/*
 * Copyright 2000-2001,2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jetspeed.services.urlmanager;

// Java classes
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Vector;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;

// Turbine classes
import org.apache.turbine.services.TurbineBaseService;

// Velocity classes
import org.apache.velocity.runtime.configuration.Configuration;

// Jetspeed classes
import org.apache.jetspeed.services.logging.JetspeedLogFactoryService;
import org.apache.jetspeed.services.logging.JetspeedLogger;
import org.apache.jetspeed.services.resources.JetspeedResources;

/**
 * <p>This implementation of the URLManagerService is backed by a simple
 * map persisted on disk in a properties file</p>
 * Added: Support for proxies. <br>
 * Example: (Set in <code>JetspeedResources.properties</code>)<br>
 * <code>services.URLManager.proxy.http.host=myproxy.mydomain</code><br>
 * <code>services.URLManager.proxy.http.port=81</code><br>
 *
 * @see URLManagerService
 * @author <a href="mailto:raphael@apache.org">Raphaël Luta</a>
 * @author <a href="mailto:sgala@hisitech.com">Santiago Gala</a>
 * @version $Id: JetspeedURLManagerService.java,v 1.16 2004/02/23 03:30:47 jford Exp $
 */
public class JetspeedURLManagerService extends TurbineBaseService implements URLManagerService 
{
    /**
     * Static initialization of the logger for this class
     */    
    private static final JetspeedLogger logger = JetspeedLogFactoryService.getLogger(JetspeedURLManagerService.class.getName());
    
    /**
    Map used to store all URL Information.
    */
    private Map urls = new HashMap();

    /**
    Path to the properties file used for persisting the data
    */
    private String path = null;

    /**
    Hashtable to store proxy configuration in
    */
    private Hashtable proxies = new Hashtable();

    /**
     * Late init. Don't return control until early init says we're done.
     */
    public void init( )
    {
        while( !getInit() ) {
            try {
                Thread.sleep(500);
            } catch (InterruptedException ie ) {
                logger.info("URLManager service: Waiting for init()..." );
            }
        }

    }



    /**
     * Called during Turbine.init()
     *
     * @param config A ServletConfig.
     */
    public synchronized void init( ServletConfig config )
    {
        //We have already been initialized...
        if( getInit() ) return;

        try
        {
            logger.info ( "JetspeedURLManagerService early init()....starting!");

        // Proxy Settings are stored as 'services.URLManager.proxy.<protocol>.port' and as
        // 'services.URLManager.proxy.<protocol>.port' in JetspeedResource.properties.
        // Get a list of settings and store them in the hashtable
            String prefix = "services." + URLManagerService.SERVICE_NAME + ".proxy.";
            Iterator resourceKeys = JetspeedResources.getKeys( prefix );

            String key, hashKey;
            Object hashValue = null;
            while( resourceKeys.hasNext() )
            {
                key = (String)resourceKeys.next();
                hashKey = key.substring(prefix.length()).toLowerCase();
                if ( hashKey.endsWith(".host") )
                {
                    hashValue = JetspeedResources.getString(key);
                    proxies.put( hashKey, hashValue );
                }
                else if ( hashKey.endsWith(".port") )
                {
                    hashValue = new Integer(JetspeedResources.getInt(key));
                    proxies.put( hashKey, hashValue );
                }
            }

            path = JetspeedResources.getString( "services."+URLManagerService.SERVICE_NAME+".url" );

            if ( path == null) 
            {
                String tempdir = new String("WEB-INF/conf/datasources.properties");
                String ps = System.getProperty("file.separator");

