package org.bouncycastle.cert;

import java.io.IOException;
import java.io.OutputStream;
import java.math.BigInteger;
import java.util.Date;
import java.util.Enumeration;
import java.util.Locale;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.DERBitString;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x509.Certificate;
import org.bouncycastle.asn1.x509.DeltaCertificateDescriptor;
import org.bouncycastle.asn1.x509.Extension;
import org.bouncycastle.asn1.x509.Extensions;
import org.bouncycastle.asn1.x509.ExtensionsGenerator;
import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo;
import org.bouncycastle.asn1.x509.TBSCertificate;
import org.bouncycastle.asn1.x509.Time;
import org.bouncycastle.asn1.x509.V3TBSCertificateGenerator;
import org.bouncycastle.operator.ContentSigner;
import org.bouncycastle.util.Exceptions;


/**
 * class to produce an X.509 Version 3 certificate.
 */
public class X509v3CertificateBuilder
{
    private V3TBSCertificateGenerator   tbsGen;
    private ExtensionsGenerator extGenerator;

    /**
     * Create a builder for a version 3 certificate.
     *
     * @param issuer the certificate issuer
     * @param serial the certificate serial number
     * @param notBefore the date before which the certificate is not valid
     * @param notAfter the date after which the certificate is not valid
     * @param subject the certificate subject
     * @param publicKeyInfo the info structure for the public key to be associated with this certificate.
     */
    public X509v3CertificateBuilder(X500Name issuer, BigInteger serial, Date notBefore, Date notAfter, X500Name subject, SubjectPublicKeyInfo publicKeyInfo)
    {
        this(issuer, serial, new Time(notBefore), new Time(notAfter), subject, publicKeyInfo);
    }

    /**
     * Create a builder for a version 3 certificate. You may need to use this constructor if the default locale
     * doesn't use a Gregorian calender so that the Time produced is compatible with other ASN.1 implementations.
     *
     * @param issuer the certificate issuer
     * @param serial the certificate serial number
     * @param notBefore the date before which the certificate is not valid
     * @param notAfter the date after which the certificate is not valid
     * @param dateLocale locale to be used for date interpretation.
     * @param subject the certificate subject
     * @param publicKeyInfo the info structure for the public key to be associated with this certificate.
     */
    public X509v3CertificateBuilder(X500Name issuer, BigInteger serial, Date notBefore, Date notAfter, Locale dateLocale, X500Name subject, SubjectPublicKeyInfo publicKeyInfo)
    {
        this(issuer, serial, new Time(notBefore, dateLocale), new Time(notAfter, dateLocale), subject, publicKeyInfo);
    }

    /**
     * Create a builder for a version 3 certificate.
     *
     * @param issuer the certificate issuer
     * @param serial the certificate serial number
     * @param notBefore the Time before which the certificate is not valid
     * @param notAfter the Time after which the certificate is not valid
     * @param subject the certificate subject
     * @param publicKeyInfo the info structure for the public key to be associated with this certificate.
     */
    public X509v3CertificateBuilder(X500Name issuer, BigInteger serial, Time notBefore, Time notAfter, X500Name subject, SubjectPublicKeyInfo publicKeyInfo)
    {
        tbsGen = new V3TBSCertificateGenerator();
        tbsGen.setSerialNumber(new ASN1Integer(serial));
        tbsGen.setIssuer(issuer);
        tbsGen.setStartDate(notBefore);
        tbsGen.setEndDate(notAfter);
        tbsGen.setSubject(subject);
        tbsGen.setSubjectPublicKeyInfo(publicKeyInfo);

        extGenerator = new ExtensionsGenerator();
    }

    /**
     * Create a builder for a version 3 certificate, initialised with another certificate.
     *
     * @param template template certificate to base the new one on.
     */
    public X509v3CertificateBuilder(X509CertificateHolder template)
    {
        tbsGen = new V3TBSCertificateGenerator();
        tbsGen.setSerialNumber(new ASN1Integer(template.getSerialNumber()));
        tbsGen.setIssuer(template.getIssuer());
        tbsGen.setStartDate(new Time(template.getNotBefore()));
        tbsGen.setEndDate(new Time(template.getNotAfter()));
        tbsGen.setSubject(template.getSubject());
        tbsGen.setSubjectPublicKeyInfo(template.getSubjectPublicKeyInfo());

        extGenerator = new ExtensionsGenerator();

