using System.Collections.Generic;

namespace Server.Engines.MyRunUO
{
  public class LayerComparer : IComparer<Item>
  {
    private static Layer PlateArms = (Layer)255;
    private static Layer ChainTunic = (Layer)254;
    private static Layer LeatherShorts = (Layer)253;

    private static Layer[] m_DesiredLayerOrder =
    {
      Layer.Cloak,
      Layer.Bracelet,
      Layer.Ring,
      Layer.Shirt,
      Layer.Pants,
      Layer.InnerLegs,
      Layer.Shoes,
      LeatherShorts,
      Layer.Arms,
      Layer.InnerTorso,
      LeatherShorts,
      PlateArms,
      Layer.MiddleTorso,
      Layer.OuterLegs,
      Layer.Neck,
      Layer.Waist,
      Layer.Gloves,
      Layer.OuterTorso,
      Layer.OneHanded,
      Layer.TwoHanded,
      Layer.FacialHair,
      Layer.Hair,
      Layer.Helm,
      Layer.Talisman
    };

    public static readonly IComparer<Item> Instance = new LayerComparer();

    static LayerComparer()
    {
      TranslationTable = new int[256];

      for (int i = 0; i < m_DesiredLayerOrder.Length; ++i)
        TranslationTable[(int)m_DesiredLayerOrder[i]] = m_DesiredLayerOrder.Length - i;
    }

    public static int[] TranslationTable{ get; }

    public int Compare(Item a, Item b)
    {
      if (a == null)
        return b == null ? 0 : 1;
      
      if (b == null)
        return -1;
      
      Layer aLayer = Fix(a.ItemID, a.Layer);
      Layer bLayer = Fix(b.ItemID, b.Layer);

      return TranslationTable[(int)bLayer] - TranslationTable[(int)aLayer];
    }

    public static bool IsValid(Item item)
    {
      return TranslationTable[(int)item.Layer] > 0;
    }

    public Layer Fix(int itemID, Layer oldLayer)
    {
      if (itemID == 0x1410 || itemID == 0x1417) // platemail arms
        return PlateArms;

      if (itemID == 0x13BF || itemID == 0x13C4) // chainmail tunic
        return ChainTunic;

      if (itemID == 0x1C08 || itemID == 0x1C09 || itemID == 0x1C00 || itemID == 0x1C01) // leather skirt/shorts
        return LeatherShorts;

      return oldLayer;
    }
  }
}