/*
 * This library is part of OpenCms -
 * the Open Source Content Management System
 *
 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * For further information about Alkacon Software GmbH & Co. KG, please see the
 * company website: http://www.alkacon.com
 *
 * For further information about OpenCms, please see the
 * project website: http://www.opencms.org
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.opencms.jsp;

import org.opencms.file.CmsObject;
import org.opencms.file.CmsProperty;
import org.opencms.file.CmsPropertyDefinition;
import org.opencms.file.CmsResource;
import org.opencms.file.CmsResourceFilter;
import org.opencms.file.types.CmsResourceTypeFolder;
import org.opencms.file.types.I_CmsResourceType;
import org.opencms.main.CmsException;
import org.opencms.main.CmsLog;
import org.opencms.main.OpenCms;
import org.opencms.util.CmsFileUtil;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import org.apache.commons.logging.Log;

/**
 * Bean to provide a convenient way to build navigation structures based on the
 * <code>{@link org.opencms.jsp.CmsJspNavElement}</code>.<p>
 *
 * Use this together with the <code>{@link org.opencms.jsp.CmsJspActionElement}</code>
 * to obtain navigation information based on the current users permissions.
 * For example, use <code>{@link #getNavigationForFolder(String)}</code> and pass the
 * value of the current OpenCms user context uri obtained
 * from <code>{@link org.opencms.file.CmsRequestContext#getUri()}</code> as argument to obtain a list
 * of all items in the navigation of the current folder. Then use a simple scriptlet to
 * iterate over these items and create a HTML navigation.<p>
 *
 * @since 6.0.0
 *
 * @see org.opencms.jsp.CmsJspNavElement
 */
public class CmsJspNavBuilder {

    /**
     * Navigation builder context.
     *
     * Stored in nav elements so they can ask the navigation builder for sub-navigation entries, with appropriate resource filter etc.
     */
    public static class NavContext {

        /** The resource filter used. */
        private CmsResourceFilter m_filter;

        /** The nav builder used. */
        private CmsJspNavBuilder m_navBuilder;

        /** The visibility option used. */
        private Visibility m_visibility;

        /**
         * Creates a new instance.
         *
         * @param navBuilder the navigation builder
         * @param visibility the visibility
         * @param filter the resource filter
         */
        public NavContext(CmsJspNavBuilder navBuilder, Visibility visibility, CmsResourceFilter filter) {

            super();
            m_visibility = visibility;
            m_filter = filter;
            m_navBuilder = navBuilder;
        }

        /**
         * Gets the resource filter.
         *
         * @return the resource filter
         */
        public CmsResourceFilter getFilter() {

            return m_filter;
        }

        /**
         * Gets the navigation builder.
         *
         * @return the navigation builder
         */
        public CmsJspNavBuilder getNavBuilder() {

            return m_navBuilder;
        }

        /**
         * Gets the visibility setting.
         *
         * @return the visibility setting
         */
        public Visibility getVisibility() {

            return m_visibility;
        }

    }

    /** The visibility mode. */
    public static enum Visibility {
        /** All entries. */
        all,
        /** Navigation including hidden entries. */
        includeHidden,
        /** Navigation only. */
        navigation
    }

    /** Default file property value to mark navigation level folders. */
    public static final String NAVIGATION_LEVEL_FOLDER = "##navigation_level_folder##";

    /** The log object for this class. */
    private static final Log LOG = CmsLog.getLog(CmsJspNavBuilder.class);

    /** The current CMS context. */
    protected CmsObject m_cms;

    /** The locale for which the property should be read. */
    protected Locale m_locale;

    /** The current request URI. */
    protected String m_requestUri;

    /** The current request folder. */
    protected String m_requestUriFolder;

    /**
     * Empty constructor, so that this bean can be initialized from a JSP.<p>
     */
    public CmsJspNavBuilder() {

