/*
 * Copyright (c) 2000, 2017 Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2021 Contributors to the Eclipse Foundation
 *
 * 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 java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicBoolean;

import com.sun.messaging.jmq.util.DestMetricsCounters;
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.jmsserver.Globals;
import com.sun.messaging.jmq.jmsserver.Broker;
import com.sun.messaging.jmq.jmsserver.config.BrokerConfig;
import com.sun.messaging.jmq.jmsserver.data.TransactionUID;
import com.sun.messaging.jmq.jmsserver.data.BaseTransaction;
import com.sun.messaging.jmq.jmsserver.persist.api.Store;
import com.sun.messaging.jmq.jmsserver.resources.BrokerResources;
import com.sun.messaging.jmq.jmsserver.util.BrokerException;
import com.sun.messaging.jmq.util.log.Logger;

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

    BrokerConfig config = Globals.getConfig();

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

    static String VRFILE_NAME = "vrfile";

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

    String storeName = "incompleteTxnStore";

    // cache of all messages of the destination; message id -> MessageInfo
    private ConcurrentHashMap<TransactionUID, TransactionWorkInfo> transactionMap = 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 txnCount and byteCount are - initialized when the PreparedTxnStore is instantiated - incremented when new
     * transaction is stored - decremented when transactions are removed - reset to 0 when all transactions are removed
     */
    private int txnCount = 0;
    private long byteCount = 0;
    private Object countLock = new Object();

    // backing file
    private VRFileRAF vrfile = null;

    int maxRecordSize = 0;

    PreparedTxnStore(MsgStore p, File dir, boolean load) throws BrokerException {

        super(dir, p.msgfdlimit, p.poollimit, p.cleanratio);
        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 {
                    // this cookie value will be written to the file header if it is
                    // being created for the first time
                    // if file exists, then this value will be ignored

                    vrfile.setCookie(BaseTransaction.CURRENT_FORMAT_VERSION);
                    vrfile.open();

                    // read back actual file cookie
                    long originalCookie = vrfile.getFileCookie();
                    if (originalCookie < BaseTransaction.CURRENT_FORMAT_VERSION) {
                        String msg = "Existing file: " + storeName + "has older cookie version than current version. " + "Current version = "
                                + BaseTransaction.CURRENT_FORMAT_VERSION + ". Original file version = " + originalCookie;
                        logger.log(Logger.WARNING, msg);
                    } else if (originalCookie > BaseTransaction.CURRENT_FORMAT_VERSION) {
                        String msg = "Existing file: " + storeName + " has newer cookie version than current version. " + "Current version = "
                                + BaseTransaction.CURRENT_FORMAT_VERSION + ". Original file version = " + originalCookie;
                        logger.log(Logger.ERROR, msg);

                    }

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

            // initialize message count and byte count
            initCounts();
        } catch (Throwable t) {
            logger.log(Logger.ERROR, "failed to load " + storeName, t);
            throw new BrokerException("failed to load " + storeName, t);
        }

        if (load) {
            loadTransactions();
        }
    }

    // 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 " + storeName, e);
                }

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

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

    TransactionWorkInfo storeTransaction(BaseTransaction baseTxn, boolean sync) throws IOException, BrokerException {

        TransactionUID id = baseTxn.getTid();

        // just check the cached map; all messages should be
        // loaded before this is called
        if (transactionMap.containsKey(id)) {
            String emsg = br.getKString(br.E_TRANSACTIONID_NOT_FOUND_IN_STORE, id) + ": " + storeName;
            logger.log(logger.ERROR, emsg);
            throw new BrokerException(emsg);
        }

        try {

            byte[] data = baseTxn.writeToBytes();

            int msgsize = data.length;
            if (sync && Store.getDEBUG_SYNC()) {
                String msg = " PreparedTxnStore storeTransaction sync " + baseTxn;
                Globals.getLogger().log(Logger.DEBUG, msg);
            }

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

                // store in vrfil
                info = new TransactionWorkInfo(this, vrfile, baseTxn, data, sync);
            } else {
                // store in individual file
                info = new TransactionWorkInfo(this, baseTxn, data, sync);
            }

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

            // increate destination message count and byte count
            incrTxnCount(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 removeTransaction(TransactionUID id, boolean sync) throws BrokerException {

        TransactionWorkInfo oldmsg = transactionMap.remove(id);

        if (oldmsg == null) {
            String emsg = br.getKString(br.E_TRANSACTIONID_NOT_FOUND_IN_STORE, id) + ": " + storeName;
            logger.log(logger.ERROR, emsg);
            throw new BrokerException(emsg);
        }

        try {
            oldmsg.free(sync);
        } catch (IOException e) {
            throw new BrokerException("failed to free transaction", e);
        }

