#if HAVE_NODECANVAS

using System;

using UnityEngine.UI;
using UnityEngine.Events;

using NodeCanvas.Framework;
using ParadoxNotion.Design;

namespace Framework.Dialogue {

  /// <summary>
  ///   Allows a transition only if the player clicked on a specific UGUI button
  /// </summary>
  [Category("UGUI")]
  public class ButtonCondition : ConditionTask {

    /// <summary>Button that will satisfy this condition when clicked</summary>
    public BBParameter<Button> RequiredButton;

    /// <summary>Generates a string describing the condition</summary>
    protected override string info {
      get {
        return "Button " + this.RequiredButton.ToString() + " clicked";
      }
    }

    /// <summary>Called once time when the condition is added to a graph</summary>
    protected override string OnInit() {
      string error = base.OnInit();
      if(error == null) {
        this.buttonClickedDelegate = new UnityAction(buttonClicked);
        this.buttonWasClicked = false;
      }

      return error;
    }

    /// <summary>
    ///   Called when the state that is the origin of the condition becomes
    ///   active and before the condition is checked for the first time
    /// </summary>
    protected override void OnEnable() {
      base.OnEnable();

      // Let's be a bit paranoid
      this.buttonWasClicked = false;

      Button button = this.RequiredButton.value;
      button.onClick.AddListener(this.buttonClickedDelegate);
    }

    /// <summary>
    ///   Called when the state that is the origin of the condition is no
    ///   longer active and before the condition is checked for the last time
    /// </summary>
    protected override void OnDisable() {
      Button button = this.RequiredButton.value;
      button.onClick.RemoveListener(this.buttonClickedDelegate);

      this.buttonWasClicked = false;

      base.OnDisable();
    }

    /// <summary>Checks whether the condition is fulfilled</summary>
    /// <returns>True if the user made the required dialogue choice</returns>
    protected override bool OnCheck() {
      return this.buttonWasClicked;
    }

    /// <summary>
    ///   Called when the user clicks on the button this condition is watching
    /// </summary>
    private void buttonClicked() {
      this.buttonWasClicked = true;
    }

    /// <summary>Delegate for the buttonClicked() method</summary>
    private UnityAction buttonClickedDelegate;
    /// <summary>Whether the user has clicked on the button</summary>
    private bool buttonWasClicked;


  }

} // namespace Framework.Dialogue

#endif // HAVE_NODECANVAS