//-----------------------------------------------------------------------
// <copyright file="AES.cs" company="Origtek">
//     AES belongs to Copyright (c) Origtek. All rights reserved.
// </copyright>
//-----------------------------------------------------------------------

namespace OT.COM.Encryption
{
    using System;
    using System.IO;
    using System.Security.Cryptography;

    /// <summary>
    /// <seealso cref="https://msdn.microsoft.com/zh-tw/library/system.security.cryptography.aes(v=vs.110).aspx"/>
    /// AES Encrypt Decrypt  
    /// </summary>
    public partial class AES : AEncryption
    {
        /// <summary>
        /// Main encrypt function
        /// </summary>
        /// <param name="plainText">
        /// Plain text to be encrypt
        /// </param>
        /// <param name="byaKey">
        /// Encrypt key
        /// </param>
        /// <param name="byaIV">
        /// Encrypt initial vector
        /// </param>
        /// <returns>
        /// Encrypt result byte
        /// </returns>
        public override byte[] EncryptStringToByte(string plainText, byte[] byaKey, byte[] byaIV)
        {
            //// Check arguments.
            if (plainText == null || plainText.Length <= 0)
            {
                throw new ArgumentNullException("plainText");
            }

            if (byaKey == null || ((byaKey.Length != 16) && (byaKey.Length != 24) && (byaKey.Length != 32)))
            {
                int nLenth = byaKey == null ? 0 : byaKey.Length;
                throw new ArgumentException($"Key == null || ((Key.Length != 16) && (Key.Length != 24) && (Key.Length != 32)) length={nLenth}");
            }

            if (byaIV == null || (byaIV.Length != 16))
            {
                int nLenth = byaIV == null ? 0 : byaIV.Length;
                throw new ArgumentException($"IV == null || (IV.Length != 16) length={nLenth}");
            }

            byte[] encrypted;
            //// Create an Aes object
            //// with the specified key and IV.

            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = byaKey;
                aesAlg.IV = byaIV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new())
                {
                    using (CryptoStream csEncrypt = new(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new(csEncrypt))
                        {
                            //// Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }

                        encrypted = msEncrypt.ToArray();
                    }
                }
            }

            //// Return the encrypted bytes from the memory stream.
            return encrypted;
        }

        /// <summary>
        /// Main decrypt function
        /// </summary>
        /// <param name="cipherText">
        /// Plain text to be decrypt
        /// </param>
        /// <param name="byaKey">
        /// decrypt key
        /// </param>
        /// <param name="byaIV">
        /// decrypt initial vector
        /// </param>
        /// <returns>
        /// decrypt result byte
        /// </returns>
        public override string DecryptByteToString(byte[] cipherText, byte[] byaKey, byte[] byaIV)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
            {
                throw new ArgumentNullException("cipherText");
            }

            if (byaKey == null || ((byaKey.Length != 16) && (byaKey.Length != 24) && (byaKey.Length != 32)))
            {
                throw new ArgumentException("Key == null || ((Key.Length != 16) && (Key.Length != 24) && (Key.Length != 32))");
            }

            if (byaIV == null || (byaIV.Length != 16))
            {
                throw new ArgumentException("IV == null || (IV.Length != 16)");
            }

            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;

            // Create an Aes object
            // with the specified key and IV.
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = byaKey;
                aesAlg.IV = byaIV;

                // Create a decrytor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for decryption.
                using (MemoryStream msDecrypt = new(cipherText))
                {
                    using (CryptoStream csDecrypt = new(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new(csDecrypt))
                        {
                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }
            }

            return plaintext;
        }
    }
}