#if HAVE_SLATE

using System;

using UnityEngine;

using Slate;
using Slate.ActionClips;

using Framework.Support;

namespace Framework.Cinematics {

  /// <summary>Fades a standard shader material using its alpha channel</summary>
  [Category("Material")]
  [Description("Fades a material in and out using its color's alpha channel")]
  public class FadeMaterialAlphaAction : ActorActionClip {

    /// <summary>For how long the text will be displayed (including fading time)</summary>
    public float Length = 2;
    /// <summary>Time over which the text will fade in</summary>
    public float BlendIn = 0.25f;
    /// <summary>Time over which the text will fade out</summary>
    public float BlendOut = 0.25f;
    /// <summary>Fading method to use for the alpha channel</summary>
    public EaseType interpolation = EaseType.QuadraticInOut;

    /// <summary>Summary of what this action does</summary>
    public override string info {
      get { return "Fade Material"; }
    }

    /// <summary>Called before the event is played back for the first time</summary>
    protected override void OnEnter() {
      this.materials = MaterialHelper.GetMeshMaterials(actor);

      int materialCount = this.materials.Length;

      this.previousAlpha = new float[materialCount];
      for(int index = 0; index < materialCount; ++index) {
        previousAlpha[index] = this.materials[index].color.a;
      }
    }

    /// <summary>Called when the action's effects should be reversed</summary>
    /// <remarks>
    ///   Called either after the event has been scrubbed/played in reverse
    ///   or when the stop button is hit after the event was played.
    /// </remarks>
    protected override void OnReverse() {
      int materialCount = this.materials.Length;

      for(int index = 0; index < materialCount; ++index) {
        Color color = this.materials[index].color;
        color.a = this.previousAlpha[index];
        this.materials[index].color = color;
      }
    }

    /// <summary>
    ///   Called every frame, if and while the action is running and until it ends
    /// </summary>
    protected override void OnUpdate(float deltaTime) {
      int materialCount = this.materials.Length;

      float weight = GetClipWeight(deltaTime);
      float opacity = Easing.Ease(this.interpolation, 0.0f, 1.0f, weight);

      for(int index = 0; index < materialCount; ++index) {
        Color color = this.materials[index].color;
        //color.a = Easing.Ease(this.interpolation, 0.0f, this.previousAlpha[index], weight);
        color.a = opacity;
        this.materials[index].color = color;
      }
    }

    /// <summary>Duration of the action in seconds</summary>
    public override float length {
      get { return this.Length; }
      set { this.Length = value; }
    }

    /// <summary>How long the fade-in should take in seconds</summary>
    public override float blendIn {
      get { return this.BlendIn; }
      set { this.BlendIn = value; }
    }

    /// <summary>How long the fade-out should take in seconds</summary>
    public override float blendOut {
      get { return this.BlendOut; }
      set { this.BlendOut = value; }
    }

    /// <summary>All materials in whom the opacity level will be changed</summary>
    [NonSerialized]
    private Material[] materials;
    /// <summary>Opacity levels the materials had before the action</summary>
    [NonSerialized]
    private float[] previousAlpha;

  }

} // namespace Framework.Cinematics

#endif // HAVE_SLATE