#if HAVE_NODECANVAS

using System;

using UnityEngine;
using UnityEngine.UI;

using NodeCanvas.Framework;
using ParadoxNotion.Design;

namespace Framework.Dialogue {

  /// <summary>
  ///   Allows a transition only if the player picked a specific choice in the last dialogue
  /// </summary>
  [Category("Dialogue")]
  public class DialogueChoiceCondition : ConditionTask {

    /// <summary>Choice on which this condition will pass</summary>
    public int ChoiceIndex = 0;

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

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

    /// <summary>Fetches the index of the selected dialogue choice from the blackboard</summary>
    /// <returns>The index of the selected choice from the blackboard</returns>
    private int? getChoiceIndexFromBlackboard() {
      const string ChoiceIndexVariableName = "DialogueChoiceIndex";

      IBlackboard choiceBlackboard = ownerBlackboard;
      if(choiceBlackboard == null) {
        Debug.LogError(
          "DialogueChoiceCondition could not find a blackboard in its state machine. " +
          "A blackboard is required to store the choices made by the player. " +
          "Conditions on multiple choice dialogue will not work."
        );
        return -1;
      }

      // If it's null, we'll already have complaine in OnInit()!
      Variable choiceIndexVariable = choiceBlackboard.GetVariable(
        ChoiceIndexVariableName, typeof(int)
      );
      if(choiceIndexVariable == null) {
        return null;
      } else {
        return (int)choiceIndexVariable.value;
      }
    }

  }

} // namespace Framework.Dialogue

#endif // HAVE_NODECANVAS