/*
 * @(#)EnvHelp.java	1.33 04/02/13
 * 
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.jmx.remote.util;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.util.Collection;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;

import javax.management.ObjectName;
import javax.management.MBeanServer;
import javax.management.InstanceNotFoundException;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXConnectorServerFactory;

public class EnvHelp {

    /**
     * <p>Name of the attribute that specifies a default class loader 
     * object.
     * The value associated with this attribute is a ClassLoader object</p>
     */
    private static final String DEFAULT_CLASS_LOADER =
        JMXConnectorFactory.DEFAULT_CLASS_LOADER;

    /**
     * <p>Name of the attribute that specifies a default class loader 
     *    ObjectName.
     * The value associated with this attribute is an ObjectName object</p>
     */
    private static final String DEFAULT_CLASS_LOADER_NAME =
        JMXConnectorServerFactory.DEFAULT_CLASS_LOADER_NAME;

    /**
     * Get the Connector Server default class loader.
     * <p>
     * Returns:
     * <p>
     * <ul>
     * <li>
     *     The ClassLoader object found in <var>env</var> for
     *     <tt>jmx.remote.default.class.loader</tt>, if any.
     * </li>
     * <li>
     *     The ClassLoader pointed to by the ObjectName found in
     *     <var>env</var> for <tt>jmx.remote.default.class.loader.name</tt>,
     *     and registered in <var>mbs</var> if any.
     * </li>
     * <li>
     *     The current thread's context classloader otherwise.
     * </li>
     * </ul>
     *
     * @param env Environment attributes.
     * @param mbs The MBeanServer for which the connector server provides
     * remote access.
     *
     * @return the connector server's default class loader.
     *
     * @exception IllegalArgumentException if one of the following is true:
     * <ul>
     * <li>both
     *     <tt>jmx.remote.default.class.loader</tt> and
     *     <tt>jmx.remote.default.class.loader.name</tt> are specified,
     * </li>
     * <li>or
     *     <tt>jmx.remote.default.class.loader</tt> is not
     *     an instance of {@link ClassLoader},
     * </li>
     * <li>or
     *     <tt>jmx.remote.default.class.loader.name</tt> is not
     *     an instance of {@link ObjectName},
     * </li>
     * <li>or
     *     <tt>jmx.remote.default.class.loader.name</tt> is specified
     *     but <var>mbs</var> is null.
     * </li>
     * @exception InstanceNotFoundException if
     * <tt>jmx.remote.default.class.loader.name</tt> is specified
     * and the ClassLoader MBean is not found in <var>mbs</var>.
     */
    public static ClassLoader resolveServerClassLoader(Map env,
                                                       MBeanServer mbs)
        throws InstanceNotFoundException {

        if (env == null)
            return Thread.currentThread().getContextClassLoader();

        Object loader = env.get(DEFAULT_CLASS_LOADER);
        Object name   = env.get(DEFAULT_CLASS_LOADER_NAME);

        if (loader != null && name != null) {
            final String msg = "Only one of " +
                DEFAULT_CLASS_LOADER + " or " +
                DEFAULT_CLASS_LOADER_NAME +
                " should be specified.";
            throw new IllegalArgumentException(msg);
        }

        if (loader == null && name == null)
            return Thread.currentThread().getContextClassLoader();

        if (loader != null) {
            if (loader instanceof ClassLoader) {
                return (ClassLoader) loader;
            } else {
                final String msg =
                    "ClassLoader object is not an instance of " +
                    ClassLoader.class.getName() + " : " +
                    loader.getClass().getName();
                throw new IllegalArgumentException(msg);
            }
        }

        ObjectName on;
        if (name instanceof ObjectName) {
            on = (ObjectName) name;
        } else {
            final String msg = 
                "ClassLoader name is not an instance of " +
                ObjectName.class.getName() + " : " +
                name.getClass().getName();
            throw new IllegalArgumentException(msg);
        }

        if (mbs == null)
            throw new IllegalArgumentException("Null MBeanServer object");

        return mbs.getClassLoader(on);
    }

    /**
     * Get the Connector Client default class loader.
     * <p>
     * Returns:
     * <p>
     * <ul>
     * <li>
     *     The ClassLoader object found in <var>env</var> for
     *     <tt>jmx.remote.default.class.loader</tt>, if any.
     * </li>
     * <li>The <tt>Thread.currentThread().getContextClassLoader()</tt>
     *     otherwise.
     * </li>
     * </ul>
     * <p>
     * Usually a Connector Client will call
     * <pre>
     * ClassLoader dcl = EnvHelp.resolveClientClassLoader(env);
     * </pre>
     * in its <tt>connect(Map env)</tt> method.
     *
     * @return The connector client default class loader.
     *
     * @exception IllegalArgumentException if
     * <tt>jmx.remote.default.class.loader</tt> is specified
     * and is not an instance of {@link ClassLoader}.
     */
    public static ClassLoader resolveClientClassLoader(Map env) {

        if (env == null)
            return Thread.currentThread().getContextClassLoader();

