/*
 * 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
 */

/*
 * @(#)DstMsgStore.java	1.31 08/31/07
 */

package com.sun.messaging.jmq.jmsserver.persist.file;

import com.sun.messaging.jmq.io.SysMessageID;
import com.sun.messaging.jmq.io.Packet;
import com.sun.messaging.jmq.jmsserver.core.*;
import com.sun.messaging.jmq.util.log.Logger;
import com.sun.messaging.jmq.jmsserver.util.*;
import com.sun.messaging.jmq.jmsserver.Globals;
import com.sun.messaging.jmq.jmsserver.config.*;
import com.sun.messaging.jmq.jmsserver.resources.*;
import com.sun.messaging.jmq.jmsserver.persist.api.Store;
import com.sun.messaging.jmq.jmsserver.Broker;
import com.sun.messaging.jmq.io.disk.VRFile;
import com.sun.messaging.jmq.io.disk.VRFileRAF;
import com.sun.messaging.jmq.io.disk.VRecordRAF;
import com.sun.messaging.jmq.util.DestMetricsCounters;

import java.io.*;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * DstMsgStore keeps track of messages for a destination. Messages are either stored in records in a vrfile or in their
 * own file.
 */
class DstMsgStore extends RandomAccessStore {

    BrokerConfig config = Globals.getConfig();

    static final String USE_FILE_CHANNEL_PROP = FileStore.FILE_PROP_PREFIX + "message.use_file_channel";
    static final boolean DEFAULT_USE_FILE_CHANNEL = false;

    static String VRFILE_NAME = "vrfile";

    /* == variables used for storing/retrieving messages == */

    static boolean useFileChannel = Globals.getConfig().getBooleanProperty(USE_FILE_CHANNEL_PROP, DEFAULT_USE_FILE_CHANNEL);

    DestinationUID myDestination = null;

    // private MsgStore parent = null;

    // cache of all messages of the destination; message id -> MessageInfo
    private ConcurrentHashMap messageMap = new ConcurrentHashMap(1000);

    //
    // These variables are related to initial loading of messages
    //
    private AtomicBoolean loaded = new AtomicBoolean(false);

    // Added byt Tom Ross fix for bug 6431962
    // 16 June 2006

    // initializing file store properties
    // growth_factor (default 50%)
    // this is a percentage of hte current size by which the file store will grow when grown
    protected float growthFactor = config.getPercentageProperty(Globals.IMQ + ".persist.file.message.vrfile.growth_factor", VRFile.DEFAULT_GROWTH_FACTOR);

    // threshold file size after which VR file start to grow
    protected long threshold = config.getLongProperty(Globals.IMQ + ".persist.file.message.vrfile.threshold", VRFile.DEFAULT_THRESHOLD);

    // this is the new value by which a file store will be grow by
    // when its size reaches the treshold above
    protected float thresholdFactor = config.getPercentageProperty(Globals.IMQ + ".persist.file.message.vrfile.threshold_factor",
            VRFile.DEFAULT_THRESHOLD_FACTOR);

    // skip 'vrfile'
    private static FilenameFilter vrfileFilter = new FilenameFilter() {
        @Override
        public boolean accept(File dir, String name) {
            return (!name.equals(VRFILE_NAME));
        }
    };

    private static Enumeration emptyEnum = new Enumeration() {
        @Override
        public boolean hasMoreElements() {
            return false;
        }

        @Override
        public Object nextElement() {
            return null;
        }
    };

    /**
     * The msgCount and byteCount are - initialized when the DstMsgStore is instantiated - incremented when new messages are
     * stored - decremented when messages are removed - and reset to 0 when the dst is purged or removed
     */
    private int msgCount = 0;
    private long byteCount = 0;
    private Object countLock = new Object();

    // backing file
    private VRFileRAF vrfile = null;

    int maxRecordSize = 0;

    DstMsgStore(MsgStore p, DestinationUID dst, File dir) throws BrokerException {
        this(p, dst, dir, false);
    }

