/*
 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package sun.management.snmp.jvminstr;

// java imports
//
import com.sun.jmx.mbeanserver.Util;
import java.io.Serializable;
import java.util.Vector;
import java.util.Map;
import java.util.TreeMap;
import java.util.Enumeration;

import java.lang.management.ThreadInfo;
import java.lang.management.ManagementFactory;

// jmx imports
//
import javax.management.MBeanServer;
import javax.management.ObjectName;
import com.sun.jmx.snmp.SnmpCounter;
import com.sun.jmx.snmp.SnmpCounter64;
import com.sun.jmx.snmp.SnmpGauge;
import com.sun.jmx.snmp.SnmpInt;
import com.sun.jmx.snmp.SnmpUnsignedInt;
import com.sun.jmx.snmp.SnmpIpAddress;
import com.sun.jmx.snmp.SnmpTimeticks;
import com.sun.jmx.snmp.SnmpOpaque;
import com.sun.jmx.snmp.SnmpString;
import com.sun.jmx.snmp.SnmpStringFixed;
import com.sun.jmx.snmp.SnmpOid;
import com.sun.jmx.snmp.SnmpNull;
import com.sun.jmx.snmp.SnmpValue;
import com.sun.jmx.snmp.SnmpVarBind;
import com.sun.jmx.snmp.SnmpStatusException;

// jdmk imports
//
import com.sun.jmx.snmp.agent.SnmpIndex;
import com.sun.jmx.snmp.agent.SnmpMib;
import com.sun.jmx.snmp.agent.SnmpMibTable;
import com.sun.jmx.snmp.agent.SnmpMibSubRequest;
import com.sun.jmx.snmp.agent.SnmpStandardObjectServer;

import sun.management.snmp.jvmmib.JvmThreadInstanceEntryMBean;
import sun.management.snmp.jvmmib.JvmThreadInstanceTableMeta;
import sun.management.snmp.util.SnmpTableCache;
import sun.management.snmp.util.SnmpCachedData;
import sun.management.snmp.util.SnmpTableHandler;
import sun.management.snmp.util.MibLogger;
import sun.management.snmp.util.JvmContextFactory;

/**
 * The class is used for implementing the "JvmThreadInstanceTable" group.
 */
public class JvmThreadInstanceTableMetaImpl
    extends JvmThreadInstanceTableMeta {

    static final long serialVersionUID = -8432271929226397492L;

    /**
     * Maximum depth of the stacktrace that might be returned through
     * SNMP.
     *
     * Since we do not export the stack trace through SNMP, we set
     * MAX_STACK_TRACE_DEPTH=0 so that ThreadMXBean.getThreadInfo(long) does
     * not compute the stack trace.
     *
     **/
    public static final int MAX_STACK_TRACE_DEPTH=0;

    /**
     * Translate from a long to a Oid. Arc follow the long big-endian order.
     * @param l The long to make the index from
     * @return The arc array.
     */
    static SnmpOid makeOid(long l) {
        long[] x =  new long [8];
        x[0] = (l >> 56) & 0xFF;
        x[1] =  (l >> 48) & 0x00FF;
        x[2] =  (l >> 40) & 0x0000FF;
        x[3] =  (l >> 32) & 0x000000FF;
        x[4] =  (l >> 24) & 0x00000000FF;
        x[5] =  (l >> 16) & 0x0000000000FF;
        x[6] =  (l >> 8)  & 0x000000000000FF;
        x[7] =  l         & 0x00000000000000FF;
        return new SnmpOid(x);
    }

    /**
     * Translate an Oid to a thread id. Arc follow the long big-endian order.
     * @param oid The oid to make the id from
     * @return The thread id.
     */
    static long makeId(SnmpOid oid) {
        long id = 0;
        long[] arcs = oid.longValue(false);

        id |= arcs[0] << 56;
        id |= arcs[1] << 48;
        id |= arcs[2] << 40;
        id |= arcs[3] << 32;
        id |= arcs[4] << 24;
        id |= arcs[5] << 16;
        id |= arcs[6] << 8;
        id |= arcs[7];

        return id;
    }

    /**
     * A concrete implementation of {@link SnmpTableCache}, for the
     * JvmThreadInstanceTable.
     **/
    private static class JvmThreadInstanceTableCache
        extends SnmpTableCache {

        static final long serialVersionUID = 4947330124563406878L;
        final private JvmThreadInstanceTableMetaImpl meta;

