package net.deterlab.abac;

import java.io.*;

import java.util.*;
import java.security.*;
import java.security.cert.*;
import javax.security.auth.x500.*;

import java.math.BigInteger;

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


/**
 * An ABAC identity.  An X509 Certificate-encoded public key.  The key
 * identifier is used as the name of the Identity.  This whole class is
 * something of a jabac extension.
 * @author <a href="http://abac.deterlab.net">ISI ABAC team</a>
 * @version 1.4
 */
public class Identity implements Comparable {
    /** Default validity period (in seconds) */
    static public long defaultValidity = 3600L * 24L * 365L;
    /** The underlying X509 certificate. */
    protected X509Certificate cert;
    /** The public key id used as this principal's name */
    protected String keyid;
    /** The common name in the certificate, used as a mnemonic */
    protected String cn;
    /** The keypair, if any, used to sign for this Identity */
    protected KeyPair kp;
    /** The expiration for this Identity */
    protected Date expiration;

    /** Make sure BouncyCastle is loaded */
    static { Context.loadBouncyCastle(); } 

    /**
     * Initialize from PEM cert in a reader.  Use a PEMReader to get
     * the certificate, and call init(cert) on it.
     * @param r a Reader containing the certificate
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    protected void init(Reader r) throws ABACException {
	PEMReader pr = new PEMReader(r);
	Object c = null;

	try {
	    while ( ( c= pr.readObject()) != null ){

		if (c instanceof X509Certificate) {
		    if ( cn == null ) 
			init((X509Certificate)c);
		    else
			throw new CertInvalidException("Two certs in one");
		}
		else if (c instanceof KeyPair) setKeyPair((KeyPair)c);
		else 
		    throw new CertInvalidException(
			    "Not an identity certificate");
	    }
	}
	catch (IOException e) {
	    throw new CertInvalidException(e.getMessage(), e);
	}
	// If there's nothing for the PEM reader to parse, the cert is invalid.
	if (cn == null) 
	    throw new CertInvalidException("Not an identity certificate");
    }

    /**
     * Initialize internals from cert.  Confirm it is self signed,  and then
     * the keyid and common name.  There's some work to get this stuff, but
     * it's all an incantation of getting the right classes to get the right
     * data.  Looks more complex than it is.
     * @param c an X509Certificate to init from
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    protected void init(X509Certificate c) throws ABACException {
	cert = (X509Certificate) c;
	try {
	    cert.verify(cert.getPublicKey());
	}
	catch (SignatureException e) {
	    throw new BadSignatureException(e.getMessage(), e);
	}
	catch (CertificateException e) {
	    throw new CertInvalidException(e.getMessage(), e);
	}
	catch (InvalidKeyException e) {
	    // XXX: the cert is not signed by the key we provided.  Right now
	    // we check each cert as if it were self-signed. Other signing
	    // strategies are allowed here by default.  We expect outside
	    // sources to validate ID certs if they expect different chains of
	    // trust.
	}
	catch (GeneralSecurityException e) {
	    throw new ABACException(e.getMessage(), e);
	}
	// Cert is valid, fill in the CN and keyid
	keyid = Context.extractKeyID(cert.getPublicKey());
	cn = cert.getSubjectDN().getName();
	expiration = cert.getNotAfter();
	/// XXX: better parse
	if (cn.startsWith("CN=")) cn = cn.substring(3);
    }

    /**
     * Construct from a string, used as a CN.  Keys are generated.
     * @param cn a String containing the menomnic name
     * @param validity a long containing the validity period (in seconds)
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    public Identity(String cn, long validity) throws ABACException {
	X509V1CertificateGenerator gen = new X509V1CertificateGenerator();
	try {
	    kp = KeyPairGenerator.getInstance("RSA").genKeyPair();
	}
	catch (NoSuchAlgorithmException e) {
	    throw new ABACException(e.getMessage(), e);
	}
	X509Certificate a = null;

	gen.setIssuerDN(new X500Principal("CN=" + cn));
	gen.setSubjectDN(new X500Principal("CN=" + cn));
	gen.setNotAfter(new Date(System.currentTimeMillis() +
		1000L * validity));
	gen.setNotBefore(new Date(System.currentTimeMillis()));
	gen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
	gen.setPublicKey(kp.getPublic());
	gen.setSignatureAlgorithm("SHA256WithRSAEncryption");
	try {
	    a = (X509Certificate) gen.generate(kp.getPrivate(), "BC");
	}
	catch (CertificateEncodingException e) {
	    throw new CertInvalidException(e.getMessage(), e);
	}
	catch (GeneralSecurityException e) {
	    throw new ABACException(e.getMessage(), e);
	}

	init(a);
    }

    /**
     * Construct from a string, used as a CN.  Keys are generated.
     * @param cn a String containing the menomnic name
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    public Identity(String cn) throws ABACException { 
	this(cn, defaultValidity);
    }

    /**
     * Construct from a file containing a self-signed PEM certificate.
     * @param file the File to read
     * @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
     * @throws ABACException if an uncategorized error occurs
     * @throws FileNotFoundException if the file is invalid
     */
    public Identity(File file) throws ABACException, FileNotFoundException { 
	kp = null;
	init(new FileReader(file));
    }

    /**
     * Construct from a reader containing a self-signed PEM certificate.
     * @param r the Reader containing the certificate
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    public Identity(Reader r) throws ABACException {
	kp = null;
	init(r);
    }

