/*
 * (C) Copyright IBM Corp. 1999-2000  All rights reserved.
 *
 * US Government Users Restricted Rights Use, duplication or
 * disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
 *
 * The program is provided "as is" without any warranty express or
 * implied, including the warranty of non-infringement and the implied
 * warranties of merchantibility and fitness for a particular purpose.
 * IBM will not be liable for any damages suffered by you as a result
 * of using the Program. In no event will IBM be liable for any
 * special, indirect or consequential damages or lost profits even if
 * IBM has been advised of the possibility of their occurrence. IBM
 * will not be liable for any third party claims against you.
 */

package asn1;

import com.ibm.xml.asn1.SAXEventDumper;
import com.ibm.xml.asn1.LabelSAX;

import com.ibm.xml.parser.Parser;
import com.ibm.xml.parser.DTD;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;

import org.apache.xerces.parsers.SAXParser;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * Sample of cascading LabelSAX
 * <pre>
 *  Usage: java asn1.LabelPKCS7 XER
 *         where XER is unlabeled XML representation of PKCS7 data
 *
 *  Limitation:
 *         Currently only SignedData is supported. See oid2ElementName() below.
 *
 *
 *  This program works as illustrated below.
 *  When LabelPKCS7 see ContentInfo.content, it "switches" the event flow
 *  the second LabelSAX that is responsible for labeling the contents.
 *  This second LabelSAX receives the name of the root element based on
 *  the contentType field of the outer data structure.  From the application
 *  point of view (SAXDump, in this case), the whole set up looks as if
 *  it is yet another SAX event source.
 *
 *
 *          ================== SAX Event Flow ===================>
 *  
 *   +------+   +--------+   +----------+    ContentInfo        +--------+   
 *   | SAX  |-->|LabelSAX|-->|LabelPKCS7|---------------------->|SAXDump |
 *   |parser|   |  #1    |   |          |--+  +--------+  +---->|        |
 *   +------+   +--------+   +----------+  |  |LabelSAX|  |     +--------+
 *                                         +->|   #2   |--+
 *                                            +--------+   
 *                                            SignedData
 * </pre>
 *
 * @author Hiroshi Maruyama
 * @author Takeshi Imamura
 */
public class LabelPKCS7 extends DefaultHandler {
    static boolean opt_d = false;
    static String inf;
    static String dtd = "pkcs7.dtd";
    static String rootElement = "root..ContentInfo";

    /**
     * Constructs an object and initializes some variables according to
     * the specified arguments.
     *
     * @param <CODE>args</CODE> arguments to this program.
     */
    public LabelPKCS7() {
      //
      // Do nothing
      //
    }


    /**
     * Labels XER encoded ASN.1 data with given DTD
     *
     * @exception java.io.IOException -
     * @exception org.xml.sax.SAXException -
     */
    private void start() throws IOException, SAXException {

	SAXEventDumper dump = new SAXEventDumper();
	Writer out = new OutputStreamWriter(System.out);
	dump.setWriter(out);
	dump.setXMLDeclaration("1.0", null);
	// dump.setDoctypeDeclaration(rootElement, dtd);

	handler = dump;

	LabelSAX lsax = new LabelSAX(this);
	DTD d = readDTD(dtd);
	lsax.setDTD(d, rootElement);
	lsax.setEncoding("base64");

	SAXParser psr = new SAXParser();
	psr.setContentHandler(lsax);
	psr.setErrorHandler(this);
	psr.parse(inf);
    }

    /**
     * Reads a DTD from a file.
     *
     * @param <CODE>name</CODE> the name of the file containing a DTD.
     *
     * @return a DTD.
     *
     * @exception java.io.IOException -
     */
    private DTD readDTD(String name) throws IOException {
	Parser psr = new Parser(name);
	psr.setErrorHandler(this);

	Reader in = new InputStreamReader((LabelPKCS7.class).getResourceAsStream(name));
	DTD dtd = psr.readDTDStream(in);

	return dtd;
    }


    //
    // Member variables for controling filtering operations 
    //

    StringBuffer buffer = null;
    String ContentType;
    ContentHandler handler;
    ContentHandler handlerSave;