        /**
         * Create a weak cache for the JvmThreadInstanceTable.
         * @param validity validity of the cached data, in ms.
         **/
        JvmThreadInstanceTableCache(JvmThreadInstanceTableMetaImpl meta,
                                   long validity) {
            this.validity = validity;
            this.meta     = meta;
        }

        /**
         * Call <code>getTableDatas(JvmContextFactory.getUserData())</code>.
         **/
        public SnmpTableHandler getTableHandler() {
            final Map<Object, Object> userData = JvmContextFactory.getUserData();
            return getTableDatas(userData);
        }

        /**
         * Return a table handler containing the Thread indexes.
         * Indexes are computed from the ThreadId.
         **/
        protected SnmpCachedData updateCachedDatas(Object userData) {

            // We are getting all the thread ids. WARNING.
            // Some of them will be not valid when accessed for data...
            // See getEntry
            long[] id = JvmThreadingImpl.getThreadMXBean().getAllThreadIds();


            // Time stamp for the cache
            final long time = System.currentTimeMillis();

            SnmpOid indexes[] = new SnmpOid[id.length];
            final TreeMap<SnmpOid, Object> table =
                    new TreeMap<>(SnmpCachedData.oidComparator);
            for(int i = 0; i < id.length; i++) {
                log.debug("", "Making index for thread id [" + id[i] +"]");
                //indexes[i] = makeOid(id[i]);
                SnmpOid oid = makeOid(id[i]);
                table.put(oid, oid);
            }

            return new SnmpCachedData(time, table);
        }

    }


    // The weak cache for this table.
    protected SnmpTableCache cache;

    /**
     * Constructor for the table. Initialize metadata for
     * "JvmThreadInstanceTableMeta".
     * The reference on the MBean server is updated so the entries created
     * through an SNMP SET will be AUTOMATICALLY REGISTERED in Java DMK.
     */
    public JvmThreadInstanceTableMetaImpl(SnmpMib myMib,
                                          SnmpStandardObjectServer objserv) {
        super(myMib, objserv);
        cache = new JvmThreadInstanceTableCache(this,
                            ((JVM_MANAGEMENT_MIB_IMPL)myMib).validity());
        log.debug("JvmThreadInstanceTableMetaImpl", "Create Thread meta");
    }

    // See com.sun.jmx.snmp.agent.SnmpMibTable
    protected SnmpOid getNextOid(Object userData)
        throws SnmpStatusException {
        log.debug("JvmThreadInstanceTableMetaImpl", "getNextOid");
        // null means get the first OID.
        return getNextOid(null,userData);
    }

    // See com.sun.jmx.snmp.agent.SnmpMibTable
    protected SnmpOid getNextOid(SnmpOid oid, Object userData)
        throws SnmpStatusException {
        log.debug("getNextOid", "previous=" + oid);


        // Get the data handler.
        //
        SnmpTableHandler handler = getHandler(userData);
        if (handler == null) {
            // This should never happen.
            // If we get here it's a bug.
            //
            log.debug("getNextOid", "handler is null!");
            throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
        }

        // Get the next oid
        //
        SnmpOid next = oid;
        while(true) {
            next = handler.getNext(next);
            if (next == null) break;
            if (getJvmThreadInstance(userData,next) != null) break;
        }

        log.debug("*** **** **** **** getNextOid", "next=" + next);

        // if next is null: we reached the end of the table.
        //
        if (next == null)
            throw new SnmpStatusException(SnmpStatusException.noSuchInstance);

        return next;
    }

    // See com.sun.jmx.snmp.agent.SnmpMibTable
    protected boolean contains(SnmpOid oid, Object userData) {

        // Get the handler.
        //
        SnmpTableHandler handler = getHandler(userData);

        // handler should never be null.
        //
        if (handler == null)
            return false;
        if(!handler.contains(oid))
            return false;

        JvmThreadInstanceEntryImpl inst = getJvmThreadInstance(userData, oid);
        return (inst != null);
    }


