/*
 * 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.handler;

import org.apache.wicket.Application;
import org.apache.wicket.Session;
import org.apache.wicket.core.request.handler.logger.PageLogData;
import org.apache.wicket.request.ILoggableRequestHandler;
import org.apache.wicket.request.IRequestCycle;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.component.IRequestablePage;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.request.handler.render.PageRenderer;
import org.apache.wicket.request.mapper.parameter.PageParameters;
import org.apache.wicket.util.lang.Args;

/**
 * {@link IRequestHandler} that renders page instance. Depending on the <code>redirectPolicy</code>
 * flag and current request strategy the handler either just renders the page to the response, or
 * redirects to render the page. <code>REDIRECT_TO_BUFFER</code> strategy is also supported.
 * <p>
 *
 * @author Matej Knopp
 */
public class RenderPageRequestHandler
        implements
                IPageRequestHandler,
                IPageClassRequestHandler,
                ILoggableRequestHandler
{
        private final IPageProvider pageProvider;

        private final RedirectPolicy redirectPolicy;

        private PageLogData logData;

        /**
         * Determines whether Wicket does a redirect when rendering a page
         *
         * @author Matej Knopp
         */
        public enum RedirectPolicy {
                /**
                 * Always redirect if current request URL is different than page URL.
                 */
                ALWAYS_REDIRECT,

                /**
                 * Never redirect - always render the page to current response.
                 */
                NEVER_REDIRECT,

                /**
                 * Redirect if necessary. The redirect will happen when all of the following conditions are
                 * met:
                 * <ul>
                 * <li>current request URL is different than page URL
                 * <li>page is not stateless or (page is stateless and session is not temporary)
                 * <li>render strategy is either REDIRECT_TO_BUFFER or REDIRECT_TO_RENDER
                 * </ul>
                 */
                AUTO_REDIRECT
        }

        /**
         * Constructor.
         *
         * @param pageClass The class of the page to render
         */
        public RenderPageRequestHandler(final Class<? extends IRequestablePage> pageClass)
        {
                this(pageClass, null);
        }

        /**
         * Constructor.
         *
         * @param pageClass The class of the page to render
         * @param parameters Wrapped query string parameters.
         */
        public RenderPageRequestHandler(final Class<? extends IRequestablePage> pageClass, final PageParameters parameters)
        {
                this(new PageProvider(pageClass, parameters));
        }

        /**
         * Constructor.
         *
         * @param page The page to render
         */
        public RenderPageRequestHandler(final IRequestablePage page)
        {
                this(new PageProvider(page));
        }

        /**
         * Construct. Renders the page with a redirect if necessary.
         *
         * @param pageProvider
         */
        public RenderPageRequestHandler(IPageProvider pageProvider)
        {
                this(pageProvider, RedirectPolicy.AUTO_REDIRECT);
        }

        /**
         * Construct.
         *
         * @param pageProvider
         * @param redirectPolicy
         */
        public RenderPageRequestHandler(IPageProvider pageProvider, RedirectPolicy redirectPolicy)
        {
                Args.notNull(pageProvider, "pageProvider");
                Args.notNull(redirectPolicy, "redirectPolicy");

                this.redirectPolicy = redirectPolicy;
                this.pageProvider = pageProvider;

                if (pageProvider.hasPageInstance())
                {
                        if (Session.exists())
                        {
                                // WICKET-5499
                                Session.get().getPageManager().touchPage(pageProvider.getPageInstance());
                        }
                }
        }

        /**
         * @return page provider
         */
        public IPageProvider getPageProvider()
        {
                return pageProvider;
        }

        /**
         * @return redirect policy
         */
        public RedirectPolicy getRedirectPolicy()
        {
                return redirectPolicy;
        }

        @Override
        public Class<? extends IRequestablePage> getPageClass()
        {
                return pageProvider.getPageClass();
        }

        @Override
        public Integer getPageId()
        {
                return pageProvider.getPageId();
        }

        @Override
        public PageParameters getPageParameters()
        {
                return pageProvider.getPageParameters();
        }

        @Override
        public void detach(IRequestCycle requestCycle)
        {
                if (logData == null)
                        logData = new PageLogData(pageProvider);
                pageProvider.detach();
        }

        @Override
        public PageLogData getLogData()
        {
                return logData;
        }

        @Override
        public IRequestablePage getPage()
        {
                return pageProvider.getPageInstance();
        }

        @Override
        public void respond(IRequestCycle requestCycle)
        {
                PageRenderer renderer = Application.get().getPageRendererProvider().apply(this);
                renderer.respond((RequestCycle)requestCycle);
        }

        @Override
        public final boolean isPageInstanceCreated()
        {
                return pageProvider.hasPageInstance();
        }

        @Override
        public final Integer getRenderCount()
        {
                return pageProvider.getRenderCount();
        }
}