        // empty
    }

    /**
     * Default constructor.<p>
     *
     * @param cms context provider for the current request
     */
    public CmsJspNavBuilder(CmsObject cms) {

        init(cms, null);
    }

    /**
     * Constructor for a version that reads properties according to a locale.<p>
     *
     * @param cms context provider for the current request
     * @param locale the locale for which properties should be accessed
     */
    public CmsJspNavBuilder(CmsObject cms, Locale locale) {

        init(cms, locale);
    }

    /**
     * Returns the full name (including VFS path) of the default file for this navigation element
     * or <code>null</code> if the navigation element is not a folder.<p>
     *
     * The default file of a folder is determined by the value of the property
     * <code>default-file</code> or the system wide property setting.<p>
     *
     * @param cms the CMS object
     * @param folder full name of the folder
     *
     * @return the name of the default file
     *
     * @deprecated use {@link CmsObject#readDefaultFile(String)} instead
     */
    @Deprecated
    public static String getDefaultFile(CmsObject cms, String folder) {

        if (folder.endsWith("/")) {
            try {
                CmsResource defaultFile = cms.readDefaultFile(folder);
                if (defaultFile != null) {
                    return cms.getSitePath(defaultFile);
                }
            } catch (CmsException e) {
                LOG.debug(e.getLocalizedMessage(), e);
            }
            return folder;
        }
        return null;
    }

    /**
     * Collect all navigation elements from the files in the given folder,
     * navigation elements are of class {@link CmsJspNavElement}.<p>
     *
     * @param cms context provider for the current request
     * @param folder the selected folder
     *
     * @return a sorted (ascending to navigation position) list of navigation elements
     *
     * @deprecated use {@link #getNavigationForFolder(String)} instead
     */
    @Deprecated
    public static List<CmsJspNavElement> getNavigationForFolder(CmsObject cms, String folder) {

        return new CmsJspNavBuilder(cms).getNavigationForFolder(folder);
    }

    /**
     * Build a navigation for the folder that is either minus levels up
     * from the given folder, or that is plus levels down from the
     * root folder towards the given folder.<p>
     *
     * If level is set to zero the root folder is used by convention.<p>
     *
     * @param cms context provider for the current request
     * @param folder the selected folder
     * @param level if negative, walk this many levels up, if positive, walk this many
     *              levels down from root folder
     *
     * @return a sorted (ascending to navigation position) list of navigation elements
     *
     * @deprecated use {@link #getNavigationForFolder(String, int)} instead
     */
    @Deprecated
    public static List<CmsJspNavElement> getNavigationForFolder(CmsObject cms, String folder, int level) {

        return new CmsJspNavBuilder(cms).getNavigationForFolder(folder, level);
    }

    /**
     * Returns a navigation element for the named resource.<p>
     *
     * @param cms context provider for the current request
     * @param resource the resource name to get the navigation information for,
     *              must be a full path name, e.g. "/docs/index.html"
     *
     * @return a navigation element for the given resource
     *
     * @deprecated use {@link #getNavigationForResource(String)} instead
     */
    @Deprecated
    public static CmsJspNavElement getNavigationForResource(CmsObject cms, String resource) {

        return new CmsJspNavBuilder(cms).getNavigationForResource(resource);
    }

    /**
     * Builds a tree navigation for the folders between the provided start and end level.<p>
     *
     * A tree navigation includes all navigation elements that are required to display a tree structure.
     * However, the data structure is a simple list.
     * Each of the navigation elements in the list has the {@link CmsJspNavElement#getNavTreeLevel()} set
     * to the level it belongs to. Use this information to distinguish between the navigation levels.<p>
     *
     * @param cms context provider for the current request
     * @param folder the selected folder
     * @param startlevel the start level
     * @param endlevel the end level
     *
     * @return a sorted list of navigation elements with the navigation tree level property set
     *
     * @deprecated use {@link #getNavigationForResource(String)} instead
     */
    @Deprecated
    public static List<CmsJspNavElement> getNavigationTreeForFolder(
        CmsObject cms,
        String folder,
        int startlevel,
        int endlevel) {

        return new CmsJspNavBuilder(cms).getNavigationTreeForFolder(folder, startlevel, endlevel);
    }

