using System;

using UnityEngine;

namespace Framework.Cameras {

  /// <summary>Helper methods for dealing with cameras</summary>
  public static class CameraHelper {

    /// <summary>Makes the specified camera the active camera</summary>
    /// <param name="camera">Camera that will become the active camera</param>
    /// <param name="disablePrevious">
    ///   Whether the game object holding the previously active camera should be
    ///   disabled, including any other components such as audio sources that it
    ///   is holding. This is usually a good idea.
    /// </param>
    public static Camera ActivateCamera(Camera camera, bool disablePrevious = true) {
      Camera previousCamera = Camera.main;

      // First tag the new camera as MainCamera. This should switch
      // what UnityEngine.Camera.main returns and leave it clear which
      // camera is to become the main camera when the previous one is off.
      camera.tag = "MainCamera";

      // If another camera was active previously, take away its MainCamera
      // tag and disable it completely if so desired by the caller
      if(previousCamera != null) {
        GameObject previousCameraGameObject = previousCamera.gameObject;
        if(!ReferenceEquals(previousCamera, camera)) {
          previousCameraGameObject.tag = "Untagged";
          if(disablePrevious) {
            previousCameraGameObject.SetActive(false);
          }
        }
      }

      // With the previous camera disabled, enable this one.
      // Doing it in this order ensures that no two cameras + audio listeners
      // or such are active at the same time.
      camera.enabled = false;
      camera.enabled = true; // Force OnEnable() for ICameraManager (does it work?)
      camera.gameObject.SetActive(true);

      return previousCamera;
    }

  }

} // namespace Framework.Cameras