    DstMsgStore(MsgStore p, DestinationUID dst, File dir, boolean load) throws BrokerException {

        super(dir, p.msgfdlimit, p.poollimit, p.cleanratio);
        // parent = p;
        myDestination = dst;

        try {
            long fsize = p.initialFileSize.getBytes();
            if (fsize > 0) {
                maxRecordSize = (int) p.maxRecordSize.getBytes();

                vrfile = new VRFileRAF(new File(dir, VRFILE_NAME), fsize, Globals.isMinimumWritesFileStore(), Broker.isInProcess());
                vrfile.setBlockSize(p.blockSize);

                try {
                    vrfile.setGrowthFactor(growthFactor);
                } catch (IllegalArgumentException iiEx) {

                    vrfile.setGrowthFactor(vrfile.DEFAULT_GROWTH_FACTOR);
                    growthFactor = vrfile.DEFAULT_GROWTH_FACTOR;

                    logger.log(logger.INFO, "Invalid growth_factor value. Using default value of 50%.");
                }

                try {
                    vrfile.setThreshold(threshold);
                } catch (IllegalArgumentException iiEx) {

                    vrfile.setThreshold(vrfile.DEFAULT_THRESHOLD);
                    threshold = vrfile.DEFAULT_THRESHOLD;

                    logger.log(logger.INFO, "Invalid threshold value. Using default value of 0.");
                }

                try {
                    vrfile.setThresholdFactor(thresholdFactor);
                } catch (IllegalArgumentException iiEx) {

                    vrfile.setThresholdFactor(vrfile.DEFAULT_THRESHOLD_FACTOR);
                    thresholdFactor = vrfile.DEFAULT_THRESHOLD_FACTOR;

                    logger.log(logger.INFO, "Invalid threshold_factor value. Using default value of 0%.");
                }

                try {
                    if (threshold != 0 || thresholdFactor != 0.0f) {
                        vrfile.checkGrowthFactorSanity();
                    }
                } catch (IllegalStateException isEx) {
                    String exMsg = isEx.getMessage();
                    logger.log(logger.INFO, exMsg);
                }

                try {
                    vrfile.open();
                } catch (com.sun.messaging.jmq.io.disk.VRFileWarning e) {
                    logger.log(logger.WARNING, "possible data loss for " + myDestination, e);
                }
            }

            // initialize message count and byte count
            initCounts();
        } catch (IOException e) {
            logger.log(logger.ERROR, br.X_LOAD_MESSAGE_FILE_FAILED, dir, dst, e);
            throw new BrokerException(br.getString(br.X_LOAD_MESSAGE_FILE_FAILED, dir, dst), e);
        } catch (Throwable t) {
            logger.log(logger.ERROR, br.X_LOAD_MESSAGE_FILE_FAILED, dir, dst, t);
            throw new BrokerException(br.getString(br.X_LOAD_MESSAGE_FILE_FAILED, dir, dst), t);
        }

        if (load) {
            loadMessages();
        }
    }

    // return info about vfile
    public HashMap getStorageInfo() throws BrokerException {

        if (vrfile == null) {
            return new HashMap();
        }

        HashMap info = new HashMap(3);
        long used = vrfile.getBytesUsed();
        long free = vrfile.getBytesFree();
        info.put(DestMetricsCounters.DISK_USED, Long.valueOf(used));
        info.put(DestMetricsCounters.DISK_RESERVED, Long.valueOf(used + free));
        info.put(DestMetricsCounters.DISK_UTILIZATION_RATIO, Integer.valueOf((int) (vrfile.getUtilizationRatio() * 100)));
        return info;
    }

    // compact the vfile
    void compact() throws BrokerException {
        if (vrfile == null) {
            return;
        }

        // synchronize on vrfile to prevent others to access this destination
        synchronized (vrfile) {
            try {
                vrfile.close();

                try {
                    vrfile.compact();
                } catch (com.sun.messaging.jmq.io.disk.VRFileWarning e) {
                    logger.log(logger.WARNING, "possible data loss for " + myDestination, e);
                }

                try {
                    vrfile.open();
                } catch (com.sun.messaging.jmq.io.disk.VRFileWarning e) {
                    logger.log(logger.WARNING, "possible data loss for " + myDestination, e);
                }

                // After the file is compacted, all VRecords needs to be reloaded.
                messageMap.clear();
                Iterator itr = vrfile.getRecords().iterator();
                Enumeration e = new MsgEnumeration(this, itr, emptyEnum);
                while (e.hasMoreElements()) {
                    e.nextElement();
                }
            } catch (IOException e) {
                throw new BrokerException("Failed to compact file: " + vrfile.getFile(), e);
            }
        }
    }

