
     */
    public static UUID fromString(String name) {

    	StringTokenizer tokenizer = new StringTokenizer(name);

        Vector<String> cs = new Vector<String>();

        while (tokenizer.hasMoreTokens())
            cs.add(tokenizer.nextToken());

        String[] components = new String[cs.size()];

        for (int a = 0; a < cs.size(); a++)
            components[a] = (String) (cs.elementAt(a));

        if (components.length != 5) {
            throw new IllegalArgumentException("Invalid UUID string: " + name);
        }

        for (int i = 0; i < 5; i++)
            components[i] = "0x" + components[i];

        long mostSigBits = Long.decode(components[0]).longValue();
        mostSigBits <<= 16;
        mostSigBits |= Long.decode(components[1]).longValue();
        mostSigBits <<= 16;
        mostSigBits |= Long.decode(components[2]).longValue();

        long leastSigBits = Long.decode(components[3]).longValue();
        leastSigBits <<= 48;
        leastSigBits |= Long.decode(components[4]).longValue();

        return new UUID(mostSigBits, leastSigBits);
    }

    // Field Accessor Methods

    /**
     * Returns the least significant 64 bits of this UUID's 128 bit value.
     *
     * @return the least significant 64 bits of this UUID's 128 bit value.
     */
    public long getLeastSignificantBits() {
        return leastSigBits;
    }

    /**
     * Returns the most significant 64 bits of this UUID's 128 bit value.
     *
     * @return the most significant 64 bits of this UUID's 128 bit value.
     */
    public long getMostSignificantBits() {
        return mostSigBits;
    }

    /**
     * The version number associated with this <tt>UUID</tt>. The version
     * number describes how this <tt>UUID</tt> was generated.
     *
     * The version number has the following meaning:
     * <p>
     * <ul>
     * <li>1 Time-based UUID
     * <li>2 DCE security UUID
     * <li>3 Name-based UUID
     * <li>4 Randomly generated UUID
     * </ul>
     *
     * @return the version number of this <tt>UUID</tt>.
     */
    public int version() {
        if (version < 0) {
            // Version is bits masked by 0x000000000000F000 in MS long
            version = (int) ((mostSigBits >> 12) & 0x0f);
        }

        return version;
    }

    /**
     * The variant number associated with this <tt>UUID</tt>. The variant
     * number describes the layout of the <tt>UUID</tt>.
     *
     * The variant number has the following meaning:
     * <p>
     * <ul>
     * <li>0 Reserved for NCS backward compatibility
     * <li>2 The Leach-Salz variant (used by this class)
     * <li>6 Reserved, Microsoft Corporation backward compatibility
     * <li>7 Reserved for future definition
     * </ul>
     *
     * @return the variant number of this <tt>UUID</tt>.
     */
    public int variant() {
        if (variant < 0) {
            // This field is composed of a varying number of bits
            if ((leastSigBits >>> 63) == 0) {
                variant = 0;
            } else if ((leastSigBits >>> 62) == 2) {
                variant = 2;
            } else {
                variant = (int) (leastSigBits >>> 61);
            }
        }

        return variant;
    }

    /**
     * The timestamp value associated with this UUID.
     *
     * <p>
     * The 60 bit timestamp value is constructed from the time_low, time_mid,
     * and time_hi fields of this <tt>UUID</tt>. The resulting timestamp is
     * measured in 100-nanosecond units since midnight, October 15, 1582 UTC.
     * <p>
     *
     * The timestamp value is only meaningful in a time-based UUID, which has
     * version type 1. If this <tt>UUID</tt> is not a time-based UUID then
     * this method throws UnsupportedOperationException.
     *
     * @throws UnsupportedOperationException
     *             if this UUID is not a version 1 UUID.
     */
    public long timestamp() {
        if (version() != 1) {
            throw new UnsupportedOperationException("Not a time-based UUID");
        }

        long result = timestamp;

        if (result < 0) {
            result = (mostSigBits & 0x0000000000000FFFL) << 48;
            result |= (((mostSigBits >> 16) & 0xFFFFL) << 32);
            result |= mostSigBits >>> 32;
            timestamp = result;
        }

        return result;
    }

    /**
     * The clock sequence value associated with this UUID.
     *
     * <p>
     * The 14 bit clock sequence value is constructed from the clock sequence
     * field of this UUID. The clock sequence field is used to guarantee
     * temporal uniqueness in a time-based UUID.
     * <p>
     *
     * The clockSequence value is only meaningful in a time-based UUID, which
     * has version type 1. If this UUID is not a time-based UUID then this
     * method throws UnsupportedOperationException.
     *
     * @return the clock sequence of this <tt>UUID</tt>.
     * @throws UnsupportedOperationException
     *             if this UUID is not a version 1 UUID.
     */
    public int clockSequence() {
        if (version() != 1) {
            throw new UnsupportedOperationException("Not a time-based UUID");
        }

        if (sequence < 0) {
            sequence = (int) ((leastSigBits & 0x3FFF000000000000L) >>> 48);
        }

