using System;
using System.Collections;
using System.IO;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.CryptoPro;
using Org.BouncyCastle.Asn1.Nist;
using Org.BouncyCastle.Asn1.Oiw;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.TeleTrust;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using Org.BouncyCastle.Utilities.Collections;

namespace Org.BouncyCastle.X509
{
	internal class X509Utilities
	{
        private static readonly IDictionary algorithms = Platform.CreateHashtable();
        private static readonly IDictionary exParams = Platform.CreateHashtable();
		private static readonly ISet        noParams = new HashSet();

		static X509Utilities()
		{
			algorithms.Add("MD2WITHRSAENCRYPTION", PkcsObjectIdentifiers.MD2WithRsaEncryption);
			algorithms.Add("MD2WITHRSA", PkcsObjectIdentifiers.MD2WithRsaEncryption);
			algorithms.Add("MD5WITHRSAENCRYPTION", PkcsObjectIdentifiers.MD5WithRsaEncryption);
			algorithms.Add("MD5WITHRSA", PkcsObjectIdentifiers.MD5WithRsaEncryption);
			algorithms.Add("SHA1WITHRSAENCRYPTION", PkcsObjectIdentifiers.Sha1WithRsaEncryption);
			algorithms.Add("SHA1WITHRSA", PkcsObjectIdentifiers.Sha1WithRsaEncryption);
			algorithms.Add("SHA224WITHRSAENCRYPTION", PkcsObjectIdentifiers.Sha224WithRsaEncryption);
			algorithms.Add("SHA224WITHRSA", PkcsObjectIdentifiers.Sha224WithRsaEncryption);
			algorithms.Add("SHA256WITHRSAENCRYPTION", PkcsObjectIdentifiers.Sha256WithRsaEncryption);
			algorithms.Add("SHA256WITHRSA", PkcsObjectIdentifiers.Sha256WithRsaEncryption);
			algorithms.Add("SHA384WITHRSAENCRYPTION", PkcsObjectIdentifiers.Sha384WithRsaEncryption);
			algorithms.Add("SHA384WITHRSA", PkcsObjectIdentifiers.Sha384WithRsaEncryption);
			algorithms.Add("SHA512WITHRSAENCRYPTION", PkcsObjectIdentifiers.Sha512WithRsaEncryption);
			algorithms.Add("SHA512WITHRSA", PkcsObjectIdentifiers.Sha512WithRsaEncryption);
			algorithms.Add("SHA1WITHRSAANDMGF1", PkcsObjectIdentifiers.IdRsassaPss);
			algorithms.Add("SHA224WITHRSAANDMGF1", PkcsObjectIdentifiers.IdRsassaPss);
			algorithms.Add("SHA256WITHRSAANDMGF1", PkcsObjectIdentifiers.IdRsassaPss);
			algorithms.Add("SHA384WITHRSAANDMGF1", PkcsObjectIdentifiers.IdRsassaPss);
			algorithms.Add("SHA512WITHRSAANDMGF1", PkcsObjectIdentifiers.IdRsassaPss);
			algorithms.Add("RIPEMD160WITHRSAENCRYPTION", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD160);
			algorithms.Add("RIPEMD160WITHRSA", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD160);
			algorithms.Add("RIPEMD128WITHRSAENCRYPTION", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD128);
			algorithms.Add("RIPEMD128WITHRSA", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD128);
			algorithms.Add("RIPEMD256WITHRSAENCRYPTION", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD256);
			algorithms.Add("RIPEMD256WITHRSA", TeleTrusTObjectIdentifiers.RsaSignatureWithRipeMD256);
			algorithms.Add("SHA1WITHDSA", X9ObjectIdentifiers.IdDsaWithSha1);
			algorithms.Add("DSAWITHSHA1", X9ObjectIdentifiers.IdDsaWithSha1);
			algorithms.Add("SHA224WITHDSA", NistObjectIdentifiers.DsaWithSha224);
			algorithms.Add("SHA256WITHDSA", NistObjectIdentifiers.DsaWithSha256);
			algorithms.Add("SHA384WITHDSA", NistObjectIdentifiers.DsaWithSha384);
			algorithms.Add("SHA512WITHDSA", NistObjectIdentifiers.DsaWithSha512);
			algorithms.Add("SHA1WITHECDSA", X9ObjectIdentifiers.ECDsaWithSha1);
			algorithms.Add("ECDSAWITHSHA1", X9ObjectIdentifiers.ECDsaWithSha1);
			algorithms.Add("SHA224WITHECDSA", X9ObjectIdentifiers.ECDsaWithSha224);
			algorithms.Add("SHA256WITHECDSA", X9ObjectIdentifiers.ECDsaWithSha256);
			algorithms.Add("SHA384WITHECDSA", X9ObjectIdentifiers.ECDsaWithSha384);
			algorithms.Add("SHA512WITHECDSA", X9ObjectIdentifiers.ECDsaWithSha512);
			algorithms.Add("GOST3411WITHGOST3410", CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x94);
			algorithms.Add("GOST3411WITHGOST3410-94", CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x94);
			algorithms.Add("GOST3411WITHECGOST3410", CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x2001);
			algorithms.Add("GOST3411WITHECGOST3410-2001", CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x2001);
			algorithms.Add("GOST3411WITHGOST3410-2001", CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x2001);

