package net.onrc.onos.ofcontroller.proxyarp;

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import net.floodlightcontroller.core.FloodlightContext;
import net.floodlightcontroller.core.IFloodlightProviderService;
import net.floodlightcontroller.core.IOFMessageListener;
import net.floodlightcontroller.core.IOFSwitch;
import net.floodlightcontroller.packet.ARP;
import net.floodlightcontroller.packet.Ethernet;
import net.floodlightcontroller.topology.ITopologyService;
import net.floodlightcontroller.topology.NodePortTuple;
import net.floodlightcontroller.util.MACAddress;

import org.openflow.protocol.OFMessage;
import org.openflow.protocol.OFPacketIn;
import org.openflow.protocol.OFPacketOut;
import org.openflow.protocol.OFPort;
import org.openflow.protocol.OFType;
import org.openflow.protocol.action.OFAction;
import org.openflow.protocol.action.OFActionOutput;
import org.openflow.util.HexString;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ProxyArpManager implements IOFMessageListener {
	private static Logger log = LoggerFactory.getLogger(ProxyArpManager.class);
	
	private final long ARP_ENTRY_TIMEOUT = 600000; //ms (== 5 mins)
	
	protected IFloodlightProviderService floodlightProvider;
	protected ITopologyService topology;
	
	protected Map<InetAddress, ArpTableEntry> arpTable;
	
	public ProxyArpManager(IFloodlightProviderService floodlightProvider,
				ITopologyService topology){
		this.floodlightProvider = floodlightProvider;
		this.topology = topology;
		
		arpTable = new HashMap<InetAddress, ArpTableEntry>();
	}
	
	@Override
	public String getName() {
		return  "ProxyArpManager";
	}

	@Override
	public boolean isCallbackOrderingPrereq(OFType type, String name) {
		return false;
	}

	@Override
	public boolean isCallbackOrderingPostreq(OFType type, String name) {
		return false;
	}

	@Override
	public Command receive(
			IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {
		
		if (msg.getType() != OFType.PACKET_IN){
			return Command.CONTINUE;
		}
		
		OFPacketIn pi = (OFPacketIn) msg;
		
		Ethernet eth = IFloodlightProviderService.bcStore.get(cntx, 
                IFloodlightProviderService.CONTEXT_PI_PAYLOAD);
		
		if (eth.getEtherType() == Ethernet.TYPE_ARP){
			
			
			ARP arp = (ARP) eth.getPayload();
			
			if (arp.getOpCode() == ARP.OP_REQUEST) {
				log.debug("ARP request received for {}", bytesToStringAddr(arp.getTargetProtocolAddress()));
				
				byte[] mac = lookupArpTable(arp.getTargetProtocolAddress());
				
				if (mac == null){
					//Mac address is not in our arp table. 
					//We need to flood the request out edge ports
					Set<NodePortTuple> broadcastPorts = topology.getBroadcastDomainPorts();
					log.debug("size {}", broadcastPorts.size());
					for (NodePortTuple nodePort : broadcastPorts){
						log.debug("Port {}", nodePort);
					}
					broadcastArpRequestOutEdge(pi, sw.getId(), pi.getInPort());
				}
				else {
					//We know the address, so send a reply
					log.debug("Sending reply of {}", MACAddress.valueOf(mac).toString());
					sendArpReply(arp, pi, mac, sw);
				}
			}
			else if (arp.getOpCode() == ARP.OP_REPLY) {
				log.debug("ARP reply recieved for {}", bytesToStringAddr(arp.getSenderProtocolAddress()));
				
				log.debug("arp table {}", arpTable.keySet());
				
				updateArpTable(arp);
			}
		}
		
		return Command.CONTINUE;
	}

	private synchronized byte[] lookupArpTable(byte[] ipAddress){
		InetAddress addr;
		try {
			addr = InetAddress.getByAddress(ipAddress);
		} catch (UnknownHostException e) {
			log.warn("Unable to create InetAddress", e);
			return null;
		}
		
		ArpTableEntry arpEntry = arpTable.get(addr);
		
		if (arpEntry == null){
			return null;
		}
		
		if (System.currentTimeMillis() - arpEntry.getTimeLastSeen() 
				> ARP_ENTRY_TIMEOUT){
			//Entry has timed out so we'll remove it and return null
			arpTable.remove(addr);
			return null;
		}
		
		return arpEntry.getMacAddress();
	}
	
	private synchronized void updateArpTable(ARP arp){
		InetAddress addr;
		try {
			addr = InetAddress.getByAddress(arp.getSenderProtocolAddress());
		} catch (UnknownHostException e) {
			log.warn("Unable to create InetAddress", e);
			return;
		}
		