    /**
     * Construct from an InputStream containing a self-signed PEM certificate.
     * @param s the InputStream containing the certificate
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    public Identity(InputStream s) throws ABACException {
	kp = null;
	init(new InputStreamReader(s));
    }

    /**
     * Construct from an X509Certificate
     * @param cert an X509Certificate to init from
     * @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
     * @throws ABACException if an uncategorized error occurs
     */
    Identity(X509Certificate cert) throws ABACException {
	kp = null;
	init(cert);
    }

    /**
     * Write the PEM key to the given writer.
     * @param w the Writer
     * @return true if the Identity had a keypair and wrote the key
     * @throws IOException if writing fails
     */
    public boolean writePrivateKey(Writer w) throws IOException {
	if (kp != null ) {
	    PEMWriter pw = new PEMWriter(w);

	    pw.writeObject(kp.getPrivate());
	    pw.flush();
	    return true;
	}
	else return false;
    }

    /**
     * Write the PEM key to a file with the given name.
     */
    public boolean writePrivateKey(String fn) 
	    throws IOException, FileNotFoundException {
	return writePrivateKey(new FileWriter(fn));
    }

    /**
     * Write the PEM key to the given file.
     * @param fn a String with the output file name
     * @return true if the Identity had a keypair and wrote the key
     * @throws IOException if writing fails
     */
    public boolean writePrivateKey(File fn) 
	    throws IOException, FileNotFoundException {
	return writePrivateKey(new FileWriter(fn));
    }

    /**
     * Write the PEM key to the given OutputStream.
     * @param s an OutputStream to write on
     * @return true if the Identity had a keypair and wrote the key
     * @throws IOException if writing fails
     */
    public boolean writePrivateKey(OutputStream s) 
	    throws IOException, FileNotFoundException {
	return writePrivateKey(new OutputStreamWriter(s));
    }


    /**
     * Write the PEM cert to the given writer.
     * @param w a Writer to write on
     * @throws IOException if writing fails
     */
    public void write(Writer w) throws IOException {
	PEMWriter pw = new PEMWriter(w);

	pw.writeObject(cert);
	pw.flush();
    }

    /**
     * Write the PEM cert to a file with the given name.
     */
    public void write(String fn) throws IOException, FileNotFoundException {
	write(new FileWriter(fn));
    }

    /**
     * Write the PEM cert to the given file.
     * @param fn a String with the output file name
     * @throws IOException if writing fails
     */
    public void write(File fn) throws IOException, FileNotFoundException {
	write(new FileWriter(fn));
    }

    /**
     * Write the PEM cert to the given OutputStream.
     * @param s an OutputStream to write on
     * @throws IOException if writing fails
     */
    public void write(OutputStream s) 
	throws IOException, FileNotFoundException {
	write(new OutputStreamWriter(s));
    }


    /**
     * Return the Identity's KeyID
     * @return the Identity's KeyID
     */
    public String getKeyID() { return keyid; }
    /**
     * Return the Identity's mnemonic name
     * @return the Identity's mnemonic name
     */
    public String getName() { return cn; }
    /**
     * Return the Identity's X509 Certificate
     * @return the Identity's X509 Certificate
     */
    public X509Certificate getCertificate() { return cert; }

    /**
     * Return the expiration time of the Identity
     * @return a Date the expiration time of the Identity
     */
    public Date getExpiration(){ return expiration; }

    /**
     * Return a simple string rep of the Identity.
     * @return a simple string rep of the Identity.
     */
    public String toString() { 
	String s = keyid + " (" + cn ;

	if (getKeyPair() != null ) s += " [keyed]";
	s += ")";
	return s;
    }
    /**
     * Associate a keypair with this Identity.  If the ID has a certificate,
     * make sure that the keypair matches it.  If not throw an
     * IllegalArgumentException.
     * @param k the KeyPair to connect
     * @throws IllegalArgumentException if the keypair does not 
     *				    match the pubkey in the X509 certificate
     */
    public void setKeyPair(KeyPair k) {
	if (keyid != null) {
	    String kid = Context.extractKeyID(k.getPublic());

	    if ( kid != null && kid.equals(keyid)) kp = k;
	    else 
		throw new IllegalArgumentException(
			"Keypair does not match certificate");
	}
	else kp = k;
    }

    /**
     * Return the keypair associated with this Identity (if any)
     * @return the keypair associated with this Identity (if any)
     */
    public KeyPair getKeyPair() { return kp; }

    /**
     * Return true if the two identites refer to teh same key.  Two Identities
     * are equal if their key ID's match.
     * @return true if the two key ID's are equal.
     */
    public boolean equals(Object o) { 
	if ( o == null ) return false;
	else if ( ! (o instanceof Identity) ) return false;
	else return getKeyID().equals(((Identity)o).getKeyID());
    }

    /**
     * Return a hash code for the Identity - the hash of its KeyID()
     * @return an int, the hashCode
     */
    public int hashCode() {
	if (keyid == null) return super.hashCode();
	return keyid.hashCode();
    }


    /**
     * Order 2 identities for sorting.  They are ordered by their key ID's.
     * @param o an Object to compare
     * @return -1 if this Identity is before, 0 if they are the same, and 1
     *		    if this Identity is after the given object.
     */
    public int compareTo(Object o) { 
	if ( ! (o instanceof Identity) ) return 1;
	else return getKeyID().compareTo(((Identity)o).getKeyID());
    }

};