package org.bouncycastle.jcajce.provider.asymmetric.x509;

import java.io.IOException;
import java.security.AlgorithmParameters;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Signature;
import java.security.SignatureException;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1Null;
import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.cryptopro.CryptoProObjectIdentifiers;
import org.bouncycastle.asn1.nist.NISTObjectIdentifiers;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.RSASSAPSSparams;
import org.bouncycastle.asn1.teletrust.TeleTrusTObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.asn1.x9.X9ObjectIdentifiers;

class SignatureUtil
{
    private static final ASN1Null derNull = new DERNull();
    
    static String getSignatureName(
        AlgorithmIdentifier sigAlgId)
    {
        ASN1Encodable params = sigAlgId.getParameters();
        
        if (params != null && !derNull.equals(params))
        {
            if (sigAlgId.getAlgorithm().equals(PKCSObjectIdentifiers.id_RSASSA_PSS))
            {
                RSASSAPSSparams rsaParams = RSASSAPSSparams.getInstance(params);
                
                return getDigestAlgName(rsaParams.getHashAlgorithm().getAlgorithm()) + "withRSAandMGF1";
            }
            if (sigAlgId.getAlgorithm().equals(X9ObjectIdentifiers.ecdsa_with_SHA2))
            {
                ASN1Sequence ecDsaParams = ASN1Sequence.getInstance(params);
                
                return getDigestAlgName((ASN1ObjectIdentifier)ecDsaParams.getObjectAt(0)) + "withECDSA";
            }
        }

        return sigAlgId.getAlgorithm().getId();
    }
    
    /**
     * Return the digest algorithm using one of the standard JCA string
     * representations rather the the algorithm identifier (if possible).
     */
    private static String getDigestAlgName(
        ASN1ObjectIdentifier digestAlgOID)
    {
        if (PKCSObjectIdentifiers.md5.equals(digestAlgOID))
        {
            return "MD5";
        }
        else if (OIWObjectIdentifiers.idSHA1.equals(digestAlgOID))
        {
            return "SHA1";
        }
        else if (NISTObjectIdentifiers.id_sha224.equals(digestAlgOID))
        {
            return "SHA224";
        }
        else if (NISTObjectIdentifiers.id_sha256.equals(digestAlgOID))
        {
            return "SHA256";
        }
        else if (NISTObjectIdentifiers.id_sha384.equals(digestAlgOID))
        {
            return "SHA384";
        }
        else if (NISTObjectIdentifiers.id_sha512.equals(digestAlgOID))
        {
            return "SHA512";
        }
        else if (TeleTrusTObjectIdentifiers.ripemd128.equals(digestAlgOID))
        {
            return "RIPEMD128";
        }
        else if (TeleTrusTObjectIdentifiers.ripemd160.equals(digestAlgOID))
        {
            return "RIPEMD160";
        }
        else if (TeleTrusTObjectIdentifiers.ripemd256.equals(digestAlgOID))
        {
            return "RIPEMD256";
        }
        else if (CryptoProObjectIdentifiers.gostR3411.equals(digestAlgOID))
        {
            return "GOST3411";
        }
        else
        {
            return digestAlgOID.getId();            
        }
    }
}