    /**
     * This method builds a complete navigation tree with entries of all branches
     * from the specified folder.<p>
     *
     * For an unlimited depth of the navigation (i.e. no <code>endLevel</code>),
     * set the <code>endLevel</code> to a value &lt; 0.<p>
     *
     *
     * @param cms the current CMS context
     * @param folder the root folder of the navigation tree
     * @param endLevel the end level of the navigation
     *
     * @return list of navigation elements, in depth first order
     *
     * @deprecated use {@link #getNavigationForResource(String)} instead
     */
    @Deprecated
    public static List<CmsJspNavElement> getSiteNavigation(CmsObject cms, String folder, int endLevel) {

        return new CmsJspNavBuilder(cms).getSiteNavigation(folder, endLevel);
    }

    /**
     * Returns whether the given resource is a folder and is marked to be a navigation level folder.<p>
     *
     * @param cms the cms context
     * @param resource the resource
     *
     * @return <code>true</code> if the resource is marked to be a navigation level folder
     */
    public static boolean isNavLevelFolder(CmsObject cms, CmsResource resource) {

        if (resource.isFolder()) {
            I_CmsResourceType type = OpenCms.getResourceManager().getResourceType(resource);
            if (CmsResourceTypeFolder.RESOURCE_TYPE_NAME.equals(type.getTypeName())) {
                try {
                    CmsProperty prop = cms.readPropertyObject(
                        resource,
                        CmsPropertyDefinition.PROPERTY_DEFAULT_FILE,
                        false);
                    return !prop.isNullProperty() && NAVIGATION_LEVEL_FOLDER.equals(prop.getValue());
                } catch (CmsException e) {
                    LOG.debug(e.getMessage(), e);
                }
            }
        }
        return false;
    }

    /**
     * Gets the CMS context used for building the navigation.
     *
     * @return the CMS context
     */
    public CmsObject getCmsObject() {

        return m_cms;
    }

    /**
     * Build a "bread crumb" path navigation to the current folder.<p>
     *
     * @return ArrayList sorted list of navigation elements
     *
     * @see #getNavigationBreadCrumb(String, int, int, boolean)
     */
    public List<CmsJspNavElement> getNavigationBreadCrumb() {

        return getNavigationBreadCrumb(m_requestUriFolder, 0, -1, true);
    }

    /**
     * Build a "bread crumb" path navigation to the current folder.<p>
     *
     * @param startlevel the start level, if negative, go down |n| steps from selected folder
     * @param currentFolder include the selected folder in navigation or not
     *
     * @return sorted list of navigation elements
     *
     * @see #getNavigationBreadCrumb(String, int, int, boolean)
     */
    public List<CmsJspNavElement> getNavigationBreadCrumb(int startlevel, boolean currentFolder) {

        return getNavigationBreadCrumb(m_requestUriFolder, startlevel, -1, currentFolder);
    }

    /**
     * Build a "bread crumb" path navigation to the current folder.<p>
     *
     * @param startlevel the start level, if negative, go down |n| steps from selected folder
     * @param endlevel the end level, if -1, build navigation to selected folder
     *
     * @return sorted list of navigation elements
     *
     * @see #getNavigationBreadCrumb(String, int, int, boolean)
     */
    public List<CmsJspNavElement> getNavigationBreadCrumb(int startlevel, int endlevel) {

        return getNavigationBreadCrumb(m_requestUriFolder, startlevel, endlevel, true);
    }