    MessageInfo storeMessage(Packet message, ConsumerUID[] iids, int[] states, boolean sync) throws IOException, BrokerException {

        SysMessageID id = message.getSysMessageID();

        // just check the cached map; all messages should be
        // loaded before this is called
        if (messageMap.containsKey(id)) {
            logger.log(logger.ERROR, br.E_MSG_EXISTS_IN_STORE, id, myDestination);
            throw new BrokerException(br.getString(br.E_MSG_EXISTS_IN_STORE, id, myDestination));
        }

        try {
            int msgsize = message.getPacketSize();

            MessageInfo info = null;
            if (vrfile != null && (maxRecordSize == 0 || msgsize < maxRecordSize)) {

                // store in vrfile
                info = new MessageInfo(this, vrfile, message, iids, states, sync);
            } else {
                // store in individual file
                info = new MessageInfo(this, message, iids, states, sync);
            }

            // cache it, make sure to use the cloned SysMessageID
            messageMap.put(info.getID(), info);

            // increate destination message count and byte count
            incrMsgCount(msgsize);

            return info;
        } catch (IOException e) {
            logger.log(logger.ERROR, br.X_PERSIST_MESSAGE_FAILED, id.toString(), e);
            throw e;
        }
    }

    /**
     * Remove the message from the persistent store. If the message has an interest list, the interest list will be removed
     * as well.
     *
     * @param id the system message id of the message to be removed
     * @exception IOException if an error occurs while removing the message
     * @exception BrokerException if the message is not found in the store
     */
    void removeMessage(SysMessageID id, boolean sync) throws IOException, BrokerException {

        MessageInfo oldmsg = (MessageInfo) messageMap.remove(id);

        if (oldmsg == null) {
            logger.log(logger.ERROR, br.E_MSG_NOT_FOUND_IN_STORE, id, myDestination);
            throw new BrokerException(br.getString(br.E_MSG_NOT_FOUND_IN_STORE, id, myDestination));
        }

        oldmsg.free(sync);

        // decrement destination message count and byte count
        decrMsgCount(oldmsg.getSize());
    }

    /**
     * Remove all messages associated with this destination.
     *
     * @exception IOException if an error occurs while removing the message
     * @exception BrokerException if the message is not found in the store
     */
    void removeAllMessages(boolean sync) throws IOException, BrokerException {

        if (vrfile != null) {
            vrfile.clear(false); // false->don't truncate
        }

        removeAllData(sync);

        messageMap.clear();
        clearCounts();
    }

    // will delete the whole directory hierarchy
    void releaseMessageDir(boolean sync) throws IOException {

        if (vrfile != null) {
            // clear backing file
            vrfile.clear(false);
            vrfile.close();
            vrfile = null;
        }

        // get rid of the whole directory
        reset(true); // true -> remove top directory
        super.close(false);

        // clear cache
        messageMap.clear();
        clearCounts();
    }

    /**
     * Return an enumeration of all persisted messages. Use the Enumeration methods on the returned object to fetch and load
     * each message sequentially.
     *
     * <p>
     * This method is to be used at broker startup to load persisted messages on demand.
     *
     * @return an enumeration of all persisted messages.
     */
    Enumeration messageEnumeration() {

        if (loaded.get()) {
            return new MsgEnumeration(this, getMessageIterator());
        } else {
            Iterator recitr = null;
            if (vrfile != null) {
                recitr = vrfile.getRecords().iterator();
            }
            // false -> not peek only but load message
            return new MsgEnumeration(this, recitr, getFileEnumeration());
        }
    }

    /**
     * return the number of messages in this file
     */
    int getMessageCount() throws BrokerException {
        if (Store.getDEBUG()) {
            logger.log(logger.DEBUG, "DstMsgStore:getMessageCount()");
        }

        return msgCount;
    }

    /**
     * return the number of bytes in this file
     */
    long getByteCount() throws BrokerException {
        if (Store.getDEBUG()) {
            logger.log(logger.DEBUG, "DstMsgStore:getByteCount()");
        }

        return byteCount;
    }

    @Override
    protected void close(boolean cleanup) {

        // vrfile
        if (vrfile != null) {
            vrfile.close();
        }

        // individual files
        super.close(cleanup);

        messageMap.clear();
    }

    VRFileRAF getVRFile() {
        return vrfile;
    }

    /**
     * Load all messages in the backing file.
     *
     * returned if no messages exist in the store
     *
     * @exception BrokerException if an error occurs while getting the data
     */
    private void loadMessages() throws BrokerException {

