/*
    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.wiki.plugin;

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

import org.apache.wiki.WikiContext;
import org.apache.wiki.WikiEngine;
import org.apache.wiki.WikiPage;
import org.apache.wiki.api.exceptions.PluginException;
import org.apache.wiki.api.exceptions.ProviderException;
import org.apache.wiki.api.plugin.WikiPlugin;
import org.apache.wiki.auth.AuthorizationManager;
import org.apache.wiki.auth.permissions.PermissionFactory;
import org.apache.wiki.util.TextUtil;

/**
 *  Inserts page contents.  Muchos thanks to Scott Hurlbert for the initial code.
 *
 *  <p>Parameters : </p>
 *  <ul>
 *  <li><b>page</b> - the name of the page to be inserted</li>
 *  <li><b>style</b> - the style to use</li>
 *  <li><b>maxlength</b> - the maximum length of the page to be inserted (page contents)</li>
 *  <li><b>class</b> - the class to use</li>
 *  <li><b>section</b> - the section of the page that has to be inserted (separated by "----"</li>
 *  <li><b>default</b> - the text to insert if the requested page does not exist</li>
 *  </ul>
 *
 *  @since 2.1.37
 */
public class InsertPage
    implements WikiPlugin
{
    /** Parameter name for setting the page.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_PAGENAME  = "page";
    /** Parameter name for setting the style.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_STYLE     = "style";
    /** Parameter name for setting the maxlength.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_MAXLENGTH = "maxlength";
    /** Parameter name for setting the class.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_CLASS     = "class";
    /** Parameter name for setting the section.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_SECTION   = "section";
    /** Parameter name for setting the default.  Value is <tt>{@value}</tt>. */
    public static final String PARAM_DEFAULT   = "default";

    private static final String DEFAULT_STYLE = "";

    /** This attribute is stashed in the WikiContext to make sure that we don't
     *  have circular references.
     */
    public static final String ATTR_RECURSE    = "org.apache.wiki.plugin.InsertPage.recurseCheck";

    /**
     *  {@inheritDoc}
     */
    @SuppressWarnings("unchecked")
    public String execute( WikiContext context, Map<String, String> params )
        throws PluginException
    {
        WikiEngine engine = context.getEngine();

        StringBuilder res = new StringBuilder();

        String clazz        = params.get( PARAM_CLASS );
        String includedPage = params.get( PARAM_PAGENAME );
        String style        = params.get( PARAM_STYLE );
        String defaultstr   = params.get( PARAM_DEFAULT );
        int    section      = TextUtil.parseIntParameter(params.get( PARAM_SECTION ), -1 );
        int    maxlen       = TextUtil.parseIntParameter(params.get( PARAM_MAXLENGTH ), -1 );

        if( style == null ) style = DEFAULT_STYLE;

        if( maxlen == -1 ) maxlen = Integer.MAX_VALUE;

        if( includedPage != null )
        {
            WikiPage page = null;
            try
            {
                String pageName = engine.getFinalPageName( includedPage );
                if( pageName != null )
                {
                    page = engine.getPage( pageName );
                }
                else
                {
                    page = engine.getPage( includedPage );
                }
            }
            catch( ProviderException e )
            {
                res.append( "<span class=\"error\">Page could not be found by the page provider.</span>" );
                return res.toString();
            }

            if( page != null )
            {
                //
                //  Check for recursivity
                //

                List<String> previousIncludes = (List<String>)context.getVariable( ATTR_RECURSE );

                if( previousIncludes != null )
                {
                    if( previousIncludes.contains( page.getName() ) )
                    {
                        return "<span class=\"error\">Error: Circular reference - you can't include a page in itself!</span>";
                    }
                }
                else
                {
                    previousIncludes = new ArrayList<String>();
                }

                previousIncludes.add( page.getName() );
                context.setVariable( ATTR_RECURSE, previousIncludes );

                //
                // Check for permissions
                //
                AuthorizationManager mgr = engine.getAuthorizationManager();

                if( !mgr.checkPermission( context.getWikiSession(),
                                          PermissionFactory.getPagePermission( page, "view") ) )
                {
                    res.append("<span class=\"error\">You do not have permission to view this included page.</span>");
                    return res.toString();
                }

                /**
                 *  We want inclusion to occur within the context of
                 *  its own page, because we need the links to be correct.
                 */

                WikiContext includedContext = (WikiContext) context.clone();
                includedContext.setPage( page );

                String pageData = engine.getPureText( page );
                String moreLink = "";

                if( section != -1 )
                {
                    try
                    {
                        pageData = TextUtil.getSection( pageData, section );
                    }
                    catch( IllegalArgumentException e )
                    {
                        throw new PluginException( e.getMessage() );
                    }
                }

                if( pageData.length() > maxlen )
                {
                    pageData = pageData.substring( 0, maxlen )+" ...";
                    moreLink = "<p><a href=\""+context.getURL(WikiContext.VIEW,includedPage)+"\">More...</a></p>";
                }

                res.append("<div style=\""+style+"\""+(clazz != null ? " class=\""+clazz+"\"" : "")+">");
                res.append( engine.textToHTML( includedContext, pageData ) );
                res.append( moreLink );
                res.append("</div>");

                //
                //  Remove the name from the stack; we're now done with this.
                //
                previousIncludes.remove( page.getName() );
                context.setVariable( ATTR_RECURSE, previousIncludes );
            }
            else
            {
                if( defaultstr != null )
                {
                    res.append( defaultstr );
                }
                else
                {
                    res.append("There is no page called '"+includedPage+"'.  Would you like to ");
                    res.append("<a href=\""+context.getURL( WikiContext.EDIT, includedPage )+"\">create it?</a>");
                }
            }
        }
        else
        {
            res.append("<span class=\"error\">");
            res.append("You have to define a page!");
            res.append("</span>");
        }

        return res.toString();
    }

}