    /**
     * Build a "bread crumb" path navigation to the given folder.<p>
     *
     * The <code>startlevel</code> marks the point where the navigation starts from, if negative,
     * the count of steps to go down from the given folder.<p>
     *
     * The <code>endlevel</code> is the maximum level of the navigation path, set it to -1 to build the
     * complete navigation to the given folder.<p>
     *
     * You can include the given folder in the navigation by setting <code>currentFolder</code> to
     * <code>true</code>, otherwise <code>false</code>.<p>
     *
     * @param folder the selected folder
     * @param startlevel the start level, if negative, go down |n| steps from selected folder
     * @param endlevel the end level, if -1, build navigation to selected folder
     * @param currentFolder include the selected folder in navigation or not
     *
     * @return sorted list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationBreadCrumb(
        String folder,
        int startlevel,
        int endlevel,
        boolean currentFolder) {

        List<CmsJspNavElement> result = new ArrayList<CmsJspNavElement>();

        int level = CmsResource.getPathLevel(folder);
        // decrease folder level if current folder is not displayed
        if (!currentFolder) {
            level -= 1;
        }
        // check current level and change endlevel if it is higher or -1
        if ((level < endlevel) || (endlevel == -1)) {
            endlevel = level;
        }

        // if startlevel is negative, display only |startlevel| links
        if (startlevel < 0) {
            startlevel = endlevel + startlevel + 1;
            if (startlevel < 0) {
                startlevel = 0;
            }
        }

        // create the list of navigation elements
        for (int i = startlevel; i <= endlevel; i++) {
            String navFolder = CmsResource.getPathPart(folder, i);
            CmsJspNavElement e = getNavigationForResource(navFolder);
            if (e != null) {
                // add element to list
                result.add(e);
            }
        }

        return result;
    }

    /**
     * Collect all navigation elements from the files of the folder of the current request URI.<p>
     *
     * @return a sorted (ascending to navigation position) list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationForFolder() {

        return getNavigationForFolder(m_requestUriFolder);
    }

    /**
     * Build a navigation for the folder that is either minus levels up
     * from of the folder of the current request URI, or that is plus levels down from the
     * root folder towards the current request URI.<p>
     *
     * If level is set to zero the root folder is used by convention.<p>
     *
     * @param level if negative, walk this many levels up, if positive, walk this many
     *                  levels down from root folder
     * @return a sorted (ascending to navigation position) list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationForFolder(int level) {

        return getNavigationForFolder(m_requestUriFolder, level);
    }

    /**
     * Collect all navigation visible elements from the files in the given folder.<p>
     *
     * @param folder the selected folder
     *
     * @return A sorted (ascending to navigation position) list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationForFolder(String folder) {

        return getNavigationForFolder(folder, Visibility.navigation, CmsResourceFilter.DEFAULT);
    }

    /**
     * Build a navigation for the folder that is either minus levels up
     * from the given folder, or that is plus levels down from the
     * root folder towards the given folder.<p>
     *
     * If level is set to zero the root folder is used by convention.<p>
     *
     * @param folder the selected folder
     * @param level if negative, walk this many levels up, if positive, walk this many
     *                  levels down from root folder
     *
     * @return a sorted (ascending to navigation position) list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationForFolder(String folder, int level) {

        folder = CmsResource.getFolderPath(folder);
        // If level is one just use root folder
        if (level == 0) {
            return getNavigationForFolder("/");
        }
        String navfolder = CmsResource.getPathPart(folder, level);
        // If navigation folder found use it to build navigation
        if (navfolder != null) {
            return getNavigationForFolder(navfolder);
        }
        // Nothing found, return empty list
        return Collections.<CmsJspNavElement> emptyList();
    }

    /**
     * Collect all navigation elements from the files in the given folder.<p>
     *
     * @param folder the selected folder
     * @param visibility the visibility mode
     * @param resourceFilter the filter to use reading the resources
     *
     * @return A sorted (ascending to navigation position) list of navigation elements
     */
    public List<CmsJspNavElement> getNavigationForFolder(
        String folder,
        Visibility visibility,
        CmsResourceFilter resourceFilter) {

        folder = CmsFileUtil.removeTrailingSeparator(folder);
        List<CmsJspNavElement> result = new ArrayList<CmsJspNavElement>();