        Object loader = env.get(DEFAULT_CLASS_LOADER);

        if (loader == null)
            return Thread.currentThread().getContextClassLoader();

        if (loader instanceof ClassLoader) {
            return (ClassLoader) loader;
        } else {
            final String msg =
                "ClassLoader object is not an instance of " +
                ClassLoader.class.getName() + " : " +
                loader.getClass().getName();
            throw new IllegalArgumentException(msg);
        }
    }

    /**
     * Init the cause field of a Throwable object.  
     * The cause field is set only if <var>t</var> has an 
     * {@link Throwable#initCause(Throwable)} method (JDK Version >= 1.4) 
     * @param t Throwable on which the cause must be set.
     * @param cause The cause to set on <var>t</var>.
     * @return <var>t</var> with or without the cause field set.
     */
    public static Throwable initCause(Throwable t, Throwable cause) {

        /* Make a best effort to set the cause, but if we don't
           succeed, too bad, you don't get that useful debugging
           information.  We jump through hoops here so that we can
           work on platforms prior to J2SE 1.4 where the
           Throwable.initCause method was introduced.  If we change
           the public interface of JMRuntimeException in a future
           version we can add getCause() so we don't need to do this.  */
        try {
            java.lang.reflect.Method initCause =
                t.getClass().getMethod("initCause",
                                       new Class[] {Throwable.class});
            initCause.invoke(t, new Object[] {cause});
        } catch (Exception e) {
	    // OK.
            // too bad, no debugging info
        }
        return t;
    }

    /**
     * Returns the cause field of a Throwable object.  
     * The cause field can be got only if <var>t</var> has an 
     * {@link Throwable#getCause()} method (JDK Version >= 1.4) 
     * @param t Throwable on which the cause must be set.
     * @return the cause if getCause() succeeded and the got value is not
     * null, otherwise return the <var>t</var>.
     */
    public static Throwable getCause(Throwable t) {
        Throwable ret = t;

        try {
            java.lang.reflect.Method getCause =
		t.getClass().getMethod("getCause", (Class[]) null);
            ret = (Throwable)getCause.invoke(t, (Object[]) null);

        } catch (Exception e) {
	    // OK.
            // it must be older than 1.4.
        }
        return (ret != null) ? ret: t;
    }

    /**
     * <p>Name of the attribute that specifies the maximum number of
     * notifications that a client will fetch from its server.. The
     * value associated with this attribute should be an
     * <code>Integer</code> object.  The default value is 1000.</p>
     */
    public static final String MAX_FETCH_NOTIFS =
        "jmx.remote.x.notification.fetch.max";

    /** 
     * Returns the maximum notification number which a client will
     * fetch every time.
     */
    public static int getMaxFetchNotifNumber(Map env) {
	return (int) getIntegerAttribute(env, MAX_FETCH_NOTIFS, 1000, 1,
					 Integer.MAX_VALUE);
    }

    /**
     * <p>Name of the attribute that specifies the timeout for a
     * client to fetch notifications from its server. The value
     * associated with this attribute should be a <code>Long</code>
     * object.  The default value is 60000 milleseconds.</p>
     */
    public static final String FETCH_TIMEOUT =
        "jmx.remote.x.notification.fetch.timeout";

    /** 
     * Returns the timeout for a client to fetch notifications.
     */
    public static long getFetchTimeout(Map env) {
	return getIntegerAttribute(env, FETCH_TIMEOUT, 60000L, 0,
				   Long.MAX_VALUE);
    }

    /**
     * Get an integer-valued attribute with name <code>name</code>
     * from <code>env</code>.  If <code>env</code> is null, or does
     * not contain an entry for <code>name</code>, return
     * <code>defaultValue</code>.  The value may be a Number, or it
     * may be a String that is parsable as a long.  It must be at
     * least <code>minValue</code> and at most<code>maxValue</code>.
     *
     * @throws IllegalArgumentException if <code>env</code> contains
     * an entry for <code>name</code> but it does not meet the
     * constraints above.
     */
    public static long getIntegerAttribute(Map env, String name,
					   long defaultValue, long minValue,
					   long maxValue) {
	final Object o;

	if (env == null || (o = env.get(name)) == null)
	    return defaultValue;

	final long result;

	if (o instanceof Number)
	    result = ((Number) o).longValue();
	else if (o instanceof String) {
	    result = Long.parseLong((String) o);
	    /* May throw a NumberFormatException, which is an
	       IllegalArgumentException.  */
	} else {
	    final String msg =
		"Attribute " + name + " value must be Integer or String: " + o;
	    throw new IllegalArgumentException(msg);
	}

	if (result < minValue) {
	    final String msg =
		"Attribute " + name + " value must be at least " + minValue +
		": " + result;
	    throw new IllegalArgumentException(msg);
	}

	if (result > maxValue) {
	    final String msg =
		"Attribute " + name + " value must be at most " + maxValue +
		": " + result;
	    throw new IllegalArgumentException(msg);
	}

        return result;
    }

    public static final String DEFAULT_ORB="java.naming.corba.orb";