        Enumeration e = this.messageEnumeration();
        while (e.hasMoreElements()) {
            e.nextElement();
        }

        logger.log(logger.DEBUG, "loaded " + messageMap.size() + " messages");
    }

    MessageInfo getMessageInfo(SysMessageID mid) throws BrokerException {

        MessageInfo info = (MessageInfo) messageMap.get(mid);
        if (info == null) {
            String emsg = br.getKString(br.E_MSG_NOT_FOUND_IN_STORE, mid, myDestination);
            logger.log(logger.ERROR, emsg);
            throw new BrokerException(emsg);
        }

        return info;
    }

    // BEGIN: implement super class (RandomAccessStore) abstract method
    /**
     * parse the message and it's associated interest list from the given buffers. This is loaded from individual message
     * files. Returns the sysMessageID.
     */
    @Override
    Object parseData(byte[] data, byte[] attachment) throws IOException {

        MessageInfo minfo = new MessageInfo(this, data, attachment);

        // if everything is ok, we cache it
        // make sure to use the cloned SysMessageID
        SysMessageID mid = minfo.getID();
        messageMap.put(mid, minfo);

        return mid;
    }

    @Override
    FilenameFilter getFilenameFilter() {
        return vrfileFilter;
    }
    // END: implement super class (RandomAccessStore) abstract method

    // synchronized access to messageMap.put()
    private void cacheMessageInfo(MessageInfo minfo) {
        messageMap.put(minfo.getID(), minfo);
    }

    // synchronized access to messageMap.keySet().iterator();
    private Iterator getMessageIterator() {
        return messageMap.keySet().iterator();
    }

    private void setLoadedFlag(boolean flag) {
        loaded.set(flag);
    }

    private void incrMsgCount(int msgSize) throws BrokerException {
        synchronized (countLock) {
            msgCount++;
            byteCount += msgSize;
        }
    }

    private void decrMsgCount(int msgSize) throws BrokerException {
        synchronized (countLock) {
            msgCount--;
            byteCount -= msgSize;
        }
    }

    private void clearCounts() {
        if (Store.getDEBUG()) {
            logger.log(logger.DEBUG, "DstMsgStore:clearCounts for " + myDestination);
        }

        synchronized (countLock) {
            msgCount = 0;
            byteCount = 0;
        }
    }

    /**
     * The msgCount and byteCount are - initialized when the DstMsgStore is instantiated - incremented when new messages are
     * stored - decremented when messages are removed - and reset to 0 when the dst is purged or removed
     */
    private void initCounts() throws BrokerException {

        // check vrfile first
        if (vrfile != null) {
            Set msgs = vrfile.getRecords();

            Iterator itr = msgs.iterator();
            while (itr.hasNext()) {
                // get all packetSize
                VRecordRAF record = (VRecordRAF) itr.next();

                // sanity check
                short cookie = record.getCookie();
                if (cookie == MessageInfo.PENDING || cookie != MessageInfo.DONE) {

                    // writing not finish: log error, free record
                    String warning = myDestination + ": found a " + "corrupted message at vrecord(" + record + "), a message might be lost";
                    logger.log(logger.WARNING, warning);

                    // free the bad VRecord
                    try {
                        vrfile.free(record);
                    } catch (IOException e) {
                        logger.log(logger.ERROR, "Failed to free the corrupted vrecord: " + e);
                    }

                } else {

                    try {
                        msgCount++;
                        byteCount += record.readInt();
                    } catch (Throwable t) {
                        logger.log(logger.ERROR, br.X_READ_FROM_VRECORD_FAILED, vrfile.getFile(), t);
                        throw new BrokerException(br.getString(br.X_READ_FROM_VRECORD_FAILED, vrfile.getFile()), t);
                    }
                }
            }
        }

        long[] cnts = initCountsFromIndividualFiles();
        msgCount += (int) cnts[0];
        byteCount += cnts[1];

        if (Store.getDEBUG()) {
            logger.log(logger.DEBUG, "DstMsgStore: initialized " + "msg count=" + msgCount + "; byte count = " + byteCount);
        }
    }

    private static class MsgEnumeration implements Enumeration {
        DstMsgStore parent = null;
        Iterator itr = null;
        Iterator recitr = null;
        Enumeration msgEnum = null;

