/*
 * (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.util.Base64;
import com.ibm.xml.asn1.ASN12SAX;
import com.ibm.xml.asn1.LabelSAX;
import com.ibm.xml.asn1.SAXEventDumper;
import com.ibm.xml.parser.DTD;
import com.ibm.xml.parser.Parser;

import java.io.FileInputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;

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.AttributesImpl;
import org.xml.sax.helpers.DefaultHandler;

/**
 * @author Takeshi IMAMURA
 */
public class LabelX509Cert implements ErrorHandler {
  private Converter      conv = null;
  private Expander       exp  = null;
  private SAXEventDumper dump = null;

  private String dtdFileName = "x509.dtd";
  private String dtdName     = "root..Certificate";
  private DTD    dtd         = null;

  public LabelX509Cert() {
    try {
      dtd = readDTD(dtdFileName);

    } catch (IOException e) {
    }

    dump = new SAXEventDumper();
    dump.setXMLDeclaration("1.0", null);
    dump.setDoctypeDeclaration(dtdName, dtdFileName);

    exp = new Expander(dump);

    conv = new Converter(exp);
    conv.setDTD(dtd, dtdName);
  }

  private DTD readDTD(String name) throws IOException {
    DTD dtd = null;

    Parser psr = new Parser(name);
    psr.setErrorHandler(this);

    Reader in = new InputStreamReader((LabelX509Cert.class).getResourceAsStream(name));
    //Reader in = new FileReader(name);
    dtd = psr.readDTDStream(in);

    return dtd;
  }

  public void start(InputStream in, Writer out) {
    try {
      dump.setWriter(out);

      conv.setInputStream(in);
      conv.start();

    } catch (SAXException saxe) {
      Exception e = saxe.getException();
      if (e == null) {
	e = saxe;
      }
      e.printStackTrace();
      System.exit(1);
    }
  }

  public class Converter {
    private ASN12SAX a2s = null;
    private LabelSAX lab = null;

    public Converter(ContentHandler handler) {
      lab = new LabelSAX(handler);
      lab.setEncoding("base64");

      a2s = new ASN12SAX(lab);
    }

    public void setByteArray(byte data[]) {
      a2s.setByteArray(data);
    }

    public void setInputStream(InputStream in) {
      a2s.setInputStream(in);
    }

    public void setPartialDecoding(boolean isPartial) {
      a2s.setPartialDecoding(isPartial);
    }

    public void setDTD(DTD dtd, String name) {
      lab.setDTD(dtd, name);
    }

    public void start() throws SAXException {
      a2s.start();
    }

    public void init() {
      a2s.init();
      lab.init();
    }
  }

  public class Expander extends DefaultHandler {
    private ContentHandler hand = null;

    private StringBuffer buf  = null;
    private OIDTable     oidt = null;
    private String       tag  = null;
    private Converter    conv = null;

    private String uri      = null;
    private String lname    = null;
    private String name     = null;
    private Attributes atts = null;

    public Expander(ContentHandler hand) {
      this.hand = hand;
    }

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

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

    public void startElement(String uri, String localName, String name, Attributes atts) throws SAXException {
      if (name.equals("Extension.extnId")) {
	buf = new StringBuffer();

	hand.startElement(uri, localName, name, atts);

      } else if (name.equals("Extension.extnValue")) {
	buf = new StringBuffer();

	this.uri = uri;
	lname = localName;
	this.name = name;
	this.atts = atts;

      } else if (name.equals("root..KeyUsage")) {
	buf = new StringBuffer();

	this.uri = uri;
	lname = localName;
	this.name = name;
	this.atts = atts;

      } else {
	hand.startElement(uri, localName, name, atts);
      }
    }

    public void endElement(String uri, String localName, String name) throws SAXException {
      if (name.equals("Extension.extnId")) {
	String s = buf.toString();  // Extension identifier
	buf = null;

	//
	// OID -> Tag name
	//
	if (oidt == null) {
	  oidt = new OIDTable();
	}
	tag = oidt.lookup(s);

	hand.characters(s.toCharArray(), 0, s.length());

      } else if (name.equals("Extension.extnValue")) {
	String s = buf.toString();  // Extension value
	buf = null;

	if (tag == null) {
	  hand.startElement(this.uri, lname, this.name, atts);
	  hand.characters(s.toCharArray(), 0, s.length());

	} else {
	  //
	  // Remove "encoding" attribute
	  //
	  AttributesImpl aa = (AttributesImpl)atts;
	  int i = aa.getIndex("encoding");
	  aa.removeAttribute(i);

	  hand.startElement(this.uri, lname, this.name, aa);

