package net.onrc.onos.core.flowprogrammer;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;

import net.floodlightcontroller.core.IOFSwitch;
import net.onrc.onos.core.flowprogrammer.IFlowPusherService.MsgPriority;
import net.onrc.onos.core.util.FlowEntryId;

import org.openflow.protocol.OFFlowMod;
import org.openflow.protocol.OFMatch;
import org.openflow.protocol.OFPort;
import org.openflow.protocol.OFStatisticsRequest;
import org.openflow.protocol.statistics.OFFlowStatisticsReply;
import org.openflow.protocol.statistics.OFFlowStatisticsRequest;
import org.openflow.protocol.statistics.OFStatistics;
import org.openflow.protocol.statistics.OFStatisticsType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * FlowSynchronizer is an implementation of FlowSyncService.
 * In addition to IFlowSyncService, FlowSynchronizer periodically reads flow
 * tables from switches and compare them with GraphDB to drop unnecessary
 * flows and/or to install missing flows.
 */
public class FlowSynchronizer implements IFlowSyncService {

    private static Logger log = LoggerFactory.getLogger(FlowSynchronizer.class);

    // TODO: fix when FlowSynchronizer is refactored
    // private DBOperation dbHandler;
    protected IFlowPusherService pusher;
    private Map<IOFSwitch, FutureTask<SyncResult>> switchThreads;

    public FlowSynchronizer() {
        // TODO: fix when FlowSynchronizer is refactored
        // dbHandler = GraphDBManager.getDBOperation();
        switchThreads = new HashMap<IOFSwitch, FutureTask<SyncResult>>();
    }

    @Override
    public Future<SyncResult> synchronize(IOFSwitch sw) {
        Synchronizer sync = new Synchronizer(sw);
        FutureTask<SyncResult> task = new FutureTask<SyncResult>(sync);
        switchThreads.put(sw, task);
        task.run();
        return task;
    }

    @Override
    public void interrupt(IOFSwitch sw) {
        FutureTask<SyncResult> t = switchThreads.remove(sw);
        if (t != null) {
            t.cancel(true);
        }
    }

    /**
     * Initialize Synchronizer.
     *
     * @param pusherService FlowPusherService used for sending messages.
     */
    public void init(IFlowPusherService pusherService) {
        pusher = pusherService;
    }

    /**
     * Synchronizer represents main thread of synchronization.
     */
    protected class Synchronizer implements Callable<SyncResult> {
        IOFSwitch sw;
        // TODO: fix when FlowSynchronizer is refactored
        // ISwitchObject swObj;

        public Synchronizer(IOFSwitch sw) {
            this.sw = sw;
            // TODO: fix when FlowSynchronizer is refactored
            // Dpid dpid = new Dpid(sw.getId());
            // this.swObj = dbHandler.searchSwitch(dpid.toString());
        }

        double graphIDTime, switchTime, compareTime, graphEntryTime, extractTime, pushTime, totalTime;

        @Override
        public SyncResult call() {
            pusher.suspend(sw);
            try {
                long start = System.nanoTime();
                Set<FlowEntryWrapper> graphEntries = getFlowEntriesFromGraph();
                long step1 = System.nanoTime();
                Set<FlowEntryWrapper> switchEntries = getFlowEntriesFromSwitch();
                if (switchEntries == null) {
                    log.debug("getFlowEntriesFromSwitch() failed");
                    return null;
                }
                long step2 = System.nanoTime();
                SyncResult result = compare(graphEntries, switchEntries);
                long step3 = System.nanoTime();
                graphIDTime = (step1 - start);
                switchTime = (step2 - step1);
                compareTime = (step3 - step2);
                totalTime = (step3 - start);
                outputTime();

                return result;
            } finally {
                pusher.resume(sw);
            }
        }

        private void outputTime() {
            double div = Math.pow(10, 6); //convert nanoseconds to ms
            graphIDTime /= div;
            switchTime /= div;
            compareTime = (compareTime - graphEntryTime - extractTime - pushTime) / div;
            graphEntryTime /= div;
            extractTime /= div;
            pushTime /= div;
            totalTime /= div;
            log.debug("Sync time (ms):{},{},{},{},{},{},{}"
                    , graphIDTime
                    , switchTime
                    , compareTime
                    , graphEntryTime
                    , extractTime
                    , pushTime
                    , totalTime);
        }

