package net.onrc.onos.apps.sdnip;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.floodlightcontroller.core.IFloodlightProviderService;
import net.floodlightcontroller.core.IOFSwitch;

import org.openflow.protocol.OFFlowMod;
import org.openflow.protocol.OFMessage;
import org.openflow.protocol.OFPort;
import org.openflow.util.HexString;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class FlowCache {
    private static final Logger log = LoggerFactory.getLogger(FlowCache.class);

    private final IFloodlightProviderService floodlightProvider;

    private final Map<Long, List<OFFlowMod>> flowCacheMap;

    private final Comparator<OFFlowMod> cookieComparator =
            new Comparator<OFFlowMod>() {
        @Override
        public int compare(OFFlowMod fm1, OFFlowMod fm2) {
            long difference = fm2.getCookie() - fm1.getCookie();

            if (difference > 0) {
                return 1;
            } else if (difference < 0) {
                return -1;
            } else {
                return 0;
            }
        }
    };

    public FlowCache(IFloodlightProviderService floodlightProvider) {
        this.floodlightProvider = floodlightProvider;

        flowCacheMap = new HashMap<Long, List<OFFlowMod>>();
    }

    public void write(long dpid, OFFlowMod flowMod) {
        synchronized (this) {
            List<OFFlowMod> flowModList = new ArrayList<OFFlowMod>(1);
            flowModList.add(flowMod);
            write(dpid, flowModList);
        }
    }

    public void write(long dpid, List<OFFlowMod> flowMods) {
        synchronized (this) {
            ensureCacheForSwitch(dpid);

            List<OFFlowMod> clones = new ArrayList<OFFlowMod>(flowMods.size());

            // Somehow the OFFlowMods we get passed in will change later on.
            // No idea how this happens, but we can just clone to prevent problems
            try {
                for (OFFlowMod fm : flowMods) {
                    clones.add(fm.clone());
                }
            } catch (CloneNotSupportedException e) {
                log.debug("Clone exception", e);
            }

            flowCacheMap.get(dpid).addAll(clones);

            IOFSwitch sw = floodlightProvider.getSwitches().get(dpid);

            if (sw == null) {
                log.debug("Switch not found when writing flow mods");
                return;
            }

            List<OFMessage> msgList = new ArrayList<OFMessage>(clones.size());
            msgList.addAll(clones);

            try {
                sw.write(msgList, null);
            } catch (IOException e) {
                log.error("Error writing to switch", e);
            }
        }
    }

    public void delete(long dpid, OFFlowMod flowMod) {
        synchronized (this) {
            List<OFFlowMod> flowModList = new ArrayList<OFFlowMod>(1);
            flowModList.add(flowMod);
            delete(dpid, flowModList);
        }
    }

    public void delete(long dpid, List<OFFlowMod> flowMods) {
        synchronized (this) {
            ensureCacheForSwitch(dpid);

            // Remove the flow mods from the cache first before we alter them
            flowCacheMap.get(dpid).removeAll(flowMods);

            // Alter the original flow mods to make them delete flow mods
            for (OFFlowMod fm : flowMods) {
                fm.setCommand(OFFlowMod.OFPFC_DELETE_STRICT)
                        .setOutPort(OFPort.OFPP_NONE)
                        .setLengthU(OFFlowMod.MINIMUM_LENGTH);

                fm.getActions().clear();
            }

            IOFSwitch sw = floodlightProvider.getSwitches().get(dpid);
            if (sw == null) {
                log.debug("Switch not found when writing flow mods");
                return;
            }

            List<OFMessage> msgList = new ArrayList<OFMessage>(flowMods.size());
            msgList.addAll(flowMods);

            try {
                sw.write(msgList, null);
            } catch (IOException e) {
                log.error("Error writing to switch", e);
            }
        }
    }

    public void switchConnected(IOFSwitch sw) {
        synchronized (this) {
            log.debug("Switch connected: {}", sw);

            ensureCacheForSwitch(sw.getId());

            List<OFFlowMod> flowMods = flowCacheMap.get(sw.getId());

            Collections.sort(flowMods, cookieComparator);

            sw.clearAllFlowMods();

            List<OFMessage> messages = new ArrayList<OFMessage>(flowMods.size());
            messages.addAll(flowMods);

            try {
                sw.write(messages, null);
            } catch (IOException e) {
                log.error("Failure writing flow mods to switch {}",
                        HexString.toHexString(sw.getId()));
            }
        }
    }

    private void ensureCacheForSwitch(long dpid) {
        if (!flowCacheMap.containsKey(dpid)) {
            flowCacheMap.put(dpid, new ArrayList<OFFlowMod>());
        }
    }
}