                try
                {
                    ServletContext sc = config.getServletContext();
                    tempdir = sc.getAttribute("javax.servlet.context.tempdir").toString()
                                           + ps + "jetspeed" 
                                           + ps + "conf"
                                           + ps + "datasources.properties";
                    logger.debug("URLMangler: will create file in servlet temp directory " + tempdir);
                }
                catch (Exception e)
                {
                    logger.debug("URLMangler: problems creating file in servlet temp directory "
                           + " falling back to WEB-INF/conf : " + e);
                }     
                path = tempdir;
            }
            else
            {
                logger.debug("URLMangler: will create file in user configured " + path);
                path = config.getServletContext().getRealPath(path);
                // should test for writability here and fallback to servlet tmp directory on failure
            }

            load();
            logger.info ( "JetspeedURLManagerService early init()....finished!");
        }
        catch (Throwable t)
        {
            logger.error ( "Cannot initialize JetspeedURLManagerService!", t );
        }
        setInit(true);

    }

    /**
     * Called during Turbine destroy(). Persist the Manager state
     * to disk
     */
    public void shutdown() {
        save();
    }

    /**
     * Registers a new URL record. If the url is already registered in 
     * the system, doesn't modify the current record.
     * 
     * @param url the url to register
     */
    public void register( String url ) {
        if ( url != null ) {
            URLInfo info = getInfo( url );
            if ( info == null ) {
                register( new URLInfo( url, URLManagerService.STATUS_OK ) );
            }
        }
    }

    /**
     * Registers a new URL record. If the url is already registered in 
     * the system, updates the status of this URL info record
     * 
     * @param url the url to register
     * @param status the status of this url
     */
    public void register( String url, int status ) {
        if ( url != null ) {
            URLInfo info = getInfo( url );
            if ( info == null ) {
                register( new URLInfo( url, status ) );
            } else {
                info.setStatus( status );
            }
        }
    }

    /**
     * Registers a new URL record. If the url is already registered in 
     * the system, updates both the status and the message of this URL 
     * info record
     * 
     * @param url the url to register
     * @param status the status of this url
     * @param message a descriptive message of the status
     */
    public void register( String url, int status, String message ) {
        if ( url != null ) {
            URLInfo info = getInfo( url );
            if ( info == null ) {
                register( new URLInfo( url, status, message ) );
            } else {
                info.setStatus( status );
                info.setMessage( message );
            }
        }
    }

    /**
     * Register or replace an URL record. All records are keyed to
     * the imutable URL of URLInfo.
     * 
     * @param info the info record to store
     */
    public void register( URLInfo info ) {
        if ( info != null) {
            synchronized (urls) {
                if( getInfo( info.getURL() ) == null ) 
                    urls.put( info.getURL().intern(), info );
            }
        }
    }

    /**
     * Unregister an URL from the repository
     * 
     * @param url the url to remove
     */
    public void unregister( String url ) {
        if ( url != null ) {
            synchronized (urls) {
                urls.remove( url.intern() );
            }
        }
    }

    /**
     * Get the information record stored in the database about
     * an URL.
     * 
     * @param url the url whose record is sought
     * @return the description record found in the repository or null.
     */
    public URLInfo getInfo( String url ) {
        URLInfo info = null;

        if ( url != null ) {
            synchronized(urls) {
                info = (URLInfo)urls.get( url.intern() );
            }
        }

        return info;
    }

    /**
     * Test whether the URL is currently believed to be OK by this 
     * repository.
     * 
     * @param url the url to be tested
     * @return false is the url is known by this repository and has
     * a status indicating an error, true otherwise.
     */
    public boolean isOK( String url ) {
        URLInfo info = getInfo( url );

        // we don't know this URL, play it safe and say it's good
        if ( info == null ) return true;

        return ( info.getStatus() == URLManagerService.STATUS_OK );
    }

    /**
     * List of the current known URLs in the repository
     *
     * @return a List of URL strings known to this repository
     */
    public List list() {
        synchronized (urls) {
            return new Vector( urls.keySet() );
        }
    }

