/*
 * Copyright 2005 Joe Walker
 *
 * Licensed 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.directwebremoting.impl;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import javax.servlet.ServletContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.directwebremoting.AccessControl;
import org.directwebremoting.AjaxFilter;
import org.directwebremoting.AjaxFilterManager;
import org.directwebremoting.Configurator;
import org.directwebremoting.Container;
import org.directwebremoting.ConverterManager;
import org.directwebremoting.Creator;
import org.directwebremoting.CreatorManager;
import org.directwebremoting.TypeHintContext;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.LogErrorHandler;
import org.directwebremoting.util.Logger;
import org.directwebremoting.util.Messages;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

/**
 * A configurator that gets its configuration by reading a dwr.xml file.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class DwrXmlConfigurator implements Configurator
{
    /**
     * Setter for the resource name that we can use to read a file from the
     * servlet context
     * @param servletResourceName The name to lookup
     * @throws IOException On file read failure
     * @throws ParserConfigurationException On XML setup failure
     * @throws SAXException On XML parse failure
     */
    public void setServletResourceName(String servletResourceName) throws IOException, ParserConfigurationException, SAXException
    {
        this.servletResourceName = servletResourceName;

        ServletContext servletContext = WebContextFactory.get().getServletContext();
        if (servletContext == null)
        {
            throw new IOException(Messages.getString("DwrXmlConfigurator.MissingServletContext")); //$NON-NLS-1$
        }

        InputStream in = null;
        try
        {
            in = servletContext.getResourceAsStream(servletResourceName);
            if (in == null)
            {
                throw new IOException(Messages.getString("DwrXmlConfigurator.MissingConfigFile", servletResourceName)); //$NON-NLS-1$
            }

            setInputStream(in);
        }
        finally
        {
            LocalUtil.close(in);
        }
    }

    /**
     * Setter for a classpath based lookup
     * @param classResourceName The resource to lookup in the classpath
     * @throws IOException On file read failure
     * @throws ParserConfigurationException On XML setup failure
     * @throws SAXException On XML parse failure
     */
    public void setClassResourceName(String classResourceName) throws IOException, ParserConfigurationException, SAXException
    {
        this.classResourceName = classResourceName;

        InputStream in = getClass().getResourceAsStream(classResourceName);
        if (in == null)
        {
            throw new IOException(Messages.getString("DwrXmlConfigurator.MissingConfigFile", classResourceName)); //$NON-NLS-1$
        }

        setInputStream(in);
    }

    /**
     * Setter for a direct input stream to configure from
     * @param in The input stream to read from.
     * @throws IOException On file read failure
     * @throws ParserConfigurationException On XML setup failure
     * @throws SAXException On XML parse failure
     */
    public void setInputStream(InputStream in) throws ParserConfigurationException, SAXException, IOException
    {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setValidating(true);

        DocumentBuilder db = dbf.newDocumentBuilder();
        db.setEntityResolver(new DTDEntityResolver());
        db.setErrorHandler(new LogErrorHandler());

        document = db.parse(in);
    }

    /**
     * To set the configuration document directly
     * @param document The new configuration document
     */
    public void setDocument(Document document)
    {
        this.document = document;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.Configurator#configure(org.directwebremoting.Container)
     */
    public void configure(Container container)
    {
        accessControl = (AccessControl) container.getBean(AccessControl.class.getName());
        ajaxFilterManager = (AjaxFilterManager) container.getBean(AjaxFilterManager.class.getName());
        converterManager = (ConverterManager) container.getBean(ConverterManager.class.getName());
        creatorManager = (CreatorManager) container.getBean(CreatorManager.class.getName());

        Element root = document.getDocumentElement();

        NodeList rootChildren = root.getChildNodes();
        for (int i = 0; i < rootChildren.getLength(); i++)
        {
            Node node = rootChildren.item(i);
            if (node.getNodeType() == Node.ELEMENT_NODE)
            {
                Element child = (Element) node;

                if (child.getNodeName().equals(ELEMENT_INIT))
                {
                    loadInits(child);
                }
                else if (child.getNodeName().equals(ELEMENT_ALLOW))
                {
                    loadAllows(child);
                }
                else if (child.getNodeName().equals(ELEMENT_SIGNATURES))
                {
                    loadSignature(child);
                }
            }
        }
    }

