NonInventPurchasingSystem/CPRNIMS.Domain/Services/SMTP/SMTP.cs

using CPRNIMS.Domain.Contracts.SMTP;
using CPRNIMS.Infrastructure.Database;
using CPRNIMS.Infrastructure.Dto.Items;
using CPRNIMS.Infrastructure.Dto.SMTP;
using CPRNIMS.Infrastructure.Entities.Purchasing;
using System.Security.Cryptography;
using CPRNIMS.Infrastructure.Entities.SMTP;
using Microsoft.Data.SqlClient;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CPRNIMS.Domain.Services.SMTP
{
    public class SMTP : ISMTP
    {
        private readonly NonInventoryDbContext _dbContext;
        
        public SMTP(NonInventoryDbContext dbContext)
        {
            _dbContext = dbContext;
        }
        public async Task<List<SMTPCredential>> GetAllSmtp(SMTPCredentialDto itemDto)
        {
            try
            {
                var allItems = await _dbContext.SMTPCredentials
                    .FromSqlRaw($"EXEC GetAllSmtp @UserId = '{itemDto.UserId}'")
                    .ToListAsync();

                return allItems ?? new List<SMTPCredential>();
            }
            catch (SqlException ex)
            {
                ex.ToString();
                throw;
            }
        }
        private static readonly byte[] Key = GetPaddedKey("MDLD_1NV3NT0RY_2o24", 32);
        public async Task<List<SMTPCredential>> GetSMTPCredential(SMTPCredentialDto itemDto)
        {
            try
            {
                var allCred = await _dbContext.SMTPCredentials
                    .FromSqlRaw($"EXEC GetSMTPCredential @UserId = '{itemDto.UserId}', @SMTPTypeId = {itemDto.SMTPTypeId}")
                    .ToListAsync();

                foreach (var cred in allCred)
                {
                    if (IsEncrypted(cred.Password))
                    {
                        cred.Password = DecryptString(cred.Password);
                    }
                }

                return allCred ?? new List<SMTPCredential>();
            }
            catch (SqlException ex)
            {
                ex.ToString();
                throw;
            }
        }

        // Decrypt string method
        private string DecryptString(string cipherText)
        {
            try
            {
                byte[] fullCipher = Convert.FromBase64String(cipherText);
                byte[] iv = new byte[16];
                byte[] cipherTextBytes = new byte[fullCipher.Length - 16];

                Array.Copy(fullCipher, iv, iv.Length);
                Array.Copy(fullCipher, iv.Length, cipherTextBytes, 0, cipherTextBytes.Length);

                using (Aes aesAlg = Aes.Create())
                {
                    aesAlg.Key = Key;
                    using (ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, iv))
                    using (MemoryStream msDecrypt = new MemoryStream(cipherTextBytes))
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {
                        return srDecrypt.ReadToEnd();
                    }
                }
            }
            catch (FormatException)
            {
                // If it's not a valid base64 string, it means it's already decrypted
                return cipherText;
            }
        }

        // Method to check if the password is encrypted
        private bool IsEncrypted(string password)
        {
            try
            {
                // Try to convert from Base64
                Convert.FromBase64String(password);
                return true;
            }
            catch (FormatException)
            {
                // If it fails, it's not Base64 encoded, hence not encrypted
                return false;
            }
        }

        public async Task<List<SMTPCredential>> GetMySmtp(SMTPCredentialDto itemDto)
        {
            try
            {
                var allItems = await _dbContext.SMTPCredentials
                   /* .FromSqlRaw("EXEC GetMySmtp @UserId = {0}", itemDto.UserId, )*/
                   .FromSqlRaw($"EXEC GetMySmtp @UserId = '{itemDto.UserId}', @SMTPCredentialId = {itemDto.SMTPCredentialId}")
                    .ToListAsync();

                //foreach (var item in allItems)
                //{
                //    item.Password = DecryptString(item.Password);
                //}

                return allItems ?? new List<SMTPCredential>();
            }
            catch (SqlException ex)
            {
                ex.ToString();
                throw;
            }
        }
        public async Task<SMTPCredential> GetMySmtpById(SMTPCredentialDto itemDto)
        {
            try
            {
                var sMTP = await _dbContext.SMTPCredentials
                    .FromSqlRaw($"EXEC GetMySmtp @UserId = '{itemDto.UserId}', @SMTPCredentialId = {itemDto.SMTPCredentialId}")
                    .ToListAsync();

                if (sMTP.Count == 0)
                {
                    return null; // No item found
                }

                var item = sMTP.First();
                item.Password = DecryptString(item.Password);

                return item;
            }
            catch (SqlException ex)
            {
                var message = ex.ToString();
                throw;
            }
        }
        

        public async Task<SMTPCredential> PostPutSmtp(SMTPCredentialDto itemDto)
        {
            try
            {
                // Encrypt the password
                string encryptedPassword = EncryptString(itemDto.Password);

                await _dbContext.Database
                   .ExecuteSqlRawAsync("EXEC PostPutSmtp " +
                   "@SMTPCredentialId, @SMTPCredentialName, @UserId, @SenderEmail, @SenderUserName," +
                   " @SenderDisplayName, @Password, @Server, @OutgoingPort, @IncomingPort ,@IsActive",
                new SqlParameter("@SMTPCredentialId", itemDto.SMTPCredentialId != null ? itemDto.SMTPCredentialId : 0L),
                //new SqlParameter("@SMTPTypeId", itemDto.SMTPTypeId),
                new SqlParameter("@SMTPCredentialName", itemDto.SMTPCredentialName ?? "N/A"),
                new SqlParameter("@UserId", itemDto.UserId),
                new SqlParameter("@SenderEmail", itemDto.SenderEmail ?? "N/A"),
                new SqlParameter("@SenderUserName", itemDto.SenderUserName ?? "N/A"),
                new SqlParameter("@SenderDisplayName", itemDto.SenderDisplayName ?? "N/A"),
                new SqlParameter("@Password", encryptedPassword),
                new SqlParameter("@Server", itemDto.Server ?? "N/A"),
                new SqlParameter("@OutgoingPort", itemDto.OutgoingPort),
                new SqlParameter("@IncomingPort", itemDto.IncomingPort),
                new SqlParameter("@IsActive", itemDto.IsActive));
                return new SMTPCredential();
            }
            catch (SqlException ex)
            {
                ex.ToString();
                throw;
            }
        }

        private static byte[] GetPaddedKey(string key, int length)
        {
            var keyBytes = Encoding.UTF8.GetBytes(key);
            if (keyBytes.Length >= length)
            {
                return keyBytes.Take(length).ToArray();
            }
            var paddedKey = new byte[length];
            Buffer.BlockCopy(keyBytes, 0, paddedKey, 0, keyBytes.Length);
            return paddedKey;
        }
        // Encrypt string
        private string EncryptString(string plainText)
        {
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = Key;
                aesAlg.GenerateIV();
                byte[] iv = aesAlg.IV;

                using (ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, iv))
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    // Prepend the IV to the encrypted content
                    msEncrypt.Write(iv, 0, iv.Length);
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        swEncrypt.Write(plainText);
                    }
                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }
    }
}