	  //
	  // Expand the value
	  //
	  if (conv == null) {
	    conv = new Converter(this);
	    //conv = new Converter(dump);
	    conv.setPartialDecoding(true);

	  } else {
	    conv.init();
	  }
	  conv.setDTD(dtd, tag);
	  tag = null;

	  byte bb[] = Base64.toByteArray(s);
	  conv.setByteArray(bb);
	  conv.start();
	}
      } else if (name.equals("root..KeyUsage")) {
	int i = Integer.parseInt(atts.getValue("length"));
	String s = com.ibm.xml.asn1.Base64.decodeBitString(buf.toString(), i);
	buf = null;

	//
	// Remove "encoding" and "length" attributes
	//
	AttributesImpl aa = (AttributesImpl)atts;
	i = aa.getIndex("encoding");
	aa.removeAttribute(i);
	i = aa.getIndex("length");
	aa.removeAttribute(i);

	hand.startElement(this.uri, lname, this.name, aa);

	//
	// Convert bits to names
	//
	s = (new KeyUsage()).toNames(s);

	hand.characters(s.toCharArray(), 0, s.length());
      }

      hand.endElement(uri, localName, name);
    }

    public void characters(char chars[], int start, int length) throws SAXException {
      if (buf == null) {
	hand.characters(chars, start, length);

      } else {
	buf.append(chars, start, length);
      }
    }
  }

  public class OIDTable {
    private final String TAGS[] = {null, null, null, null, null,
				   null, null, null, null,
				   "root..SubjectDirectoryAttributes",  // 9
				   null, null, null, null,
				   "root..SubjectKeyIdentifier",        // 14
				   "root..KeyUsage",                    // 15
				   "root..PrivateKeyUsagePeriod",       // 16
				   "root..SubjectAltName",              // 17
				   "root..IssuerAltName",               // 18
				   "root..BasicConstraints",            // 19
				   null, null, null, null, null,
				   null, null, null, null, null,
				   "root..NameConstraints",             // 30
				   "root..CRLDistPointsSyntax",         // 31
				   "root..CertificatePolicies",         // 21
				   "root..PolicyMappings",              // 33
				   null,
				   "root..AuthorityKeyIdentifier",      // 35
				   "root..PolicyConstraints",           // 36
				   "root..ExtKeyUsageSyntax",           // 37
				   null, null};

    public String lookup(String oid) {
      String tag = null;

      if (oid.startsWith("2.5.29.")) {
	int i = Integer.parseInt(oid.substring("2.5.29.".length()));
	if (i > -1 && i < 40) {
	  tag = TAGS[i];
	}
      }

      return tag;
    }
  }

  public class KeyUsage {
    private final String USAGE[] = {"digitalSignature",
				    "nonRepudiation",
				    "keyEncipherment",
				    "dataEncipherment",
				    "keyAgreement",
				    "keyCertSign",
				    "cRLSign",
				    "encipherOnly",
				    "decipherOnly" };

    public String toNames(String bits) {
      StringBuffer names = new StringBuffer();

      String s = "";
      for (int i = 0, j = bits.length(); i < j && i < 9; i++) {
	//for (int i = 0; i < 9; i++) {
	if (bits.charAt(i) == '1') {
	  names.append(s+USAGE[i]);
	  s = ",";
	}
      }

      return names.toString();
    }
  }


  //
  // ErrorHandler methods
  //

  public void warning(SAXParseException exc) {
    System.err.println("[Warning] "+getLocation(exc)+": "+exc.getMessage());
  }

  public void error(SAXParseException exc) {
    System.err.println("[Error] "+getLocation(exc)+": "+exc.getMessage());
  }

  public void fatalError(SAXParseException exc) throws SAXException {
    System.err.println("[Fatal Error] "+getLocation(exc)+": "+exc.getMessage());
    throw exc;
  }

  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 method
  //

  public static void main(String args[]) {
    InputStream in = null;
    Writer out = new PrintWriter(System.out);  // Default

    try {
      if (args.length > 0) {
	in = new FileInputStream(args[0]);

	if (args.length > 1) {
	  out = new FileWriter(args[1]);
	}
      } else {
	throw new Exception();
      }
    } catch (Exception e) {
      System.err.println("Usage: java asn1.LabelX509Cert <src> [<des>]");
      System.exit(1);
    }

    LabelX509Cert lab = new LabelX509Cert();
    lab.start(in, out);
  }
}