using System;

using UnityEngine;

namespace Framework.Dialogue {

  /// <summary>Helper methods for retrieving and checking dialogue layer index</summary>
  public static class DialogueLayerHelper {

    /// <summary>Index of the layer on which the dialogue UI and hints are placed</summary>
    public static int LayerIndex {
      get {
        if(!layerIndexLookedUp) {
          layerIndex = LayerMask.NameToLayer("Dialogue");
          if(layerIndex == -1) {
            Debug.LogWarning(
              "No 'Dialogue' layer has been set up. The DialogueManager requires this " +
              "layer to locate placements. Dialogue will likely not function."
            );
          }

          layerIndexLookedUp = true;
        }

        return layerIndex;
      }
    }

    /// <summary>
    ///   Checks that the specified game object is set up correctly as a dialogue placement
    /// </summary>
    /// <param name="gameObject">Game object that will be checked</param>
    public static void CheckDialoguePlacement(GameObject gameObject) {
      ensureColliderPresent(gameObject);
      ensureDialogueLayerUsed(gameObject);
    }

    /// <summary>Makes sure that the game object is on the dialogue layer</summary>
    /// <param name="gameObject">Game object that will be checked and fixed</param>
    private static void ensureDialogueLayerUsed(GameObject gameObject) {
      int dialogueLayerIndex = LayerIndex;
      if(dialogueLayerIndex != -1) {
        if(gameObject.layer != dialogueLayerIndex) {
          Debug.LogWarning(
            "GameObject '" + gameObject.name + "' has a DialogueOwner but " +
            "is not on the 'Dialogue' layer. Forcefully moving game object to " +
            "that layer. If the GameObject is used for more than just dialogue " +
            "this will likely break collision for it."
          );
          gameObject.layer = dialogueLayerIndex;
        }
      }
    }

    /// <summary>Makes sure that the game object has a collider</summary>
    /// <param name="gameObject">Game object that will be checked and fixed</param>
    private static void ensureColliderPresent(GameObject gameObject) {
      Collider collider = gameObject.GetComponent<Collider>();
      if(collider == null) {
        Debug.LogWarning(
          "DialogueOwner on '" + gameObject.name + "' could not find a collider " +
          "on its GameObject (required by the DialogueManager to locate placements), " +
          "so a default SphereCollider was added."
        );

        SphereCollider sphereCollider = gameObject.AddComponent<SphereCollider>();
        sphereCollider.radius = DialogueManager.DefaultMaximumDistance;
      }
    }

    /// <summary>Whether we attempted to look up the dialogue layer index yet</summary>
    private static bool layerIndexLookedUp;
    /// <summary>Index of the layer on which dialogue placements and UI are</summary>
    private static int layerIndex;

  }

} // namespace Framework.Dialogue