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using System.IO;
using System.Text;

// Reading Adobe Swatch Exchange (ase) files using C#
// http://www.cyotek.com/blog/reading-adobe-swatch-exchange-ase-files-using-csharp

// Reading Photoshop Color Swatch (aco) files using C#
// http://www.cyotek.com/blog/reading-photoshop-color-swatch-aco-files-using-csharp

namespace AdobeSwatchExchangeLoader
{
  internal static class StreamExtensions
  {
    #region Static Methods

    /// <summary>
    /// Reads a ASCII string of the specified length.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <param name="length">The number of characters in the string.</param>
    /// <returns>The string read from the stream.</returns>
    public static string ReadAsciiString(this Stream stream, int length)
    {
      byte[] buffer;

      buffer = new byte[length];

      stream.Read(buffer, 0, buffer.Length);

      return Encoding.ASCII.GetString(buffer);
    }

    /// <summary>
    /// Reads a 4-byte floating point value from the current stream using big-endian encoding and advances the position of the stream by four bytes.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <returns>A 4-byte floating point value read from the source stream.</returns>
    public static float ReadSingleBigEndian(this Stream stream)
    {
      unsafe
      {
        int value;

        value = stream.ReadUInt32BigEndian();

        return *(float*)&value;
      }
    }

    /// <summary>
    /// Reads a unicode string of the specified length in big-endian format.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <param name="length">The number of characters in the string.</param>
    /// <returns>The string read from the stream.</returns>
    public static string ReadStringBigEndian(this Stream stream, int length)
    {
      byte[] buffer;

      buffer = new byte[length * 2];

      stream.Read(buffer, 0, buffer.Length);

      return Encoding.BigEndianUnicode.GetString(buffer);
    }

    /// <summary>
    /// Reads a unicode string from the current stream in big-endian format. The string is prefixed with the length.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <returns>The string read from the stream.</returns>
    public static string ReadStringBigEndian(this Stream stream)
    {
      int length;
      string value;

      // string is null terminated, value saved in file includes the terminator

      length = stream.ReadUInt16BigEndian() - 1;
      value = stream.ReadStringBigEndian(length);
      stream.ReadUInt16BigEndian(); // read and discard the terminator

      return value;
    }

    /// <summary>
    /// Reads a 2-byte unsigned integer from the current stream using big-endian encoding and advances the position of the stream by two bytes.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <returns>A 2-byte unsigned integer read from the source stream.</returns>
    public static int ReadUInt16BigEndian(this Stream stream)
    {
      return (stream.ReadByte() << 8) | stream.ReadByte();
    }

    /// <summary>
    /// Reads a 4-byte unsigned integer from the current stream using big-endian encoding and advances the position of the stream by four bytes.
    /// </summary>
    /// <param name="stream">The stream to read the data from.</param>
    /// <returns>A 4-byte unsigned integer read from the source stream.</returns>
    public static int ReadUInt32BigEndian(this Stream stream)
    {
      return ((byte)stream.ReadByte() << 24) | ((byte)stream.ReadByte() << 16) | ((byte)stream.ReadByte() << 8) |
             (byte)stream.ReadByte();
    }

    #endregion
  }
}