        Logger logger = Globals.getLogger();
        BrokerResources br = Globals.getBrokerResources();

        Object objToReturn = null;

        MsgEnumeration(DstMsgStore p, Iterator i) {
            parent = p;
            itr = i;
        }

        MsgEnumeration(DstMsgStore p, Iterator i, Enumeration e) {
            parent = p;
            recitr = i;
            msgEnum = e;
        }

        @Override
        public boolean hasMoreElements() {
            Packet msg = null;
            if (itr != null) {
                if (itr.hasNext()) {
                    objToReturn = itr.next();
                    return true; // RETURN TRUE
                } else {
                    return false;
                }
            } else {
                if (recitr != null) {
                    while (recitr.hasNext()) {
                        // load message from VRecordRAF
                        try {
                            MessageInfo minfo = new MessageInfo(parent, (VRecordRAF) recitr.next());
                            objToReturn = minfo.getMessage();

                            // first time loaded from file; cache info
                            parent.cacheMessageInfo(minfo);

                            return true; // RETURN TRUE
                        } catch (IOException e) {
                            // log an error and continue
                            logger.log(logger.ERROR, br.X_PARSE_MESSAGE_FAILED, parent.myDestination, e);
                        }
                    }
                }

                if (msgEnum.hasMoreElements()) {
                    // load message from individual file
                    objToReturn = msgEnum.nextElement();
                    return true;
                } else {
                    parent.setLoadedFlag(true);
                    return false;
                }
            }
        }

        @Override
        public Object nextElement() {
            if (objToReturn != null) {
                Object result = null;
                
                if (objToReturn instanceof SysMessageID) {
                    try {
                        result = parent.getMessage((SysMessageID) objToReturn);
                    } catch (IOException e) {
                        // failed to load message
                        // log error; and continue
                        logger.log(logger.ERROR, br.X_RETRIEVE_MESSAGE_FAILED, objToReturn, parent.myDestination, e);
                        throw new NoSuchElementException();
                    } catch (BrokerException e) {
                        // msg not found
                        // log error; and continue
                        logger.log(logger.ERROR, br.X_RETRIEVE_MESSAGE_FAILED, objToReturn, parent.myDestination, e);
                        throw new NoSuchElementException();
                    }
                } else {
                    result = objToReturn;
                }
                objToReturn = null;
                return result;
            } else {
                throw new NoSuchElementException();
            }
        }
    }

    /**
     * Get debug information about the store.
     *
     * @return A Hashtable of name value pair of information
     */
    Hashtable getDebugState() {
        int numInVrfile = 0;
        if (vrfile != null) {
            numInVrfile = vrfile.getNRecords();
        }
        int numInFiles = msgCount - numInVrfile;

        Hashtable t = new Hashtable();
        t.put((myDestination + ":messages in vrfile"), String.valueOf(numInVrfile));
        t.put((myDestination + ":messages in its own file"), String.valueOf(numInFiles));
        return t;
    }

    // the following 3 methods are added to make sure
    // writing/reading to/from the backing file is synchronized

    void storeInterestStates(SysMessageID mid, ConsumerUID[] iids, int[] states, boolean sync) throws IOException, BrokerException {

        getMessageInfo(mid).storeStates(iids, states, sync);
    }

    void updateInterestState(SysMessageID mid, ConsumerUID iid, int state, boolean sync) throws IOException, BrokerException {

        getMessageInfo(mid).updateState(iid, state, sync);
    }

    boolean containsMsg(SysMessageID mid) {
        return messageMap.containsKey(mid);
    }

    Packet getMessage(SysMessageID mid) throws IOException, BrokerException {
        MessageInfo msginfo = (MessageInfo) messageMap.get(mid);
        if (msginfo == null) {
            String emsg = br.getKString(br.E_MSG_NOT_FOUND_IN_STORE, mid, myDestination);
            logger.log(logger.ERROR, emsg);
            throw new BrokerException(emsg);
        } else {
            return msginfo.getMessage();
        }
    }

    void sync() throws BrokerException {
        try {
            if (Store.getDEBUG_SYNC()) {
                logger.log(Logger.DEBUG, "sync called on " + myDestination);
            }
            vrfile.force();
        } catch (IOException e) {
            throw new BrokerException("Failed to synchronize data to disk for file: " + vrfile, e);
        }
    }
}
