using System;
using System.Collections.Generic;

using Org.BouncyCastle.Asn1.Rosstandart;
using Org.BouncyCastle.Asn1.X9;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Math.EC.Multiplier;
using Org.BouncyCastle.Utilities.Collections;
using Org.BouncyCastle.Utilities.Encoders;

namespace Org.BouncyCastle.Asn1.CryptoPro
{
    /// <summary>Elliptic curve registry for GOST 3410-2001 / 2012.</summary>
    public static class ECGost3410NamedCurves
    {
        private static X9ECPoint ConfigureBasepoint(ECCurve curve, BigInteger x, BigInteger y)
        {
            ECPoint G = curve.CreatePoint(x, y);
            WNafUtilities.ConfigureBasepoint(G);
            return new X9ECPoint(G, false);
        }

        private static ECCurve ConfigureCurve(ECCurve curve)
        {
            return curve;
        }

        private static BigInteger FromHex(string hex)
        {
            return new BigInteger(1, Hex.DecodeStrict(hex));
        }

        internal class Holder_gostR3410_2001_CryptoPro_A
            : X9ECParametersHolder
        {
            private Holder_gostR3410_2001_CryptoPro_A() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_gostR3410_2001_CryptoPro_A();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD97");
                BigInteger mod_q = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF6C611070995AD10045841B09B761B893");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD94"),
                    FromHex("A6"),
                    mod_q, BigInteger.One, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    BigInteger.One,
                    FromHex("8D91E471E0989CDA27DF505A453F2B7635294F2DDF23E3B122ACC99C9E9F1E14"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_gostR3410_2001_CryptoPro_B
            : X9ECParametersHolder
        {
            private Holder_gostR3410_2001_CryptoPro_B() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_gostR3410_2001_CryptoPro_B();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("8000000000000000000000000000000000000000000000000000000000000C99");
                BigInteger mod_q = FromHex("800000000000000000000000000000015F700CFFF1A624E5E497161BCC8A198F");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("8000000000000000000000000000000000000000000000000000000000000C96"),
                    FromHex("3E1AF419A269A5F866A7D3C25C3DF80AE979259373FF2B182F49D4CE7E1BBC8B"),
                    mod_q, BigInteger.One, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    BigInteger.One,
                    FromHex("3FA8124359F96680B83D1C3EB2C070E5C545C9858D03ECFB744BF8D717717EFC"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_gostR3410_2001_CryptoPro_C
            : X9ECParametersHolder
        {
            private Holder_gostR3410_2001_CryptoPro_C() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_gostR3410_2001_CryptoPro_C();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("9B9F605F5A858107AB1EC85E6B41C8AACF846E86789051D37998F7B9022D759B");
                BigInteger mod_q = FromHex("9B9F605F5A858107AB1EC85E6B41C8AA582CA3511EDDFB74F02F3A6598980BB9");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("9B9F605F5A858107AB1EC85E6B41C8AACF846E86789051D37998F7B9022D7598"),
                    FromHex("805A"),
                    mod_q, BigInteger.One, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    BigInteger.Zero,
                    FromHex("41ECE55743711A8C3CBF3783CD08C0EE4D4DC440D4641A8F366E550DFDB3BB67"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_id_tc26_gost_3410_12_256_paramSetA
            : X9ECParametersHolder
        {
            private Holder_id_tc26_gost_3410_12_256_paramSetA() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_id_tc26_gost_3410_12_256_paramSetA();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFD97");
                BigInteger mod_q = FromHex("400000000000000000000000000000000FD8CDDFC87B6635C115AF556C360C67");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("C2173F1513981673AF4892C23035A27CE25E2013BF95AA33B22C656F277E7335"),
                    FromHex("295F9BAE7428ED9CCC20E7C359A9D41A22FCCD9108E17BF7BA9337A6F8AE9513"),
                    mod_q, BigInteger.Four, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    FromHex("91E38443A5E82C0D880923425712B2BB658B9196932E02C78B2582FE742DAA28"),
                    FromHex("32879423AB1A0375895786C4BB46E9565FDE0B5344766740AF268ADB32322E5C"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_id_tc26_gost_3410_12_512_paramSetA
            : X9ECParametersHolder
        {
            private Holder_id_tc26_gost_3410_12_512_paramSetA() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_id_tc26_gost_3410_12_512_paramSetA();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFDC7");
                BigInteger mod_q = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF27E69532F48D89116FF22B8D4E0560609B4B38ABFAD2B85DCACDB1411F10B275");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFDC4"),
                    FromHex("E8C2505DEDFC86DDC1BD0B2B6667F1DA34B82574761CB0E879BD081CFD0B6265EE3CB090F30D27614CB4574010DA90DD862EF9D4EBEE4761503190785A71C760"),
                    mod_q, BigInteger.One, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    BigInteger.Three,
                    FromHex("7503CFE87A836AE3A61B8816E25450E6CE5E1C93ACF1ABC1778064FDCBEFA921DF1626BE4FD036E93D75E6A50E3A41E98028FE5FC235F5B889A589CB5215F2A4"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_id_tc26_gost_3410_12_512_paramSetB
            : X9ECParametersHolder
        {
            private Holder_id_tc26_gost_3410_12_512_paramSetB() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_id_tc26_gost_3410_12_512_paramSetB();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("8000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006F");
                BigInteger mod_q = FromHex("800000000000000000000000000000000000000000000000000000000000000149A1EC142565A545ACFDB77BD9D40CFA8B996712101BEA0EC6346C54374F25BD");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("8000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006C"),
                    FromHex("687D1B459DC841457E3E06CF6F5E2517B97C7D614AF138BCBF85DC806C4B289F3E965D2DB1416D217F8B276FAD1AB69C50F78BEE1FA3106EFB8CCBC7C5140116"),
                    mod_q, BigInteger.One, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    BigInteger.Two,
                    FromHex("1A8F7EDA389B094C2C071E3647A8940F3C123B697578C213BE6DD9E6C8EC7335DCB228FD1EDF4A39152CBCAAF8C0398828041055F94CEEEC7E21340780FE41BD"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        internal class Holder_id_tc26_gost_3410_12_512_paramSetC
            : X9ECParametersHolder
        {
            private Holder_id_tc26_gost_3410_12_512_paramSetC() {}

