using System;

using UnityEngine;

using Framework.Services;

namespace Framework.Navigation.Platformer {

  /// <summary>A navigation target from and to which paths can be calculated</summary>
  public class Locator : ScriptComponent {

    /// <summary>Ground the game object is currently on or has most recently touched</summary>
    public Ground CurrentGround;

    /// <summary>Called when the component is loaded into a game object</summary>
    protected override void Awake() {
      base.Awake();

      // Needed to filter colliders touched by the locator to only see things meant
      // for the navigation system.
      this.navigationLayer = LayerMask.NameToLayer("Navigation");
      if(this.navigationLayer == -1) {
        Debug.LogWarning("No 'Navigation' layer defined. Locator will not work!");
      }

      // If the locator is on a layer that is not configured to collide with
      // the navigation layer, then the locator cannot work!
      if(Physics.GetIgnoreLayerCollision(gameObject.layer, this.navigationLayer)) {
        string layerName = LayerMask.LayerToName(gameObject.layer);
        Debug.LogWarning(
          "Navigation target '" + gameObject.name + "' is on layer '" + layerName + "', " +
          "which ignores collisions with the 'Navigation' layer. Locator will not work!"
        );
      }

      // If the locator has no collider, create one
      Collider collider = gameObject.GetComponent<Collider>();
      if(collider == null) {
        SphereCollider sphereCollider = gameObject.AddComponent<SphereCollider>();
        sphereCollider.radius = 0.1f;
        sphereCollider.isTrigger = true;
      }

    }

    /// <summary>Called when another collider enters the navigation target</summary>
    /// <param name="other">Other collider that has made contact</param>
    protected virtual void OnTriggerEnter(Collider other) {
#if false
      if(transform.parent == null) {
        Debug.Log("Target " + name + " touched " + other.name);
      } else {
        Debug.Log("Target " + transform.parent.name + " touched " + other.name);
      }
#endif
      int otherLayer = other.gameObject.layer;
      if(otherLayer == this.navigationLayer) {
        Transform otherTransform = other.transform;
        while(otherTransform != null) {
          Ground ground = otherTransform.GetComponent<Ground>();
          if(ground != null) {
            this.CurrentGround = ground;
            return;
          }

          otherTransform = otherTransform.parent;
        }
      }
    }

    /// <summary>Index of the layer the navigation colliders are on</summary>
    private int navigationLayer;

  }

} // namespace Framework.Navigation.Platformer