using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Pcb.Domain;

namespace Pcb.Common
{
    /// <summary>
    /// AI验证
    /// </summary>
    public static class AIVerification
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="points"></param>
        /// <returns></returns>
        public static bool IsAI(List<MouseTrajectory> points)
        {
            bool flag = true;

            List<double> pointx = points.Select(t => t.x).ToList();
            List<double> pointy = points.Select(t => t.y).ToList();

            //标准差低于1时认定为是机器人
            if (CalculateStdDev(pointy) > 1)
            {
                flag = false;
            }

            if (flag)
            {
                flag = Judge(CalculateSlope(points));
            }
            return flag;
        }

        /// <summary>
        /// 计算标准差
        /// </summary>
        /// <param name="values"></param>
        /// <returns></returns>
        private static double CalculateStdDev(IEnumerable<double> values)
        {
            double ret = 0;
            if (values.Count() > 0)
            {
                //  计算平均数   
                double avg = values.Average();
                //  计算各数值与平均数的差值的平方，然后求和 
                double sum = values.Sum(d => Math.Pow(d - avg, 2));
                //  除以数量，然后开方
                ret = Math.Sqrt(sum / values.Count());
            }
            return ret;
        }

        /// <summary>
        /// 计算斜率,返回斜率的变化率
        /// </summary>
        private static List<double> CalculateSlope(List<MouseTrajectory> source)
        {
            List<double> slope = new List<double>();
            for (int i = 0; i < source.Count - 1; i++)
            {
                double s = (source[i + 1].y - source[i].y) / (source[i + 1].x - source[i].x);
                slope.Add(s);
            }
            List<double> result = new List<double>();
            for (int i = 0; i < slope.Count - 1; i++)
            {
                if ((slope[i] > 0 && slope[i + 1] < 0) || (slope[i] < 0 && slope[i] > 0))
                {
                    result.Add(1);
                }
                else
                {
                    result.Add(0);
                }
            }
            return result;
        }

        /// <summary>
        /// 任意Num个连续数字之和不能超过3
        /// </summary>
        /// <param name="rate"></param>
        /// <param name="num">连续数字个数，默认为4</param>
        /// <returns>false为不通过</returns>
        private static bool Judge(List<double> rate, int num = 4)
        {
            bool flag = rate.Sum() < 3;
            flag = rate.Count < 4;
            if (!flag)
            {
                for (int i = 0; i < rate.Count - 3; i++)
                {
                    double sum = 0;
                    for (int j = 0; j < num; j++)
                    {
                        sum += rate[i + j];
                    }
                    if (sum > 3)
                    {
                        flag = true;
                        break;
                    }
                }
            }
            return flag;
        }
    }
}