using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.IO;

namespace Common
{
    public class Encryption
    {
        //Admin password Test123
        public string HashString(string mytext)
        {
            SHA256 myAlg = SHA256.Create();//initialize the algorithm instance

            byte[] input = Encoding.UTF32.GetBytes(mytext); //converting from string to byte[]
            byte[] digest = myAlg.ComputeHash(input); //converting from string to byte[]

            return Convert.ToBase64String(digest); //converting back from byte[] to string
        }

        public SymetricParamaters GenerateSymmetricParamaters(string input)
        {
            Rfc2898DeriveBytes rfc = new Rfc2898DeriveBytes(input, new byte[] { 20, 255, 1, 60, 54, 78, 52, 30 });

            Rijndael myAlg = Rijndael.Create();

            SymetricParamaters myParams = new SymetricParamaters()
            {
                SecretKey = rfc.GetBytes(myAlg.KeySize / 8),
                IV = rfc.GetBytes(myAlg.BlockSize / 8)
            };

            return myParams;
        }

        //Still needs to be implemented in Index.cshtml
        public string EncryptString(string input, string passwordToBeUsedInSecretKey)
        {
            SymetricParamaters myParameters = GenerateSymmetricParamaters(passwordToBeUsedInSecretKey);

            Rijndael myAlg = Rijndael.Create();
            myAlg.Key = myParameters.SecretKey;
            myAlg.IV = myParameters.IV;

            byte[] clearDataAsBytes = Encoding.UTF32.GetBytes(input);

            MemoryStream msClearData = new MemoryStream(clearDataAsBytes);
            CryptoStream cs = new CryptoStream(msClearData, myAlg.CreateEncryptor(), CryptoStreamMode.Read);

            MemoryStream msEncrypteData = new MemoryStream();
            cs.CopyTo(msEncrypteData);

            byte[] encrypteDataAsBytes = msEncrypteData.ToArray();
            string encrypteddata = Convert.ToBase64String(encrypteDataAsBytes); //converting to string the cryptographic data

            encrypteddata = encrypteddata.Replace('=', '|');
            encrypteddata = encrypteddata.Replace('/', '_');
            encrypteddata = encrypteddata.Replace('+', '*');

            return encrypteddata;
        }

        public string DecryptString(string input, string passwordToBeUsedInSecretKey)
        {

            input = input.Replace('|', '=');
            input = input.Replace('_', '/');
            input = input.Replace('*', '+');

            //Need to change below
            SymetricParamaters myParameters = GenerateSymmetricParamaters(passwordToBeUsedInSecretKey);

            Rijndael myAlg = Rijndael.Create();
            myAlg.Key = myParameters.SecretKey;
            myAlg.IV = myParameters.IV;

            byte[] encryptedDataAsBytes = Convert.FromBase64String(input); //Make decoding;

            MemoryStream msEncryptedData = new MemoryStream(encryptedDataAsBytes);
            CryptoStream cs = new CryptoStream(msEncryptedData, myAlg.CreateDecryptor(), CryptoStreamMode.Read);

            MemoryStream msClearData = new MemoryStream();
            cs.CopyTo(msClearData);

            byte[] clearDataAsBytes = msClearData.ToArray();
            string clearData = Encoding.UTF32.GetString(clearDataAsBytes); //converting to string the cryptographic data

            return clearData;
        }
    }

    public class SymetricParamaters
    {
        public byte[] SecretKey { get; set; }
        public byte[] IV { get; set; }

    }
}