// Fallback Headset|SDK_Fallback|002
namespace VRTK
{
    using UnityEngine;

    /// <summary>
    /// The Fallback System SDK script provides a fallback collection of methods that return null or default Headset values.
    /// </summary>
    /// <remarks>
    /// This is the fallback class that will just return default values.
    /// </remarks>
    public class SDK_FallbackHeadset : SDK_BaseHeadset
    {
        /// <summary>
        /// The GetHeadset method returns the Transform of the object that is used to represent the headset in the scene.
        /// </summary>
        /// <returns>A transform of the object representing the headset in the scene.</returns>
        public override Transform GetHeadset()
        {
            return null;
        }

        /// <summary>
        /// The GetHeadsetCamera method returns the Transform of the object that is used to hold the headset camera in the scene.
        /// </summary>
        /// <returns>A transform of the object holding the headset camera in the scene.</returns>
        public override Transform GetHeadsetCamera()
        {
            return null;
        }

        /// <summary>
        /// The HeadsetFade method is used to apply a fade to the headset camera to progressively change the colour.
        /// </summary>
        /// <param name="color">The colour to fade to.</param>
        /// <param name="duration">The amount of time the fade should take to reach the given colour.</param>
        /// <param name="fadeOverlay">Determines whether to use an overlay on the fade.</param>
        public override void HeadsetFade(Color color, float duration, bool fadeOverlay = false)
        {
        }

        /// <summary>
        /// The HasHeadsetFade method checks to see if the given game object (usually the camera) has the ability to fade the viewpoint.
        /// </summary>
        /// <param name="obj">The Transform to check to see if a camera fade is available on.</param>
        /// <returns>Returns true if the headset has fade functionality on it.</returns>
        public override bool HasHeadsetFade(Transform obj)
        {
            return false;
        }

        /// <summary>
        /// The AddHeadsetFade method attempts to add the fade functionality to the game object with the camera on it.
        /// </summary>
        /// <param name="camera">The Transform to with the camera on to add the fade functionality to.</param>
        public override void AddHeadsetFade(Transform camera)
        {
        }

        private void Awake()
        {
            Debug.LogError("Fallback Headset SDK is being used. Have you selected a valid Headset SDK in the SDK Manager? If you are unsure, then click the GameObject with the `VRTK_SDKManager` script attached to it in Edit Mode and select a Headset SDK from the dropdown.");
        }
    }
}