/*
 * $Id$
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the
 * LICENSE file included with these sources.
 */

package org.apache.fop.configuration;

// sax
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.XMLReader;
import org.xml.sax.SAXException;
import java.io.IOException;
import org.xml.sax.InputSource;

// fop
import org.apache.fop.apps.Driver;
import org.apache.fop.messaging.MessageHandler;
import org.apache.fop.apps.FOPException;
import org.apache.fop.configuration.Configuration;

/**
 * entry class for reading configuration from file and creating a configuration
 * class. typical use looks like that: <br>
 *
 * <code>ConfigurationReader reader = new ConfigurationReader ("config.xml","standard");
 * try {
 * reader.start();
 * } catch (org.apache.fop.apps.FOPException error) {
 * reader.dumpError(error);
 * }
 * </code>
 * Once the configuration has been setup, the information can be accessed with
 * the methods of StandardConfiguration.
 */
public class ConfigurationReader {

    /**
     * show a full dump on error
     */
    private static boolean errorDump = false;

    /**
     * inputsource for configuration file
     */
    private InputSource filename;


    /**
     * creates a configuration reader
     * @param filename the file which contains the configuration information
     */
    public ConfigurationReader(InputSource filename) {
        this.filename = filename;
    }

    /**
     * intantiates parser and starts parsing of config file
     */
    public void start() throws FOPException {
        XMLReader parser = createParser();

        // setting the parser features
        try {
            parser.setFeature("http://xml.org/sax/features/namespace-prefixes",
                              false);
        } catch (SAXException e) {
            throw new FOPException("You need a parser which supports SAX version 2",
                                   e);
        }
        ConfigurationParser configurationParser = new ConfigurationParser();
        parser.setContentHandler(configurationParser);

        try {
            parser.parse(filename);
        } catch (SAXException e) {
            if (e.getException() instanceof FOPException) {
                throw (FOPException)e.getException();
            } else {
                throw new FOPException(e);
            }
        } catch (IOException e) {
            throw new FOPException(e);
        }
    }

    /**
     * creates a SAX parser, using the value of org.xml.sax.parser
     * defaulting to org.apache.xerces.parsers.SAXParser
     *
     * @return the created SAX parser
     */
    public static XMLReader createParser() throws FOPException {
        String parserClassName = Driver.getParserClassName();
        if (errorDump) {
            MessageHandler.logln("configuration reader using SAX parser "
                                 + parserClassName);
        }

        try {
            return (XMLReader)Class.forName(parserClassName).newInstance();
        } catch (ClassNotFoundException e) {
            throw new FOPException("Could not find " + parserClassName, e);
        } catch (InstantiationException e) {
            throw new FOPException("Could not instantiate "
                                   + parserClassName, e);
        } catch (IllegalAccessException e) {
            throw new FOPException("Could not access " + parserClassName, e);
        } catch (ClassCastException e) {
            throw new FOPException(parserClassName + " is not a SAX driver",
                                   e);
        }
    }

    /**
     * Dumps an error
     */
    public void dumpError(Exception e) {
        if (errorDump) {
            if (e instanceof SAXException) {
                e.printStackTrace();
                if (((SAXException)e).getException() != null) {
                    ((SAXException)e).getException().printStackTrace();
                }
            } else {
                e.printStackTrace();
            }
        }
    }

    /**
     * long or short error messages
     *
     */
    public void setDumpError(boolean dumpError) {
        errorDump = dumpError;
    }

}