/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Velocity", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.velocity.tools.view.servlet;

import javax.servlet.ServletConfig;

import java.io.InputStream;

import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.resource.Resource;
import org.apache.velocity.runtime.resource.loader.ResourceLoader;

import org.apache.velocity.exception.ResourceNotFoundException;

import org.apache.commons.collections.ExtendedProperties;

import org.apache.velocity.tools.view.servlet.WebappLoaderAppContext;

/**
 * <p>
 * Blatantly copied from velocity-tools' WebappLoader. The reason for using
 * a modified version is to provide a means for the loader to get pages from
 * a default location without having to put this location prefix everywhere
 * they're specified in struts-config.xml, etc.
 * </p>
 *
 * @author Donnie Hale
 *
 * @version $Id:  $
 */
public class ConfigurableWebappLoader extends ResourceLoader
{
    /**
     *  This is abstract in the base class, so we need it
     */
    public void init(ExtendedProperties configuration)
    {
        rsvc.info("WebappLoader : initialization starting.");

        Object o = rsvc.getApplicationAttribute(
            ConfigurableViewServlet.class.getName());

        if (o instanceof ConfigurableViewServlet.AppLoaderConfig)
        {
            servletConfig =
                ((ConfigurableViewServlet.AppLoaderConfig) o).getServletConfig();

            pagePrefix = servletConfig.getInitParameter(LOADER_PAGE_PREFIX_PARAM);
            if (pagePrefix == null)
            {
                pagePrefix = "";
            }

            rsvc.info(
                "WebappLoader : initialization complete. Page prefix: " + pagePrefix);
        }
        else
        {
            rsvc.error("WebappLoader : unable to retrieve ServletContext");
        }
    }

    /**
     * Get an InputStream so that the Runtime can build a
     * template with it.
     *
     * @param name name of template to get
     * @return InputStream containing the template
     * @throws ResourceNotFoundException if template not found
     *         in  classpath.
     */
    public synchronized InputStream getResourceStream(String name)
        throws ResourceNotFoundException
    {
        InputStream result = null;

        if (name == null || name.length() == 0)
        {
            throw new ResourceNotFoundException ("No template name provided");
        }

        try
        {
            if (!name.startsWith("/"))
            {
                name = "/" + name;
            }
            name = pagePrefix + name;

            result = servletConfig.getServletContext().getResourceAsStream(name);
        }
        catch (Exception fnfe)
        {
            /*
             *  log and convert to a general Velocity ResourceNotFoundException
             */
            servletConfig.getServletContext().log(
                "Unable to retrieve resource stream for " + name, fnfe);
            throw new ResourceNotFoundException(fnfe.getMessage());
        }

        return result;
    }

    /**
     * Defaults to return false.
     */
    public boolean isSourceModified(Resource resource)
    {
        return false;
    }

    /**
     * Defaults to return 0
     */
    public long getLastModified(Resource resource)
    {
        return 0;
    }

    private ServletConfig servletConfig;
    private String pagePrefix;

    public static final String LOADER_PAGE_PREFIX_PARAM = "loader.page.prefix";
}