        // decrement destination message count and byte count
        decrTxnCount(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 removeAllTransactions(boolean sync) throws IOException, BrokerException {

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

        removeAllData(sync);

        transactionMap.clear();
        clearCounts();
    }

    // will delete the whole directory hierarchy
    void releasePreparedTxnDir(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
        transactionMap.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<BaseTransaction> txnEnumeration() {

        if (loaded.get()) {
            if (Store.getDEBUG()) {
                String msg = getPrefix() + " returning getTransactionIterator()";
                logger.log(Logger.DEBUG, msg);
            }
            return new TxnEnumeration(this, getTransactionIterator());
        } else {
            Iterator recitr = null;
            if (vrfile != null) {
                recitr = vrfile.getRecords().iterator();
            }
            // false -> not peek only but load message
            if (Store.getDEBUG()) {
                String msg = getPrefix() + " returning getEnumeration()";
                logger.log(logger.DEBUG, msg);
            }
            return new TxnEnumeration(this, recitr, getFileEnumeration());
        }
    }

    /**
     * return the number of transactions in this file
     */
    int getTransactionCount() throws BrokerException {
        if (Store.getDEBUG()) {
            logger.log(logger.DEBUG, "PreparedTxnStore:getTransactionCount() " + txnCount);
        }

        return txnCount;
    }

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

        return byteCount;
    }

    @Override
    protected void close(boolean cleanup) {

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

        // individual files
        super.close(cleanup);

        transactionMap.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
     */
    public void loadTransactions() throws BrokerException {

        Enumeration<BaseTransaction> e = this.txnEnumeration();
        while (e.hasMoreElements()) {
            e.nextElement();
        }

        logger.log(Logger.DEBUG, getPrefix() + " loaded " + transactionMap.size() + " transactions");
    }

    TransactionWorkInfo getTransactionInfo(TransactionUID tid) throws BrokerException {

        TransactionWorkInfo info = transactionMap.get(tid);
        if (info == null) {
            String emsg = br.getKString(br.E_TRANSACTIONID_NOT_FOUND_IN_STORE, tid) + ": " + storeName;
            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 {

        TransactionWorkInfo minfo = new TransactionWorkInfo(this, data);

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

        return tid;
    }

    @Override
    FilenameFilter getFilenameFilter() {
        return vrfileFilter;
    }

    // END: implement super class (RandomAccessStore) abstract method

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

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

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

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

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

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

        synchronized (countLock) {
            txnCount = 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 = storeName + ": 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 {
                        txnCount++;
                        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();
        txnCount += (int) cnts[0];
        byteCount += cnts[1];

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

    private static class TxnEnumeration implements Enumeration {
        PreparedTxnStore parent = null;
        Iterator itr = null;
        Iterator recitr = null;
        Enumeration msgEnum = null;

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

        Object objToReturn = null;

        TxnEnumeration(PreparedTxnStore p, Iterator i) {
            parent = p;
            itr = i;
        }

        TxnEnumeration(PreparedTxnStore p, Iterator i, Enumeration e) {
            parent = p;
            recitr = i;
            msgEnum = e;
        }

        @Override
        public boolean hasMoreElements() {
            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 {
                            TransactionWorkInfo minfo = new TransactionWorkInfo(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.storeName, 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 TransactionUID) {
                    try {
                        result = parent.getTransaction((TransactionUID) objToReturn);
                    } catch (IOException | BrokerException e) {
                        // failed to load message
                        // log error; and continue
                        logger.log(logger.ERROR, br.X_RETRIEVE_MESSAGE_FAILED, objToReturn, parent.storeName, 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 = txnCount - numInVrfile;

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

    boolean containsTransaction(TransactionUID tid) {
        return transactionMap.containsKey(tid);
    }

    BaseTransaction getTransaction(TransactionUID mid) throws IOException, BrokerException {
        TransactionWorkInfo msginfo = transactionMap.get(mid);
        if (msginfo == null) {
            String emsg = br.getKString(br.E_TRANSACTIONID_NOT_FOUND_IN_STORE, mid) + ": " + storeName;
            logger.log(logger.ERROR, emsg);
            throw new BrokerException(emsg);
        } else {
            return msginfo.getMessage();
        }
    }

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

    void updateTransactionState(TransactionUID tid, int state, boolean sync) throws IOException, BrokerException {

        getTransactionInfo(tid).updateState(state, sync);
    }

    void updateTransactionCompletion(TransactionUID tid, boolean complete, boolean sync) throws IOException, BrokerException {

        int completionVal = (complete ? 1 : 0);
        getTransactionInfo(tid).updateCompletion(completionVal, sync);
    }

    String getPrefix() {
        return "PreparedTxStore: " + Thread.currentThread().getName();
    }
}
