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/*
 * Copyright (c) 2010-2017, KolibriFX AS. Licensed under the Apache License, version 2.0.
 */

package com.kolibrifx.plovercrest.server.internal.protocol;

import java.util.Collection;
import org.apache.log4j.Logger;
import com.kolibrifx.common.Disposable;
import com.kolibrifx.common.dispatcher.Dispatcher;
import com.kolibrifx.common.dispatcher.DispatcherQueue;
import com.kolibrifx.common.dispatcher.ThreadedDispatcher;

public class ThreadedSubscriberEntryWriter implements Disposable {
    private static final Logger log = Logger.getLogger(ThreadedSubscriberEntryWriter.class);

    private final SubscriberWriteHandler handler;

    interface SubscriberWriteHandler {
        void writeEntryCollection(SubscriberEntryCollection c);

        void writeStandaloneEvent(StandaloneSubscriberEvent event);
    }

    private final Dispatcher dispatcher = new ThreadedDispatcher("TableSubscriptionHandler");
    private final DispatcherQueue queue = new DispatcherQueue(dispatcher) {
        private boolean writeIfNeeded(final SubscriberEntryCollection c) {
            if (!c.getEntriesByTableIndex().isEmpty()) {
                handler.writeEntryCollection(c);
                return true;
            }
            return false;
        }

        @Override
        protected void processChunk(final Collection elements) {
            SubscriberEntryCollection c = new SubscriberEntryCollection();
            for (final SubscriberEvent e : elements) {
                if (e instanceof SubscriberEntry) {
                    final SubscriberEntry entry = (SubscriberEntry) e;
                    final SubscriberEntry lastEntry = c.getLastEntry(entry.subscriptionId);
                    if (lastEntry != null && !SubscriberEntry.areSuccessiveEntries(lastEntry, entry)) {
                        // this will happen if the subscriber has been rewinded
                        if (log.isTraceEnabled()) {
                            log.trace("Last entry index " + lastEntry.entryIndex + " vs " + entry.entryIndex
                                    + " -- flush needed");
                        }
                        writeIfNeeded(c);
                        c = new SubscriberEntryCollection();
                    }
                    c.add(entry);
                } else if (e instanceof StandaloneSubscriberEvent) {
                    if (writeIfNeeded(c)) {
                        c = new SubscriberEntryCollection();
                    }
                    handler.writeStandaloneEvent((StandaloneSubscriberEvent) e);
                } else {
                    log.error("Unknown event type " + e.getClass().getName());
                }
            }
            writeIfNeeded(c);
        }
    };

    public ThreadedSubscriberEntryWriter(final SubscriberWriteHandler handler) {
        this.handler = handler;
    }

    public void put(final SubscriberEvent event) {
        try {
            queue.put(event);
        } catch (final InterruptedException e) {
            log.error("Unexpected interrupt", e);
        }
    }

    @Override
    public void close() {
        dispatcher.close();
    }
}