    /**
     * List of the current known URLs in the repository which have 
     * the given status.
     *
     * @param status the status to be retrieved. May be 
     * {@link URLManagerService#STATUS_ANY} to indicate any status
     * @return a List of URL strings known to this repository with this status
     */
    public List list( int status ) {
        Vector result = new Vector();

        synchronized (urls) {
            Iterator i = urls.entrySet().iterator();
            while( i.hasNext() ) {
                Map.Entry entry = (Map.Entry)i.next();
                URLInfo info = (URLInfo)entry.getValue();
                if ( ( info.getStatus() & status ) != 0 ) {
                    result.addElement( entry.getKey() );
                }
            }
        }

        return result;
    }

    /**
     * Load the persisted state of the repository from disk
     */
    private synchronized void load() {

        Map store = new HashMap();
        Configuration config = null;

        logger.info( "Restoring the URLs from disk: " + path );

        try {
            config = new Configuration( path );

            int count = 1;
            String url = null;

            while ( ( url = ( config
                              .getString("entry."+count+".url") ) ) != null ) {
                //Intern the url to ensure we can use "==" to compare
                //and synchronize on it
                url = url.intern();
                int status = config.getInteger("entry."+count+".status", URLManagerService.STATUS_OK );
                if( store.get( url ) == null )
                    store.put( url, new URLInfo( url, status ) );
                count++;
            }

            logger.info( "URLManager loaded " + count + " urls" );                    

        } catch ( Exception e ) {
            logger.error( "Could not restore URLManager state", e );
            return;
        } finally {
            // set the loaded store as the new store
            this.urls = store;
        }

    }

    /**
     * Persist the state of the repository on disk in a properties file
     */
    private synchronized void save() {
        PrintWriter pw = null ;

        try {

            File propfile = new File(path); // FileWriter doesn't always do this
            propfile.getParentFile().mkdirs();
            propfile.createNewFile();

            pw = new PrintWriter( new BufferedWriter( new FileWriter( propfile ) ) );
            synchronized (urls) {
                Iterator i = urls.values().iterator();
                int entryNum = 1;
                while( i.hasNext() ) {
                    URLInfo info = (URLInfo)i.next();
                    pw.print( "entry." );
                    pw.print( entryNum );
                    pw.print( ".url=" );
                    writeEscaped( pw, info.getURL() );
                    pw.println( "" );
                    pw.print( "entry." );
                    pw.print( entryNum );
                    pw.print( ".status=" );
                    pw.print( info.getStatus() );
                    pw.println( "" );
                    entryNum++;
                }
            }
        } 
        catch ( Throwable t ) 
        {
            logger.error( "Impossible to save URLManager state to "+path, t );
        } 
        finally 
        {
            if( pw != null )
            {
                pw.close();
            }
        }
    }

    /**
     * Return the port of a proxy
     * @param protocol The protocol that the proxy supports, e.g. 'http'
     * @return The port number (1-65535), or -1 if no port was specified (= use default)
     */
    public int getProxyPort( String protocol ) {
        Integer proxyPort = (Integer)proxies.get( (protocol + ".port").toLowerCase() );

        if (proxyPort != null)
            return proxyPort.intValue();
        else
            return -1;
    }

    /**
     * Return a proxy's hostname
     * @param protocol The protocol that the proxy supports, e.g. 'http'
     * @return The hostname of the proxy, or <code>null</code> if no proxy is specified for this protocol
     */
    public String getProxyHost( String protocol ) {
        String proxyHost = (String)proxies.get( (protocol + ".host").toLowerCase() );

        return proxyHost;
    }

    /**
     * <p>Escape values when saving.
     * Appends a String to a StringBuffer, escaping commas.</p>
     * <p>We assume that commas are unescaped.</p>
     * @param sink a StringBuffer to write output
     * @param element a value to be written
     */
    protected void writeEscaped( PrintWriter sink, String element ) {
        int upTo = element.indexOf(",");
        if( upTo == -1 ) {
            sink.print( element );
            return;
        }
        sink.print( element.substring( 0, upTo ) );
        sink.print( "\\," );
        writeEscaped( sink, element.substring( upTo+1, element.length() ) );
        return;
    }
}
