/*
 * 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.jasper.compiler;

import java.io.InputStream;
import java.util.Iterator;
import java.util.Vector;
import java.net.URL;

import javax.servlet.ServletContext;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.jasper.JasperException;
import org.apache.jasper.xmlparser.ParserUtils;
import org.apache.jasper.xmlparser.TreeNode;
import org.xml.sax.InputSource;

/**
 * Handles the jsp-config element in WEB_INF/web.xml.  This is used
 * for specifying the JSP configuration information on a JSP page
 *
 * @author Kin-man Chung
 */

public class JspConfig {

    private static final String WEB_XML = "/WEB-INF/web.xml";

    // Logger
    private Log log = LogFactory.getLog(JspConfig.class);

    private Vector jspProperties = null;
    private ServletContext ctxt;
    private boolean initialized = false;

    private String defaultIsXml = null;		// unspecified
    private String defaultIsELIgnored = null;	// unspecified
    private String defaultIsScriptingInvalid = "false";
    private JspProperty defaultJspProperty;

    public JspConfig(ServletContext ctxt) {
	this.ctxt = ctxt;
    }

    private void processWebDotXml(ServletContext ctxt) throws JasperException {

        InputStream is = null;

        try {
            URL uri = ctxt.getResource(WEB_XML);
            if (uri == null) {
	        // no web.xml
                return;
	    }

            is = uri.openStream();
            InputSource ip = new InputSource(is);
            ip.setSystemId(uri.toExternalForm()); 

            ParserUtils pu = new ParserUtils();
	    TreeNode webApp = pu.parseXMLDocument(WEB_XML, ip);

	    if (webApp == null
                    || !"2.4".equals(webApp.findAttribute("version"))) {
	        defaultIsELIgnored = "true";
	        return;
	    }
	    TreeNode jspConfig = webApp.findChild("jsp-config");
	    if (jspConfig == null) {
	        return;
	    }

            jspProperties = new Vector();
            Iterator jspPropertyList = jspConfig.findChildren("jsp-property-group");
            while (jspPropertyList.hasNext()) {

                TreeNode element = (TreeNode) jspPropertyList.next();
                Iterator list = element.findChildren();

                Vector urlPatterns = new Vector();
                String pageEncoding = null;
                String scriptingInvalid = null;
                String elIgnored = null;
                String isXml = null;
                Vector includePrelude = new Vector();
                Vector includeCoda = new Vector();

                while (list.hasNext()) {

                    element = (TreeNode) list.next();
                    String tname = element.getName();

                    if ("url-pattern".equals(tname))
                        urlPatterns.addElement( element.getBody() );
                    else if ("page-encoding".equals(tname))
                        pageEncoding = element.getBody();
                    else if ("is-xml".equals(tname))
                        isXml = element.getBody();
                    else if ("el-ignored".equals(tname))
                        elIgnored = element.getBody();
                    else if ("scripting-invalid".equals(tname))
                        scriptingInvalid = element.getBody();
                    else if ("include-prelude".equals(tname))
                        includePrelude.addElement(element.getBody());
                    else if ("include-coda".equals(tname))
                        includeCoda.addElement(element.getBody());
                }

                if (urlPatterns.size() == 0) {
                    continue;
                }
 
                // Add one JspPropertyGroup for each URL Pattern.  This makes
                // the matching logic easier.
                for( int p = 0; p < urlPatterns.size(); p++ ) {
                    String urlPattern = (String)urlPatterns.elementAt( p );
                    String path = null;
                    String extension = null;
 
                    if (urlPattern.indexOf('*') < 0) {
                        // Exact match
                        path = urlPattern;
                    } else {
                        int i = urlPattern.lastIndexOf('/');
                        String file;
                        if (i >= 0) {
                            path = urlPattern.substring(0,i+1);
                            file = urlPattern.substring(i+1);
                        } else {
                            file = urlPattern;
                        }
 
                        // pattern must be "*", or of the form "*.jsp"
                        if (file.equals("*")) {
                            extension = "*";
                        } else if (file.startsWith("*.")) {
                            extension = file.substring(file.indexOf('.')+1);
                        }

