/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1999 by Sun Microsystems, Inc.
 * All rights reserved.
 *
 */

//  ServiceLocationManager.java : The service locator object.
//  Author:           Erik Guttman
//

package com.sun.slp;

import java.util.*;
import java.io.*;
import java.lang.reflect.*;

/**
 * The ServiceLocationManager class provides entry to SLP services.
 * The ServiceLocationManager class uses static methods
 * to provide objects encapsulating the connection with the Service
 * Location facility. In addition, it provides access to known
 * scopes.
 *
 * @author Erik Guttman
 *
 */

abstract public class ServiceLocationManager extends Object {

    // Properties.

    protected static DATable dat = null;
    protected static SLPConfig config = null;

    protected static Hashtable locators = new Hashtable();
    protected static Hashtable advertisers = new Hashtable();
    protected static Class locatorClass = null;
    protected static Class advertiserClass = null;

    // Public interface

    /**
     * The property accessor for the Locator object. If user agent
     * functionality is not available, returns null.
     *
     * @param locale The Locale of the Locator object. Use null for default.
     * @return The Locator object.
     * @exception ServiceLocationException Thrown if the locator can't
     *                                    be created.
     *
     */

    public static Locator getLocator(Locale locale)
        throws ServiceLocationException
    {

        if (locale == null) {
            locale = config.getLocale();

        }

        String lang = locale.getLanguage();
        Locator locator = (Locator)locators.get(lang);

        if (locator == null) {

            if (locatorClass == null) {
                String className =
                    System.getProperty("sun.net.slp.LocatorImpl");
                if (className == null) {
                    className = "com.sun.slp.UARequester";
                }
                locatorClass = getClass(className);
            }

            locator = (Locator)getInstance(locatorClass, locale);

            if (locator != null) {
                locators.put(lang, locator);

            }
        }

        return locator;
    }

    /**
     * The property accessor for the Advertiser object. If service agent
     * functionality is not available, returns null.
     *
     * @param locale The Locale of the Advertiser object. Use null for default.
     * @return The Advertiser object.
     * @exception ServiceLocationException Thrown if the locator can't
     *                                    be created.
     *
     */

    public static Advertiser getAdvertiser(Locale locale)
        throws ServiceLocationException {

        if (locale == null) {
            locale = config.getLocale();

        }

        String lang = locale.getLanguage();
        Advertiser advertiser = (Advertiser)advertisers.get(lang);

        if (advertiser == null) {

            if (advertiserClass == null) {
                String className =
                    System.getProperty("sun.net.slp.AdvertiserImpl");
                if (className == null) {
                    className = "com.sun.slp.SARequester";
                }
                advertiserClass = getClass(className);
            }

            advertiser = (Advertiser)getInstance(advertiserClass, locale);

            if (advertiser != null) {
                advertisers.put(lang, advertiser);

            }
        }

        return advertiser;
    }

    /**
     * Returns a vector of known scope names.  It will include any
     * scopes defined in the configuration file and ensure that the
     * <i>order</i> of those scope strings is kept in the list of
     * scopes which is returned. This method enforces the constraint
     * that the default scope is returned if no other is available.
     *
     * @param typeHint Type to look for if SA advertisment required.
     * @return Vector containing Strings with scope names.
     */

    public static synchronized Vector findScopes()
        throws ServiceLocationException {

        Vector accessableScopes = null;

        // For the UA, return configured scopes if we have them.

        accessableScopes = config.getConfiguredScopes();

        // If no configured scopes, get discovered scopes from
        //  DA table.

        if (accessableScopes.size() <= 0) {
            accessableScopes = dat.findScopes();

            // If still none, perform SA discovery.

            if (accessableScopes.size() <= 0) {
                accessableScopes = performSADiscovery();

                // If still none, then return default scope. The client won`t
                //  be able to contact anyone because there`s nobody out there.

                if (accessableScopes.size() <= 0) {
                    accessableScopes.addElement(Defaults.DEFAULT_SCOPE);

                }
            }
        }

        return accessableScopes;
    }

    /**
     * Returns the maximum across all DAs of the min-refresh-interval
     * attribute.  This value satisfies the advertised refresh interval
     * bounds for all DAs, and, if used by the SA, assures that no
     * refresh registration will be rejected.  If no DA advertises a
     * min-refresh-interval attribute, a value of 0 is returned.
     *
     * @return The maximum min-refresh-interval attribute value.
     */

    public static int getRefreshInterval() throws ServiceLocationException {

        // Get the min-refresh-interval attribute values for all DA's from
        //  the server.

