/**
 * Fedid
 *
 * Wrapper around a federated is
 */

package net.deterlab.isi;

import java.security.MessageDigest;
import java.security.PublicKey;
import java.security.NoSuchAlgorithmException;
import java.security.cert.X509Certificate;

public class Fedid {

    /** The bytes in the fedid */
    protected byte[] buf;


    /**
     * Empty constructor
     */
    public Fedid() { buf = null; }

    /**
     * Copy Constructor
     */
    public Fedid(Fedid f) { assign( f != null ? f.getBytes() : null); }
    /**
     * Create from a byte array
     */
    public Fedid(byte[] b) { assign(b); }

    /**
     * Create from X.509 certificate.
     */
    public Fedid(X509Certificate c) throws NoSuchAlgorithmException {
	assign(c);
    }

    public void assign(byte[] b) { 
	if ( b == null )
	    buf = null;
	else{
	    buf = new byte[b.length];
	    System.arraycopy(b, 0, buf, 0, b.length);
	}
    }

    public void assign(X509Certificate c) throws NoSuchAlgorithmException {
	if ( c != null ) {
	    MessageDigest md = MessageDigest.getInstance("SHA1");
	    PublicKey pk = c.getPublicKey();
	    
	    if (pk.getFormat() == "X.509" && pk.getAlgorithm() == "RSA") {
		// This 22 is a hack, but I don't want to parse the ASN.1
		byte[] asn1 = pk.getEncoded();
		byte[] bits = new byte[asn1.length -22];

		System.arraycopy(asn1, 22, bits, 0, bits.length);

		buf = md.digest(bits);
	    }
	    else {
		throw new IllegalArgumentException("Unknown Key type");
	    }
	}
	else buf = null;
    }

    /**
     * Printable version of the Fedid
     *
     * throws Null exception if the Fedid is uninitialized
     */
    public String toString() {
	String rv ="fedid:";

	for ( byte b : buf) {
	    rv += String.format("%02x", b);
	}
	return rv;
    }

    public byte[] getBytes() { return buf; }

    public boolean equals(Fedid f) {
	byte[] b = f.getBytes();

	if (buf.length != b.length) return false;
	else {
	    for ( int i =0; i < b.length; i++) 
		if ( buf[i] != b[i]) return false;
	    return true;
	}
    }
}