// Copyright 2025 Yubico AB
//
// Licensed under the Apache License, Version 2.0 (the "License").
// You may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Security.Cryptography;

namespace Yubico.Core.Cryptography
{
    /// <summary>
    /// An .NET implementation of the IAesGcmPrimitives interface, exposing
    /// AES-GCM primitives to the SDK.
    /// </summary>
    public class AesGcmPrimitivesNet : IAesGcmPrimitives
    {
        private const int NonceLength = 12;
        private const int AuthTagLength = 16;

        /// <inheritdoc />
        public void EncryptAndAuthenticate(
            ReadOnlySpan<byte> keyData,
            ReadOnlySpan<byte> nonce,
            ReadOnlySpan<byte> plaintext,
            Span<byte> ciphertext,
            Span<byte> tag,
            ReadOnlySpan<byte> associatedData)
        {
            if (nonce.Length != NonceLength || ciphertext.Length != plaintext.Length
                || tag.Length != AuthTagLength)
            {
                throw new ArgumentException(ExceptionMessages.InvalidAesGcmInput);
            }

            if (keyData.Length != 16 && keyData.Length != 24 && keyData.Length != 32)
            {
                throw new ArgumentException("Invalid key length.");
            }

            using var aesGcm = new AesGcm(keyData);
            aesGcm.Encrypt(nonce, plaintext, ciphertext, tag, associatedData);
        }

        /// <inheritdoc />
        public bool DecryptAndVerify(
            ReadOnlySpan<byte> keyData,
            ReadOnlySpan<byte> nonce,
            ReadOnlySpan<byte> ciphertext,
            ReadOnlySpan<byte> tag,
            Span<byte> plaintext,
            ReadOnlySpan<byte> associatedData)
        {

            if (nonce.Length != NonceLength || ciphertext.Length != plaintext.Length
                || tag.Length != AuthTagLength)
            {
                throw new ArgumentException(ExceptionMessages.InvalidAesGcmInput);
            }

            if (keyData.Length != 16 && keyData.Length != 24 && keyData.Length != 32)
            {
                throw new ArgumentException("Invalid key length.");
            }

            try
            {
                using var aesGcm = new AesGcm(keyData);
                aesGcm.Decrypt(nonce, ciphertext, tag, plaintext, associatedData);
                return true;
            }
            catch (CryptographicException)
            {
                return false;
            }
        }
    }
}