using System.Collections.Generic;

namespace Palettizer
{
	public class Palette
	{
		public Dictionary<Color, byte> ColorToGrayscaleMap { get; }
		public byte GrayscaleIndex { get; set; }
		public List<byte[]> AlternateColorRows { get; }

		public int Width { get => ColorToGrayscaleMap.Count; }
		public int Height { get => AlternateColorRows.Count + 1; }

		public Palette()
		{
			ColorToGrayscaleMap = new Dictionary<Color, byte>();
			GrayscaleIndex = 0;
			AlternateColorRows = new List<byte[]>();
		}

		public void AddColor(Color color, byte grayscaleIndex)
		{
			ColorToGrayscaleMap.Add(color, grayscaleIndex);
		}

		public void AddAlternateColorRow(Color[] colors)
		{
			var byteArray = new byte[ColorToGrayscaleMap.Count * 4];

			foreach (var color in colors)
			{
				if (ColorToGrayscaleMap.ContainsKey(color))
				{
					var grayscaleIndex = ColorToGrayscaleMap[color];

					byteArray[grayscaleIndex] = color.R;
					byteArray[grayscaleIndex + 1] = color.G;
					byteArray[grayscaleIndex + 2] = color.B;
					byteArray[grayscaleIndex + 3] = color.A;
				}
				else
				{
					System.Console.WriteLine("That color doesn't exist in the grayscale palette!! Bailing!!!");
				}
			}

			AlternateColorRows.Add(byteArray);
		}

		public byte[] CreateIndexedPaletteBitmap()
		{
			var paletteBitmap = new byte[ColorToGrayscaleMap.Count * 4 * (AlternateColorRows.Count + 1)];

			var index = 0;
			foreach (KeyValuePair<Color, byte> kv in ColorToGrayscaleMap)
			{
				var color = kv.Key;
				var grayscale = kv.Value;

				paletteBitmap[index] = grayscale;
				paletteBitmap[index + 1] = grayscale;
				paletteBitmap[index + 2] = grayscale;
				paletteBitmap[index + 3] = 255;

				var alternateIndex = 1;
				foreach (var alternateColorRow in AlternateColorRows)
				{
					for (var j = 0; j < ColorToGrayscaleMap.Count * 4; j += 4)
					{
						paletteBitmap[index +     (ColorToGrayscaleMap.Count * alternateIndex)] = alternateColorRow[j];
						paletteBitmap[index + 1 + (ColorToGrayscaleMap.Count * alternateIndex)] = alternateColorRow[j + 1];
						paletteBitmap[index + 2 + (ColorToGrayscaleMap.Count * alternateIndex)] = alternateColorRow[j + 2];
						paletteBitmap[index + 3 + (ColorToGrayscaleMap.Count * alternateIndex)] = alternateColorRow[j + 3];
					}

					alternateIndex += 1;
				}

				index += 4;
			}

			return paletteBitmap;
		}
	}
}