using System;
using System.Runtime.CompilerServices;

namespace UnityEngine.InputSystem.Utilities
{
    internal static class NumberHelpers
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static int AlignToMultipleOf(this int number, int alignment)
        {
            var remainder = number % alignment;
            if (remainder == 0)
                return number;

            return number + alignment - remainder;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static long AlignToMultipleOf(this long number, long alignment)
        {
            var remainder = number % alignment;
            if (remainder == 0)
                return number;

            return number + alignment - remainder;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static uint AlignToMultipleOf(this uint number, uint alignment)
        {
            var remainder = number % alignment;
            if (remainder == 0)
                return number;

            return number + alignment - remainder;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static bool Approximately(double a, double b)
        {
            return Math.Abs(b - a) <  Math.Max(1E-06 * Math.Max(Math.Abs(a), Math.Abs(b)), double.Epsilon * 8);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static float IntToNormalizedFloat(int value, int minValue, int maxValue)
        {
            if (value <= minValue)
                return 0.0f;
            if (value >= maxValue)
                return 1.0f;
            // using double here because int.MaxValue is not representable in floats
            // as int.MaxValue = 2147483647 will become 2147483648.0 when casted to a float
            return (float)(((double)value - minValue) / ((double)maxValue - minValue));
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static int NormalizedFloatToInt(float value, int intMinValue, int intMaxValue)
        {
            if (value <= 0.0f)
                return intMinValue;
            if (value >= 1.0f)
                return intMaxValue;
            return (int)(value * ((double)intMaxValue - intMinValue) + intMinValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static float UIntToNormalizedFloat(uint value, uint minValue, uint maxValue)
        {
            if (value <= minValue)
                return 0.0f;
            if (value >= maxValue)
                return 1.0f;
            // using double here because uint.MaxValue is not representable in floats
            return (float)(((double)value - minValue) / ((double)maxValue - minValue));
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static uint NormalizedFloatToUInt(float value, uint uintMinValue, uint uintMaxValue)
        {
            if (value <= 0.0f)
                return uintMinValue;
            if (value >= 1.0f)
                return uintMaxValue;
            return (uint)(value * ((double)uintMaxValue - uintMinValue) + uintMinValue);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static uint RemapUIntBitsToNormalizeFloatToUIntBits(uint value, uint inBitSize, uint outBitSize)
        {
            var inMaxValue = (uint)((1UL << (int)inBitSize) - 1);
            var outMaxValue = (uint)((1UL << (int)outBitSize) - 1);

            var normFloat = UIntToNormalizedFloat(value, 0, inMaxValue);
            return NormalizedFloatToUInt(normFloat, 0, outMaxValue);
        }
    }
}