    /* Check that all attributes have a key that is a String.
       Could make further checks, e.g. appropriate types for attributes.  */
    public static void checkAttributes(Map attributes) {
        for (Iterator it = attributes.keySet().iterator(); it.hasNext(); ) {
            Object key = it.next();
            if (!(key instanceof String)) {
                final String msg =
                    "Attributes contain key that is not a string: " + key;
                throw new IllegalArgumentException(msg);
            }
        }
    }

    /* Return a writable map containing only those attributes that are
       serializable, and that are not hidden by
       jmx.remote.x.hidden.attributes or the default list of hidden
       attributes.  */
    public static Map filterAttributes(Map attributes) {
        if (logger.traceOn()) {
            logger.trace("filterAttributes", "starts");
        }

        SortedMap map = new TreeMap(attributes);
	purgeUnserializable(map.values());
	hideAttributes(map);
        return map;
    }

    /**
     * Remove from the given Collection any element that is not a
     * serializable object.
     */
    private static void purgeUnserializable(Collection objects) {
	logger.trace("purgeUnserializable", "starts");
	ObjectOutputStream oos = null;
	int i = 0;
	for (Iterator it = objects.iterator(); it.hasNext(); i++) {
	    Object v = it.next();

	    if (v == null || v instanceof String) {
		if (logger.traceOn()) {
		    logger.trace("purgeUnserializable",
				 "Value trivially serializable: " + v);
		}
		continue;
	    }

	    try {
		if (oos == null)
		    oos = new ObjectOutputStream(new SinkOutputStream());
		oos.writeObject(v);
		if (logger.traceOn()) {
		    logger.trace("purgeUnserializable",
				 "Value serializable: " + v);
		}
	    } catch (IOException e) {
		if (logger.traceOn()) {
		    logger.trace("purgeUnserializable",
				 "Value not serializable: " + v + ": " +
				 e);
		}
		it.remove();
		oos = null; // ObjectOutputStream invalid after exception
	    }
	}
    }

    /**
       The value of this attribute, if present, is a string specifying
       what other attributes should not appear in
       JMXConnectorServer.getAttributes().  It is a space-separated
       list of attribute patterns, where each pattern is either an
       attribute name, or an attribute prefix followed by a "*"
       character.  The "*" has no special significance anywhere except
       at the end of a pattern.  By default, this list is added to the
       list defined by {@link #DEFAULT_HIDDEN_ATTRIBUTES} (which
       uses the same format).  If the value of this attribute begins
       with an "=", then the remainder of the string defines the
       complete list of attribute patterns.
     */
    public static final String HIDDEN_ATTRIBUTES =
	"jmx.remote.x.hidden.attributes";

    /**
       Default list of attributes not to show.
       @see #HIDDEN_ATTRIBUTES
     */
    /* This list is copied directly from the spec, plus
       java.naming.security.*.  Most of the attributes here would have
       been eliminated from the map anyway because they are typically
       not serializable.  But just in case they are, we list them here
       to conform to the spec.  */
    public static final String DEFAULT_HIDDEN_ATTRIBUTES =
	"java.naming.security.* " +
	"jmx.remote.authenticator " +
	"jmx.remote.context " +
	"jmx.remote.default.class.loader " +
	"jmx.remote.message.connection.server " +
	"jmx.remote.object.wrapping " +
	"jmx.remote.rmi.client.socket.factory " +
	"jmx.remote.rmi.server.socket.factory " +
	"jmx.remote.sasl.callback.handler " +
	"jmx.remote.tls.socket.factory " +
	"jmx.remote.x.access.file " +
	"jmx.remote.x.password.file ";

    private static final SortedSet defaultHiddenStrings = new TreeSet();
    private static final SortedSet defaultHiddenPrefixes = new TreeSet();

    private static void hideAttributes(SortedMap map) {
	if (map.isEmpty())
	    return;

	final SortedSet hiddenStrings;
	final SortedSet hiddenPrefixes;

