using System.Drawing;
using System.Drawing.Imaging;

namespace XCGApp
{
    /// <summary>
    /// 驗證碼輔助類
    /// </summary>
    public class ValidateCodeUtil
    {
        /// <summary>
        /// 驗證碼長度 
        /// </summary>
        public int CodeLen { get; set; }
        /// <summary>
        /// 驗證碼
        /// </summary>
        public string VCode { get; private set; }
        /// <summary>
        /// 驗證碼圖像
        /// </summary>
        public Bitmap VCodeImg { get; private set; }

        private int fineness = 70;//圖片清晰度  數值越大越清晰
        private int imgWidth = 48;//圖片寬度
        private int imgHeight = 24;//圖片高度 
        private int fontSize = 14;//字體大小
        private string fontFamily = "Microsoft YaHei";//字體名稱

        /// <summary>
        /// 生成驗證碼 
        /// </summary>
        public string CreateVCode(int codeLen = 4)
        {
            CodeLen = codeLen;

            string vCode = "";
            Random random = new Random();
            for (int i = 0; i < CodeLen; i++)
            {
                int n = random.Next(10);
                vCode += n.ToString();
            }
            VCode = vCode;
            return vCode;
        }

        /// <summary>
        /// 驗證碼圖像Byte
        /// </summary>
        /// <returns></returns>
        public byte[] GetCodeImgByte()
        {
            VCodeImg = new Bitmap(imgWidth, imgHeight);
            //生成像素點
            DrawPixel(VCodeImg);
            //繪制驗證碼圖像
            DrewVCode(VCodeImg, VCode);
            //Bitmap轉byte[]
            byte[] imgByte = BitmapToByte(VCodeImg);

            return imgByte;
        }
        /// <summary>
        /// 驗證碼圖像Byte
        /// </summary>
        /// <returns></returns>
        public byte[] GetCodeImgByte(string code)
        {
            VCodeImg = new Bitmap(imgWidth, imgHeight);
            //生成像素點
            DrawPixel(VCodeImg);
            //繪制驗證碼圖像
            DrewVCode(VCodeImg, code);
            //Bitmap轉byte[]
            byte[] imgByte = BitmapToByte(VCodeImg);
            return imgByte;
        }

        /// <summary>
        /// 生成像素點
        /// </summary>
        private void DrawPixel(Bitmap bitmap)
        {
            Random random = new Random();
            for (int i = 0; i < bitmap.Width; i++)
            {
                for (int j = 0; j < bitmap.Height; j++)
                {
                    if (random.Next(90) <= fineness)
                        bitmap.SetPixel(i, j, Color.LightGray);
                }
            }
        }

        /// <summary>
        /// 繪制驗證碼圖像 
        /// </summary>
        /// <param name="bitmap"></param>
        private void DrewVCode(Bitmap bitmap, string vCode)
        {
            Graphics g = Graphics.FromImage(bitmap);
            Font font = new Font(fontFamily, fontSize, FontStyle.Regular);
            g.DrawString(vCode, font, Brushes.Black, 0, 0);
        }

        /// <summary>
        /// Bitmap轉byte[]
        /// </summary>
        private byte[] BitmapToByte(Bitmap bitmap)
        {
            MemoryStream ms = new MemoryStream();
            bitmap.Save(ms, ImageFormat.Bmp);
            byte[] imgByte = ms.GetBuffer();
            return imgByte;
        }
    }
}

[HttpGet]
public ActionResult ShowCode(string key)
{
    var codeObj = RedisUtil.GetRedis().Get(key);
    if (codeObj == null)
    {
        ApiResult res = new ApiResult()
        {
            Code = "-1",
            Message = "驗證碼失效，請刷新重試。"
        };
        return Json(res);
    }
    else
    {
        string vCode = codeObj.ToString();
        //生成驗證碼圖像Byte
        ValidateCodeUtil validateCode = new ValidateCodeUtil();
        byte[] imgByte = validateCode.GetCodeImgByte(vCode);
        return File(imgByte, "image/jpeg");
    }
}

[HttpPost]
public ApiResult GenerateValidateNo([FromBody]VCDto dto)
{
    ApiResult res = new ApiResult()
    {
        Code = "-1",
        Message = "請求失敗"
    };
    try
    {
        if (!string.IsNullOrEmpty(dto.OldKey))
        {
            //移除舊驗證碼
            RedisUtil.GetRedis().Remove(dto.OldKey);
        }

        //驗證碼的RedisKey
        var guid = Guid.NewGuid().ToString().Replace("-", "");
        //生成驗證碼
        ValidateCodeUtil validateCode = new ValidateCodeUtil();
        string vCode = validateCode.CreateVCode();
        //保存進Redis，1分鐘有效。
        RedisUtil.GetRedis().Insert(guid, vCode, DateTime.Now.AddMinutes(1));
        res.Code = "";
        res.Message = "OK";
        res.Data = guid;
        return res;
    }
    catch (Exception e)
    {
        res.Message = "驗證碼生成異常：" + e.Message;
        return res;
    }
}

mounted() {
    this.GetVerifyCode();
},
methods: {
    GetVerifyCode() {
      let vcSrc = that.$refs.imgvcode.src;
      var q = vcSrc.match(new RegExp('[?&]' + 'key' + '=([^&#]*)'));
      let oldKey = (q && q[1]) || '';
      let para = { "OldKey": oldKey };
      PostRequestAPI("Test/GenerateValidateNo", para).then((res) => {
        if (res.Code == "") {
          that.form.validateCodeKey = res.Data;
          that.$refs.imgvcode.src = '/Test/ShowCode?key=' + res.Data;
        } else {
          alert(res.Message);
        }
      });
    },
}