using System;
using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Splines;

namespace samples.Runtime
{
	/// <summary>
	/// Animate extruding a section of a spline.
	/// </summary>
	[RequireComponent(typeof(SplineExtrude))]
	class AnimateSplineExtrude : MonoBehaviour
	{
		SplineExtrude m_Extrude;

		[SerializeField, Range(.0001f, 2f)]
		float m_Speed = .25f;

		float m_Span;

		[SerializeField]
		bool m_RebuildExtrudeOnUpdate = true;

		void Start()
		{
			m_Extrude = GetComponent<SplineExtrude>();
			m_Span = (m_Extrude.range.y - m_Extrude.range.x) * .5f;
		}

		void Update()
		{
			bool closed = m_Extrude.spline.Closed;
			float t = closed
				? Time.time * m_Speed
				: Mathf.Lerp(-m_Span, 1 + m_Span, math.frac(Time.time * m_Speed));
			m_Extrude.range = new float2(t - m_Span, t + m_Span);

			if (m_RebuildExtrudeOnUpdate)
				m_Extrude.Rebuild();
		}
	}
}