/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.wicket.core.request.mapper;

import java.lang.reflect.Modifier;
import java.util.List;

import org.apache.wicket.protocol.http.WebApplication;
import org.apache.wicket.request.Request;
import org.apache.wicket.request.Url;
import org.apache.wicket.request.component.IRequestablePage;
import org.apache.wicket.request.mapper.info.PageComponentInfo;
import org.apache.wicket.request.mapper.parameter.IPageParametersEncoder;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.request.mapper.parameter.PageParametersEncoder;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.lang.PackageName;
import org.apache.wicket.util.string.Strings;

/**
 * A request mapper that mounts all bookmarkable pages in a given package.
 * <p>
 * To mount this mapper onto a path use the {@link WebApplication#mountPackage(String, Class)}, ex:
 *
 * <pre>
 * MyApp#init() {
 *
 *   super.init();
 *   mountPackage(&quot;/my/path&quot;, MyPage.class);
 * }
 * </pre>
 *
 * will result in urls like {@code /my/path/MyPage}
 * </p>
 *
 * <pre>
 *  Page Class - Render (BookmarkablePageRequestHandler)
 *  /MyPage
 *  (will redirect to hybrid alternative if page is not stateless)
 *
 *  Page Instance - Render Hybrid (RenderPageRequestHandler for pages that were created using bookmarkable URLs)
 *  /MyPage?2
 *
 *  Page Instance - Bookmarkable Listener (BookmarkableListenerRequestHandler)
 *  /MyPage?2-click-foo-bar-baz
 *  /MyPage?2-click.1-foo-bar-baz (1 is behavior index)
 *  (these will redirect to hybrid if page is not stateless)
 * </pre>
 */
public class PackageMapper extends AbstractBookmarkableMapper
{
        /**
         * the name of the package for which all bookmarkable pages should be mounted
         */
        private final PackageName packageName;

        /**
         * Constructor.
         *
         * @param packageName
         */
        public PackageMapper(String mountPath, final PackageName packageName)
        {
                this(mountPath, packageName, new PageParametersEncoder());
        }

        /**
         * Constructor.
         *
         * @param packageName
         * @param pageParametersEncoder
         */
        public PackageMapper(String mountPath, final PackageName packageName,
                final IPageParametersEncoder pageParametersEncoder)
        {
                super(mountPath, pageParametersEncoder);

                Args.notNull(packageName, "packageName");

                this.packageName = packageName;
        }

        @Override
        protected Url buildUrl(UrlInfo info)
        {
                Class<? extends IRequestablePage> pageClass = info.getPageClass();
                PackageName pageClassPackageName = PackageName.forClass(pageClass);
                if (pageClassPackageName.equals(packageName))
                {
                        Url url = new Url();
                        for (String s : mountSegments)
                        {
                                url.getSegments().add(s);
                        }

                        String fullyQualifiedClassName = pageClass.getName();
                        String packageRelativeClassName = fullyQualifiedClassName;
                        int packageNameLength = packageName.getName().length();
                        if (packageNameLength > 0)
                        {
                                packageRelativeClassName = fullyQualifiedClassName.substring(packageNameLength + 1);
                        }
                        packageRelativeClassName = transformForUrl(packageRelativeClassName);
                        url.getSegments().add(packageRelativeClassName);
                        encodePageComponentInfo(url, info.getPageComponentInfo());

                        PageParameters copy = newPageParameters();
                        copy.mergeWith(info.getPageParameters());
                        if (setPlaceholders(copy, url) == false)
                        {
                                // mandatory parameter is not provided => cannot build Url
                                return null;
                        }

                        return encodePageParameters(url, copy, pageParametersEncoder);
                }

                return null;
        }

        @Override
        protected UrlInfo parseRequest(Request request)
        {
                Url url = request.getUrl();
                if (urlStartsWithMountedSegments(url))
                {
                        // try to extract page and component information from URL
                        PageComponentInfo info = getPageComponentInfo(url);

                        final List<String> segments = url.getSegments();
                        if (segments.size() <= mountSegments.length)
                        {
                                return null;
                        }

                        // load the page class
                        String name = segments.get(mountSegments.length);

                        if (Strings.isEmpty(name))
                        {
                                return null;
                        }

                        String className = cleanClassName(name);

                        if (isValidClassName(className) == false)
                        {
                                return null;
                        }

                        className = transformFromUrl(className);
                        String fullyQualifiedClassName = packageName.getName() + '.' + className;
                        Class<? extends IRequestablePage> pageClass = getPageClass(fullyQualifiedClassName);

                        if (pageClass != null && Modifier.isAbstract(pageClass.getModifiers()) == false &&
                                IRequestablePage.class.isAssignableFrom(pageClass))
                        {
                                // extract the PageParameters from URL if there are any
                                Url urlWithoutPageSegment = new Url(url);
                                urlWithoutPageSegment.getSegments().remove(mountSegments.length);
                                Request requestWithoutPageSegment = request.cloneWithUrl(urlWithoutPageSegment);
                                PageParameters pageParameters = extractPageParameters(requestWithoutPageSegment, urlWithoutPageSegment);

                                return new UrlInfo(info, pageClass, pageParameters);
                        }
                }
                return null;
        }

        /**
         * filter out invalid class names for package mapper. getting trash for class names
         * can e.g. happen when the home page is in the same package that is mounted by package mapper
         * but the request was previously mapped by e.g. {@link HomePageMapper}. We then get some
         * strange url like '/example/..' and wicket tries to look up class name '..'.
         * <p/>
         *  @see <a href="https://issues.apache.org/jira/browse/WICKET-4303">WICKET-4303</a>
         *  <p/>
         */
        private boolean isValidClassName(String className)
        {
                // darn simple check - feel free to enhance this method to your needs
                if (Strings.isEmpty(className))
                {
                        return false;
                }
                // java class names never start with '.'
                if (className.startsWith("."))
                {
                        return false;
                }
                return true;
        }

        /**
         * Gives a chance to specializations of this mapper to transform the alias of the class name to
         * the real class name
         *
         * @param classNameAlias
         *            the alias for the class name
         * @return the real class name
         */
        protected String transformFromUrl(final String classNameAlias)
        {
                return classNameAlias;
        }

        /**
         * Gives a chance to specializations of this mapper to transform the real class name to an alias
         * which is prettier to represent in the Url
         *
         * @param className
         *            the real class name
         * @return the class name alias
         */
        protected String transformForUrl(final String className)
        {
                return className;
        }

        @Override
        protected boolean pageMustHaveBeenCreatedBookmarkable()
        {
                return false;
        }
        
        @Override
        protected boolean checkPageClass(Class<? extends IRequestablePage> pageClass)
        {
                if (pageClass == null)
                {
                        return false;
                }
                PackageName pageClassPackageName = PackageName.forClass(pageClass);
                return packageName.equals(pageClassPackageName);
        }
}