package net.onrc.onos.core.intent.runtime;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

import net.floodlightcontroller.core.IFloodlightProviderService;
import net.floodlightcontroller.core.module.FloodlightModuleContext;
import net.floodlightcontroller.core.module.FloodlightModuleException;
import net.floodlightcontroller.core.module.IFloodlightModule;
import net.floodlightcontroller.core.module.IFloodlightService;
import net.onrc.onos.core.datagrid.IDatagridService;
import net.onrc.onos.core.datagrid.IEventChannel;
import net.onrc.onos.core.datagrid.IEventChannelListener;
import net.onrc.onos.core.flowprogrammer.IFlowPusherService;
import net.onrc.onos.core.intent.FlowEntry;
import net.onrc.onos.core.intent.Intent.IntentState;
import net.onrc.onos.core.intent.IntentOperation;
import net.onrc.onos.core.intent.IntentOperationList;
import net.onrc.onos.core.topology.ITopologyService;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PlanInstallModule implements IFloodlightModule {
    protected volatile IFloodlightProviderService floodlightProvider;
    protected volatile ITopologyService topologyService;
    protected volatile IDatagridService datagridService;
    protected volatile IFlowPusherService flowPusher;
    private PlanCalcRuntime planCalc;
    private PlanInstallRuntime planInstall;
    private EventListener eventListener;
    private IEventChannel<Long, IntentStateList> intentStateChannel;
    private static final Logger log = LoggerFactory.getLogger(PlanInstallModule.class);

    private static final String PATH_INTENT_CHANNEL_NAME = "onos.pathintent";
    private static final String INTENT_STATE_EVENT_CHANNEL_NAME = "onos.pathintent_state";


    @Override
    public void init(FloodlightModuleContext context)
            throws FloodlightModuleException {
        floodlightProvider = context.getServiceImpl(IFloodlightProviderService.class);
        topologyService = context.getServiceImpl(ITopologyService.class);
        datagridService = context.getServiceImpl(IDatagridService.class);
        flowPusher = context.getServiceImpl(IFlowPusherService.class);
        planCalc = new PlanCalcRuntime();
        planInstall = new PlanInstallRuntime(floodlightProvider, flowPusher);
        eventListener = new EventListener();
    }

    class EventListener extends Thread
            implements IEventChannelListener<Long, IntentOperationList> {

        private BlockingQueue<IntentOperationList> intentQueue = new LinkedBlockingQueue<>();
        private Long key = Long.valueOf(0);

        @Override
        public void run() {
            while (true) {
                try {
                    IntentOperationList intents = intentQueue.take();
                    //TODO: consider draining the remaining intent lists
                    //      and processing in one big batch
//                  List<IntentOperationList> remaining = new LinkedList<>();
//                  intentQueue.drainTo(remaining);

                    processIntents(intents);
                } catch (InterruptedException e) {
                    log.warn("Error taking from intent queue: {}", e.getMessage());
                }
            }
        }

        private void processIntents(IntentOperationList intents) {
            log("start_processIntents");
            log.debug("Processing OperationList {}", intents);
            log("begin_computePlan");
            List<Set<FlowEntry>> plan = planCalc.computePlan(intents);
            log("end_computePlan");
            log.debug("Plan: {}", plan);
            log("begin_installPlan");
            boolean success = planInstall.installPlan(plan);
            log("end_installPlan");
            Set<Long> domainSwitchDpids = floodlightProvider.getSwitches().keySet();
            log("begin_sendInstallNotif");
            sendNotifications(intents, true, success, domainSwitchDpids);
            log("end_sendInstallNotif");
            log("finish");
        }

        /***
         * This function is for sending intent state notification to other ONOS instances.
         * The argument of "domainSwitchDpids" is required for dispatching this ONOS's managed switches.
         * @param intents
         * @param installed
         * @param success
         * @param domainSwitchDpids
         */
        private void sendNotifications(IntentOperationList intents, boolean installed, boolean success, Set<Long> domainSwitchDpids) {
            IntentStateList states = new IntentStateList();
            for (IntentOperation i : intents) {
                IntentState newState;
                switch (i.operator) {
                    case REMOVE:
                        if (installed) {
                            newState = success ? IntentState.DEL_ACK : IntentState.DEL_PENDING;
                        } else {
                            newState = IntentState.DEL_REQ;
                        }
                        break;
                    case ADD:
                    default:
                        if (installed) {
                            if (domainSwitchDpids != null) {
                                states.domainSwitchDpids.addAll(domainSwitchDpids);
                            }
                            newState = success ? IntentState.INST_ACK : IntentState.INST_NACK;
                        } else {
                            newState = IntentState.INST_REQ;
                        }
                        break;
                }
                states.put(i.intent.getId(), newState);
            }

            if (log.isTraceEnabled()) {
                log.trace("domainSwitchDpids {}", states.domainSwitchDpids);
            }

            intentStateChannel.addTransientEntry(key, states);
            // XXX: Send notifications using the same key every time
            // and receive them by entryAdded() and entryUpdated()
            // key += 1;
        }

        @Override
        public void entryAdded(IntentOperationList value) {
            entryUpdated(value);
        }

        @Override
        public void entryRemoved(IntentOperationList value) {
            // This channel is a queue, so this method is not needed
        }

        @Override
        public void entryUpdated(IntentOperationList value) {
            log("start_intentNotifRecv");
            log("begin_sendReceivedNotif");
            sendNotifications(value, false, false, null);
            log("end_sendReceivedNotif");
            log("finish");

            log.debug("Added OperationList {}", value);
            try {
                intentQueue.put(value);
            } catch (InterruptedException e) {
                log.warn("Error putting to intent queue: {}", e.getMessage());
            }
        }
    }

    public static void log(String step) {
        log.debug("Time:{}, Step:{}", System.nanoTime(), step);
    }

    @Override
    public void startUp(FloodlightModuleContext context) {
        // start subscriber
        datagridService.addListener(PATH_INTENT_CHANNEL_NAME,
                eventListener,
                Long.class,
                IntentOperationList.class);
        eventListener.start();
        // start publisher
        intentStateChannel = datagridService.createChannel(INTENT_STATE_EVENT_CHANNEL_NAME,
                Long.class,
                IntentStateList.class);
    }

    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleDependencies() {
        Collection<Class<? extends IFloodlightService>> l =
                new ArrayList<Class<? extends IFloodlightService>>();
        l.add(IFloodlightProviderService.class);
        l.add(ITopologyService.class);
        l.add(IDatagridService.class);
        l.add(IFlowPusherService.class);
        return l;
    }

    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleServices() {
        // no services, for now
        return null;
    }

    @Override
    public Map<Class<? extends IFloodlightService>, IFloodlightService> getServiceImpls() {
        // no services, for now
        return null;
    }
}