using System;

namespace TBL.CSharp.Utilities.Random.Generator
{
    /// <summary>
    /// 简易随机数生成器
    /// <para>用于生成低质量的随机数；表现在不同设备上可以做到统一</para>
    /// </summary>
    public class SimpleGenerator : IRandom<SimpleGenerator.Seed>
    {
        /// <summary>
        /// 种子值
        /// </summary>
        private int _seed;

        /// <summary>
        /// 从种子构造
        /// </summary>
        /// <param name="seed">种子值</param>
        public SimpleGenerator(int seed) => RestoreBySeed(new Seed(seed));

        public int NextRaw()
        {
            _seed++;
            var a = _seed * 15485863;
            return a * a * a % 2038074743;
        }

        /// <summary>
        /// 获取一个 <c>0.0</c> ~ <c>1.0</c> 之间的随机数
        /// </summary>
        public double NextDouble()
        {
            _seed++;
            var a = _seed * 15485863;
            return Math.Abs((a * a * a % 2038074743) / 2038074743.0f);
        }

        public Seed DumpSeed() => new Seed(_seed);

        public void RestoreBySeed(Seed seed) => _seed = seed.SeedValue;

        /// <summary>
        /// 种子
        /// </summary>
        public readonly struct Seed
        {
            /// <summary>
            /// 种子值
            /// </summary>
            public readonly int SeedValue;

            /// <summary>
            /// 构造
            /// </summary>
            public Seed(int seed)
            {
                SeedValue = seed;
            }
        }
    }
}