    /**
     * Internal method to load the inits element
     * @param child The element to read
     */
    private void loadInits(Element child)
    {
        NodeList inits = child.getChildNodes();
        for (int j = 0; j < inits.getLength(); j++)
        {
            if (inits.item(j).getNodeType() == Node.ELEMENT_NODE)
            {
                Element initer = (Element) inits.item(j);

                if (initer.getNodeName().equals(ATTRIBUTE_CREATOR))
                {
                    String id = initer.getAttribute(ATTRIBUTE_ID);
                    String className = initer.getAttribute(ATTRIBUTE_CLASS);
                    creatorManager.addCreatorType(id, className);
                }
                else if (initer.getNodeName().equals(ATTRIBUTE_CONVERTER))
                {
                    String id = initer.getAttribute(ATTRIBUTE_ID);
                    String className = initer.getAttribute(ATTRIBUTE_CLASS);
                    converterManager.addConverterType(id, className);
                }
            }
        }
    }

    /**
     * Internal method to load the create/convert elements
     * @param child The element to read
     */
    private void loadAllows(Element child)
    {
        NodeList allows = child.getChildNodes();
        for (int j = 0; j < allows.getLength(); j++)
        {
            if (allows.item(j).getNodeType() == Node.ELEMENT_NODE)
            {
                Element allower = (Element) allows.item(j);

                if (allower.getNodeName().equals(ELEMENT_CREATE))
                {
                    loadCreate(allower);
                }
                else if (allower.getNodeName().equals(ELEMENT_CONVERT))
                {
                    loadConvert(allower);
                }
                else if (allower.getNodeName().equals(ELEMENT_FILTER))
                {
                    loadFilter(allower);
                }
            }
        }
    }

    /**
     * Internal method to load the convert element
     * @param allower The element to read
     */
    private void loadConvert(Element allower)
    {
        String match = allower.getAttribute(ATTRIBUTE_MATCH);
        String type = allower.getAttribute(ATTRIBUTE_CONVERTER);

        try
        {
            Map params = createSettingMap(allower);
            converterManager.addConverter(match, type, params);
        }
        catch (NoClassDefFoundError ex)
        {
            log.info("Convertor '" + type + "' not loaded due to NoClassDefFoundError. (match='" + match + "'). Cause: " + ex.getMessage()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
        }
        catch (Exception ex)
        {
            log.error("Failed to add convertor: match=" + match + ", type=" + type, ex); //$NON-NLS-1$ //$NON-NLS-2$
        }
    }

    /**
     * Internal method to load the create element
     * @param allower The element to read
     */
    private void loadCreate(Element allower)
    {
        String type = allower.getAttribute(ATTRIBUTE_CREATOR);
        String javascript = allower.getAttribute(ATTRIBUTE_JAVASCRIPT);

        try
        {
            Map params = createSettingMap(allower);
            creatorManager.addCreator(javascript, type, params);

            processPermissions(javascript, allower);
            processAuth(javascript, allower);
            processParameters(javascript, allower);
            processAjaxFilters(javascript, allower);
        }
        catch (NoClassDefFoundError ex)
        {
            log.info("Creator '" + type + "' not loaded due to NoClassDefFoundError. (javascript='" + javascript + "'). Cause: " + ex.getMessage()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
        }
        catch (Exception ex)
        {
            log.error("Failed to add creator: type=" + type + ", javascript=" + javascript, ex); //$NON-NLS-1$ //$NON-NLS-2$
        }
    }

    /**
     * Internal method to load the convert element
     * @param allower The element to read
     */
    private void loadFilter(Element allower)
    {
        String type = allower.getAttribute(ATTRIBUTE_CLASS);

        try
        {
            Class impl = LocalUtil.classForName(type);
            AjaxFilter object = (AjaxFilter) impl.newInstance();

            LocalUtil.setParams(object, createSettingMap(allower), ignore);

            ajaxFilterManager.addAjaxFilter(object);
        }
        catch (ClassCastException ex)
        {
            log.error(type + " does not implement " + AjaxFilter.class.getName(), ex); //$NON-NLS-1$
        }
        catch (NoClassDefFoundError ex)
        {
            log.info("Missing class for filter (class='" + type + "'). Cause: " + ex.getMessage()); //$NON-NLS-1$ //$NON-NLS-2$
        }
        catch (Exception ex)
        {
            log.error("Failed to add filter: class=" + type, ex); //$NON-NLS-1$
        }
    }

    /**
     * Create a parameter map from nested <param name="foo" value="blah"/>