/**
 *  Implementation of Ethernet layer using jpcap (background thread)
 *  
 *  @author     ETSI / STF424
 *  @version    $URL$
 *                $Id$
 *
 */
package org.etsi.its.adapter.layers;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.Stack;

import org.etsi.its.adapter.IManagementLayers;
import org.etsi.its.adapter.PcapMultiplexer;

/**
 *  Implementation of Ethernet layer using jpcap (background thread)
 */
public class EthernetLayer extends Layer {
    
    /**
     * Well-known Ethernet broadcast address
     */
    public static byte[] MAC_BROADCAST = new byte[]{(byte)0xFF,(byte)0xFF,(byte)0xFF,(byte)0xFF,(byte)0xFF,(byte)0xFF};
    
    /**
     * Parameter name for Link-Layer destination
     */
    public static final String LINK_LAYER_DESTINATION = "LinkLayerDestination";
    
    /**
     * Constructor
     * @param  management   Layer management instance
     * @param  lowerStack   Lower protocol stack   
     */
    public EthernetLayer(IManagementLayers management, Stack<String> lowerStack) {
        super(management, lowerStack);  
    }

    /* (non-Javadoc)
     * @see org.etsi.its.adapter.layers.Layer#register(org.etsi.its.adapter.layers.Layer)
     */
    @Override
    public void register(Layer upperLayer) {
        if(registeredUpperLayer == null) {
            super.register(upperLayer);
            
            try {
                Method getEthernetType = registeredUpperLayer.getClass().getMethod("getEthernetType", (Class<?>[])null);
                if (getEthernetType != null) {
                    upperLayerFrameType = (Short) getEthernetType.invoke(registeredUpperLayer, (Object[]) null); 
                }
            } catch (SecurityException e) {
                e.printStackTrace();
            } catch (NoSuchMethodException e) {
                e.printStackTrace();
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
            
            localMacAddress = management.getLinkLayerAddress();
            PcapMultiplexer.getInstance().register(this, localMacAddress, upperLayerFrameType);
            
        }
    }
    
    /* (non-Javadoc)
     * @see org.etsi.its.adapter.layers.Layer#send(byte[], java.util.Map)
     */
    @Override
    public boolean send(byte[] message, Map<String, Object> params) {
        
        byte[] dst = (byte[])params.get(LINK_LAYER_DESTINATION);
        if(dst == null) {
            dst = MAC_BROADCAST;
        }
            
        byte[] sent = PcapMultiplexer.getInstance().sendPacket(this, dst, message); 

        return super.send(sent, params);
    }
    
    /* (non-Javadoc)
     * @see org.etsi.its.adapter.layers.Layer#unregister(org.etsi.its.adapter.layers.Layer)
     */
    @Override
    public void unregister(Layer upperLayer) {
        
        PcapMultiplexer.getInstance().unregister(this);
    }
              
    /**
     * Local Ethernet address 
     */
    private byte[] localMacAddress;
    
    /**
     * Upper layer's frame type
     */
    private short upperLayerFrameType;

}