    // See com.sun.jmx.snmp.agent.SnmpMibTable
    public Object getEntry(SnmpOid oid)
        throws SnmpStatusException {
        log.debug("*** **** **** **** getEntry", "oid [" + oid + "]");
        if (oid == null || oid.getLength() != 8) {
            log.debug("getEntry", "Invalid oid [" + oid + "]");
            throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
        }

        // Get the request contextual cache (userData).
        //
        final Map<Object,Object> m = JvmContextFactory.getUserData();

        // Get the handler.
        //
        SnmpTableHandler handler = getHandler(m);

        // handler should never be null.
        //
        if (handler == null || !handler.contains(oid))
            throw new SnmpStatusException(SnmpStatusException.noSuchInstance);

        final JvmThreadInstanceEntryImpl entry = getJvmThreadInstance(m,oid);

        if (entry == null)
            throw new SnmpStatusException(SnmpStatusException.noSuchInstance);

        return entry;
    }

    /**
     * Get the SnmpTableHandler that holds the jvmThreadInstanceTable data.
     * First look it up in the request contextual cache, and if it is
     * not found, obtain it from the weak cache.
     * <br>The request contextual cache will be released at the end of the
     * current requests, and is used only to process this request.
     * <br>The weak cache is shared by all requests, and is only
     * recomputed when it is found to be obsolete.
     * <br>Note that the data put in the request contextual cache is
     *     never considered to be obsolete, in order to preserve data
     *     coherency.
     **/
    protected SnmpTableHandler getHandler(Object userData) {
        final Map<Object, Object> m;
        if (userData instanceof Map) m=Util.cast(userData);
        else m=null;

        // Look in the contextual cache.
        if (m != null) {
            final SnmpTableHandler handler =
                (SnmpTableHandler)m.get("JvmThreadInstanceTable.handler");
            if (handler != null) return handler;
        }

        // No handler in contextual cache, make a new one.
        final SnmpTableHandler handler = cache.getTableHandler();

        if (m != null && handler != null )
            m.put("JvmThreadInstanceTable.handler",handler);

        return handler;
    }

    private ThreadInfo getThreadInfo(long id) {
        return JvmThreadingImpl.getThreadMXBean().
                  getThreadInfo(id,MAX_STACK_TRACE_DEPTH);
    }

    private ThreadInfo getThreadInfo(SnmpOid oid) {
        return getThreadInfo(makeId(oid));
    }

    private JvmThreadInstanceEntryImpl getJvmThreadInstance(Object userData,
                                                            SnmpOid oid) {
        JvmThreadInstanceEntryImpl cached = null;
        String entryTag = null;
        Map<Object, Object> map = null;
        final boolean dbg = log.isDebugOn();

        if (userData instanceof Map) {
            map = Util.cast(userData);

            // We're going to use this name to store/retrieve the entry in
            // the request contextual cache.
            //
            // Revisit: Probably better programming to put all these strings
            //          in some interface.
            //
            entryTag = "JvmThreadInstanceTable.entry." + oid.toString();

            cached = (JvmThreadInstanceEntryImpl) map.get(entryTag);
        }

        // If the entry is in the cache, simply return it.
        //
        if (cached != null) {
            if (dbg) log.debug("*** getJvmThreadInstance",
                               "Entry found in cache: " + entryTag);
            return cached;
        }

        if (dbg) log.debug("*** getJvmThreadInstance", "Entry [" +
                           oid + "] is not in cache");

        // Entry not in cache. We will create one if needed.
        //
        ThreadInfo info = null;
        try {
            info = getThreadInfo(oid);
        } catch (RuntimeException r) {
            log.trace("*** getJvmThreadInstance",
                      "Failed to get thread info for rowOid: " + oid);
            log.debug("*** getJvmThreadInstance",r);
        }

        // No thread by that id => no entry.
        //
        if(info == null) {
            if (dbg) log.debug("*** getJvmThreadInstance",
                               "No entry by that oid [" + oid + "]");
            return null;
        }

        cached = new JvmThreadInstanceEntryImpl(info, oid.toByte());
        if (map != null) map.put(entryTag, cached);
        if (dbg) log.debug("*** getJvmThreadInstance",
                           "Entry created for Thread OID [" + oid + "]");
        return cached;
    }

     static final MibLogger log =
        new MibLogger(JvmThreadInstanceTableMetaImpl.class);
}
