using Esiur.Data;
using Esiur.Engine;
using Esiur.Misc;
using Esiur.Security.Cryptography;
using Esiur.Security.Integrity;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace Esiur.Security.Authority
{
    public abstract class Certificate
    {
        protected DateTime issueDate, expireDate;
        protected RSA rsa;
        protected  Aes aes;

        protected byte[] publicRawData;
        protected byte[] privateRawData;
        protected ulong id;
        protected HashFunctionType hashFunction;

        public Certificate(ulong id, DateTime issueDate, DateTime expireDate, HashFunctionType hashFunction)
        {
            this.id = id;
            this.issueDate = issueDate;
            this.expireDate = expireDate;
            this.hashFunction = hashFunction;
        }

        public ulong Id
        {
            get { return id; }
        }

        public AsymetricEncryptionAlgorithmType AsymetricEncryptionAlgorithm
        {
            get { return AsymetricEncryptionAlgorithmType.RSA; }
        }

        public byte[] AsymetricEncrypt(byte[] message)
        {
            return rsa.Encrypt(message, RSAEncryptionPadding.OaepSHA512);
        }


        public byte[] AsymetricEncrypt(byte[] message, uint offset, uint length)
        {
            if (message.Length != length)
                return rsa.Encrypt(DC.Clip(message, offset, length), RSAEncryptionPadding.OaepSHA512);
            else
                return rsa.Encrypt(message, RSAEncryptionPadding.OaepSHA512);
        }

        public byte[] AsymetricDecrypt(byte[] message)
        {
            try
            {
                return rsa.Decrypt(message, RSAEncryptionPadding.OaepSHA512);
            }
            catch (Exception ex)
            {
                Global.Log("Certificate", LogType.Error, ex.ToString());
                return null;
            }
        }

        public byte[] AsymetricDecrypt(byte[] message, uint offset, uint length)
        {
            try
            {
                if (message.Length != length)
                    return rsa.Decrypt(DC.Clip(message, offset, length), RSAEncryptionPadding.OaepSHA512);
                else
                    return rsa.Decrypt(message, RSAEncryptionPadding.OaepSHA512);

            }
            catch (Exception ex)
            {
                Global.Log("Certificate", LogType.Error, ex.ToString());
                return null;
            }
        }

        public byte[] SymetricEncrypt(byte[] message, uint offset, uint length)
        {
            byte[] rt = null;

            using (var ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
                    cs.Write(message, (int)offset, (int)length);

                rt = ms.ToArray();
            }

            return rt;
        }

        public byte[] SymetricEncrypt(byte[] message)
        {
            return SymetricEncrypt(message, 0, (uint)message.Length);
        }

        public byte[] SymetricDecrypt(byte[] message, uint offset, uint length)
        {
            byte[] rt = null;

            using (var ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
                    cs.Write(message, (int)offset, (int)length);

                rt = ms.ToArray();
            }

            return rt;
        }

        public byte[] SymetricDecrypt(byte[] message)
        {
            return SymetricDecrypt(message, 0, (uint)message.Length);
        }

        public byte[] Sign(byte[] message)
        {
            return Sign(message, 0, (uint)message.Length);
        }

        public byte[] Sign(byte[] message, uint offset, uint length)
        {
            if (hashFunction == HashFunctionType.SHA1)
                return rsa.SignData(message, (int)offset, (int)length, HashAlgorithmName.SHA1, RSASignaturePadding.Pkcs1);
            else if (hashFunction == HashFunctionType.MD5)
                return rsa.SignData(message, (int)offset, (int)length, HashAlgorithmName.MD5, RSASignaturePadding.Pkcs1);
            else if (hashFunction == HashFunctionType.SHA256)
                return rsa.SignData(message, (int)offset, (int)length, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
            else if (hashFunction == HashFunctionType.SHA384)
                return rsa.SignData(message, (int)offset, (int)length, HashAlgorithmName.SHA384, RSASignaturePadding.Pkcs1);
            else if (hashFunction == HashFunctionType.SHA512)
                return rsa.SignData(message, (int)offset, (int)length, HashAlgorithmName.SHA512, RSASignaturePadding.Pkcs1);

            return null;
        }

        public bool InitializeSymetricCipher(SymetricEncryptionAlgorithmType algorithm, int keyLength, byte[] key, byte[] iv)
        {
            if (algorithm == SymetricEncryptionAlgorithmType.AES)
            {
                if (keyLength == 0) // 128 bit
                {
                    aes = Aes.Create();
                    aes.Mode = CipherMode.CBC;
                    aes.Padding = PaddingMode.PKCS7;
                    aes.Key = key;
                    aes.IV = iv;

                    return true;
                }
            }

            return false;
        }


        public abstract bool Save(string filename, bool includePrivate = false);
        public abstract byte[] Serialize(bool includePrivate = false);

        public static Certificate Load(string filename)
        {
            byte[] ar = File.ReadAllBytes(filename);
            var t = (CertificateType)ar[0];

            switch (t)
            {
                case CertificateType.CAPublic:
                    return new CACertificate(ar, 1, (uint)ar.Length - 1);
                case CertificateType.CAPrivate:
                    return new CACertificate(ar, 1, (uint)ar.Length - 1, true);
                case CertificateType.DomainPublic:
                    return new DomainCertificate(ar, 1, (uint)ar.Length - 1);
                case CertificateType.DomainPrivate:
                    return new DomainCertificate(ar, 1, (uint)ar.Length - 1, true);
                case CertificateType.UserPublic:
                    return new UserCertificate(ar, 1, (uint)ar.Length - 1);
                case CertificateType.UserPrivate:
                    return new UserCertificate(ar, 1, (uint)ar.Length - 1, true);
            }

            return null;
        }
    }

}