using MEU.API.Config;
//using MEU.API.Models;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using EncryptDataLib;

namespace MEU.API.Utils
{
    public class CryptoUtils
    {
        private static String encryptDataKey = ConfigEnvironment.DATA_ENCRYPTED_KEY;

        public static string CalculateMD5Hash(string input) 
        {
            // step 1, calculate MD5 hash from input
            MD5 md5 = System.Security.Cryptography.MD5.Create();
            byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
            byte[] hash = md5.ComputeHash(inputBytes);

            // step 2, convert byte array to hex string
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < hash.Length; i++)
            {
                sb.Append(hash[i].ToString("X2"));
            }
            return sb.ToString();
        }

        protected static string Encrypt(string text, string keyString)
        {
            var key = Encoding.UTF8.GetBytes(keyString);

            using (var aesAlg = Aes.Create())
            {
                using (var encryptor = aesAlg.CreateEncryptor(key, aesAlg.IV))
                {
                    using (var msEncrypt = new MemoryStream())
                    {
                        using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                        using (var swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(text);
                        }

                        var iv = aesAlg.IV;

                        var decryptedContent = msEncrypt.ToArray();

                        var result = new byte[iv.Length + decryptedContent.Length];

                        Buffer.BlockCopy(iv, 0, result, 0, iv.Length);
                        Buffer.BlockCopy(decryptedContent, 0, result, iv.Length, decryptedContent.Length);

                        return Convert.ToBase64String(result);
                    }
                }
            }
        }

        protected static string Decrypt(string cipherText, string keyString)
        {
            var fullCipher = Convert.FromBase64String(cipherText);

            var iv = new byte[16];
            var cipher = new byte[fullCipher.Length - iv.Length]; //changes here

            Buffer.BlockCopy(fullCipher, 0, iv, 0, iv.Length);
            // Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, cipher.Length);
            Buffer.BlockCopy(fullCipher, iv.Length, cipher, 0, fullCipher.Length - iv.Length); // changes here
            var key = Encoding.UTF8.GetBytes(keyString);

            using (var aesAlg = Aes.Create())
            {
                using (var decryptor = aesAlg.CreateDecryptor(key, iv))
                {
                    string result;
                    using (var msDecrypt = new MemoryStream(cipher))
                    {
                        using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                        {
                            using (var srDecrypt = new StreamReader(csDecrypt))
                            {
                                result = srDecrypt.ReadToEnd();
                            }
                        }
                    }

                    return result;
                }
            }
        }
        public static String EncryptData(String data)
        {
            return CryptoUtils.Encrypt(data, CryptoUtils.encryptDataKey);
        }

        public static String EncodeBase64(String data)
        {
            byte[] encodedBytes = System.Text.Encoding.UTF8.GetBytes(data);
            return Convert.ToBase64String(encodedBytes);
        }

        public static String DecodeBase64(String data)
        {
            var base64EncodedBytes = System.Convert.FromBase64String(data);
            return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
        }

        public static String DecryptData(String encryptedData)
        {
            return CryptoUtils.Decrypt(encryptedData, CryptoUtils.encryptDataKey);
        }
    }
}