/*
 * Copyright (c) 2000, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

/*
 * @(#)BrowserConsumer.java	1.18 06/27/07
 */

package com.sun.messaging.jmq.jmsclient;

import javax.jms.*;
import java.util.*;
import java.io.*;
import com.sun.messaging.jmq.io.*;
import com.sun.messaging.AdministeredObject;
import com.sun.messaging.ConnectionConfiguration;

/**
 * A BrowserConsumer consumes a browser's messages for enumeration
 *
 * Some of potential optimizations: 1. recycle interestIds for BrowserConsumers in a QueueBrowser (require recycle
 * interestIds support in general globaly) 2. receiveQueue max size limit 3. a common cache in a QueueBrowser for its
 * BrowserConsumers
 */

class BrowserConsumer extends Consumer implements Enumeration, Traceable {

    protected SessionImpl session = null;
    protected QueueBrowserImpl browser = null;

    protected ReceiveQueue receiveQueue = null;

    private long browseTimeout = 60000;
    private int browseChunkLimit = 1000;

    private SysMessageID[] messageIDs = null;
    private int cursor = 0;
    private int cursorEnd = 0;
    private int waitCounter = 0;

    public BrowserConsumer(QueueBrowserImpl browser, Destination dest) throws JMSException {

        this(browser, dest, null);
    }

    public BrowserConsumer(QueueBrowserImpl browser, Destination dest, String messageSelector) throws JMSException {

        super(browser.getSession().getConnection(), dest, messageSelector, false);
        this.browser = browser;
        this.session = browser.getSession();
        try {
            browseTimeout = Long.parseLong(session.getConnection().getProperty(ConnectionConfiguration.imqQueueBrowserRetrieveTimeout));
            browseChunkLimit = Integer.parseInt(session.getConnection().getProperty(ConnectionConfiguration.imqQueueBrowserMaxMessagesPerRetrieve));
        } catch (NumberFormatException nfe) {
            // Use hardcoded defaults
        }
        init();
    }

    private void init() throws JMSException {
        receiveQueue = new ReceiveQueue();
        // XXX PROTOCOL2.1
        // messageIDs = session.getMessageIdSet(getDestination(), getMessageSelector());
        messageIDs = session.getMessageIdSet(this);
        cursorEnd = messageIDs.length - 1;
        cursor = 0;

        addInterest();

        waitCounter = 0;

        moreMessage();
    }

    private void addInterest() {
        // XXX PROTOCOL2.1
        // session.addBrowserConsumer(this);
        connection.addLocalInterest(this);
    }

    private void removeInterest() {
        connection.removeLocalInterest(this);
        session.removeBrowserConsumer(this);

        FlowControl fc = connection.getReadChannel().flowControl;
        fc.removeConsumerFlowControl(this);
    }

    @Override
    protected Long getReadQueueId() {
        return session.getSessionId();
    }

    /*
     * This method is called by SessionReader. Messages are delivered to the receiveQueue
     */
    @Override
    protected void onMessage(MessageImpl message) throws JMSException {
        if (receiveQueue.getIsClosed()) {
            return;
        }
        receiveQueue.enqueueNotify(message);
    }

    private Message receive(long timeout) throws JMSException {
        MessageImpl message = null;

        try {
            message = (MessageImpl) receiveQueue.dequeueWait(timeout);

            if (message != null) {
                message.setIsBrowserMsg(true);
            }

        } finally {
            receiveQueue.setReceiveInProcess(false);
        }

        return message;
    }

    private void moreMessage() throws JMSException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream(ProtocolHandler.ACK_MESSAGE_BODY_SIZE);
        DataOutputStream dos = new DataOutputStream(bos);

        boolean moreComming = false;
        SysMessageID messageID = null;
        while (!moreComming && cursor <= cursorEnd) {
            int count = 0;
            while (cursor <= cursorEnd && count < browseChunkLimit) {
                messageID = messageIDs[cursor];
                try {
                    messageID.writeID(dos);
                } catch (IOException e) {
                    ExceptionHandler.handleException(e, AdministeredObject.cr.X_CAUGHT_EXCEPTION);
                }
                cursor++;
                count++;
            }
            if (count > 0) {
                try {
                    dos.flush();
                    bos.flush();
                } catch (IOException e) {
                    ExceptionHandler.handleException(e, AdministeredObject.cr.X_CAUGHT_EXCEPTION);
                }
                moreComming = session.requestMessages(bos, this);
                bos.reset();
            }
        }
        if (moreComming) {
            waitCounter++;
        }
    }

    @Override
    public boolean hasMoreElements() {
        if (receiveQueue.getIsClosed()) {
            String errorString = AdministeredObject.cr.getKString(AdministeredObject.cr.X_BROWSER_CLOSED);
            throw new NoSuchElementException(errorString);
        }
        synchronized (this) {
            return (!(waitCounter == 0));
        }
    }

    @Override
    public Object nextElement() {

        Message message = null;

        synchronized (this) {
            if (!hasMoreElements()) {
                String errorString = AdministeredObject.cr.getKString(AdministeredObject.cr.X_BROWSER_END);
                throw new NoSuchElementException(errorString);
            }
            try { // waitCounter must be > 0
                message = receive(browseTimeout);
                if (message != null && isLast((MessageImpl) message)) {
                    waitCounter--;
                    moreMessage();
                }
            } catch (JMSException e) {
                close();
                throw new NoSuchElementException(e.getMessage());
            }
        }

        // message is null when either timeout or closed
        if (message == null) {
            if (receiveQueue.getIsClosed()) {
                String errorString = AdministeredObject.cr.getKString(AdministeredObject.cr.X_BROWSER_CLOSED);
                throw new NoSuchElementException(errorString);
            }
            close();
            String errorString = AdministeredObject.cr.getKString(AdministeredObject.cr.X_BROWSER_TIMEOUT);
            throw new NoSuchElementException(errorString);
        }

        return message;
    }

    private boolean isLast(MessageImpl message) {
        return message.getPacket().getIsLast();
    }

    protected QueueBrowserImpl getBrowser() {
        return browser;
    }

    protected SessionImpl getSession() {
        return session;
    }

    protected void close() {
        if (receiveQueue.getIsClosed()) {
            return;
        }
        receiveQueue.close();

        removeInterest();

        if (debug) {
            Debug.println("browser consumer closed ...");
            Debug.println(this);
        }
    }

    @Override
    public void dump(PrintStream ps) {

        ps.println("------ BrowserConsumer dump ------");

        ps.println("Interest ID: " + getInterestId());
        ps.println("destination: " + getDestination());
        ps.println("selector: " + messageSelector);
        ps.println("waitCounter: " + waitCounter);

        if (receiveQueue != null) {
            receiveQueue.dump(ps);
        } else {
            ps.println("receiveQueue is null.");
        }
    }
}