        Extensions exts = template.getExtensions();

        for (Enumeration en = exts.oids(); en.hasMoreElements();)
        {
            ASN1ObjectIdentifier oid = (ASN1ObjectIdentifier)en.nextElement();
            // we remove the altSignatureAlgorithm, altSignatureValue, and subjectAltPublicKeyInfo
            // extensions as they probably need to be regenerated.
            if (Extension.subjectAltPublicKeyInfo.equals(oid)
                || Extension.altSignatureAlgorithm.equals(oid)
                || Extension.altSignatureValue.equals(oid))
            {
                continue;
            }
            extGenerator.addExtension(exts.getExtension(oid));
        }
    }

    /**
     * Return if the extension indicated by OID is present.
     *
     * @param oid the OID for the extension of interest.
     * @return the Extension, or null if it is not present.
     */
    public boolean hasExtension(ASN1ObjectIdentifier oid)
    {
         return doGetExtension(oid) != null;
    }

    /**
     * Return the current value of the extension for OID.
     *
     * @param oid the OID for the extension we want to fetch.
     * @return true if a matching extension is present, false otherwise.
     */
    public Extension getExtension(ASN1ObjectIdentifier oid)
    {
         return doGetExtension(oid);
    }

    private Extension doGetExtension(ASN1ObjectIdentifier oid)
    {
        if (extGenerator.isEmpty())
        {
            return null;
        }
        
        Extensions exts = extGenerator.generate();

        return exts.getExtension(oid);
    }

    /**
     * Set the subjectUniqueID - note: it is very rare that it is correct to do this.
     *
     * @param uniqueID a boolean array representing the bits making up the subjectUniqueID.
     * @return this builder object.
     */
    public X509v3CertificateBuilder setSubjectUniqueID(boolean[] uniqueID)
    {
        tbsGen.setSubjectUniqueID(booleanToBitString(uniqueID));

        return this;
    }

    /**
     * Set the issuerUniqueID - note: it is very rare that it is correct to do this.
     *
     * @param uniqueID a boolean array representing the bits making up the issuerUniqueID.
     * @return this builder object.
     */
    public X509v3CertificateBuilder setIssuerUniqueID(boolean[] uniqueID)
    {
        tbsGen.setIssuerUniqueID(booleanToBitString(uniqueID));

        return this;
    }

    /**
     * Add a given extension field for the standard extensions tag (tag 3)
     *
     * @param oid the OID defining the extension type.
     * @param isCritical true if the extension is critical, false otherwise.
     * @param value the ASN.1 structure that forms the extension's value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the OID oid has already been used.
     */
    public X509v3CertificateBuilder addExtension(
        ASN1ObjectIdentifier oid,
        boolean isCritical,
        ASN1Encodable value)
        throws CertIOException
    {
        try
        {
            extGenerator.addExtension(oid, isCritical, value);
        }
        catch (IOException e)
        {
            throw new CertIOException("cannot encode extension: " + e.getMessage(), e);
        }

        return this;
    }

    /**
     * Add a given extension field for the standard extensions tag (tag 3).
     *
     * @param extension the full extension value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the OID oid has already been used.
     */
    public X509v3CertificateBuilder addExtension(
        Extension extension)
        throws CertIOException
    {
        extGenerator.addExtension(extension);

        return this;
    }

    /**
     * Add a given extension field for the standard extensions tag (tag 3) using a byte encoding of the
     * extension value.
     *
     * @param oid the OID defining the extension type.
     * @param isCritical true if the extension is critical, false otherwise.
     * @param encodedValue a byte array representing the encoding of the extension value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the OID oid has already been allocated.
     */
    public X509v3CertificateBuilder addExtension(
        ASN1ObjectIdentifier oid,
        boolean isCritical,
        byte[] encodedValue)
        throws CertIOException
    {
        extGenerator.addExtension(oid, isCritical, encodedValue);