        /**
         * Compare flows entries in GraphDB and switch to pick up necessary
         * messages.
         * After picking up, picked messages are added to FlowPusher.
         *
         * @param graphEntries  Flow entries in GraphDB.
         * @param switchEntries Flow entries in switch.
         */
        private SyncResult compare(Set<FlowEntryWrapper> graphEntries, Set<FlowEntryWrapper> switchEntries) {
            int added = 0, removed = 0, skipped = 0;
            for (FlowEntryWrapper entry : switchEntries) {
                if (graphEntries.contains(entry)) {
                    graphEntries.remove(entry);
                    skipped++;
                } else {
                    // remove flow entry from the switch
                    entry.removeFromSwitch(sw);
                    removed++;
                }
            }
            for (FlowEntryWrapper entry : graphEntries) {
                // add flow entry to switch
                entry.addToSwitch(sw);
                graphEntryTime += entry.dbTime;
                extractTime += entry.extractTime;
                pushTime += entry.pushTime;
                added++;
            }
            log.debug("Flow entries added {}, " +
                    "Flow entries removed {}, " +
                    "Flow entries skipped {}"
                    , added
                    , removed
                    , skipped);

            return new SyncResult(added, removed, skipped);
        }

        /**
         * Read GraphDB to get FlowEntries associated with a switch.
         *
         * @return set of FlowEntries
         */
        private Set<FlowEntryWrapper> getFlowEntriesFromGraph() {
            Set<FlowEntryWrapper> entries = new HashSet<FlowEntryWrapper>();

            // TODO: fix when FlowSynchronizer is refactored
        /*
        for(IFlowEntry entry : swObj.getFlowEntries()) {
        FlowEntryWrapper fe = new FlowEntryWrapper(entry);
        entries.add(fe);
        }
        */
            return entries;
        }

        /**
         * Read flow table from switch and derive FlowEntries from table.
         *
         * @return set of FlowEntries
         */
        private Set<FlowEntryWrapper> getFlowEntriesFromSwitch() {

            int lengthU = 0;
            OFMatch match = new OFMatch();
            match.setWildcards(OFMatch.OFPFW_ALL);

            OFFlowStatisticsRequest stat = new OFFlowStatisticsRequest();
            stat.setOutPort((short) 0xffff); //TODO: OFPort.OFPP_NONE
            stat.setTableId((byte) 0xff); // TODO: fix this with enum (ALL TABLES)
            stat.setMatch(match);
            List<OFStatistics> stats = new ArrayList<OFStatistics>();
            stats.add(stat);
            lengthU += stat.getLength();

            OFStatisticsRequest req = new OFStatisticsRequest();
            req.setStatisticType(OFStatisticsType.FLOW);
            req.setStatistics(stats);
            lengthU += req.getLengthU();
            req.setLengthU(lengthU);

            List<OFStatistics> entries = null;
            try {
                Future<List<OFStatistics>> dfuture = sw.getStatistics(req);
                entries = dfuture.get();
            } catch (IOException e) {
                log.error("Error getting statistics", e);
                return null;
            } catch (InterruptedException e) {
                log.error("Error getting statistics", e);
                return null;
            } catch (ExecutionException e) {
                log.error("Error getting statistics", e);
                return null;
            }

            Set<FlowEntryWrapper> results = new HashSet<FlowEntryWrapper>();
            for (OFStatistics result : entries) {
                OFFlowStatisticsReply entry = (OFFlowStatisticsReply) result;
                FlowEntryWrapper fe = new FlowEntryWrapper(entry);
                results.add(fe);
            }
            return results;
        }

