using System;
using System.Linq;

namespace Swan {
  /// <summary>
  /// Provides various extension methods for byte arrays and streams.
  /// </summary>
  public static class ByteArrayExtensions {
    /// <summary>
    /// Converts an array of bytes to a base-64 encoded string.
    /// </summary>
    /// <param name="bytes">The bytes.</param>
    /// <returns>A <see cref="String" /> converted from an array of bytes.</returns>
    public static String ToBase64(this Byte[] bytes) => Convert.ToBase64String(bytes);

    /// <summary>
    /// Converts a set of hexadecimal characters (uppercase or lowercase)
    /// to a byte array. String length must be a multiple of 2 and
    /// any prefix (such as 0x) has to be avoided for this to work properly.
    /// </summary>
    /// <param name="this">The hexadecimal.</param>
    /// <returns>
    /// A byte array containing the results of encoding the specified set of characters.
    /// </returns>
    /// <exception cref="ArgumentNullException">hex.</exception>
    public static Byte[] ConvertHexadecimalToBytes(this String @this) {
      if(String.IsNullOrWhiteSpace(@this)) {
        throw new ArgumentNullException(nameof(@this));
      }

      return Enumerable.Range(0, @this.Length / 2).Select(x => Convert.ToByte(@this.Substring(x * 2, 2), 16)).ToArray();
    }
  }
}