        return sequence;
    }

    /**
     * The node value associated with this UUID.
     *
     * <p>
     * The 48 bit node value is constructed from the node field of this UUID.
     * This field is intended to hold the IEEE 802 address of the machine that
     * generated this UUID to guarantee spatial uniqueness.
     * <p>
     *
     * The node value is only meaningful in a time-based UUID, which has version
     * type 1. If this UUID is not a time-based UUID then this method throws
     * UnsupportedOperationException.
     *
     * @return the node value of this <tt>UUID</tt>.
     * @throws UnsupportedOperationException
     *             if this UUID is not a version 1 UUID.
     */
    public long node() {
        if (version() != 1) {
            throw new UnsupportedOperationException("Not a time-based UUID");
        }

        if (node < 0) {
            node = leastSigBits & 0x0000FFFFFFFFFFFFL;
        }

        return node;
    }

    // Object Inherited Methods

    /**
     * Returns a <code>String</code> object representing this
     * <code>UUID</code>.
     *
     * <p>
     * The UUID string representation is as described by this BNF :
     *
     * <pre>
     *
     *
     *    UUID                   = &lt;time_low&gt; &quot;-&quot; &lt;time_mid&gt; &quot;-&quot;
     *                             &lt;time_high_and_version&gt; &quot;-&quot;
     *                             &lt;variant_and_sequence&gt; &quot;-&quot;
     *                             &lt;node&gt;
     *    time_low               = 4*&lt;hexOctet&gt;
     *    time_mid               = 2*&lt;hexOctet&gt;
     *    time_high_and_version  = 2*&lt;hexOctet&gt;
     *    variant_and_sequence   = 2*&lt;hexOctet&gt;
     *    node                   = 6*&lt;hexOctet&gt;
     *    hexOctet               = &lt;hexDigit&gt;&lt;hexDigit&gt;
     *    hexDigit               =
     *          &quot;0&quot; | &quot;1&quot; | &quot;2&quot; | &quot;3&quot; | &quot;4&quot; | &quot;5&quot; | &quot;6&quot; | &quot;7&quot; | &quot;8&quot; | &quot;9&quot;
     *          | &quot;a&quot; | &quot;b&quot; | &quot;c&quot; | &quot;d&quot; | &quot;e&quot; | &quot;f&quot;
     *          | &quot;A&quot; | &quot;B&quot; | &quot;C&quot; | &quot;D&quot; | &quot;E&quot; | &quot;F&quot;
     *
     *
     * </pre>
     *
     * @return a string representation of this <tt>UUID</tt>.
     */
    public String toString() {
        return (digits(mostSigBits >> 32, 8) + "-" +
        digits(mostSigBits >> 16, 4) + "-" + digits(mostSigBits, 4) + "-" +
        digits(leastSigBits >> 48, 4) + "-" + digits(leastSigBits, 12));
    }

    /** Returns val represented by the specified number of hex digits. */
    private static String digits(long val, int digits) {
        long hi = 1L << (digits * 4);

        return Long.toHexString(hi | (val & (hi - 1))).substring(1);
    }

    /**
     * Returns a hash code for this <code>UUID</code>.
     *
     * @return a hash code value for this <tt>UUID</tt>.
     */
    public int hashCode() {
        if (hashCode == -1) {
            hashCode = (int) ((mostSigBits >> 32) ^ mostSigBits ^
                (leastSigBits >> 32) ^ leastSigBits);
        }

        return hashCode;
    }

    /**
     * Compares this object to the specified object. The result is <tt>true</tt>
     * if and only if the argument is not <tt>null</tt>, is a <tt>UUID</tt>
     * object, has the same variant, and contains the same value, bit for bit,
     * as this <tt>UUID</tt>.
     *
     * @param obj
     *            the object to compare with.
     * @return <code>true</code> if the objects are the same;
     *         <code>false</code> otherwise.
     */
    public boolean equals(Object obj) {
        if (!(obj instanceof UUID)) {
            return false;
        }

        if (((UUID) obj).variant() != this.variant()) {
            return false;
        }

        UUID id = (UUID) obj;

        return ((mostSigBits == id.mostSigBits) &&
        (leastSigBits == id.leastSigBits));
    }

    // Comparison Operations

    /**
     * Compares this UUID with the specified UUID.
     *
     * <p>
     * The first of two UUIDs follows the second if the most significant field
     * in which the UUIDs differ is greater for the first UUID.
     *
     * @param val
     *            <tt>UUID</tt> to which this <tt>UUID</tt> is to be
     *            compared.
     * @return -1, 0 or 1 as this <tt>UUID</tt> is less than, equal to, or
     *         greater than <tt>val</tt>.
     */
    public int compareTo(UUID val) {
        // The ordering is intentionally set up so that the UUIDs
        // can simply be numerically compared as two numbers
        return ((this.mostSigBits < val.mostSigBits) ? (-1)
                                                     : ((this.mostSigBits > val.mostSigBits)
        ? 1
        : ((this.leastSigBits < val.leastSigBits) ? (-1)
                                                  : ((this.leastSigBits > val.leastSigBits)
        ? 1 : 0))));
    }

    /**
     * Reconstitute the <tt>UUID</tt> instance from a stream (that is,
     * deserialize it). This is necessary to set the transient fields to their
     * correct uninitialized value so they will be recomputed on demand.
     */
    private void readObject(java.io.ObjectInputStream in)
        throws java.io.IOException, ClassNotFoundException {
        in.defaultReadObject();

        // Set "cached computation" fields to their initial values
        version = -1;
        variant = -1;
        timestamp = -1;
        sequence = -1;
        node = -1;
        hashCode = -1;
    }
}
