// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Runtime.Versioning;
using Internal.Cryptography;

namespace System.Security.Cryptography
{
    [UnsupportedOSPlatform("browser")]
    [UnsupportedOSPlatform("ios")]
    [UnsupportedOSPlatform("tvos")]
    public sealed partial class AesCcm : IDisposable
    {
        public static KeySizes NonceByteSizes { get; } = new KeySizes(7, 13, 1);
        public static KeySizes TagByteSizes { get; } = new KeySizes(4, 16, 2);

        /// <summary>
        /// Gets the size of the key, in bytes.
        /// </summary>
        /// <value>
        /// The size of the key, in bytes.
        /// </value>
        public int KeySizeInBytes { get; }

        public AesCcm(ReadOnlySpan<byte> key)
        {
            ThrowIfNotSupported();

            AesAEAD.CheckKeySize(key.Length);
            KeySizeInBytes = key.Length;
            ImportKey(key);
        }

        public AesCcm(byte[] key)
        {
            ThrowIfNotSupported();

            ArgumentNullException.ThrowIfNull(key);

            AesAEAD.CheckKeySize(key.Length);
            KeySizeInBytes = key.Length;
            ImportKey(key);
        }

        public void Encrypt(byte[] nonce, byte[] plaintext, byte[] ciphertext, byte[] tag, byte[]? associatedData = null)
        {
            ArgumentNullException.ThrowIfNull(nonce);
            ArgumentNullException.ThrowIfNull(plaintext);
            ArgumentNullException.ThrowIfNull(ciphertext);
            ArgumentNullException.ThrowIfNull(tag);

            Encrypt((ReadOnlySpan<byte>)nonce, plaintext, ciphertext, tag, associatedData);
        }

        public void Encrypt(
            ReadOnlySpan<byte> nonce,
            ReadOnlySpan<byte> plaintext,
            Span<byte> ciphertext,
            Span<byte> tag,
            ReadOnlySpan<byte> associatedData = default)
        {
            CheckParameters(plaintext, ciphertext, nonce, tag);
            EncryptCore(nonce, plaintext, ciphertext, tag, associatedData);
        }

        public void Decrypt(byte[] nonce, byte[] ciphertext, byte[] tag, byte[] plaintext, byte[]? associatedData = null)
        {
            ArgumentNullException.ThrowIfNull(nonce);
            ArgumentNullException.ThrowIfNull(ciphertext);
            ArgumentNullException.ThrowIfNull(tag);
            ArgumentNullException.ThrowIfNull(plaintext);

            Decrypt((ReadOnlySpan<byte>)nonce, ciphertext, tag, plaintext, associatedData);
        }

        public void Decrypt(
            ReadOnlySpan<byte> nonce,
            ReadOnlySpan<byte> ciphertext,
            ReadOnlySpan<byte> tag,
            Span<byte> plaintext,
            ReadOnlySpan<byte> associatedData = default)
        {
            CheckParameters(plaintext, ciphertext, nonce, tag);
            DecryptCore(nonce, ciphertext, tag, plaintext, associatedData);
        }

        private static void CheckParameters(
            ReadOnlySpan<byte> plaintext,
            ReadOnlySpan<byte> ciphertext,
            ReadOnlySpan<byte> nonce,
            ReadOnlySpan<byte> tag)
        {
            if (plaintext.Length != ciphertext.Length)
                throw new ArgumentException(SR.Cryptography_PlaintextCiphertextLengthMismatch);

            if (!nonce.Length.IsLegalSize(NonceByteSizes))
                throw new ArgumentException(SR.Cryptography_InvalidNonceLength, nameof(nonce));

            if (!tag.Length.IsLegalSize(TagByteSizes))
                throw new ArgumentException(SR.Cryptography_InvalidTagLength, nameof(tag));
        }

        private static void ThrowIfNotSupported()
        {
            if (!IsSupported)
            {
                throw new PlatformNotSupportedException(SR.Format(SR.Cryptography_AlgorithmNotSupported, nameof(AesCcm)));
            }
        }
    }
}