using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using UnityEngine;

namespace Assets.AR
{

    public class VideoPoint
    {
        public float Distance { get; set; }

        public float Time { get; set; }
    }
    public class VideoPointsSync 
    {
        private const float DefaultFps = 29.97f;
        protected float[] videoDistances;
        protected float[] videoTimes;
        protected float fps;

        public int Count => this.videoDistances.Length;

        public float LastVideoFrame => this.videoTimes[this.videoTimes.Length - 1] * this.fps;

        public VideoPointsSync(IEnumerable<VideoPoint> videoPoints, float fps = 29.97f)
        {
            List<VideoPoint> list = videoPoints.ToList<VideoPoint>();
            list.Sort((Comparison<VideoPoint>)((x, y) => x.Distance.CompareTo(y.Distance)));
            VideoPoint videoPoint1 = list[0];
            for (int index = 1; index < list.Count; ++index)
            {
                VideoPoint videoPoint2 = list[index];
                if ((double)videoPoint2.Distance == (double)videoPoint1.Distance)
                {
                    list.RemoveAt(index);
                    --index;
                }
                else
                    videoPoint1 = videoPoint2;
            }
            this.videoDistances = list.Select<VideoPoint, float>((Func<VideoPoint, float>)(x => x.Distance)).ToArray<float>();
            this.videoTimes = list.Select<VideoPoint, float>((Func<VideoPoint, float>)(x => x.Time)).ToArray<float>();
            this.fps = fps;
        }

        public float GetVideoSpeedAtDistance(float distance)
        {
            int index = this.IndexOfVideoPointForDistance(distance);
            return index == 0 || index == this.Count ? 0.0f : (float)(((double)this.videoDistances[index] - (double)this.videoDistances[index - 1]) / ((double)this.videoTimes[index] - (double)this.videoTimes[index - 1]));
        }

        public int IndexOfVideoPointForDistance(float distance)
        {
            int num = Array.BinarySearch<float>(this.videoDistances, distance);
            return num < 0 ? ~num : num;
        }

        public int IndexOfVideoPointForTime(float time)
        {
            int num = Array.BinarySearch<float>(this.videoTimes, time);
            return num < 0 ? ~num : num;
        }

        public float GetVideoFrameAtDistance(float distance)
        {
            int index = this.IndexOfVideoPointForDistance(distance);
            if (index == 0)
                return this.videoTimes[0] * this.fps;
            if (index == this.Count)
                return this.videoTimes[this.Count - 1] * this.fps;
            float t = Mathf.InverseLerp(this.videoDistances[index - 1], this.videoDistances[index], distance);
            return Mathf.Lerp(this.videoTimes[index - 1], this.videoTimes[index], t) * this.fps;
        }

        public float GetDistanceForVideoFrame(float frame)
        {
            float time = frame / this.fps;
            int index = this.IndexOfVideoPointForTime(time);
            if (index == 0)
                return this.videoDistances[0];
            if (index == this.Count)
                return this.videoDistances[this.Count - 1];
            float t = Mathf.InverseLerp(this.videoTimes[index - 1], this.videoTimes[index], time);
            return Mathf.Lerp(this.videoDistances[index - 1], this.videoDistances[index], t);
        }

        public float AverageVideoSpeed(float startFrame, float endFrame) => (double)startFrame == (double)endFrame ? this.GetVideoSpeedAtDistance(this.GetDistanceForVideoFrame(startFrame)) : (float)(((double)this.GetDistanceForVideoFrame(endFrame) - (double)this.GetDistanceForVideoFrame(startFrame)) * ((double)this.fps / ((double)endFrame - (double)startFrame)));
    }
}