using System.Security.Cryptography;
using System.Text;
using Application.Services.Encryption;
using Microsoft.Extensions.Configuration;

namespace Infrastructure.Services.Encryption;

public class EncryptionService : IEncryptionService
{
    private readonly byte[] _medicalRecordsKey;
    
        public EncryptionService(IConfiguration configuration)
        {
            var keyString = configuration["MedicalRecordsKey"];
            _medicalRecordsKey = Convert.FromBase64String(keyString);  // Ensure the key is correctly formatted and of proper length.
        }

    public string? Sha256Algorithm(string? password)
    {
        if (password == null) return null;

        using var sha256 = SHA256.Create();
        var bytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(password));
        return Convert.ToBase64String(bytes);
    }

public byte[] EncryptDocument(byte[] data)
{
    using var aesAlg = Aes.Create();
    aesAlg.Key = _medicalRecordsKey;
    aesAlg.GenerateIV();

    using var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
    using var msEncrypt = new MemoryStream();
    // Writing the IV directly to the start of the stream
    msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);

    using (var cryptoStream = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
    {
        cryptoStream.Write(data, 0, data.Length);
    }

    return msEncrypt.ToArray();
}

    public byte[] DecryptDocument(byte[] data)
    {
        using var aesAlg = Aes.Create();
        aesAlg.Key = _medicalRecordsKey;

        // Extract the IV from the beginning of the data array
        var iv = new byte[aesAlg.BlockSize / 8];
        Array.Copy(data, 0, iv, 0, iv.Length);
        aesAlg.IV = iv;

        using var decryptor = aesAlg.CreateDecryptor(aesAlg.Key, iv);
        using var msDecrypt = new MemoryStream();
        using var cryptoStream = new CryptoStream(new MemoryStream(data, iv.Length, data.Length - iv.Length), 
            decryptor, CryptoStreamMode.Read);
        cryptoStream.CopyTo(msDecrypt);
        return msDecrypt.ToArray();
    }
}