/************************************************************************************
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 UnityEngine;
using System.Collections.Generic;

#if UNITY_EDITOR_WIN || UNITY_STANDALONE_WIN || UNITY_ANDROID

internal class OVRCompositionUtil {

	public static void SafeDestroy(GameObject obj)
	{
		if (Application.isPlaying)
		{
			GameObject.Destroy(obj);
		}
		else
		{
			GameObject.DestroyImmediate(obj);
		}
	}

	public static void SafeDestroy(ref GameObject obj)
	{
        if (obj != null)
        {
            SafeDestroy(obj);
            obj = null;
        }
    }

	public static OVRPlugin.CameraDevice ConvertCameraDevice(OVRManager.CameraDevice cameraDevice)
	{
		if (cameraDevice == OVRManager.CameraDevice.WebCamera0)
		{
			return OVRPlugin.CameraDevice.WebCamera0;
		}
		else if (cameraDevice == OVRManager.CameraDevice.WebCamera1)
		{
			return OVRPlugin.CameraDevice.WebCamera1;
		}
		else if (cameraDevice == OVRManager.CameraDevice.ZEDCamera)
		{
			return OVRPlugin.CameraDevice.ZEDCamera;
		}
		else
		{
			return OVRPlugin.CameraDevice.None;
		}
	}

	public static OVRBoundary.BoundaryType ToBoundaryType(OVRManager.VirtualGreenScreenType type)
	{
		if (type == OVRManager.VirtualGreenScreenType.OuterBoundary)
		{
			return OVRBoundary.BoundaryType.OuterBoundary;
		}
		else if (type == OVRManager.VirtualGreenScreenType.PlayArea)
		{
			return OVRBoundary.BoundaryType.PlayArea;
		}
		else
		{
			Debug.LogWarning("Unmatched VirtualGreenScreenType");
			return OVRBoundary.BoundaryType.OuterBoundary;
		}
	}

	public static Vector3 GetWorldPosition(Vector3 trackingSpacePosition)
	{
		OVRPose tsPose;
		tsPose.position = trackingSpacePosition;
		tsPose.orientation = Quaternion.identity;
		OVRPose wsPose = OVRExtensions.ToWorldSpacePose(tsPose);
		Vector3 pos = wsPose.position;
		return pos;
	}

	public static float GetMaximumBoundaryDistance(Camera camera, OVRBoundary.BoundaryType boundaryType)
	{
		if (!OVRManager.boundary.GetConfigured())
		{
			return float.MaxValue;
		}

		Vector3[] geometry = OVRManager.boundary.GetGeometry(boundaryType);
		if (geometry.Length == 0)
		{
			return float.MaxValue;
		}

		float maxDistance = -float.MaxValue;
		foreach (Vector3 v in geometry)
		{
			Vector3 pos = GetWorldPosition(v);
			float distance = Vector3.Dot(camera.transform.forward, pos);
			if (maxDistance < distance)
			{
				maxDistance = distance;
			}
		}
		return maxDistance;
	}

	public static Mesh BuildBoundaryMesh(OVRBoundary.BoundaryType boundaryType, float topY, float bottomY)
	{
		if (!OVRManager.boundary.GetConfigured())
		{
			return null;
		}

		List<Vector3> geometry = new List<Vector3>(OVRManager.boundary.GetGeometry(boundaryType));
		if (geometry.Count == 0)
		{
			return null;
		}

		geometry.Add(geometry[0]);
		int numPoints = geometry.Count;

		Vector3[] vertices = new Vector3[numPoints * 2];
		Vector2[] uvs = new Vector2[numPoints * 2];
		for (int i = 0; i < numPoints; ++i)
		{
			Vector3 v = geometry[i];
			vertices[i] = new Vector3(v.x, bottomY, v.z);
			vertices[i + numPoints] = new Vector3(v.x, topY, v.z);
			uvs[i] = new Vector2((float)i / (numPoints - 1), 0.0f);
			uvs[i + numPoints] = new Vector2(uvs[i].x, 1.0f);
		}

		int[] triangles = new int[(numPoints - 1) * 2 * 3];
		for (int i = 0; i < numPoints - 1; ++i)
		{
			// the geometry is built clockwised. only the back faces should be rendered in the camera frame mask

			triangles[i * 6 + 0] = i;
			triangles[i * 6 + 1] = i + numPoints;
			triangles[i * 6 + 2] = i + 1 + numPoints;

			triangles[i * 6 + 3] = i;
			triangles[i * 6 + 4] = i + 1 + numPoints;
			triangles[i * 6 + 5] = i + 1;
		}

		Mesh mesh = new Mesh();
		mesh.vertices = vertices;
		mesh.uv = uvs;
		mesh.triangles = triangles;
		return mesh;
	}

}

#endif