/*
 * Copyright (c) 2004-2012, Willem Cazander
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided
 * that the following conditions are met:
 * 
 * * Redistributions of source code must retain the above copyright notice, this list of conditions and the
 *   following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
 *   the following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.x4o.xml.sax;

import  java.io.ByteArrayInputStream;
import java.io.File;
import  java.io.FileInputStream;
import  java.io.FileNotFoundException;
import  java.io.IOException;
import  java.io.InputStream;
import java.net.URL;

import  org.xml.sax.SAXException;
import  javax.xml.parsers.ParserConfigurationException;

/**
 * This is a base class for building an SAX XML parser.
 * It adds methode's for parsing different input types of 
 * xml data which gets wrapped into an InputStream for parsing.
 * 
 * @author Willem Cazander
 * @version 1.0 Aug 11, 2005
 */
abstract public class AbstractXMLParser {
        
        /**
         * Method to parse the xml data.
         * @param input The inputStream to parse.
         * @throws ParserConfigurationException
         * @throws SAXException
         * @throws IOException
         */
        abstract public void parse(InputStream input,String systemId,URL basePath) throws ParserConfigurationException,SAXException,IOException;
        
        /**
         * Reads the file fileName and parses it as an InputStream.
         * @param fileName      The file name to parse.
         * @throws ParserConfigurationException
         * @throws FileNotFoundException
         * @throws SecurityException
         * @throws NullPointerException
         * @throws SAXException
         * @throws IOException
         * @see org.x4o.xml.sax.AbstractXMLParser#parse(java.io.InputStream,java.lang.String,java.net.URL)
         */
        public void parseFile(String fileName) throws ParserConfigurationException,FileNotFoundException,SecurityException,NullPointerException,SAXException,IOException {
                if (fileName==null) {
                        throw new NullPointerException("Can't convert null fileName to file object.");
                }               
                parseFile(new File(fileName));
        }
        
        /**
         * Reads the file and parses it as an InputStream.
         * @param file  The file to parse.
         * @throws ParserConfigurationException
         * @throws FileNotFoundException
         * @throws SecurityException
         * @throws NullPointerException
         * @throws SAXException
         * @throws IOException
         * @see org.x4o.xml.sax.AbstractXMLParser#parse(java.io.InputStream,java.lang.String,java.net.URL)
         */
        public void parseFile(File file) throws ParserConfigurationException,FileNotFoundException,SecurityException,NullPointerException,SAXException,IOException {
                if (file==null) {
                        throw new NullPointerException("Can't load null file.");
                }
                if (file.exists()==false) {
                        throw new FileNotFoundException("File does not exists; "+file);
                }
                if (file.canRead()==false) {
                        throw new IOException("File exists but can't read file: "+file);
                }
                URL basePath = new File(file.getAbsolutePath()).toURI().toURL();
                InputStream inputStream = new FileInputStream(file);
                try {
                        parse(inputStream,file.getAbsolutePath(),basePath);
                } finally {
                        if(inputStream!=null) {
                                inputStream.close();
                        }
                }
        }
        
        /**
         * Parses an resource locaction.
         * @param resourceName  The resource to parser.
         * @throws ParserConfigurationException
         * @throws FileNotFoundException
         * @throws SecurityException
         * @throws NullPointerException
         * @throws SAXException
         * @throws IOException
         */
        public void parseResource(String resourceName) throws ParserConfigurationException,FileNotFoundException,SecurityException,NullPointerException,SAXException,IOException {
                if (resourceName==null) {
                        throw new NullPointerException("Can't load null resourceName from classpath.");
                }
                ClassLoader cl = Thread.currentThread().getContextClassLoader();
                if (cl == null) cl = getClass().getClassLoader(); // fallback
                URL url = cl.getResource(resourceName);
                if (url==null) {
                        throw new NullPointerException("Could not find resource on classpath: "+resourceName);
                }
                String baseUrl = url.toExternalForm();
                int lastSlash = baseUrl.lastIndexOf('/');
                if (lastSlash > 0 && (lastSlash+1) < baseUrl.length()) {
                        baseUrl = baseUrl.substring(0,lastSlash+1);
                }
                URL basePath = new URL(baseUrl);
                InputStream inputStream = cl.getResourceAsStream(resourceName);
                try {
                        parse(inputStream,url.toExternalForm(),basePath);
                } finally {
                        if(inputStream!=null) {
                                inputStream.close();
                        }
                }
        }
        
        /**
         * Converts a String to a InputStream to is can me parsed by SAX.
         * @param xmlString     The xml as String to parse.
         * @throws ParserConfigurationException
         * @throws SAXException
         * @throws IOException
         * @throws NullPointerException
         * @see org.x4o.xml.sax.AbstractXMLParser#parse(java.io.InputStream,java.lang.String,java.net.URL)
         */
        public void parseXml(String xmlString) throws ParserConfigurationException,SAXException,IOException,NullPointerException {
                if (xmlString==null) {
                        throw new NullPointerException("Can't parse null xml string.");
                }
                URL basePath = new File(System.getProperty("user.dir")).toURI().toURL();
                parse(new ByteArrayInputStream(xmlString.getBytes()),"inline-xml",basePath);
        }
        
        /**
         * Fetched the data direct from remote url to a InputStream to is can me parsed by SAX.
         * @param url   The url to parse.
         * @throws ParserConfigurationException
         * @throws SAXException
         * @throws IOException
         * @throws NullPointerException
         * @see org.x4o.xml.sax.AbstractXMLParser#parse(java.io.InputStream,java.lang.String,java.net.URL)
         */
        public void parseUrl(URL url) throws ParserConfigurationException,SAXException,IOException,NullPointerException {
                if (url==null) {
                        throw new NullPointerException("Can't parse null url.");
                }
                URL basePath = new URL(url.toExternalForm().substring(0,url.toExternalForm().length()-url.getFile().length()));
                parse(url.openStream(),url.toExternalForm(),basePath);
        }
}