package net.deterlab.abac;

import java.io.*;

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

import net.deterlab.abac.Identity;

import org.bouncycastle.asn1.*;
import org.bouncycastle.x509.*;
import org.bouncycastle.jce.provider.X509AttrCertParser;
import org.bouncycastle.jce.provider.X509CertificateObject;
import org.bouncycastle.openssl.PEMReader;

public class Credential {
    protected static Vector<Identity> s_ids = new Vector<Identity>();

    /**
     * A dummy credential.
     */
    public Credential() {
	m_head = m_tail = null;
	m_ac = null;
	m_id = null;
    }
    /**
     * Create a credential from a head and tail role. This is only for testing.
     * In a real implementation the Credential must be loaded from an X.509
     * attribute cert.
     */
    public Credential(Role head, Role tail) {
        m_head = head;
        m_tail = tail;
	m_ac = null; 
	m_id = null;
    }

    /**
     * Do the credential initialization from a filename.
     */
    protected void init(InputStream stream) throws Exception {
        X509AttrCertParser parser = new X509AttrCertParser();
        parser.engineInit(stream);
        m_ac = (X509V2AttributeCertificate)parser.engineRead();
	m_id = null;

	for (Identity id: s_ids) {
	    try {
		m_ac.verify(id.getCertificate().getPublicKey(), "BC");
		m_id = id;
		break;
	    }
	    catch (InvalidKeyException e) { }
	}
	if (m_id == null) throw new InvalidKeyException("Unknown identity");

        load_roles();
    }

    /**
     * Create a credential from an attribute cert. Throws an exception if the
     * cert file can't be opened or if there's a format problem with the cert.
     */
    public Credential(String filename) throws Exception {
	init(new FileInputStream(filename));
    }

    /**
     * Create a credential from an attribute cert. Throws an exception if the
     * cert file can't be opened or if there's a format problem with the cert.
     */
    public Credential(File file) throws Exception {
	init(new FileInputStream(file));
    }

    /**
     * Create a credential from an InputStream.
     */
    public Credential(InputStream s) throws Exception { 
	init(s);
    }


    /**
     * Load the roles off the attribute cert. Throws a RuntimeException if
     * there's something wrong with the cert.
     */
    private void load_roles() throws RuntimeException {
        String roles = null;
        try {
            X509Attribute attr = m_ac.getAttributes()[0];

            DERSequence    java     = (DERSequence)attr.getValues()[0];
            DERSequence    fucking  = (DERSequence)java.getObjectAt(0);
            DERUTF8String  sucks    = (DERUTF8String)fucking.getObjectAt(0);

            roles = sucks.getString();
        }
        catch (Exception e) {
            throw new RuntimeException("Your attribute certificate is funky and I'm not gonna debug it", e);
        }

        String[] parts = roles.split("\\s*<--?\\s*");
        if (parts.length != 2)
            throw new RuntimeException("Invalid attribute: " + roles);

        m_head = new Role(parts[0]);
        m_tail = new Role(parts[1]);
    }

    /**
     * Get the head role from the credential.
     */
    public Role head() {
        return m_head;
    }

    /**
     * Get the tail role from the credential
     */
    public Role tail() {
        return m_tail;
    }

    /**
     * Gets the cert associated with this credential (if any).
     */
    public X509V2AttributeCertificate cert() {
        return m_ac;
    }

    /**
     * Turn the credential into string form. The format is head &lt;- tail. For
     * example: A.r1 &lt;- B.r2.r3.
     */
    public String toString() {
        return m_head + " <- " + m_tail;
    }

    public String simpleString() {
	return m_head.simpleString() + " <- " + m_tail.simpleString();
    }

    public void write(OutputStream s) throws IOException {
	s.write(m_ac.getEncoded());
    }

    public void write(String fn) throws IOException, FileNotFoundException {
	write(new FileOutputStream(fn));
    }

    public boolean hasCertificate() { return m_ac != null; }

    private Role m_head, m_tail;

    private X509V2AttributeCertificate m_ac;
    private Identity m_id;

    public static void addIdentity(Identity id) { 
	s_ids.add(id);
	if (id.getName() != null && id.getKeyID() != null) 
	    Role.add_mapping(id.getName(), id.getKeyID());
    }
    public static Collection<Identity> identities() { return s_ids; }
}