/************************************************************************************
Copyright : Copyright (c) Facebook Technologies, LLC and its affiliates. All rights reserved.

Your use of this SDK or tool is subject to the Oculus SDK License Agreement, available at
https://developer.oculus.com/licenses/oculussdk/

Unless required by applicable law or agreed to in writing, the Utilities SDK distributed
under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
ANY KIND, either express or implied. See the License for the specific language governing
permissions and limitations under the License.
************************************************************************************/

using System;
using System.Runtime.InteropServices;
using UnityEngine;

/// <summary>
/// An infrared camera that tracks the position of a head-mounted display.
/// </summary>
public class OVRTracker
{
	/// <summary>
	/// The (symmetric) visible area in front of the sensor.
	/// </summary>
	public struct Frustum
	{
		/// <summary>
		/// The sensor's minimum supported distance to the HMD.
		/// </summary>
		public float nearZ;
		/// <summary>
		/// The sensor's maximum supported distance to the HMD.
		/// </summary>
		public float farZ;
		/// <summary>
		/// The sensor's horizontal and vertical fields of view in degrees.
		/// </summary>
		public Vector2 fov;
	}

	/// <summary>
	/// If true, a sensor is attached to the system.
	/// </summary>
	public bool isPresent
	{
		get {
			if (!OVRManager.isHmdPresent)
				return false;

			return OVRPlugin.positionSupported;
		}
	}

	/// <summary>
	/// If true, the sensor is actively tracking the HMD's position. Otherwise the HMD may be temporarily occluded, the system may not support position tracking, etc.
	/// </summary>
	public bool isPositionTracked
	{
		get {
			return OVRPlugin.positionTracked;
		}
	}

	/// <summary>
	/// If this is true and a sensor is available, the system will use position tracking when isPositionTracked is also true.
	/// </summary>
	public bool isEnabled
	{
		get {
			if (!OVRManager.isHmdPresent)
				return false;

			return OVRPlugin.position;
        }

		set {
			if (!OVRManager.isHmdPresent)
				return;

			OVRPlugin.position = value;
		}
	}

	/// <summary>
	/// Returns the number of sensors currently connected to the system.
	/// </summary>
	public int count
	{
		get {
			int count = 0;

			for (int i = 0; i < (int)OVRPlugin.Tracker.Count; ++i)
			{
				if (GetPresent(i))
					count++;
			}

			return count;
		}
	}

	/// <summary>
	/// Gets the sensor's viewing frustum.
	/// </summary>
	public Frustum GetFrustum(int tracker = 0)
	{
		if (!OVRManager.isHmdPresent)
			return new Frustum();

		return OVRPlugin.GetTrackerFrustum((OVRPlugin.Tracker)tracker).ToFrustum();
	}

	/// <summary>
	/// Gets the sensor's pose, relative to the head's pose at the time of the last pose recentering.
	/// </summary>
	public OVRPose GetPose(int tracker = 0)
	{
		if (!OVRManager.isHmdPresent)
			return OVRPose.identity;

		OVRPose p;
		switch (tracker)
		{
			case 0:
				p = OVRPlugin.GetNodePose(OVRPlugin.Node.TrackerZero, OVRPlugin.Step.Render).ToOVRPose();
				break;
			case 1:
				p = OVRPlugin.GetNodePose(OVRPlugin.Node.TrackerOne, OVRPlugin.Step.Render).ToOVRPose();
				break;
			case 2:
				p = OVRPlugin.GetNodePose(OVRPlugin.Node.TrackerTwo, OVRPlugin.Step.Render).ToOVRPose();
				break;
			case 3:
				p = OVRPlugin.GetNodePose(OVRPlugin.Node.TrackerThree, OVRPlugin.Step.Render).ToOVRPose();
				break;
			default:
				return OVRPose.identity;
		}

		return new OVRPose()
		{
			position = p.position,
			orientation = p.orientation * Quaternion.Euler(0, 180, 0)
		};
	}

	/// <summary>
	/// If true, the pose of the sensor is valid and is ready to be queried.
	/// </summary>
	public bool GetPoseValid(int tracker = 0)
	{
		if (!OVRManager.isHmdPresent)
			return false;

		switch (tracker)
		{
			case 0:
				return OVRPlugin.GetNodePositionTracked(OVRPlugin.Node.TrackerZero);
			case 1:
				return OVRPlugin.GetNodePositionTracked(OVRPlugin.Node.TrackerOne);
			case 2:
				return OVRPlugin.GetNodePositionTracked(OVRPlugin.Node.TrackerTwo);
			case 3:
				return OVRPlugin.GetNodePositionTracked(OVRPlugin.Node.TrackerThree);
			default:
				return false;
		}
	}

	public bool GetPresent(int tracker = 0)
	{
		if (!OVRManager.isHmdPresent)
			return false;

		switch (tracker)
		{
			case 0:
				return OVRPlugin.GetNodePresent(OVRPlugin.Node.TrackerZero);
			case 1:
				return OVRPlugin.GetNodePresent(OVRPlugin.Node.TrackerOne);
			case 2:
				return OVRPlugin.GetNodePresent(OVRPlugin.Node.TrackerTwo);
			case 3:
				return OVRPlugin.GetNodePresent(OVRPlugin.Node.TrackerThree);
			default:
				return false;
		}
	}
}