using UnityEngine;

namespace BitGames.Terrain
{
  internal static class RuntimeGlobals
  {
    public const float TILE_SIZE = 2.5f;
    public static readonly SizeOption[] SizeOptions = { new(32), new(64), new(128), new(256) };

    private static Material _instancedMaterial;
    private static int _materialDependencies;
    private static TerrainAsset _currentAsset;

    private static readonly int ControlMapId = Shader.PropertyToID("ControlMap");
    private static readonly int ShadowMapId = Shader.PropertyToID("ShadowMap");
    private static readonly int ShadowColorId = Shader.PropertyToID("ShadowColor");
    private static readonly int TileSizeId = Shader.PropertyToID("TileSize");

    public static Material RegisterMaterialUser(ITerrainMaterialUser user)
    {
      if (_materialDependencies == 0 || _instancedMaterial == null)
      {
        _instancedMaterial = new Material(Shader.Find("Terrain/Tile Terrain")) { name = "Terrain (instance)" };
      }

      _materialDependencies++;
      return _instancedMaterial;
    }

    public static void RemoveMaterialUser(ITerrainMaterialUser user)
    {
      _materialDependencies--;

      if (_materialDependencies == 0)
      {
        SafeDestroy(_instancedMaterial);
      }
    }

    private static void SafeDestroy(Object obj)
    {
#if UNITY_EDITOR
      if(UnityEditor.EditorApplication.isPlaying)
        Object.Destroy(obj);
      else
        Object.DestroyImmediate(obj);
#else
      Object.Destroy(obj);
#endif
    }

    public static void ActivateAsset(TerrainAsset asset)
    {
      _currentAsset = asset;

      Shader.SetGlobalTexture(ControlMapId, asset.ControlTexture);
      Shader.SetGlobalTexture(ShadowMapId, asset.ShadowTexture);
      Shader.SetGlobalColor(ShadowColorId, asset.ShadowColor);
      Shader.SetGlobalFloat(TileSizeId, TILE_SIZE);
    }
  }
}