/************************************************************************************

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

See SampleFramework license.txt for license terms.  Unless required by applicable law 
or agreed to in writing, the sample code is provided “AS IS” WITHOUT WARRANTIES OR 
CONDITIONS OF ANY KIND, either express or implied.  See the license for specific 
language governing permissions and limitations under the license.

************************************************************************************/

using UnityEngine;
using UnityEngine.Assertions;

namespace OculusSampleFramework
{
	public class TrainTrack : MonoBehaviour
	{
		[SerializeField] private float _gridSize = 0.5f;
		[SerializeField] private int _subDivCount = 20;
		[SerializeField] private Transform _segmentParent = null;
		[SerializeField] private Transform _trainParent = null;
		// regeneration is optional
		[SerializeField] private bool _regnerateTrackMeshOnAwake = false;

		private float _trainLength = -1.0f;
		private TrackSegment[] _trackSegments = null;

		public float TrackLength
		{
			get
			{
				return _trainLength;
			}
			private set
			{
				_trainLength = value;
			}
		}

		private void Awake()
		{
			Assert.IsNotNull(_segmentParent);
			Assert.IsNotNull(_trainParent);
			Regenerate();
		}

		public TrackSegment GetSegment(float distance)
		{
			int childCount = _segmentParent.childCount;

			for (int i = 0; i < childCount; i++)
			{
				var segment = _trackSegments[i];
				var nextSegment = _trackSegments[(i + 1) % childCount];
				if (distance >= segment.StartDistance && (distance < nextSegment.StartDistance || i == childCount - 1))
				{
					return segment;
				}
			}

			return null;
		}

		public void Regenerate()
		{
			_trackSegments = _segmentParent.GetComponentsInChildren<TrackSegment>();
			TrackLength = 0;
			int childCount = _segmentParent.childCount;
			TrackSegment lastSegment = null;

			var ratio = 0.0f;
			for (int i = 0; i < childCount; i++)
			{
				var segment = _trackSegments[i];
				segment.SubDivCount = _subDivCount;
				ratio = segment.setGridSize(_gridSize);
				if (lastSegment != null)
				{
					var endPose = lastSegment.EndPose;
					segment.transform.position = endPose.Position;
					segment.transform.rotation = endPose.Rotation;
					segment.StartDistance = TrackLength;
				}

				if (_regnerateTrackMeshOnAwake)
				{
					segment.RegenerateTrackAndMesh();
				}

				TrackLength += segment.SegmentLength;
				lastSegment = segment;
			}

			SetScale(ratio);
		}

		private void SetScale(float ratio)
		{
			_trainParent.localScale = new Vector3(ratio, ratio, ratio);
			var cars = _trainParent.GetComponentsInChildren<TrainCar>();
			var locomotive = _trainParent.GetComponentInChildren<TrainLocomotive>();
			locomotive.Scale = ratio;
			foreach (var car in cars)
			{
				car.Scale = ratio;
			}
		}
	}
}