            internal static readonly X9ECParametersHolder Instance = new Holder_id_tc26_gost_3410_12_512_paramSetC();

            protected override ECCurve CreateCurve()
            {
                BigInteger mod_p = FromHex("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFDC7");
                BigInteger mod_q = FromHex("3FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFC98CDBA46506AB004C33A9FF5147502CC8EDA9E7A769A12694623CEF47F023ED");

                return ConfigureCurve(new FpCurve(
                    mod_p,
                    FromHex("DC9203E514A721875485A529D2C722FB187BC8980EB866644DE41C68E143064546E861C0E2C9EDD92ADE71F46FCF50FF2AD97F951FDA9F2A2EB6546F39689BD3"),
                    FromHex("B4C4EE28CEBC6C2C8AC12952CF37F16AC7EFB6A9F69F4B57FFDA2E4F0DE5ADE038CBC2FFF719D2C18DE0284B8BFEF3B52B8CC7A5F5BF0A3C8D2319A5312557E1"),
                    mod_q, BigInteger.Four, isInternal: true));
            }

            protected override X9ECParameters CreateParameters()
            {
                byte[] S = null;
                ECCurve curve = Curve;

                X9ECPoint G = ConfigureBasepoint(curve,
                    FromHex("E2E31EDFC23DE7BDEBE241CE593EF5DE2295B7A9CBAEF021D385F7074CEA043AA27272A7AE602BF2A7B9033DB9ED3610C6FB85487EAE97AAC5BC7928C1950148"),
                    FromHex("F5CE40D95B5EB899ABBCCFF5911CB8577939804D6527378B8C108C3D2090FF9BE18E2D33E3021ED2EF32D85822423B6304F726AA854BAE07D0396E9A9ADDC40F"));

                return new X9ECParameters(curve, G, curve.Order, curve.Cofactor, S);
            }
        };

        private static readonly Dictionary<string, DerObjectIdentifier> objIds =
            new Dictionary<string, DerObjectIdentifier>(StringComparer.OrdinalIgnoreCase);
        private static readonly Dictionary<DerObjectIdentifier, X9ECParametersHolder> curves =
            new Dictionary<DerObjectIdentifier, X9ECParametersHolder>();
        private static readonly Dictionary<DerObjectIdentifier, string> names =
            new Dictionary<DerObjectIdentifier, string>();

        private static void DefineCurve(string name, DerObjectIdentifier oid, X9ECParametersHolder holder)
        {
            objIds.Add(name, oid);
            names.Add(oid, name);
            curves.Add(oid, holder);
        }

