/// <summary>
/// 获取验证码
/// </summary>
public List<VerificationCode.Model.WenZhi> GetCodeText()
{
    const string sql = "SELECT * FROM wenzhi ORDER BY RAND() LIMIT 4";
    var dataReader = dbHelper.GetDataReader(sql);
    var list = DataReaderToList(dataReader);
    dataReader.Close();
    return list;
}

/// <summary>
/// 获取答案备选
/// </summary>
/// <param name="buShouCode">部首编码</param>
/// <param name="id">当前文字ID</param>
/// <param name="number">数量</param>
/// <returns></returns>
public List<VerificationCode.Model.WenZhi> GetAnswer(string buShouCode, int id,int number=1)
{
    string sql = $"SELECT * FROM wenzhi where BuShouCode='{buShouCode}' and ID <> {id} ORDER BY RAND() LIMIT "+ number;
    var dataReader = dbHelper.GetDataReader(sql);
    var list = DataReaderToList(dataReader);
    dataReader.Close();
    return list;
}

public Model.Code GetCode()
       {
         
           var wenzlist = _wenZhiDal.GetCodeText();  //获取验证码
           var listAnsuwr = new List<Answer>();//实例化备选答案对象
           var answerCode = string.Empty;//答案
           var result = new Model.Code
           {
               Id = Guid.NewGuid().ToString()
           };
           //根据验证码获取备选答案并把添加到答案添加到备选答案集合
           foreach (var item in wenzlist)
           {
               answerCode += item.ID + ",";
               result.AnswerValue += item.Text;
               var answerList = _wenZhiDal.GetAnswer(item.BuShouCode, item.ID);
               listAnsuwr.Add(new Answer { Id = item.ID.ToString(), Img = GetImage(item.Text) });
               listAnsuwr.AddRange(answerList.Select(answer => new Answer { Id = answer.ID.ToString(), Img = GetImage(answer.Text) }));
           }
           //如果答案个数不够就再去取几个
           if (listAnsuwr.Count < 9)
           {
               var ran = new Random();
               var randKey = ran.Next(0, 4);
               var item = wenzlist[randKey];
               var answerList = _wenZhiDal.GetAnswer(item.BuShouCode, item.ID, 9 - listAnsuwr.Count);
               listAnsuwr.AddRange(answerList.Select(answer => new Answer { Id = answer.ID.ToString(), Img = GetImage(answer.Text) }));
           }
           result.CodeImg = GetImage(result.AnswerValue);//获取图片
           result.AnswerValue = answerCode.TrimEnd(',');
           result.Answer = RandomSortList(listAnsuwr);//打乱正确答案与形近字的顺序
           return result;
       }

/// <summary>
/// 随机排列集合
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="listT"></param>
/// <returns></returns>
private static List<T> RandomSortList<T>(IEnumerable<T> listT)
{
    var random = new Random();
    var newList = new List<T>();
    foreach (var item in listT)
    {
        newList.Insert(random.Next(newList.Count + 1), item);
    }
    return newList;
}

private static string GetImage(string text)
        {
            Image image;
            switch (text.Length)
            {
                case 1:
                    image = new Bitmap(50, 40);
                    break;
                case 4:
                    image = new Bitmap(120, 40);
                    break;
                default:
                    image = new Bitmap(50, 40);
                    break;
            }
            Brush brushText = new SolidBrush(Color.FromArgb(255, 0, 0, 0));
            var graphics = Graphics.FromImage(image);
            graphics.SmoothingMode = SmoothingMode.AntiAlias;
            graphics.Clear(Color.White);
            var font = new Font(new FontFamily("华文彩云"), 20, FontStyle.Regular);
            if (text.Length > 1)//画验证码
            {
                //先来两条直线做干扰 然后再画文字
                graphics.DrawLine(new Pen(brushText, new Random().Next(1, 3)), new Point(new Random().Next(0, 10), new Random().Next(10, 40)), new Point(new Random().Next(100, 120), new Random().Next(10, 30)));
                graphics.DrawLine(new Pen(brushText, new Random().Next(1, 3)), new Point(new Random().Next(20, 50), new Random().Next(0, 10)), new Point(new Random().Next(100, 120), new Random().Next(30, 40)));
                graphics.DrawString(text, font, brushText, 0, 10);

            }
            else//画备选答案
            {
                Point middle = new Point(25, 20);
                graphics.TranslateTransform(middle.X, middle.Y);
                //这里是360°随机旋转 
                graphics.RotateTransform(new Random().Next(0, 360));
                var format = new StringFormat(StringFormatFlags.NoClip)
                {
                    Alignment = StringAlignment.Center,
                    LineAlignment = StringAlignment.Center
                };
                graphics.DrawString(text, font, brushText, 0, 0, format);

            }
            brushText.Dispose();
            graphics.Dispose();
            return ImageToBase64(image);
        }

public string GetVerCode()
{
    var code = new VerificationCode.Code().GetCode();
    Session["VERCODE"] = code.AnswerValue;
    code.AnswerValue = "";
    return JsonConvert.SerializeObject(code);
}