	String hide = (String) map.get(HIDDEN_ATTRIBUTES);
	if (hide != null) {
	    if (hide.startsWith("="))
		hide = hide.substring(1);
	    else
		hide += " " + DEFAULT_HIDDEN_ATTRIBUTES;
	    hiddenStrings = new TreeSet();
	    hiddenPrefixes = new TreeSet();
	    parseHiddenAttributes(hide, hiddenStrings, hiddenPrefixes);
	} else {
	    hide = DEFAULT_HIDDEN_ATTRIBUTES;
	    synchronized (defaultHiddenStrings) {
		if (defaultHiddenStrings.isEmpty()) {
		    parseHiddenAttributes(hide,
					  defaultHiddenStrings,
					  defaultHiddenPrefixes);
		}
		hiddenStrings = defaultHiddenStrings;
		hiddenPrefixes = defaultHiddenPrefixes;
	    }
	}

	/* Construct a string that is greater than any key in the map.
	   Setting a string-to-match or a prefix-to-match to this string
	   guarantees that we will never call next() on the corresponding
	   iterator.  */
	String sentinelKey = map.lastKey() + "X";
	Iterator keyIterator = map.keySet().iterator();
	Iterator stringIterator = hiddenStrings.iterator();
	Iterator prefixIterator = hiddenPrefixes.iterator();

	String nextString;
	if (stringIterator.hasNext())
	    nextString = (String) stringIterator.next();
	else
	    nextString = sentinelKey;
	String nextPrefix;
	if (prefixIterator.hasNext())
	    nextPrefix = (String) prefixIterator.next();
	else
	    nextPrefix = sentinelKey;

	/* Read each key in sorted order and, if it matches a string
	   or prefix, remove it. */
    keys:
	while (keyIterator.hasNext()) {
	    String key = (String) keyIterator.next();

	    /* Continue through string-match values until we find one
	       that is either greater than the current key, or equal
	       to it.  In the latter case, remove the key.  */
	    int cmp = +1;
	    while ((cmp = nextString.compareTo(key)) < 0) {
		if (stringIterator.hasNext())
		    nextString = (String) stringIterator.next();
		else
		    nextString = sentinelKey;
	    }
	    if (cmp == 0) {
		keyIterator.remove();
		continue keys;
	    }

	    /* Continue through the prefix values until we find one
	       that is either greater than the current key, or a
	       prefix of it.  In the latter case, remove the key.  */
	    while (nextPrefix.compareTo(key) <= 0) {
		if (key.startsWith(nextPrefix)) {
		    keyIterator.remove();
		    continue keys;
		}
		if (prefixIterator.hasNext())
		    nextPrefix = (String) prefixIterator.next();
		else
		    nextPrefix = sentinelKey;
	    }
	}
    }

    private static void parseHiddenAttributes(String hide,
					      SortedSet hiddenStrings,
					      SortedSet hiddenPrefixes) {
	final StringTokenizer tok = new StringTokenizer(hide);
	while (tok.hasMoreTokens()) {
	    String s = tok.nextToken();
	    if (s.endsWith("*"))
		hiddenPrefixes.add(s.substring(0, s.length() - 1));
	    else
		hiddenStrings.add(s);
	}
    }

    /**
     * <p>Name of the attribute that specifies the timeout to keep a
     * server side connection after answering last client request.
     * The default value is 120000 milliseconds.</p>
     */
    public static final String SERVER_CONNECTION_TIMEOUT =
	"jmx.remote.x.server.connection.timeout";

    /** 
     * Returns the server side connection timeout.
     */
    public static long getServerConnectionTimeout(Map env) {
	return getIntegerAttribute(env, SERVER_CONNECTION_TIMEOUT, 120000L,
				   0, Long.MAX_VALUE);
    }

    /**
     * <p>Name of the attribute that specifies the period in
     * millisecond for a client to check its connection.  The default
     * value is 60000 milliseconds.</p>
     */
    public static final String CLIENT_CONNECTION_CHECK_PERIOD =
	"jmx.remote.x.client.connection.check.period";

    /** 
     * Returns the client connection check oeriod.
     */
    public static long getConnectionCheckPeriod(Map env) {
	return getIntegerAttribute(env, CLIENT_CONNECTION_CHECK_PERIOD, 60000L,
				   0, Long.MAX_VALUE);
    }

    /**
     * Converts a map into a valid hash table, i.e.
     * it removes all the 'null' values from the map.
     */
    public static Hashtable mapToHashtable(Map map) {
        HashMap m = new HashMap(map);
        if (m.containsKey(null)) m.remove(null);
        for (Iterator i = m.values().iterator(); i.hasNext(); )
            if (i.next() == null) i.remove();
        return new Hashtable(m);
    }

    private static final class SinkOutputStream extends OutputStream {
	public void write(byte[] b, int off, int len) {}
	public void write(int b) {}
    }

    private static final ClassLogger logger =
	new ClassLogger("javax.management.remote.misc", "EnvHelp");
}