        return this;
    }

    /**
     * Replace the extension field for the passed in extension's extension ID
     * with a new version.
     *
     * @param oid the OID defining the extension type.
     * @param isCritical true if the extension is critical, false otherwise.
     * @param value the ASN.1 structure that forms the extension's value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the extension to be replaced is not present.
     */
    public X509v3CertificateBuilder replaceExtension(
        ASN1ObjectIdentifier oid,
        boolean isCritical,
        ASN1Encodable value)
        throws CertIOException
    {
        try
        {
            extGenerator = CertUtils.doReplaceExtension(extGenerator, new Extension(oid, isCritical, value.toASN1Primitive().getEncoded(ASN1Encoding.DER)));
        }
        catch (IOException e)
        {
            throw new CertIOException("cannot encode extension: " + e.getMessage(), e);
        }

        return this;
    }

    /**
     * Replace the extension field for the passed in extension's extension ID
     * with a new version.
     *
     * @param extension the full extension value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the extension to be replaced is not present.
     */
    public X509v3CertificateBuilder replaceExtension(
        Extension extension)
        throws CertIOException
    {
        extGenerator = CertUtils.doReplaceExtension(extGenerator, extension);

        return this;
    }

    /**
     * Replace a given extension field for the standard extensions tag (tag 3) with the passed in
     * byte encoded extension value.
     *
     * @param oid the OID defining the extension type.
     * @param isCritical true if the extension is critical, false otherwise.
     * @param encodedValue a byte array representing the encoding of the extension value.
     * @return this builder object.
     * @throws CertIOException if there is an issue with the new extension value.
     * @throws IllegalArgumentException if the extension to be replaced is not present.
     */
    public X509v3CertificateBuilder replaceExtension(
        ASN1ObjectIdentifier oid,
        boolean isCritical,
        byte[] encodedValue)
        throws CertIOException
    {
        extGenerator = CertUtils.doReplaceExtension(extGenerator, new Extension(oid, isCritical, encodedValue));

        return this;
    }

    /**
     * Remove the extension indicated by OID.
     *
     * @param oid the OID of the extension to be removed.
     * @return this builder object.
     * @throws IllegalArgumentException if the extension to be removed is not present.
     */
    public X509v3CertificateBuilder removeExtension(ASN1ObjectIdentifier oid)
    {
        extGenerator = CertUtils.doRemoveExtension(extGenerator, oid);

        return this;
    }

    /**
     * Add a given extension field for the standard extensions tag (tag 3)
     * copying the extension value from another certificate.
     *
     * @param oid the OID defining the extension type.
     * @param isCritical true if the copied extension is to be marked as critical, false otherwise.
     * @param certHolder the holder for the certificate that the extension is to be copied from.
     * @return this builder object.
     */
    public X509v3CertificateBuilder copyAndAddExtension(
        ASN1ObjectIdentifier oid,
        boolean isCritical,
        X509CertificateHolder certHolder)
    {
        Certificate cert = certHolder.toASN1Structure();

        Extension extension = cert.getTBSCertificate().getExtensions().getExtension(oid);

        if (extension == null)
        {
            throw new NullPointerException("extension " + oid + " not present");
        }

        extGenerator.addExtension(oid, isCritical, extension.getExtnValue().getOctets());

        return this;
    }

    /**
     * Generate an X.509 certificate, based on the current issuer and subject
     * using the passed in signer.
     *
     * @param signer the content signer to be used to generate the signature validating the certificate.
     * @return a holder containing the resulting signed certificate.
     */
    public X509CertificateHolder build(
        ContentSigner signer)
    {
        tbsGen.setSignature(signer.getAlgorithmIdentifier());

        if (!extGenerator.isEmpty())
        {
            if (extGenerator.hasExtension(Extension.deltaCertificateDescriptor))
            {
                Extension deltaExt = extGenerator.getExtension(Extension.deltaCertificateDescriptor);
                DeltaCertificateDescriptor deltaDesc = DeltaCertificateDescriptor.getInstance(deltaExt.getParsedValue());

                try
                {
                    extGenerator.replaceExtension(Extension.deltaCertificateDescriptor, deltaExt.isCritical(),
                        deltaDesc.trimTo(tbsGen.generateTBSCertificate(), extGenerator.generate()));
                }
                catch (IOException e)
                {
                    throw new IllegalStateException("unable to replace deltaCertificateDescriptor: " + e.getMessage()) ;
                }
            }
            tbsGen.setExtensions(extGenerator.generate());
        }

        try
        {
            TBSCertificate tbsCert = tbsGen.generateTBSCertificate();
            return new X509CertificateHolder(generateStructure(tbsCert, signer.getAlgorithmIdentifier(), generateSig(signer, tbsCert)));
        }
        catch (IOException e)
        {
            throw Exceptions.illegalArgumentException("cannot produce certificate signature", e);
        }
    }

