using System;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace Controller.Bicycle
{
    struct Booster
    {
        public float Start { get; }
        public float End { get; }
        public float MaxValue { get; }
        public bool Increasing { get; }

        public Booster(float start, float end, float maxValue, bool increasing)
        {
            this.Start = start;
            this.End = end;
            this.MaxValue = maxValue;
            this.Increasing = increasing;
        }
    }

    public class BikeSpeedBooster
    {
        #region singleton

        private static readonly Lazy<BikeSpeedBooster>
            lazy =
                new Lazy<BikeSpeedBooster>
                    (() => new BikeSpeedBooster());

        public static BikeSpeedBooster Instance => lazy.Value;

        private readonly List<Booster> activeBooster = new List<Booster>();

        #endregion

        private const float ZERO_SLOPE_THRES = 0.05f;

        public float Boost { get; private set; }


        public void OnSlopeChanged(float timestamp, float slope)
        {
            if (Mathf.Abs(slope) < ZERO_SLOPE_THRES) return; //TODO: what happens when zero?
            var duration = 0f; //TODO: calculate
            var maxValue = 0f; //TODO
            activeBooster.Add(new Booster(Time.time, Time.time + duration, maxValue, slope < 0f));
        }

        public void OnFixedUpdate()
        {
            foreach (var b in activeBooster.Where(b => b.End <= Time.fixedTime))
            {
                activeBooster.Remove(b);
            }

            //TODO: clamp
            Boost = activeBooster.Sum(b => b.MaxValue * 0.7f); //TODO: factor
        }
    }
}