    }

    /**
     * FlowEntryWrapper represents abstract FlowEntry which is embodied
     * by FlowEntryId (from GraphDB) or OFFlowStatisticsReply (from switch).
     */
    class FlowEntryWrapper {
        FlowEntryId flowEntryId;
        // TODO: fix when FlowSynchronizer is refactored
        // IFlowEntry iFlowEntry;
        OFFlowStatisticsReply statisticsReply;


        // TODO: fix when FlowSynchronizer is refactored
    /*
    public FlowEntryWrapper(IFlowEntry entry) {
        flowEntryId = new FlowEntryId(entry.getFlowEntryId());
        iFlowEntry = entry;
    }
    */

        public FlowEntryWrapper(OFFlowStatisticsReply entry) {
            flowEntryId = new FlowEntryId(entry.getCookie());
            statisticsReply = entry;
        }

        /**
         * Install this FlowEntry to a switch via FlowPusher.
         *
         * @param sw Switch to which flow will be installed.
         */
        double dbTime, extractTime, pushTime;

        public void addToSwitch(IOFSwitch sw) {
            if (statisticsReply != null) {
                log.error("Error adding existing flow entry {} to sw {}",
                        statisticsReply.getCookie(), sw.getId());
                return;
            }

            double startDB = System.nanoTime();
            // Get the Flow Entry state from the Network Graph
            // TODO: fix when FlowSynchronizer is refactored
        /*
        if (iFlowEntry == null) {
            try {
        // TODO: fix when FlowSynchronizer is refactored
                iFlowEntry = dbHandler.searchFlowEntry(flowEntryId);
            } catch (Exception e) {
                log.error("Error finding flow entry {} in Network Graph",
                        flowEntryId);
                return;
            }
        }
        */
            dbTime = System.nanoTime() - startDB;

            //
            // TODO: The old FlowDatabaseOperation class is gone, so the code
            //
        /*
        double startExtract = System.nanoTime();
        FlowEntry flowEntry =
        FlowDatabaseOperation.extractFlowEntry(iFlowEntry);
        if (flowEntry == null) {
        log.error("Cannot add flow entry {} to sw {} : flow entry cannot be extracted",
              flowEntryId, sw.getId());
        return;
        }
        extractTime = System.nanoTime() - startExtract;

        double startPush = System.nanoTime();
        pusher.pushFlowEntry(sw, flowEntry, MsgPriority.HIGH);
        pushTime = System.nanoTime() - startPush;
        */
        }

        /**
         * Remove this FlowEntry from a switch via FlowPusher.
         *
         * @param sw Switch from which flow will be removed.
         */
        public void removeFromSwitch(IOFSwitch sw) {
            if (statisticsReply == null) {
                log.error("Error removing non-existent flow entry {} from sw {}",
                        flowEntryId, sw.getId());
                return;
            }

            // Convert Statistics Reply to Flow Mod, then write it
            OFFlowMod fm = new OFFlowMod();
            fm.setCookie(statisticsReply.getCookie());
            fm.setCommand(OFFlowMod.OFPFC_DELETE_STRICT);
            fm.setLengthU(OFFlowMod.MINIMUM_LENGTH);
            fm.setMatch(statisticsReply.getMatch());
            fm.setPriority(statisticsReply.getPriority());
            fm.setOutPort(OFPort.OFPP_NONE);

            pusher.add(sw, fm, MsgPriority.HIGH);
        }

        /**
         * Return the hash code of the Flow Entry ID.
         */
        @Override
        public int hashCode() {
            return flowEntryId.hashCode();
        }

        /**
         * Returns true of the object is another Flow Entry ID with
         * the same value; otherwise, returns false.
         *
         * @param obj to compare
         * @return true if the object has the same Flow Entry ID.
         */
        @Override
        public boolean equals(Object obj) {
            if (obj != null && obj.getClass() == this.getClass()) {
                FlowEntryWrapper entry = (FlowEntryWrapper) obj;
                // TODO: we need to actually compare the match + actions
                return this.flowEntryId.equals(entry.flowEntryId);
            }
            return false;
        }

        @Override
        public String toString() {
            return flowEntryId.toString();
        }
    }
}