HashDeviceIdComponentEncoder.cs

using System;
using System.Security.Cryptography;
using System.Text;

namespace DeviceId.Encoders;

/// <summary>
/// An implementation of <see cref="IDeviceIdComponentEncoder"/> that encodes components as hashes.
/// </summary>
public class HashDeviceIdComponentEncoder : IDeviceIdComponentEncoder
{
    /// <summary>
    /// The <see cref="IByteArrayHasher"/> to use to hash the component value.
    /// </summary>
    private readonly IByteArrayHasher _byteArrayHasher;

    /// <summary>
    /// The <see cref="IByteArrayEncoder"/> to use to encode the resulting hash.
    /// </summary>
    private readonly IByteArrayEncoder _byteArrayEncoder;

    /// <summary>
    /// Initializes a new instance of the <see cref="HashDeviceIdComponentEncoder"/> class.
    /// </summary>
    /// <param name="byteArrayHasher">The <see cref="IByteArrayHasher"/> to use to hash the component value.</param>
    /// <param name="byteArrayEncoder">The <see cref="IByteArrayEncoder"/> to use to encode the resulting hash.</param>
    public HashDeviceIdComponentEncoder(IByteArrayHasher byteArrayHasher, IByteArrayEncoder byteArrayEncoder)
    {
        _byteArrayHasher = byteArrayHasher ?? throw new ArgumentNullException(nameof(byteArrayHasher));
        _byteArrayEncoder = byteArrayEncoder ?? throw new ArgumentNullException(nameof(byteArrayEncoder));
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="HashDeviceIdComponentEncoder"/> class.
    /// </summary>
    /// <param name="hashAlgorithm">A function that returns the hash algorithm to use.</param>
    /// <param name="byteArrayEncoder">The <see cref="IByteArrayEncoder"/> to use to encode the resulting hash.</param>
    public HashDeviceIdComponentEncoder(Func<HashAlgorithm> hashAlgorithm, IByteArrayEncoder byteArrayEncoder)
        : this(new ByteArrayHasher(hashAlgorithm ?? throw new ArgumentNullException(nameof(hashAlgorithm))), byteArrayEncoder) { }

    /// <summary>
    /// Encodes the specified <see cref="IDeviceIdComponent"/> as a string.
    /// </summary>
    /// <param name="component">The component to encode.</param>
    /// <returns>The component encoded as a string.</returns>
    public string Encode(IDeviceIdComponent component)
    {
        var value = component.GetValue() ?? string.Empty;
        var bytes = Encoding.UTF8.GetBytes(value);
        var hash = _byteArrayHasher.Hash(bytes);
        var output = _byteArrayEncoder.Encode(hash);
        return output;
    }
}