    //
    // The following five methods implements ContentHandler
    //

    public void startDocument() throws SAXException {
	handler.startDocument();
    }

    public void endDocument() throws SAXException {
	handler.endDocument();
    }

    public void startElement(String uri, String localName, String name, Attributes atts) throws SAXException {
	try {
	  handler.startElement(uri, localName, name, atts);
	    if (name.equals("ContentInfo.contentType")) {
		this.buffer = new StringBuffer();
	    } else if (name.equals("ContentInfo.content")) {
	        //
		// Start processing Content
		//   1. Create another LabelSAX
	        //
		LabelSAX lsaxContents = new LabelSAX(handler);
		DTD d;
		d = readDTD(dtd);
		lsaxContents.setDTD(d, oid2ElementName(ContentType));
		lsaxContents.setEncoding("base64");

		//
		//   2. Redirect SAX events
		//
		handlerSave = handler;
		handler = lsaxContents;
	    }
	} catch (IOException ioe) {
	    ioe.printStackTrace();
	}

    }

    public void endElement(String uri, String localName, String name) throws SAXException {
	if (name.equals("ContentInfo.contentType")) {
	    this.ContentType = this.buffer.toString();
	    // System.err.println("ContentType:"+this.ContentType);
	    this.buffer = null;
	} else if (name.equals("ContentInfo.content")) {
	    // Restore handler
	    handler = handlerSave;
	}
	handler.endElement(uri, localName, name);
    }

    public void characters(char chars[], int start, int length) throws SAXException {
	handler.characters(chars,start,length);
	if (this.buffer != null) {
	    this.buffer.append(chars, start, length);
	}
    }


    /**
     * oid2ElementName translation table
     * This table should be expanded as necessary.
     */
    String oid2ElementName(String oid) {
	if (oid.equals("1.2.840.113549.1.7.2")) return "root..SignedData";
	return "";
    }


    //
    // The following three methods implements ErrorHandler
    //

    /**
     * Receive notification of a warning.  The warning information is
     * printed.
     *
     * @param <CODE>exc</CODE> the warning information encapsulated in a
     * SAX parse exception.
     */
    public void warning(SAXParseException exc) {
	System.err.println("[Warning] "+getLocation(exc)+": "+exc.getMessage());
    }

    /**
     * Receive notification of a recoverable error.  The error
     * information is printed.
     *
     * @param <CODE>exc</CODE> the error information encapsulated in a
     * SAX parse exception.
     */
    public void error(SAXParseException exc) {
	System.err.println("[Error] "+getLocation(exc)+": "+exc.getMessage());
    }

    /**
     * Receive notification of a non-recoverable error.  The error
     * information is printed and the exception is thrown again.
     *
     * @param <CODE>exc</CODE> the error information encapsulated in a
     * SAX parse exception.
     *
     * @exception org.xml.sax.SAXException -
     */
    public void fatalError(SAXParseException exc) throws SAXException {
	System.err.println("[Fatal Error] "+getLocation(exc)+": "+exc.getMessage());
	throw exc;
    }

    /**
     * Gets the location where the exception is thrown.
     *
     * @param <CODE>exc</CODE> the warning or error information
     * encapsulated in a SAX parse exception.
     */
    private String getLocation(SAXParseException exc) {
	StringBuffer buf = new StringBuffer();

	String id = exc.getSystemId();
	if (id != null) {
	    int i = id.lastIndexOf('/');
	    if (i != -1) {
		id = id.substring(i+1);
	    }
	    if (!id.equals("")) {
		buf.append(id+", ");
	    }
	}
	buf.append(exc.getLineNumber()+", ");
	buf.append(exc.getColumnNumber());

	return buf.toString();
    }


    //
    // Main
    //

    /**
     * Creates this object and starts a translation.
     */
    public static void main(String args[]) {
	int i=0;
	if (args.length<1) {
	    usage(-1);
	} else if (args[0].equals("-d")) {
	    opt_d = true;
	    i++;
	}
	if (args.length<i+1) {
	    usage(-1);
	}
	inf = args[i];
	try {
	    LabelPKCS7 lp7 = new LabelPKCS7();
	    lp7.start();

	} catch (Exception e) {
	    e.printStackTrace();
	}
    }

    /**
     * Prints the help message and exits this program with a status.
     *
     * @param <CODE>stat</CODE> a status of this program.
     */
    private static void usage(int stat) {
      System.err.println("Usage: java asn1.LabelPKCS7 <src.xer>");
      System.exit(stat);
    }
}