using System;

using UnityEngine;

namespace Framework.Terrain {

  /// <summary>Terrain data import settings</summary>
  [RequireComponent(typeof(UnityEngine.Terrain))]
  public class TerrainImportSettings : MonoBehaviour {

    /// <summary>Texture to use for controlled height map re-imports</summary>
    [Tooltip("Texture from which the height map will be read.")]
    public Texture2D HeightMapTexture;

    /// <summary>Height of the terrain at its lowest point</summary>
    [Tooltip("Absolute height level of the terrain at its lowest point.")]
    public float MinHeight = 0.0f;

    /// <summary>Height of the terrain at its highest point</summary>
    [Tooltip("Absolute height level of the terrain at its highest point.")]
    public float MaxHeight = 100.0f;

    /// <summary>Texture to import up to four splat layers from</summary>
    [Tooltip("Texture from which up to four splat layers will be imported.")]
    public Texture2D SplatMapTexture;

    /// <summary>Texture to import up to four additional splat layers from</summary>
    [Tooltip("Texture from which up to four additional splat layers will be imported.")]
    public Texture2D SecondarySplatMapTexture;

    /// <summary>Which color channel to map to each splat layer index</summary>
    [Tooltip("Color channels to map to each of the splat weight layers.")]
    public int[] SplatColorIndices;

    /// <summary>Resizes the splat layer index array to the specified size</summary>
    /// <param name="layerCount">Number of splat layer indices that are required</param>
    /// <remarks>
    ///   Tries to preserves the contents of the splat layer indices.
    /// </remarks>
    public void ResizeSplatColorIndices(int layerCount) {
      if(this.SplatColorIndices == null) {
        this.SplatColorIndices = new int[layerCount];
        for(int index = 0; index < layerCount; ++index) {
          this.SplatColorIndices[index] = (index + 1);
        }
      } else {
        int existingLayerCount = this.SplatColorIndices.Length;
        if(existingLayerCount != layerCount) {
          int[] newLayerIndices = new int[layerCount];
          Array.Copy(
            this.SplatColorIndices, newLayerIndices,
            Math.Min(layerCount, existingLayerCount)
          );
          for(int index = existingLayerCount; index < layerCount; ++index) {
            newLayerIndices[index] = (index + 1);
          }
          this.SplatColorIndices = newLayerIndices;
        }
      }
    }

    /// <summary>
    ///   Whether the current splat layer indices reference the primary splat map texture
    /// </summary>
    public bool ReferencesPrimarySplatMapTexture {
      get {
        if(this.SplatColorIndices != null) {
          int splatLayerIndexCount = this.SplatColorIndices.Length;
          for(int index = 0; index < splatLayerIndexCount; ++index) {
            int splatLayerIndex = this.SplatColorIndices[index];
            if((splatLayerIndex >= 1) && (splatLayerIndex <= 4)) {
              return true;
            }
          }
        }

        return false;
      }
    }

    /// <summary>
    ///   Whether the current splat layer indices reference the secondary splat map texture
    /// </summary>
    public bool ReferencesSecondarySplatMapTexture {
      get {
        if(this.SplatColorIndices != null) {
          int splatLayerIndexCount = this.SplatColorIndices.Length;
          for(int index = 0; index < splatLayerIndexCount; ++index) {
            int splatLayerIndex = this.SplatColorIndices[index];
            if((splatLayerIndex >= 5) && (splatLayerIndex <= 8)) {
              return true;
            }
          }
        }

        return false;
      }
    }

  }

} // namespace Framework.Terrain