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// ObjectId.java

package cn.tom.kit;

import java.math.BigInteger;
import java.net.*;
import java.nio.*;
import java.util.*;
import java.util.concurrent.atomic.*;
import java.util.logging.*;

/**
 * A globally unique identifier for objects.
 * Consists of 12 bytes, divided as follows:
 * 
 * 
 * 
 *     
 * 
 *     
 * 0 1 2 3 4 5 6 7 8 9 10 11
time machine pid inc
 * 
 *
 * @dochub objectids
 */
public class ObjectId implements Comparable , java.io.Serializable {

    private static final long serialVersionUID = -4415279469780082174L;

    static final Logger LOGGER = Logger.getLogger( "org.bson.ObjectId" );

    /** Gets a new object id.
     * @return the new id
     */
    public static ObjectId get(){
        return new ObjectId();
    }

    /** Checks if a string could be an ObjectId.
     * @return whether the string could be an object id
     */
    public static boolean isValid( String s ){
        if ( s == null )
            return false;

        final int len = s.length();
        if ( len != 24 )
            return false;

        for ( int i=0; i= '0' && c <= '9' )
                continue;
            if ( c >= 'a' && c <= 'f' )
                continue;
            if ( c >= 'A' && c <= 'F' )
                continue;

            return false;
        }

        return true;
    }

    /** Turn an object into an ObjectId, if possible.
     * Strings will be converted into ObjectIds, if possible, and ObjectIds will
     * be cast and returned.  Passing in null returns null.
     * @param o the object to convert
     * @return an ObjectId if it can be massaged, null otherwise
     */
    public static ObjectId massageToObjectId( Object o ){
        if ( o == null )
            return null;

        if ( o instanceof ObjectId )
            return (ObjectId)o;

        if ( o instanceof String ){
            String s = o.toString();
            if ( isValid( s ) )
                return new ObjectId( s );
        }

        return null;
    }

    public ObjectId( Date time ){
        this(time, _genmachine, _nextInc.getAndIncrement());
    }

    public ObjectId( Date time , int inc ){
        this( time , _genmachine , inc );
    }

    public ObjectId( Date time , int machine , int inc ){
        _time = (int)(time.getTime() / 1000);
        _machine = machine;
        _inc = inc;
        _new = false;
    }

    /** Creates a new instance from a string.
     * @param s the string to convert
     * @throws IllegalArgumentException if the string is not a valid id
     */
    public ObjectId( String s ){
        this( s , false );
    }

    public ObjectId( String s , boolean babble ){

        if ( ! isValid( s ) )
            throw new IllegalArgumentException( "invalid ObjectId [" + s + "]" );

        if ( babble )
            s = babbleToMongod( s );

        byte b[] = new byte[12];
        for ( int i=0; i=0; i-- )
            buf.append( _pos( b , i ) );
        for ( int i=11; i>=8; i-- )
            buf.append( _pos( b , i ) );

        return buf.toString();
    }

    public String toString(){
        return toStringMongod();
    }

    int _compareUnsigned( int i , int j ){
        long li = 0xFFFFFFFFL;
        li = i & li;
        long lj = 0xFFFFFFFFL;
        lj = j & lj;
        long diff = li - lj;
        if (diff < Integer.MIN_VALUE)
            return Integer.MIN_VALUE;
        if (diff > Integer.MAX_VALUE)
            return Integer.MAX_VALUE;
        return (int) diff;
    }

    public int compareTo( ObjectId id ){
        if ( id == null )
            return -1;

        int x = _compareUnsigned( _time , id._time );
        if ( x != 0 )
            return x;

        x = _compareUnsigned( _machine , id._machine );
        if ( x != 0 )
            return x;

        return _compareUnsigned( _inc , id._inc );
    }

    public int getMachine(){
        return _machine;
    }

    /**
     * Gets the time of this ID, in milliseconds
     */
    public long getTime(){
        return _time * 1000L;
    }

    /**
     * Gets the time of this ID, in seconds
     */
    public int getTimeSecond(){
        return _time;
    }

    public int getInc(){
        return _inc;
    }

    public int _time(){
        return _time;
    }
    public int _machine(){
        return _machine;
    }
    public int _inc(){
        return _inc;
    }

    public boolean isNew(){
        return _new;
    }

    public void notNew(){
        _new = false;
    }

    /**
     * Gets the generated machine ID, identifying the machine / process / class loader
     */
    public static int getGenMachineId() {
        return _genmachine;
    }

    /**
     * Gets the current value of the auto increment
     */
    public static int getCurrentInc() {
        return _nextInc.get();
    }

    final int _time;
    final int _machine;
    final int _inc;

    boolean _new;

    public static int _flip( int x ){
        int z = 0;
        z |= ( ( x << 24 ) & 0xFF000000 );
        z |= ( ( x << 8 )  & 0x00FF0000 );
        z |= ( ( x >> 8 )  & 0x0000FF00 );
        z |= ( ( x >> 24 ) & 0x000000FF );
        return z;
    }

    private static AtomicInteger _nextInc = new AtomicInteger( (new java.util.Random()).nextInt() );

    private static final int _genmachine;
    static {

        try {
            // build a 2-byte machine piece based on NICs info
            int machinePiece;
            {
                try {
                    StringBuilder sb = new StringBuilder();
                    Enumeration e = NetworkInterface.getNetworkInterfaces();
                    while ( e.hasMoreElements() ){
                        NetworkInterface ni = e.nextElement();
                        sb.append( ni.toString() );
                    }
                    machinePiece = sb.toString().hashCode() << 16;
                } catch (Throwable e) {
                    // exception sometimes happens with IBM JVM, use random
                    LOGGER.log(Level.WARNING, e.getMessage(), e);
                    machinePiece = (new Random().nextInt()) << 16;
                }
                LOGGER.fine( "machine piece post: " + Integer.toHexString( machinePiece ) );
            }

            // add a 2 byte process piece. It must represent not only the JVM but the class loader.
            // Since static var belong to class loader there could be collisions otherwise
            final int processPiece;
            {
                int processId = new java.util.Random().nextInt();
                try {
                    processId = java.lang.management.ManagementFactory.getRuntimeMXBean().getName().hashCode();
                }
                catch ( Throwable t ){
                }

                ClassLoader loader = ObjectId.class.getClassLoader();
                int loaderId = loader != null ? System.identityHashCode(loader) : 0;

                StringBuilder sb = new StringBuilder();
                sb.append(Integer.toHexString(processId));
                sb.append(Integer.toHexString(loaderId));
                processPiece = sb.toString().hashCode() & 0xFFFF;
                LOGGER.fine( "process piece: " + Integer.toHexString( processPiece ) );
            }

            _genmachine = machinePiece | processPiece;
            LOGGER.fine( "machine : " + Integer.toHexString( _genmachine ) );
        }
        catch ( Exception e ){
            throw new RuntimeException( e );
        }
    }
    
}