package org.objectweb.jonas.jtests.beans.relation.tier;

/**
 * Utility class for Tiemor.
 */
public class TiemorUtil {

    private static Object lookupHome(java.util.Hashtable environment, String jndiName, Class narrowTo)
            throws javax.naming.NamingException {
        // Obtain initial context
        javax.naming.InitialContext initialContext = new javax.naming.InitialContext(environment);
        try {
            Object objRef = initialContext.lookup(jndiName);
            // only narrow if necessary
            if (narrowTo.isInstance(java.rmi.Remote.class))
                return javax.rmi.PortableRemoteObject.narrow(objRef, narrowTo);
            else
                return objRef;
        } finally {
            initialContext.close();
        }
    }

    // Home interface lookup methods

    /**
     * Obtain local home interface from default initial context
     * @return Local home interface for Tiemor. Lookup using COMP_NAME
     */
    public static TiemorLocalHome getLocalHome() throws javax.naming.NamingException {
        return (TiemorLocalHome) lookupHome(null, TiemorLocalHome.COMP_NAME, TiemorLocalHome.class);
    }

    /** Cached per JVM server IP. */
    private static String hexServerIP = null;

    // initialise the secure random instance
    private static final java.security.SecureRandom seeder = new java.security.SecureRandom();

    /**
     * A 32 byte GUID generator (Globally Unique ID). These artificial keys
     * SHOULD <strong>NOT </strong> be seen by the user, not even touched by the
     * DBA but with very rare exceptions, just manipulated by the database and
     * the programs. Usage: Add an id field (type java.lang.String) to your EJB,
     * and add setId(XXXUtil.generateGUID(this)); to the ejbCreate method.
     */
    public static final String generateGUID(Object o) {
        StringBuffer tmpBuffer = new StringBuffer(16);
        if (hexServerIP == null) {
            java.net.InetAddress localInetAddress = null;
            try {
                // get the inet address

                localInetAddress = java.net.InetAddress.getLocalHost();
            } catch (java.net.UnknownHostException uhe) {
                System.err.println("TiemorUtil: Could not get the local IP address using InetAddress.getLocalHost()!");
                // todo: find better way to get around this...
                uhe.printStackTrace();
                return null;
            }
            byte serverIP[] = localInetAddress.getAddress();
            hexServerIP = hexFormat(getInt(serverIP), 8);
        }

        String hashcode = hexFormat(System.identityHashCode(o), 8);
        tmpBuffer.append(hexServerIP);
        tmpBuffer.append(hashcode);

        long timeNow = System.currentTimeMillis();
        int timeLow = (int) timeNow & 0xFFFFFFFF;
        int node = seeder.nextInt();

        StringBuffer guid = new StringBuffer(32);
        guid.append(hexFormat(timeLow, 8));
        guid.append(tmpBuffer.toString());
        guid.append(hexFormat(node, 8));
        return guid.toString();
    }

    private static int getInt(byte bytes[]) {
        int i = 0;
        int j = 24;
        for (int k = 0; j >= 0; k++) {
            int l = bytes[k] & 0xff;
            i += l << j;
            j -= 8;
        }
        return i;
    }

    private static String hexFormat(int i, int j) {
        String s = Integer.toHexString(i);
        return padHex(s, j) + s;
    }

    private static String padHex(String s, int i) {
        StringBuffer tmpBuffer = new StringBuffer();
        if (s.length() < i) {
            for (int j = 0; j < i - s.length(); j++) {
                tmpBuffer.append('0');
            }
        }
        return tmpBuffer.toString();
    }

}