                        // The url patterns are reconstructed as the follwoing:
                        // path != null, extension == null:  / or /foo/bar.ext
                        // path == null, extension != null:  *.ext
                        // path != null, extension == "*":   /foo/*
                        boolean isStar = "*".equals(extension);
                        if ((path == null && (extension == null || isStar))
                                || (path != null && !isStar)) {
                            if (log.isWarnEnabled()) {
			        log.warn(Localizer.getMessage(
                                    "jsp.warning.bad.urlpattern.propertygroup",
                                    urlPattern));
                            }
                            continue;
                        }
                    }

                    JspProperty property = new JspProperty(isXml,
                                                           elIgnored,
                                                           scriptingInvalid,
                                                           pageEncoding,
                                                           includePrelude,
                                                           includeCoda);
                    JspPropertyGroup propertyGroup =
                        new JspPropertyGroup(path, extension, property);

                    jspProperties.addElement(propertyGroup);
                }
            }
        } catch (Exception ex) {
            throw new JasperException(ex);
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (Throwable t) {}
            }
        }
    }

    private void init() throws JasperException {

	if (!initialized) {
	    processWebDotXml(ctxt);
	    defaultJspProperty = new JspProperty(defaultIsXml,
						 defaultIsELIgnored,
						 defaultIsScriptingInvalid,
						 null, null, null);
	    initialized = true;
	}
    }

    /**
     * Select the property group that has more restrictive url-pattern.
     * In case of tie, select the first.
     */
    private JspPropertyGroup selectProperty(JspPropertyGroup prev,
                                            JspPropertyGroup curr) {
        if (prev == null) {
            return curr;
        }
        if (prev.getExtension() == null) {
            // exact match
            return prev;
        }
        if (curr.getExtension() == null) {
            // exact match
            return curr;
        }
        String prevPath = prev.getPath();
        String currPath = curr.getPath();
        if (prevPath == null && currPath == null) {
            // Both specifies a *.ext, keep the first one
            return prev;
        }
        if (prevPath == null && currPath != null) {
            return curr;
        }
        if (prevPath != null && currPath == null) {
            return prev;
        }
        if (prevPath.length() >= currPath.length()) {
            return prev;
        }
        return curr;
    }
            

    /**
     * Find a property that best matches the supplied resource.
     * @param uri the resource supplied.
     * @return a JspProperty indicating the best match, or some default.
     */
    public JspProperty findJspProperty(String uri) throws JasperException {

	init();

	// JSP Configuration settings do not apply to tag files	    
	if (jspProperties == null || uri.endsWith(".tag")
	        || uri.endsWith(".tagx")) {
	    return defaultJspProperty;
	}

	String uriPath = null;
	int index = uri.lastIndexOf('/');
	if (index >=0 ) {
	    uriPath = uri.substring(0, index+1);
	}
	String uriExtension = null;
	index = uri.lastIndexOf('.');
	if (index >=0) {
	    uriExtension = uri.substring(index+1);
	}

	Vector includePreludes = new Vector();
	Vector includeCodas = new Vector();

	JspPropertyGroup isXmlMatch = null;
	JspPropertyGroup elIgnoredMatch = null;
	JspPropertyGroup scriptingInvalidMatch = null;
	JspPropertyGroup pageEncodingMatch = null;

	Iterator iter = jspProperties.iterator();
	while (iter.hasNext()) {

	    JspPropertyGroup jpg = (JspPropertyGroup) iter.next();
	    JspProperty jp = jpg.getJspProperty();

             // (arrays will be the same length)
             String extension = jpg.getExtension();
             String path = jpg.getPath();
 
             if (extension == null) {
                 // exact match pattern: /a/foo.jsp
                 if (!uri.equals(path)) {
                     // not matched;
                     continue;
                 }
             } else {
                 // Matching patterns *.ext or /p/*
                 if (path != null && uriPath != null &&
                         ! uriPath.startsWith(path)) {
                     // not matched
                     continue;
                 }
                 if (!extension.equals("*") &&
                                 !extension.equals(uriExtension)) {
                     // not matched
                     continue;
                 }
             }
             // We have a match
             // Add include-preludes and include-codas
             if (jp.getIncludePrelude() != null) {
                 includePreludes.addAll(jp.getIncludePrelude());
             }
             if (jp.getIncludeCoda() != null) {
                 includeCodas.addAll(jp.getIncludeCoda());
             }

