#if HAVE_NODECANVAS

using System;

using UnityEngine;

using ParadoxNotion.Design;
using NodeCanvas.Framework;

namespace Framework.Support {

  /// <summary>Ticks down a countdown timer in sync with in-game time passing</summary>
  [Category("Utility")]
  [Description("Ticks down a countdown timer until it reaches zero")]
  public class TickDownRemainingTimeTask : ActionTask {

    /// <summary>Remaining time counter that will be ticked down</summary>
    [RequiredField]
    public BBParameter<float> RemainingTime;

    /// <summary>Summary of what this action does</summary>
    protected override string info {
      get { return "Tick down " + this.RemainingTime.name; }
    }
    
    /// <summary>Called once when the action is executed</summary>
    protected override void OnExecute() {
      this.initialRemainingTime = this.RemainingTime.value;
      this.gameTimeAtTaskStart = Time.time;
    }

    /// <summary>Called while the action is running</summary>
    protected override void OnUpdate() {
      if(this.RemainingTime.value > 0.0f) {
        float passedTime = Time.time - this.gameTimeAtTaskStart;
        this.RemainingTime.value = Mathf.Max(0.0f, this.initialRemainingTime - passedTime);
      }      
    }

    /// <summary>Remaining time when the task was entered</summary>
    /// <remarks>
    ///   Instead of decrementing the remaining time by tiny amounts, we just remember
    ///   the initial value and calculate the entire remaining time from there to
    ///   avoid floating point issues if the game is running at very high frame rates. 
    /// </remarks>
    private float initialRemainingTime;

    /// <summary>Game time when the task started running</summary>
    private float gameTimeAtTaskStart;

  }

} // namespace Framework.Support

#endif // HAVE_NODECANVAS