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/*
 *  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 groovy.servlet;

import groovy.lang.Closure;
import groovy.util.GroovyScriptEngine;
import groovy.util.ResourceException;
import groovy.util.ScriptException;
import org.codehaus.groovy.runtime.GroovyCategorySupport;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * This servlet will run Groovy scripts as Groovlets.  Groovlets are scripts
 * with these objects implicit in their scope:
 *
 * 
 *  request - the HttpServletRequest
 *  response - the HttpServletResponse
 *  application - the ServletContext associated with the servlet
 *  session - the HttpSession associated with the HttpServletRequest
 *  out - the PrintWriter associated with the ServletRequest
 * 
 *
 * Your script sources can be placed either in your web application's normal
 * web root (allows for subdirectories) or in /WEB-INF/groovy/* (also allows
 * subdirectories).
 *
 * 
To make your web application more groovy, you must add the GroovyServlet
 * to your application's web.xml configuration using any mapping you like, so
 * long as it follows the pattern *.* (more on this below).  Here is the
 * web.xml entry:
 *
 * 
 * {@code
 *    
 *      Groovy
 *      groovy.servlet.GroovyServlet
 *    
 *
 *    
 *      Groovy
 *      *.groovy
 *      *.gdo
 *    
 * }
 * 
 *
 * The URL pattern does not require the "*.groovy" mapping.  You can, for
 * example, make it more Struts-like but groovy by making your mapping "*.gdo".
 *
 * @see groovy.servlet.ServletBinding
 */
public class GroovyServlet extends AbstractHttpServlet {

    /**
     * The script engine executing the Groovy scripts for this servlet
     */
    private GroovyScriptEngine gse;

    /**
     * Initialize the GroovyServlet.
     *
     * @throws ServletException
     *  if this method encountered difficulties
     */
    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        // Set up the scripting engine
        gse = createGroovyScriptEngine();

        servletContext.log("Groovy servlet initialized on " + gse + ".");
    }

    /**
     * Handle web requests to the GroovyServlet
     */
    @Override
    public void service(HttpServletRequest request, HttpServletResponse response) throws IOException {

        // Get the script path from the request - include aware (GROOVY-815)
        final String scriptUri = getScriptUri(request);

        // Set it to HTML by default
        response.setContentType("text/html; charset="+encoding);

        // Set up the script context
        final ServletBinding binding = new ServletBinding(request, response, servletContext);
        setVariables(binding);

        // Run the script
        try {
            Closure closure = new Closure