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

namespace Gibbed.Borderlands2.GameInfo
{
    public static class Experience
    {
        private const float _Multiplier = 60.0f;
        private const float _Power = 2.8f;
        private const float _Offset = 7.33f;

        private static int Compute(int level)
        {
            return (int)Math.Floor((Math.Pow(level, _Power) + _Offset) * _Multiplier);
        }

        private static readonly int _MinimumLevel;
        private static readonly int _MaximumLevel;
        private static readonly int _Reduction;
        private static readonly KeyValuePair<int, int>[] _LevelsAndTheirRequiredPoints;

        static Experience()
        {
            _MinimumLevel = 1;
            _MaximumLevel = 50 + 11 + 11; // TODO: put this in a resource generated by datamining

            _Reduction = Compute(_MinimumLevel);
            _LevelsAndTheirRequiredPoints = Enumerable
                .Range(1, _MaximumLevel)
                .Select(l => new KeyValuePair<int, int>(l, GetPointsForLevel(l)))
                .ToArray();
        }

        public static int GetPointsForLevel(int level)
        {
            if (level <= _MinimumLevel)
            {
                return 0;
            }

            return Compute(level) - _Reduction;
        }

        public static int GetLevelForPoints(int points)
        {
            if (points < 0)
            {
                return _MinimumLevel;
            }

            if (points >= _LevelsAndTheirRequiredPoints.Last().Value)
            {
                return _MaximumLevel;
            }

            return _LevelsAndTheirRequiredPoints
                       .First(lp => points < lp.Value)
                       .Key - 1;
        }
    }
}