package net.deterlab.abac;

import java.io.*;
import java.math.*;

import java.util.*;
import java.security.*;
import java.security.cert.*;

import javax.security.auth.x500.*;

import org.bouncycastle.asn1.*;
import org.bouncycastle.asn1.x509.*;
import org.bouncycastle.x509.*;
import org.bouncycastle.x509.util.*;
import org.bouncycastle.openssl.*;

/**
 * An Internal Credential, used to represent extra arcs in the proof graph.  It
 * should never be converted to a cert or output.
 * @author <a href="http://abac.deterlab.net">ISI ABAC team</a>
 * @version 1.4
 */
public class InternalCredential extends Credential {

    /**
     * Create an empty InternalCredential.
     */
    public InternalCredential() { super(); }
    /**
     * Create a credential from a head and tail role.  This credential has no
     * underlying certificate, and cannot be exported or used in real proofs.
     * @param head the Role at the head of the credential
     * @param tail the Role at the tail of the credential
     */
    public InternalCredential(Role head, Role tail) {super(head, tail); }

    /**
     * Create a credential from an attribute cert in a file.  This will always
     * fail for in InternalCredential.
     * @param filename a String containing the filename to read
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *				    certificate
     * @throws BadSignatureException if the signature check fails
     */
    public InternalCredential(String filename, Collection<Identity> ids) 
	throws ABACException { this(); }

    /**
     * Create a credential from an attribute cert in a file.   This will always
     * * fail for in InternalCredential.
     * @param file the File to read
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *				    certificate
     * @throws BadSignatureException if the signature check fails
     */
    public InternalCredential(File file, Collection<Identity> ids) 
	    throws ABACException {
	 this();
    }

    /**
     * Create a credential from an InputStream.  This will always
     * fail for in InternalCredential.
     * @param ids a Collection of Identities to use in validating the cert
     * @throws CertInvalidException if the stream is unparsable
     * @throws MissingIssuerException if none of the Identities can validate the
     *				    certificate
     * @throws BadSignatureException if the signature check fails
     */
    public InternalCredential(InputStream s, Collection<Identity> ids) 
	    throws ABACException {
	 this();
    }


    /**
     * Create a certificate from this credential issued by the given identity.
     * This will always fail for an InternalCredential.
     * @param i the Identity that will issue the certificate
     * @throws ABACException for Credential-specific errors
     * @throws MissingIssuerException the identity is invalid
     * @throws BadSignatureException if the signature creation fails
     */
    public void make_cert(Identity i) throws ABACException {
	throw new ABACException("Cannot create certificate for " +
		"an InternalCredential");
    }

    /**
     * Output the DER formatted attribute certificate associated with this
     * Credential to the OutputStream.  This will always fail for an
     * InternalCredential.
     * @param s the OutputStream on which to write
     * @throws IOException if there is an error writing.
     */
    public void write(OutputStream s) throws IOException {
	throw new IOException("Cannot write certificate for " +
		"an InternalCredential");
    }

    /**
     * Output the DER formatted attribute certificate associated with this
     * Credential to the filename given.  This will always fail for an
     * InternalCredential.
     * @param fn a String containing the output filename
     * @throws IOException if there is an error writing.
     */
    public void write(String fn) 
	throws IOException, FileNotFoundException {
	write((OutputStream) null);
    }

    /**
     * Return true if this Credential has a certificate associated.  A jabac
     * extension.  Always false for an InternalCredential.
     * @return true if this Credential has a certificate associated.
     */
    public boolean hasCertificate() { return false; }

}