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

namespace Encompass
{
    internal class TimeManager
    {
        private readonly List<TimeDilationData> timeDilationDatas = new List<TimeDilationData>(32);

        private double Linear(double t, double b, double c, double d)
        {
            return (c * t / d) + b;
        }

        public double TimeDilationFactor
        {
            get
            {
                return timeDilationDatas.Count == 0 ? 1 : timeDilationDatas.Select(data => data.Factor).Average();
            }
        }

        public bool TimeDilationActive
        {
            get => timeDilationDatas.Count != 0;
        }

        public void Update(double dt)
        {
            for (var i = timeDilationDatas.Count - 1; i >= 0; i--)
            {
                var data = timeDilationDatas[i];

                data.elapsedTime += dt;

                if (data.elapsedTime > data.easeInTime + data.activeTime + data.easeOutTime)
                {
                    timeDilationDatas.RemoveAt(i);
                }
                else
                {
                    timeDilationDatas[i] = data;
                }
            }
        }

        public void ActivateTimeDilation(double factor, double easeInTime, double activeTime, double easeOutTime)
        {
            ActivateTimeDilation(factor, easeInTime, Linear, activeTime, easeOutTime, Linear);
        }

        public void ActivateTimeDilation(double factor, double easeInTime, System.Func<double, double, double, double, double> easeInFunction, double activeTime, double easeOutTime)
        {
            ActivateTimeDilation(factor, easeInTime, easeInFunction, activeTime, easeOutTime, Linear);
        }

        public void ActivateTimeDilation(double factor, double easeInTime, double activeTime, double easeOutTime, System.Func<double, double, double, double, double> easeOutFunction)
        {
            ActivateTimeDilation(factor, easeInTime, Linear, activeTime, easeOutTime, easeOutFunction);
        }

        public void ActivateTimeDilation(double factor, double easeInTime, System.Func<double, double, double, double, double> easeInFunction, double activeTime, double easeOutTime, System.Func<double, double, double, double, double> easeOutFunction)
        {
            timeDilationDatas.Add(new TimeDilationData
            {
                elapsedTime = 0,
                easeInTime = easeInTime,
                easeInFunction = easeInFunction,
                activeTime = activeTime,
                easeOutTime = easeOutTime,
                easeOutFunction = easeOutFunction,
                factor = factor
            });
        }
    }
}