// Copyright (C) 2024 Vaughn Nugent
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

using System;

using VNLib.Utils.Native;
using VNLib.Utils.Extensions;

using NCResult = System.Int64;

namespace VNLib.Utils.Cryptography.Noscrypt.@internal
{

    internal unsafe readonly struct FunctionTable
    {

        public readonly NCGetContextStructSizeDelegate NCGetContextStructSize;
        public readonly NCInitContextDelegate NCInitContext;
        public readonly NCReInitContextDelegate NCReInitContext;
        public readonly NCDestroyContextDelegate NCDestroyContext;
        public readonly NCGetPublicKeyDelegate NCGetPublicKey;
        public readonly NCValidateSecretKeyDelegate NCValidateSecretKey;
        public readonly NCSignDataDelegate NCSignData;
        public readonly NCVerifyDataDelegate NCVerifyData;
        public readonly NCEncryptDelegate NCEncrypt;
        public readonly NCDecryptDelegate NCDecrypt;
        public readonly NCVerifyMacDelegate NCVerifyMac;
        public readonly NCComputeMacDelegate NCComputeMac;

#if DEBUG
        public readonly NCGetConversationKeyDelegate NCGetConversationKey;
#endif

        private FunctionTable(SafeLibraryHandle library)
        {
            //Load the required high-level api functions
            NCGetContextStructSize = library.DangerousGetFunction<NCGetContextStructSizeDelegate>();
            NCInitContext = library.DangerousGetFunction<NCInitContextDelegate>();
            NCReInitContext = library.DangerousGetFunction<NCReInitContextDelegate>();
            NCDestroyContext = library.DangerousGetFunction<NCDestroyContextDelegate>();
            NCGetPublicKey = library.DangerousGetFunction<NCGetPublicKeyDelegate>();
            NCValidateSecretKey = library.DangerousGetFunction<NCValidateSecretKeyDelegate>();
            NCSignData = library.DangerousGetFunction<NCSignDataDelegate>();
            NCVerifyData = library.DangerousGetFunction<NCVerifyDataDelegate>();
            NCSignData = library.DangerousGetFunction<NCSignDataDelegate>();
            NCVerifyData = library.DangerousGetFunction<NCVerifyDataDelegate>();
            NCEncrypt = library.DangerousGetFunction<NCEncryptDelegate>();
            NCDecrypt = library.DangerousGetFunction<NCDecryptDelegate>();
            NCVerifyMac = library.DangerousGetFunction<NCVerifyMacDelegate>();
            NCComputeMac = library.DangerousGetFunction<NCComputeMacDelegate>();

#if DEBUG
            NCGetConversationKey = library.DangerousGetFunction<NCGetConversationKeyDelegate>();
#endif
        }

        /// <summary>
        /// Initialize a new function table from the specified library
        /// </summary>
        /// <param name="library"></param>
        /// <returns>The function table structure</returns>
        /// <exception cref="MissingMemberException"></exception>
        /// <exception cref="EntryPointNotFoundException"></exception>
        public static FunctionTable BuildFunctionTable(SafeLibraryHandle library) => new (library);

        /*
         * ################################################
         * 
         *      Functions match the noscrypt.h header file
         * 
         * ################################################
         */

        //FUCNTIONS
        [SafeMethodName("NCGetContextStructSize")]
        internal delegate uint NCGetContextStructSizeDelegate();

        [SafeMethodName("NCInitContext")]
        internal delegate NCResult NCInitContextDelegate(IntPtr ctx, byte* entropy32);

        [SafeMethodName("NCReInitContext")]
        internal delegate NCResult NCReInitContextDelegate(IntPtr ctx, byte* entropy32);

        [SafeMethodName("NCDestroyContext")]
        internal delegate NCResult NCDestroyContextDelegate(IntPtr ctx);

        [SafeMethodName("NCGetPublicKey")]
        internal delegate NCResult NCGetPublicKeyDelegate(IntPtr ctx, NCSecretKey* secKey, NCPublicKey* publicKey);

        [SafeMethodName("NCValidateSecretKey")]
        internal delegate NCResult NCValidateSecretKeyDelegate(IntPtr ctx, NCSecretKey* secKey);

        [SafeMethodName("NCSignData")]
        internal delegate NCResult NCSignDataDelegate(IntPtr ctx, NCSecretKey* sk, byte* random32, byte* data, uint dataSize, byte* sig64);

        [SafeMethodName("NCVerifyData")]
        internal delegate NCResult NCVerifyDataDelegate(IntPtr ctx, NCPublicKey* sk, byte* data, uint dataSize, byte* sig64);

        [SafeMethodName("NCEncrypt")]
        internal delegate NCResult NCEncryptDelegate(IntPtr ctx, NCSecretKey* sk, NCPublicKey* pk, NCEncryptionArgs* data);

        [SafeMethodName("NCDecrypt")]
        internal delegate NCResult NCDecryptDelegate(IntPtr ctx, NCSecretKey* sk, NCPublicKey* pk, NCEncryptionArgs* data);

        [SafeMethodName("NCVerifyMac")]
        internal delegate NCResult NCVerifyMacDelegate(IntPtr ctx, NCSecretKey* sk, NCPublicKey* pk, NCMacVerifyArgs* args);

        [SafeMethodName("NCComputeMac")]
        internal delegate NCResult NCComputeMacDelegate(IntPtr ctx, byte* hmacKey32, byte* payload, uint payloadSize, byte* hmacOut32);

        [SafeMethodName("NCGetConversationKey")]
        internal delegate NCResult NCGetConversationKeyDelegate(nint ctx, NCSecretKey* sk, NCPublicKey* pk, byte* keyOut32);

    }
}