        List<CmsResource> resources = null;
        try {

            resources = m_cms.getResourcesInFolder(folder, resourceFilter);
        } catch (Exception e) {
            // should never happen
            LOG.error(e.getLocalizedMessage(), e);
        }
        if (resources == null) {
            return Collections.<CmsJspNavElement> emptyList();
        }
        boolean includeAll = visibility == Visibility.all;
        boolean includeHidden = visibility == Visibility.includeHidden;
        for (CmsResource r : resources) {
            CmsJspNavElement element = getNavigationForResource(m_cms.getSitePath(r), resourceFilter);
            if ((element != null)
                && (includeAll
                    || (element.isInNavigation() && (includeHidden || !element.isHiddenNavigationEntry())))) {
                element.setNavContext(new NavContext(this, visibility, resourceFilter));
                result.add(element);
            }
        }
        Collections.sort(result);
        return result;
    }

    /**
     * Returns a navigation element for the resource of the current request URI.<p>
     *
     * @return a navigation element for the resource of the current request URI
     */
    public CmsJspNavElement getNavigationForResource() {

        return getNavigationForResource(m_requestUri);
    }

    /**
     * Returns a navigation element for the named resource.<p>
     *
     * @param sitePath the resource name to get the navigation information for,
     *              must be a full path name, e.g. "/docs/index.html"
     *
     * @return a navigation element for the given resource
     */
    public CmsJspNavElement getNavigationForResource(String sitePath) {

        CmsJspNavElement result = getNavigationForResource(sitePath, CmsResourceFilter.DEFAULT, false);
        if ((result != null) && (result.getNavContext() == null)) {
            result.setNavContext(new NavContext(this, Visibility.navigation, CmsResourceFilter.DEFAULT));
        }
        return result;
    }

    /**
     * Returns a navigation element for the named resource.<p>
     *
     * @param sitePath the resource name to get the navigation information for,
     *              must be a full path name, e.g. "/docs/index.html"
     * @param reourceFilter the resource filter
     *
     * @return a navigation element for the given resource
     */
    public CmsJspNavElement getNavigationForResource(String sitePath, CmsResourceFilter reourceFilter) {

        return getNavigationForResource(sitePath, reourceFilter, false);
    }

    /**
     * Builds a tree navigation for the folders between the provided start and end level.<p>
     *
     * @param startlevel the start level
     * @param endlevel the end level
     *
     * @return a sorted list of navigation elements with the navigation tree level property set
     *
     * @see #getNavigationTreeForFolder(String, int, int)
     */
    public List<CmsJspNavElement> getNavigationTreeForFolder(int startlevel, int endlevel) {

        return getNavigationTreeForFolder(m_requestUriFolder, startlevel, endlevel);
    }

    /**
     * Builds a tree navigation for the folders between the provided start and end level.<p>
     *
     * @param folder the selected folder
     * @param startlevel the start level
     * @param endlevel the end level
     *
     * @return a sorted list of navigation elements with the navigation tree level property set
     */
    public List<CmsJspNavElement> getNavigationTreeForFolder(String folder, int startlevel, int endlevel) {

        folder = CmsResource.getFolderPath(folder);
        // Make sure start and end level make sense
        if (endlevel < startlevel) {
            return Collections.<CmsJspNavElement> emptyList();
        }
        int currentlevel = CmsResource.getPathLevel(folder);
        if (currentlevel < endlevel) {
            endlevel = currentlevel;
        }
        if (startlevel == endlevel) {
            return getNavigationForFolder(CmsResource.getPathPart(folder, startlevel), startlevel);
        }

