name.martingeisse.admin.navigation.NavigationUtil.java Source code

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Here is the source code for name.martingeisse.admin.navigation.NavigationUtil.java

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/**
 * Copyright (c) 2011 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.admin.navigation;

import org.apache.commons.lang3.StringUtils;
import org.apache.wicket.Component;
import org.apache.wicket.Page;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.util.string.StringValue;

/**
 * Helper methods to deal with the implicit page parameter used
 * for navigation-mounted pages.
 */
public final class NavigationUtil {

    /**
     * The name of the implicit page parameter.
     */
    public static final String NAVIGATION_PATH_PAGE_PARAMETER_NAME = "name.martingeisse.admin.navigation.path";

    /**
     * Prevent instantiation.
     */
    private NavigationUtil() {
    }

    /**
     * Returns the value of the implicit navigation path parameter.
     * 
     * @param parameters the page parameters to take the value from (may be null)
     * @return the parameter value, or null if no such parameter is set
     * or if the parameters argument is null
     */
    public static String getParameterValue(final PageParameters parameters) {
        if (parameters == null) {
            return null;
        }
        final StringValue value = parameters.get(NAVIGATION_PATH_PAGE_PARAMETER_NAME);
        return (value == null ? null : value.toString());
    }

    /**
     * Returns the value of the implicit navigation path parameter,
     * optionally enforcing that the parameter is present.
     * 
     * @param parameters the page parameters to take the value from (may be null)
     * @param required whether the path is required
     * @return the parameter value, or null if no such parameter is set
     * or if the parameters argument is null (only possible if the required flag
     * is false).
     * @throws IllegalArgumentException if no path was found and required is true
     */
    public static String getParameterValue(final PageParameters parameters, final boolean required)
            throws IllegalArgumentException {
        final String navigationPath = getParameterValue(parameters);
        if (navigationPath != null) {
            return navigationPath;
        } else if (required) {
            throw new IllegalArgumentException(
                    "page parameter for the navigation path is missing from parameters: " + parameters);
        } else {
            return null;
        }
    }

    /**
     * Sets the value of the implicit navigation path parameter to the specified
     * value, or clears it if the value is null.
     * 
     * @param parameters the parameters collection to set the parameter for
     * @param value the value, or null to clear
     */
    public static void setParameterValue(final PageParameters parameters, final String value) {
        if (parameters == null) {
            throw new IllegalArgumentException("'parameters' argument cannot be null");
        } else if (value == null) {
            parameters.remove(NAVIGATION_PATH_PAGE_PARAMETER_NAME);
        } else {
            parameters.set(NAVIGATION_PATH_PAGE_PARAMETER_NAME, value);
        }
    }

    /**
     * Obtains the current navigation node for the specified path.
     * 
     * @param path the navigation path to obtain the node for (may be null)
     * @param required whether the node is required
     * @return the current node, or null if no node was found and required is false
     * @throws IllegalArgumentException if no node was found and required is true
     */
    public static NavigationNode getNavigationNodeForPath(final String path, final boolean required)
            throws IllegalArgumentException {
        final NavigationNode node = (path == null ? null : NavigationTree.get().getNodesByPath().get(path));
        if (node != null) {
            return node;
        } else if (required) {
            throw new IllegalArgumentException(
                    "page parameter for the navigation path does not match any known path: " + path);
        } else {
            return null;
        }
    }

    /**
     * Obtains the current navigation node from the page parameters.
     * 
     * @param parameters the page parameters (may be null)
     * @param required whether the parameter for the current node is required
     * @return the current node, or null if no node was found and required is false
     * @throws IllegalArgumentException if no node was found and required is true
     */
    public static NavigationNode getNavigationNodeFromParameter(final PageParameters parameters,
            final boolean required) throws IllegalArgumentException {
        return getNavigationNodeForPath(getParameterValue(parameters, required), required);
    }

    /**
     * Obtains the navigation path for the specified page. This tries to use the page
     * as an {@link INavigationLocationAware} and also attempts to find page parameters
     * set by a {@link NavigationMountedRequestMapper}.
     * 
     * @param page the page to return the navigation path for 
     * @return the navigation path, or null if not found
     */
    public static String getNavigationPathForPage(final Page page) {

        // try INavigationLocator
        if (page instanceof INavigationLocationAware) {
            final INavigationLocationAware aware = (INavigationLocationAware) page;
            final String result = aware.getNavigationPath();
            if (result != null) {
                return result;
            }
        }

        // try the implicit page parameter
        return getParameterValue(page.getPageParameters());

    }

    /**
     * Returns the current navigation node for the specified component.
     * @param component the component
     * @return the navigation node
     */
    public static NavigationNode getNavigationNodeForComponent(final Component component) {
        return getNavigationNodeForPage(component.getPage());
    }

    /**
     * Returns the current navigation node for the specified page.
     * @param page the page
     * @return the navigation node (never null -- if no actual node can be found,
     * this method returns the root not)
     */
    public static NavigationNode getNavigationNodeForPage(final Page page) {
        final String currentNavigationPath = StringUtils
                .defaultString(NavigationUtil.getNavigationPathForPage(page));
        return NavigationTree.get().getRoot().findMostSpecificNode(currentNavigationPath);
    }

}