        static ECGost3410NamedCurves()
        {
            DefineCurve("GostR3410-2001-CryptoPro-A",
                CryptoProObjectIdentifiers.GostR3410x2001CryptoProA,
                Holder_gostR3410_2001_CryptoPro_A.Instance);
            DefineCurve("GostR3410-2001-CryptoPro-B",
                CryptoProObjectIdentifiers.GostR3410x2001CryptoProB,
                Holder_gostR3410_2001_CryptoPro_B.Instance);
            DefineCurve("GostR3410-2001-CryptoPro-C",
                CryptoProObjectIdentifiers.GostR3410x2001CryptoProC,
                Holder_gostR3410_2001_CryptoPro_C.Instance);
            DefineCurve("GostR3410-2001-CryptoPro-XchA",
                CryptoProObjectIdentifiers.GostR3410x2001CryptoProXchA,
                Holder_gostR3410_2001_CryptoPro_A.Instance);
            DefineCurve("GostR3410-2001-CryptoPro-XchB",
                CryptoProObjectIdentifiers.GostR3410x2001CryptoProXchB,
                Holder_gostR3410_2001_CryptoPro_C.Instance);
            DefineCurve("Tc26-Gost-3410-12-256-paramSetA",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_256_paramSetA,
                Holder_id_tc26_gost_3410_12_256_paramSetA.Instance);
            DefineCurve("Tc26-Gost-3410-12-256-paramSetB",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_256_paramSetB,
                Holder_gostR3410_2001_CryptoPro_A.Instance);
            DefineCurve("Tc26-Gost-3410-12-256-paramSetC",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_256_paramSetC,
                Holder_gostR3410_2001_CryptoPro_B.Instance);
            DefineCurve("Tc26-Gost-3410-12-256-paramSetD",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_256_paramSetD,
                Holder_gostR3410_2001_CryptoPro_C.Instance);
            DefineCurve("Tc26-Gost-3410-12-512-paramSetA",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_512_paramSetA,
                Holder_id_tc26_gost_3410_12_512_paramSetA.Instance);
            DefineCurve("Tc26-Gost-3410-12-512-paramSetB",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_512_paramSetB,
                Holder_id_tc26_gost_3410_12_512_paramSetB.Instance);
            DefineCurve("Tc26-Gost-3410-12-512-paramSetC",
                RosstandartObjectIdentifiers.id_tc26_gost_3410_12_512_paramSetC,
                Holder_id_tc26_gost_3410_12_512_paramSetC.Instance);
        }

        /// <summary>Look up the <see cref="X9ECParameters"/> for the curve with the given name.</summary>
        /// <param name="name">The name of the curve.</param>
        public static X9ECParameters GetByName(string name)
        {
            DerObjectIdentifier oid = GetOid(name);
            return oid == null ? null : GetByOid(oid);
        }

        /// <summary>Look up an <see cref="X9ECParametersHolder"/> for the curve with the given name.</summary>
        /// <remarks>
        /// Allows accessing the <see cref="ECCurve">curve</see> without necessarily triggering the creation of the
        /// full <see cref="X9ECParameters"/>.
        /// </remarks>
        /// <param name="name">The name of the curve.</param>
        public static X9ECParametersHolder GetByNameLazy(string name)
        {
            DerObjectIdentifier oid = GetOid(name);
            return oid == null ? null : GetByOidLazy(oid);
        }

        /// <summary>Look up the <see cref="X9ECParameters"/> for the curve with the given
        /// <see cref="DerObjectIdentifier">OID</see>.</summary>
        /// <param name="oid">The <see cref="DerObjectIdentifier">OID</see> for the curve.</param>
        public static X9ECParameters GetByOid(DerObjectIdentifier oid)
        {
            return GetByOidLazy(oid)?.Parameters;
        }

        /// <summary>Look up an <see cref="X9ECParametersHolder"/> for the curve with the given
        /// <see cref="DerObjectIdentifier">OID</see>.</summary>
        /// <remarks>
        /// Allows accessing the <see cref="ECCurve">curve</see> without necessarily triggering the creation of the
        /// full <see cref="X9ECParameters"/>.
        /// </remarks>
        /// <param name="oid">The <see cref="DerObjectIdentifier">OID</see> for the curve.</param>
        public static X9ECParametersHolder GetByOidLazy(DerObjectIdentifier oid)
        {
            return CollectionUtilities.GetValueOrNull(curves, oid);
        }

        /// <summary>Look up the name of the curve with the given <see cref="DerObjectIdentifier">OID</see>.</summary>
        /// <param name="oid">The <see cref="DerObjectIdentifier">OID</see> for the curve.</param>
        public static string GetName(DerObjectIdentifier oid)
        {
            return CollectionUtilities.GetValueOrNull(names, oid);
        }

        /// <summary>Look up the <see cref="DerObjectIdentifier">OID</see> of the curve with the given name.</summary>
        /// <param name="name">The name of the curve.</param>
        public static DerObjectIdentifier GetOid(string name)
        {
            return CollectionUtilities.GetValueOrNull(objIds, name);
        }

        /// <summary>Enumerate the available curve names in this registry.</summary>
        public static IEnumerable<string> Names
        {
            get { return CollectionUtilities.Proxy(objIds.Keys); }
        }
    }
}