using System;
using UnityEngine;

namespace NEG.Utils.Timing
{
    public class TimeMachine
    {
        private double timeInternal;

        public TimeMachine()
        {
            timeInternal = 0;
        }

        /// <summary>
        /// Adds time into the TimeMachine
        /// </summary>
        /// <param name="time">Amount of time to be added</param>
        public void Accumulate(double time) => timeInternal += time;

        /// <summary>
        /// Retrieves given amount of time from the TimeMachine
        /// </summary>
        /// <param name="maxTime"></param>
        /// <returns>Amount of time retrieved</returns>
        public double Retrieve(double maxTime) 
        {
            if(!double.IsFinite(maxTime))
            {
                double timeRetrieved = timeInternal;
                timeInternal = 0;
                return timeRetrieved;
            }
            double timeLeft = timeInternal - maxTime;
            timeInternal = Math.Max(timeLeft, 0);
            return Math.Min(maxTime + timeLeft, maxTime);
        }

        /// <summary>
        /// Attempts to retrieves given amount of time from the TimeMachine <br/>
        /// If there is enough <paramref name="time"/> accumulated in this machine subtracts that amount and returns true, otherwise returns false
        /// </summary>
        /// <param name="time"></param>
        public bool TryRetrieve(double time)
        {
            if (!(timeInternal >= time)) 
                return false;
            timeInternal -= time;
            return true;
        }

        /// <summary>
        /// Result is equivalent to calling <see cref="TryRetrieve(double)"/> as many times as possible, but is faster for larger <paramref name="limit"/> values
        /// </summary>
        /// <param name="interval">Single unit of warp time, must be positive</param>
        /// <param name="limit">Maximum amount of warps, must be positive</param>
        /// <returns>Amount of warps</returns>
        public int RetrieveAll(double interval, int limit = int.MaxValue)
        {
            int result = Mathf.FloorToInt((float)(timeInternal / interval));
            result = Math.Clamp(result, 0, limit);
            timeInternal -= result * interval;
            return result;
        }
    }
}