        List<CmsJspNavElement> result = new ArrayList<CmsJspNavElement>();
        float parentcount = 0;

        for (int i = startlevel; i <= endlevel; i++) {
            String currentfolder = CmsResource.getPathPart(folder, i);
            List<CmsJspNavElement> entries = getNavigationForFolder(currentfolder);
            // Check for parent folder
            if (parentcount > 0) {
                for (CmsJspNavElement e : entries) {
                    e.setNavPosition(e.getNavPosition() + parentcount);
                }
            }
            // Add new entries to result
            result.addAll(entries);
            Collections.sort(result);
            // Finally spread the values of the navigation items so that there is enough room for further items
            float pos = 0;
            int count = 0;
            String nextfolder = CmsResource.getPathPart(folder, i + 1);
            parentcount = 0;
            for (CmsJspNavElement e : result) {
                pos = 10000 * (++count);
                e.setNavPosition(pos);
                if (e.getResourceName().startsWith(nextfolder)) {
                    parentcount = pos;
                }
            }
            if (parentcount == 0) {
                parentcount = pos;
            }
        }
        return result;
    }

    /**
     * This method builds a complete site navigation tree with entries of all branches.<p>
     *
     * @see #getSiteNavigation(String, int)
     *
     * @return list of navigation elements, in depth first order
     */
    public List<CmsJspNavElement> getSiteNavigation() {

        return getSiteNavigation("/", Visibility.navigation, -1);
    }

    /**
     * This method builds a complete navigation tree with entries of all branches
     * from the specified folder.<p>
     *
     * @param folder folder the root folder of the navigation tree
     * @param endLevel the end level of the navigation
     *
     * @return list of navigation elements, in depth first order
     */
    public List<CmsJspNavElement> getSiteNavigation(String folder, int endLevel) {

        return getSiteNavigation(folder, Visibility.navigation, endLevel);
    }

    /**
     * This method builds a complete navigation tree with entries of all branches
     * from the specified folder.<p>
     *
     * @param folder folder the root folder of the navigation tree
     * @param visibility controls whether entries hidden from navigation or not in navigation at all should be included
     * @param endLevel the end level of the navigation
     *
     * @return list of navigation elements, in depth first order
     */
    public List<CmsJspNavElement> getSiteNavigation(String folder, Visibility visibility, int endLevel) {

        folder = CmsFileUtil.addTrailingSeparator(folder);
        // check if a specific end level was given, if not, build the complete navigation
        boolean noLimit = false;
        if (endLevel < 0) {
            noLimit = true;
        }
        List<CmsJspNavElement> list = new ArrayList<CmsJspNavElement>();
        // get the navigation for this folder
        List<CmsJspNavElement> curnav = getNavigationForFolder(folder, visibility, CmsResourceFilter.DEFAULT);
        // loop through all navigation entries
        for (CmsJspNavElement ne : curnav) {
            // add the navigation entry to the result list
            list.add(ne);
            // check if navigation entry is a folder or navigation level and below the max level -> if so, get the navigation from this folder as well
            if ((ne.isFolderLink() || ne.isNavigationLevel()) && (noLimit || (ne.getNavTreeLevel() < endLevel))) {
                List<CmsJspNavElement> subnav = getSiteNavigation(
                    m_cms.getSitePath(ne.getResource()),
                    visibility,
                    endLevel);
                // copy the result of the subfolder to the result list
                list.addAll(subnav);
            }
        }
        return list;
    }

    /**
     * Initializes this bean.<p>
     *
     * @param cms the current cms context
     */
    public void init(CmsObject cms) {

        init(cms, null, cms.getRequestContext().getUri());
    }

    /**
     * Initializes this bean.<p>
     *
     * @param cms the current cms context
     * @param locale the locale for which properties should be read
     */
    public void init(CmsObject cms, Locale locale) {

        init(cms, locale, cms.getRequestContext().getUri());
    }

    /**
     * Initializes this bean.<p>
     *
     * @param cms the current cms context
     * @param locale the locale for which properties should be read
     * @param requestUri the request URI
     */
    public void init(CmsObject cms, Locale locale, String requestUri) {

        m_cms = cms;
        m_locale = locale;
        m_requestUri = requestUri;
        m_requestUriFolder = CmsResource.getFolderPath(m_requestUri);
    }

