using Unosquare.Swan;
using System;
using System.Linq;

namespace Unosquare.RaspberryIO.Camera {
  /// <summary>
  /// A simple RGB color class to represent colors in RGB and YUV colorspaces.
  /// </summary>
  public class CameraColor {
    /// <summary>
    /// Initializes a new instance of the <see cref="CameraColor"/> class.
    /// </summary>
    /// <param name="r">The red.</param>
    /// <param name="g">The green.</param>
    /// <param name="b">The blue.</param>
    public CameraColor(Int32 r, Int32 g, Int32 b)
        : this(r, g, b, String.Empty) {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="CameraColor"/> class.
    /// </summary>
    /// <param name="r">The red.</param>
    /// <param name="g">The green.</param>
    /// <param name="b">The blue.</param>
    /// <param name="name">The well-known color name.</param>
    public CameraColor(Int32 r, Int32 g, Int32 b, String name) {
      this.RGB = new[] { Convert.ToByte(r.Clamp(0, 255)), Convert.ToByte(g.Clamp(0, 255)), Convert.ToByte(b.Clamp(0, 255)) };

      Single y = this.R * .299000f + this.G * .587000f + this.B * .114000f;
      Single u = this.R * -.168736f + this.G * -.331264f + this.B * .500000f + 128f;
      Single v = this.R * .500000f + this.G * -.418688f + this.B * -.081312f + 128f;

      this.YUV = new Byte[] { (Byte)y.Clamp(0, 255), (Byte)u.Clamp(0, 255), (Byte)v.Clamp(0, 255) };
      this.Name = name;
    }

    #region Static Definitions

    /// <summary>
    /// Gets the predefined white color.
    /// </summary>
    public static CameraColor White => new CameraColor(255, 255, 255, nameof(White));

    /// <summary>
    /// Gets the predefined red color.
    /// </summary>
    public static CameraColor Red => new CameraColor(255, 0, 0, nameof(Red));

    /// <summary>
    /// Gets the predefined green color.
    /// </summary>
    public static CameraColor Green => new CameraColor(0, 255, 0, nameof(Green));

    /// <summary>
    /// Gets the predefined blue color.
    /// </summary>
    public static CameraColor Blue => new CameraColor(0, 0, 255, nameof(Blue));

    /// <summary>
    /// Gets the predefined black color.
    /// </summary>
    public static CameraColor Black => new CameraColor(0, 0, 0, nameof(Black));

    #endregion

    /// <summary>
    /// Gets the well-known color name.
    /// </summary>
    public String Name {
      get;
    }

    /// <summary>
    /// Gets the red byte.
    /// </summary>
    public Byte R => this.RGB[0];

    /// <summary>
    /// Gets the green byte.
    /// </summary>
    public Byte G => this.RGB[1];

    /// <summary>
    /// Gets the blue byte.
    /// </summary>
    public Byte B => this.RGB[2];

    /// <summary>
    /// Gets the RGB byte array (3 bytes).
    /// </summary>
    public Byte[] RGB {
      get;
    }

    /// <summary>
    /// Gets the YUV byte array (3 bytes).
    /// </summary>
    public Byte[] YUV {
      get;
    }

    /// <summary>
    /// Returns a hexadecimal representation of the RGB byte array.
    /// Preceded by 0x and all in lowercase
    /// </summary>
    /// <param name="reverse">if set to <c>true</c> [reverse].</param>
    /// <returns>A string</returns>
    public String ToRgbHex(Boolean reverse) {
      Byte[] data = this.RGB.ToArray();
      if(reverse) {
        Array.Reverse(data);
      }

      return ToHex(data);
    }

    /// <summary>
    /// Returns a hexadecimal representation of the YUV byte array.
    /// Preceded by 0x and all in lowercase
    /// </summary>
    /// <param name="reverse">if set to <c>true</c> [reverse].</param>
    /// <returns>A string</returns>
    public String ToYuvHex(Boolean reverse) {
      Byte[] data = this.YUV.ToArray();
      if(reverse) {
        Array.Reverse(data);
      }

      return ToHex(data);
    }

    /// <summary>
    /// Returns a hexadecimal representation of the data byte array
    /// </summary>
    /// <param name="data">The data.</param>
    /// <returns>A string</returns>
    private static String ToHex(Byte[] data) => $"0x{BitConverter.ToString(data).Replace("-", String.Empty).ToLowerInvariant()}";
  }
}