			//
			// According to RFC 3279, the ASN.1 encoding SHALL (id-dsa-with-sha1) or MUST (ecdsa-with-SHA*) omit the parameters field.
			// The parameters field SHALL be NULL for RSA based signature algorithms.
			//
			noParams.Add(X9ObjectIdentifiers.ECDsaWithSha1);
			noParams.Add(X9ObjectIdentifiers.ECDsaWithSha224);
			noParams.Add(X9ObjectIdentifiers.ECDsaWithSha256);
			noParams.Add(X9ObjectIdentifiers.ECDsaWithSha384);
			noParams.Add(X9ObjectIdentifiers.ECDsaWithSha512);
			noParams.Add(X9ObjectIdentifiers.IdDsaWithSha1);
			noParams.Add(NistObjectIdentifiers.DsaWithSha224);
			noParams.Add(NistObjectIdentifiers.DsaWithSha256);
			noParams.Add(NistObjectIdentifiers.DsaWithSha384);
			noParams.Add(NistObjectIdentifiers.DsaWithSha512);

			//
			// RFC 4491
			//
			noParams.Add(CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x94);
			noParams.Add(CryptoProObjectIdentifiers.GostR3411x94WithGostR3410x2001);

			//
			// explicit params
			//
			AlgorithmIdentifier sha1AlgId = new AlgorithmIdentifier(OiwObjectIdentifiers.IdSha1, DerNull.Instance);
			exParams.Add("SHA1WITHRSAANDMGF1", CreatePssParams(sha1AlgId, 20));

			AlgorithmIdentifier sha224AlgId = new AlgorithmIdentifier(NistObjectIdentifiers.IdSha224, DerNull.Instance);
			exParams.Add("SHA224WITHRSAANDMGF1", CreatePssParams(sha224AlgId, 28));

			AlgorithmIdentifier sha256AlgId = new AlgorithmIdentifier(NistObjectIdentifiers.IdSha256, DerNull.Instance);
			exParams.Add("SHA256WITHRSAANDMGF1", CreatePssParams(sha256AlgId, 32));

			AlgorithmIdentifier sha384AlgId = new AlgorithmIdentifier(NistObjectIdentifiers.IdSha384, DerNull.Instance);
			exParams.Add("SHA384WITHRSAANDMGF1", CreatePssParams(sha384AlgId, 48));

			AlgorithmIdentifier sha512AlgId = new AlgorithmIdentifier(NistObjectIdentifiers.IdSha512, DerNull.Instance);
			exParams.Add("SHA512WITHRSAANDMGF1", CreatePssParams(sha512AlgId, 64));
		}

		private static RsassaPssParameters CreatePssParams(
			AlgorithmIdentifier	hashAlgId,
			int					saltSize)
		{
			return new RsassaPssParameters(
				hashAlgId,
				new AlgorithmIdentifier(PkcsObjectIdentifiers.IdMgf1, hashAlgId),
				new DerInteger(saltSize),
				new DerInteger(1));
		}

		internal static DerObjectIdentifier GetAlgorithmOid(
			string algorithmName)
		{
			algorithmName = Platform.ToUpperInvariant(algorithmName);

            if (algorithms.Contains(algorithmName))
			{
				return (DerObjectIdentifier) algorithms[algorithmName];
			}

			return new DerObjectIdentifier(algorithmName);
		}

		internal static AlgorithmIdentifier GetSigAlgID(
			DerObjectIdentifier sigOid,
			string				algorithmName)
		{
			if (noParams.Contains(sigOid))
			{
				return new AlgorithmIdentifier(sigOid);
			}

            algorithmName = Platform.ToUpperInvariant(algorithmName);

			if (exParams.Contains(algorithmName))
			{
				return new AlgorithmIdentifier(sigOid, (Asn1Encodable) exParams[algorithmName]);
			}

			return new AlgorithmIdentifier(sigOid, DerNull.Instance);
		}

		internal static IEnumerable GetAlgNames()
		{
			return new EnumerableProxy(algorithms.Keys);
		}

		internal static byte[] GetSignatureForObject(
			DerObjectIdentifier		sigOid, // TODO Redundant now?
			string					sigName,
			AsymmetricKeyParameter	privateKey,
			SecureRandom			random,
			Asn1Encodable			ae)
		{
			if (sigOid == null)
				throw new ArgumentNullException("sigOid");

			ISigner sig = SignerUtilities.GetSigner(sigName);

			if (random != null)
			{
				sig.Init(true, new ParametersWithRandom(privateKey, random));
			}
			else
			{
				sig.Init(true, privateKey);
			}

			byte[] encoded = ae.GetDerEncoded();
			sig.BlockUpdate(encoded, 0, encoded.Length);

			return sig.GenerateSignature();
		}
	}
}