    /**
     * Collect all navigation elements from the files in the given folder.<p>
    *
    * @param folder the selected folder
    * @param includeInvisible <code>true</code> to include elements not visible in navigation
    * @param resourceFilter the filter to use reading the resources
    * @param shallow <code>true</code> for a shallow look up, not regarding next level resources
    *
    * @return A sorted (ascending to navigation position) list of navigation elements
    */
    private List<CmsJspNavElement> getNavigationForFolder(
        String folder,
        boolean includeInvisible,
        CmsResourceFilter resourceFilter,
        boolean shallow) {

        folder = CmsResource.getFolderPath(folder);
        List<CmsJspNavElement> result = new ArrayList<CmsJspNavElement>();

        List<CmsResource> resources;
        try {
            resources = m_cms.getResourcesInFolder(folder, resourceFilter);
        } catch (Exception e) {
            // should never happen
            LOG.error(e.getLocalizedMessage(), e);
            return Collections.<CmsJspNavElement> emptyList();
        }

        for (CmsResource r : resources) {
            CmsJspNavElement element = getNavigationForResource(m_cms.getSitePath(r), resourceFilter, shallow);
            if ((element != null) && (includeInvisible || element.isInNavigation())) {
                result.add(element);
            }
        }
        Collections.sort(result);
        return result;
    }

    /**
     * Returns a navigation element for the named resource.<p>
     *
     * @param sitePath the resource name to get the navigation information for,
     *              must be a full path name, e.g. "/docs/index.html"
     * @param resourceFilter the filter to use reading the resources
     * @param shallow <code>true</code> for a shallow look up, not regarding next level resources
     *
     * @return a navigation element for the given resource
     */
    private CmsJspNavElement getNavigationForResource(
        String sitePath,
        CmsResourceFilter resourceFilter,
        boolean shallow) {

        CmsResource resource;
        Map<String, String> propertiesMap;
        int level = CmsResource.getPathLevel(sitePath);
        if (sitePath.endsWith("/")) {
            level--;
        }
        try {
            resource = m_cms.readResource(sitePath, resourceFilter);
            List<CmsProperty> properties = m_cms.readPropertyObjects(resource, false);
            propertiesMap = CmsProperty.toMap(properties);
            if (resource.isFolder()) {
                if (resourceFilter.equals(CmsResourceFilter.DEFAULT)
                    && !NAVIGATION_LEVEL_FOLDER.equals(
                        propertiesMap.get(CmsPropertyDefinition.PROPERTY_DEFAULT_FILE))) {
                    try {
                        CmsResource defaultFile = m_cms.readDefaultFile(resource, resourceFilter);
                        if ((defaultFile != null)
                            && !defaultFile.isReleasedAndNotExpired(m_cms.getRequestContext().getRequestTime())) {
                            // do not show navigation entries for unreleased or expired resources
                            return null;
                        }
                    } catch (@SuppressWarnings("unused") CmsException e) {
                        // may happen if permissions are not sufficient can be ignored
                    }
                }
                if (!sitePath.endsWith("/")) {
                    sitePath = sitePath + "/";
                }
                if (!shallow
                    && (NAVIGATION_LEVEL_FOLDER.equals(
                        propertiesMap.get(CmsPropertyDefinition.PROPERTY_DEFAULT_FILE)))) {
                    // this folder is marked as a navigation level, set the site path to the first sub element
                    List<CmsJspNavElement> subElements = getNavigationForFolder(sitePath, false, resourceFilter, true);
                    if (!subElements.isEmpty()) {
                        CmsJspNavElement subElement = subElements.get(0);
                        subElement = getNavigationForResource(subElement.getSitePath(), resourceFilter, false);
                        sitePath = subElement.getSitePath();
                    }
                }
            }
        } catch (Exception e) {
            // may happen if permissions are not sufficient
            LOG.warn(e.getLocalizedMessage(), e);
            return null;
        }

        return new CmsJspNavElement(sitePath, resource, propertiesMap, level, m_locale);
    }
}