		ArpTableEntry arpEntry = arpTable.get(addr);
		
		if (arpEntry != null 
				&& arpEntry.getMacAddress() == arp.getSenderHardwareAddress()){
			arpEntry.setTimeLastSeen(System.currentTimeMillis());
		}
		else {
			arpTable.put(addr, 
					new ArpTableEntry(arp.getSenderHardwareAddress(), 
										System.currentTimeMillis()));
		}
	}
	
	private void broadcastArpRequestOutEdge(OFPacketIn pi, long inSwitch, short inPort){
		for (IOFSwitch sw : floodlightProvider.getSwitches().values()){
			Collection<Short> enabledPorts = sw.getEnabledPortNumbers();
			Set<Short> linkPorts = topology.getPortsWithLinks(sw.getId());
			
			if (linkPorts == null){
				//I think this means the switch isn't known to topology yet.
				//Maybe it only just joined.
				continue;
			}
			
			OFPacketOut po = new OFPacketOut();
			po.setInPort(OFPort.OFPP_NONE)
				.setBufferId(-1)
				.setPacketData(pi.getPacketData());
				
			List<OFAction> actions = new ArrayList<OFAction>();
			
			for (short portNum : enabledPorts){
				if (linkPorts.contains(portNum) || 
						(sw.getId() == inSwitch && portNum == inPort)){
					//If this port isn't an edge port or is the ingress port
					//for the ARP, don't broadcast out it
					continue;
				}
				
				actions.add(new OFActionOutput(portNum));
				log.debug("Broadcasting out {}/{}", HexString.toHexString(sw.getId()), portNum);
			}
			
			po.setActions(actions);
			short actionsLength = (short) (actions.size() * OFActionOutput.MINIMUM_LENGTH);
			po.setActionsLength(actionsLength);
			po.setLengthU(OFPacketOut.MINIMUM_LENGTH + actionsLength 
					+ pi.getPacketData().length);
			
			List<OFMessage> msgList = new ArrayList<OFMessage>();
			msgList.add(po);
			
			try {
				sw.write(msgList, null);
				sw.flush();
			} catch (IOException e) {
				log.error("Failure writing packet out to switch", e);
			}
		}
	}
	
	private void sendArpReply(ARP arpRequest, OFPacketIn pi, byte[] macRequested, IOFSwitch sw){
		ARP arpReply = new ARP();
		arpReply.setHardwareType(ARP.HW_TYPE_ETHERNET)
			.setProtocolType(ARP.PROTO_TYPE_IP)
			.setHardwareAddressLength((byte)Ethernet.DATALAYER_ADDRESS_LENGTH)
			.setProtocolAddressLength((byte)4) //can't find the constant anywhere
			.setOpCode(ARP.OP_REPLY)
			.setSenderHardwareAddress(macRequested)
			.setSenderProtocolAddress(arpRequest.getTargetProtocolAddress())
			.setTargetHardwareAddress(arpRequest.getSenderHardwareAddress())
			.setTargetProtocolAddress(arpRequest.getSenderProtocolAddress());
		
		Ethernet eth = new Ethernet();
		eth.setDestinationMACAddress(arpRequest.getSenderHardwareAddress())
			.setSourceMACAddress(macRequested)
			.setEtherType(Ethernet.TYPE_ARP)
			.setPayload(arpReply);
		
		List<OFAction> actions = new ArrayList<OFAction>();
		actions.add(new OFActionOutput(pi.getInPort()));
		
		OFPacketOut po = new OFPacketOut();
		po.setInPort(OFPort.OFPP_NONE)
			.setBufferId(-1)
			.setPacketData(eth.serialize())
			.setActions(actions)
			.setActionsLength((short)OFActionOutput.MINIMUM_LENGTH)
			.setLengthU(OFPacketOut.MINIMUM_LENGTH + OFActionOutput.MINIMUM_LENGTH
					+ po.getPacketData().length);
		
		List<OFMessage> msgList = new ArrayList<OFMessage>();
		msgList.add(po);
		
		try {
			log.debug("Sending ARP reply to {}/{}", HexString.toHexString(sw.getId()), pi.getInPort());
			sw.write(msgList, null);
			sw.flush();
		} catch (IOException e) {
			log.warn("Failure writing packet out to switch", e);
		}
	}

	//TODO this should be put somewhere more central. I use it in BgpRoute as well.
	//We need a HexString.toHexString() equivalent.
	private String bytesToStringAddr(byte[] bytes){
		InetAddress addr;
		try {
			addr = InetAddress.getByAddress(bytes);
		} catch (UnknownHostException e) {
			log.warn(" ", e);
			return "";
		}
		if (addr == null) return "";
		else return addr.getHostAddress();
	}
}