    /**
     * Generate an X.509 certificate, based on the current issuer and subject
     * using the passed in signer and containing altSignatureAlgorithm and altSignatureValue extensions
     * based on the passed altSigner.
     *
     * @param signer the content signer to be used to generate the signature validating the certificate.
     * @param altSigner the content signer used to create the altSignatureAlgorithm and altSignatureValue extension.
     * @return a holder containing the resulting signed certificate.
     */
    public X509CertificateHolder build(
        ContentSigner signer,
        boolean isCritical,
        ContentSigner altSigner)
    {
        try
        {
            extGenerator.addExtension(Extension.altSignatureAlgorithm, isCritical, altSigner.getAlgorithmIdentifier());
        }
        catch (IOException e)
        {
            throw Exceptions.illegalStateException("cannot add altSignatureAlgorithm extension", e);
        }

        if (extGenerator.hasExtension(Extension.deltaCertificateDescriptor))
        {
            tbsGen.setSignature(signer.getAlgorithmIdentifier());
            
            Extension deltaExt = extGenerator.getExtension(Extension.deltaCertificateDescriptor);
            DeltaCertificateDescriptor deltaDesc = DeltaCertificateDescriptor.getInstance(deltaExt.getParsedValue());

            try
            {
                // the altSignatureValue is not present yet, but it must be in the deltaCertificate and
                // it must be different (by definition!). We add a dummy one to trigger inclusion.
                ExtensionsGenerator tmpExtGen = new ExtensionsGenerator();
                tmpExtGen.addExtension(extGenerator.generate());
                tmpExtGen.addExtension(Extension.altSignatureValue, false, DERNull.INSTANCE);

                extGenerator.replaceExtension(Extension.deltaCertificateDescriptor, deltaExt.isCritical(),
                    deltaDesc.trimTo(tbsGen.generateTBSCertificate(), tmpExtGen.generate()));
            }
            catch (IOException e)
            {
                throw new IllegalStateException("unable to replace deltaCertificateDescriptor: " + e.getMessage());
            }
        }

        tbsGen.setSignature(null);

        tbsGen.setExtensions(extGenerator.generate());

        try
        {
            extGenerator.addExtension(Extension.altSignatureValue, isCritical, new DERBitString(generateSig(altSigner, tbsGen.generatePreTBSCertificate())));

            tbsGen.setSignature(signer.getAlgorithmIdentifier());

            tbsGen.setExtensions(extGenerator.generate());
            
            TBSCertificate tbsCert = tbsGen.generateTBSCertificate();
            return new X509CertificateHolder(generateStructure(tbsCert, signer.getAlgorithmIdentifier(), generateSig(signer, tbsCert)));
        }
        catch (IOException e)
        {
            throw Exceptions.illegalArgumentException("cannot produce certificate signature", e);
        }
    }

    private static byte[] generateSig(ContentSigner signer, ASN1Object tbsObj)
        throws IOException
    {
        OutputStream sOut = signer.getOutputStream();
        tbsObj.encodeTo(sOut, ASN1Encoding.DER);
        sOut.close();

        return signer.getSignature();
    }

    private static Certificate generateStructure(TBSCertificate tbsCert, AlgorithmIdentifier sigAlgId, byte[] signature)
    {
        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(tbsCert);
        v.add(sigAlgId);
        v.add(new DERBitString(signature));

        return Certificate.getInstance(new DERSequence(v));
    }

    static DERBitString booleanToBitString(boolean[] id)
    {
        byte[] bytes = new byte[(id.length + 7) / 8];

        for (int i = 0; i != id.length; i++)
        {
            bytes[i / 8] |= (id[i]) ? (1 << ((7 - (i % 8)))) : 0;
        }

        int pad = id.length % 8;

        if (pad == 0)
        {
            return new DERBitString(bytes);
        }
        else
        {
            return new DERBitString(bytes, 8 - pad);
        }
    }
}