             // If there is a previous match for the same property, remember
             // the one that is more restrictive.
             if (jp.isXml() != null) {
                 isXmlMatch = selectProperty(isXmlMatch, jpg);
             }
             if (jp.isELIgnored() != null) {
                 elIgnoredMatch = selectProperty(elIgnoredMatch, jpg);
             }
             if (jp.isScriptingInvalid() != null) {
                 scriptingInvalidMatch =
                     selectProperty(scriptingInvalidMatch, jpg);
             }
             if (jp.getPageEncoding() != null) {
                 pageEncodingMatch = selectProperty(pageEncodingMatch, jpg);
             }
	}


	String isXml = defaultIsXml;
	String isELIgnored = defaultIsELIgnored;
	String isScriptingInvalid = defaultIsScriptingInvalid;
	String pageEncoding = null;

	if (isXmlMatch != null) {
	    isXml = isXmlMatch.getJspProperty().isXml();
	}
	if (elIgnoredMatch != null) {
	    isELIgnored = elIgnoredMatch.getJspProperty().isELIgnored();
	}
	if (scriptingInvalidMatch != null) {
	    isScriptingInvalid =
		scriptingInvalidMatch.getJspProperty().isScriptingInvalid();
	}
	if (pageEncodingMatch != null) {
	    pageEncoding = pageEncodingMatch.getJspProperty().getPageEncoding();
	}

	return new JspProperty(isXml, isELIgnored, isScriptingInvalid,
			       pageEncoding, includePreludes, includeCodas);
    }

    /**
     * To find out if an uri matches an url pattern in jsp config.  If so,
     * then the uri is a JSP page.  This is used primarily for jspc.
     */
    public boolean isJspPage(String uri) throws JasperException {

        init();
        if (jspProperties == null) {
            return false;
        }

        String uriPath = null;
        int index = uri.lastIndexOf('/');
        if (index >=0 ) {
            uriPath = uri.substring(0, index+1);
        }
        String uriExtension = null;
        index = uri.lastIndexOf('.');
        if (index >=0) {
            uriExtension = uri.substring(index+1);
        }

        Iterator iter = jspProperties.iterator();
        while (iter.hasNext()) {

            JspPropertyGroup jpg = (JspPropertyGroup) iter.next();
            JspProperty jp = jpg.getJspProperty();

            String extension = jpg.getExtension();
            String path = jpg.getPath();

            if (extension == null) {
                if (uri.equals(path)) {
                    // There is an exact match
                    return true;
                }
            } else {
                if ((path == null || path.equals(uriPath)) &&
                    (extension.equals("*") || extension.equals(uriExtension))) {
                    // Matches *, *.ext, /p/*, or /p/*.ext
                    return true;
                }
            }
        }
        return false;
    }

    static class JspPropertyGroup {
	private String path;
	private String extension;
	private JspProperty jspProperty;

	JspPropertyGroup(String path, String extension,
			 JspProperty jspProperty) {
	    this.path = path;
	    this.extension = extension;
	    this.jspProperty = jspProperty;
	}

	public String getPath() {
	    return path;
	}

	public String getExtension() {
	    return extension;
	}

	public JspProperty getJspProperty() {
	    return jspProperty;
	}
    }

    static public class JspProperty {

	private String isXml;
	private String elIgnored;
	private String scriptingInvalid;
	private String pageEncoding;
	private Vector includePrelude;
	private Vector includeCoda;

	public JspProperty(String isXml, String elIgnored,
		    String scriptingInvalid, String pageEncoding,
		    Vector includePrelude, Vector includeCoda) {

	    this.isXml = isXml;
	    this.elIgnored = elIgnored;
	    this.scriptingInvalid = scriptingInvalid;
	    this.pageEncoding = pageEncoding;
	    this.includePrelude = includePrelude;
	    this.includeCoda = includeCoda;
	}

	public String isXml() {
	    return isXml;
	}

	public String isELIgnored() {
	    return elIgnored;
	}

	public String isScriptingInvalid() {
	    return scriptingInvalid;
	}

	public String getPageEncoding() {
	    return pageEncoding;
	}

	public Vector getIncludePrelude() {
	    return includePrelude;
	}

	public Vector getIncludeCoda() {
	    return includeCoda;
	}
    }
}