package net.i2p.client.impl;

/*
 * free (adj.): unencumbered; not under the control of others
 * Written by jrandom in 2003 and released into the public domain 
 * with no warranty of any kind, either expressed or implied.  
 * It probably won't  make your computer catch on fire, or eat 
 * your children, but it might.  Use at your own risk.
 *
 */

import net.i2p.I2PAppContext;
import net.i2p.client.I2PSessionException;
import net.i2p.data.DataFormatException;
import net.i2p.data.Payload;
import net.i2p.data.i2cp.I2CPMessage;
import net.i2p.data.i2cp.MessagePayloadMessage;
import net.i2p.data.i2cp.ReceiveMessageEndMessage;
import net.i2p.util.Log;

/**
 * Handle I2CP MessagePayloadMessages from the router delivering the contents
 * of a message by accepting it, decrypting the payload, adding it to the set of
 * recieved messages, and telling the router that it has been recieved correctly.
 *
 * We don't really decrypt (no more end-to-end crypto)
 *
 * @author jrandom
 */
class MessagePayloadMessageHandler extends HandlerImpl {
    public MessagePayloadMessageHandler(I2PAppContext context) {
        super(context, MessagePayloadMessage.MESSAGE_TYPE);
    }
    
    public void handleMessage(I2CPMessage message, I2PSessionImpl session) {
        if (_log.shouldLog(Log.DEBUG))
            _log.debug("Handle message " + message + " for session " + session);
        try {
            MessagePayloadMessage msg = (MessagePayloadMessage) message;
            long id = msg.getMessageId();
            decryptPayload(msg, session);
            session.addNewMessage(msg);

            // Small chance of this, but
            // if we are a new I2P lib talking to an old router
            // and we don't send this, the router will OOM as it has
            // no cleaner for old messages.
            // Check router version from handshake
            // and send it all the time if 0.9.3 or less
            // (needs router version saving support in SetDateMessageHandler)
            if (!session.getFastReceive()) {
                ReceiveMessageEndMessage m = new ReceiveMessageEndMessage();
                m.setMessageId(id);
                m.setSessionId(msg.getSessionId());
                session.sendMessage(m);
            }
        } catch (DataFormatException dfe) {
            session.propogateError("Error handling a new payload message", dfe);
        } catch (I2PSessionException ise) {
            session.propogateError("Error handling a new payload message", ise);
        }
    }

    /**
     * Decrypt the payload
     *
     * We don't really decrypt (no more end-to-end crypto)
     * If we do, we need to use the correct key manager in the decrypt() call below
     */
    private Payload decryptPayload(MessagePayloadMessage msg, I2PSessionImpl session) throws DataFormatException {
        Payload payload = msg.getPayload();
        //if (!I2CPMessageProducer.END_TO_END_CRYPTO) {
            payload.setUnencryptedData(payload.getEncryptedData());
            return payload;
        //}
            
        //byte[] data = _context.elGamalAESEngine().decrypt(payload.getEncryptedData(), session.getDecryptionKey());
        //if (data == null) {
        //    if (_log.shouldLog(Log.WARN))
        //        _log.warn("Error decrypting the payload");
        //    throw new DataFormatException("Unable to decrypt the payload");
        //}
        //payload.setUnencryptedData(data);
        //return payload;
    }
}