        Vector tags = new Vector();
        tags.addElement(Defaults.MIN_REFRESH_INTERVAL_ATTR_ID);

        // We don't simply do Locator.findAttributes() here because we
        //  need to contact the SA server directly.

        Vector saOnlyScopes = config.getSAOnlyScopes();

        CAttrMsg msg = new CAttrMsg(Defaults.locale,
                                    Defaults.SUN_DA_SERVICE_TYPE,
                                    saOnlyScopes,
                                    tags);

        // Send it down the pipe to the IPC process. It's a bad bug
        //  if the reply comes back as not a CAttrMsg.

        CAttrMsg rply =
            (CAttrMsg)Transact.transactTCPMsg(config.getLoopback(), msg, true);

        // Check error code.

        if (rply == null ||
            rply.getErrorCode() != ServiceLocationException.OK) {
            short errCode =
                (rply == null ?
                 ServiceLocationException.INTERNAL_SYSTEM_ERROR :
                 rply.getErrorCode());
            throw
                new ServiceLocationException(errCode,
                                             "loopback_error",
                                             new Object[] {
                    Short.valueOf(errCode)});

        }

        // Sort through the attribute values to determine reply.

        int ri = 0;
        Vector attrs = rply.attrList;
        ServiceLocationAttribute attr =
            (attrs.size() > 0 ?
            (ServiceLocationAttribute)attrs.elementAt(0):
            null);
        Vector values = (attr != null ? attr.getValues():new Vector());
        int i, n = values.size();

        for (i = 0; i < n; i++) {
            Integer mri = (Integer)values.elementAt(i);
            int mriv = mri.intValue();

            if (mriv > ri) {
                ri = mriv;

            }
        }

        return ri;
    }

    //
    // Private implementation.
    //

    // Return the requested class, or null if it can't be found.

    private static Class getClass(String name) {

        Class ret = null;

        try {

            ret = Class.forName(name);

        } catch (ClassNotFoundException ex) {

        }

        return ret;

    }

    // Return an instance from the class.

    private static Object getInstance(Class cobj, Locale locale) {

        Object ret = null;

        if (cobj != null) {

            try {
                Class[] paramClasses = {locale.getClass()};

                Constructor con = cobj.getDeclaredConstructor(paramClasses);

                Object[] params = {locale};

                ret = con.newInstance(params);

            } catch (InstantiationException ex) {

            } catch (IllegalAccessException ex) {

            } catch (InvocationTargetException ex) {

            } catch (NoSuchMethodException ex) {

            }
        }

        return ret;
    }

    // Perform SA discovery, since no DA scopes found.

    private static Vector performSADiscovery()
        throws ServiceLocationException {

        // Get type hint if any.

        Vector hint = config.getTypeHint();

        // Format query.

        StringBuffer buf = new StringBuffer();
        int i, n = hint.size();

        for (i = 0; i < n; i++) {
            buf.append("(");
            buf.append(Defaults.SERVICE_TYPE_ATTR_ID);
            buf.append("=");
            buf.append(hint.elementAt(i).toString());

        }

        // Add logical disjunction if more than one element.

        if (i > 1) {
            buf.insert(0, "(|");
            buf.append(")");
        }

        // Form SA discovery request.

        CSrvMsg rqst = new CSrvMsg(config.getLocale(),
                                   Defaults.SA_SERVICE_TYPE,
                                   new Vector(),    // seeking scopes...
                                   buf.toString());

        // Transact the advert request.

        Vector scopes =
            Transact.transactActiveAdvertRequest(Defaults.SA_SERVICE_TYPE,
                                                 rqst,
                                                 null);
                                                // DA table not needed...

        return scopes;

    }

    // Initialize SLPConfig and DATable.

    static {

        if (config == null) {
            config = SLPConfig.getSLPConfig();

        }

        if (dat == null) {
            dat = DATable.getDATable();

        }
    }
}