/// <summary>
/// evaluate captcha
/// </summary>
/// <param name="imageId"></param>
/// <param name="value"></param>
/// <returns></returns>
public async Task <RServiceResult <bool> > Evaluate(Guid imageId, string value)
{
try
{
RCaptchaImage captcha = await _context.CaptchaImages.Where(c => c.RImageId == imageId).FirstOrDefaultAsync();
if (captcha == null)
{
return(new RServiceResult <bool>(false, "Captcha not found"));
}
bool bRes = captcha.Value.ToLower() == value.ToLower();
if (bRes)
{
_context.CaptchaImages.Remove(captcha);
await _context.SaveChangesAsync();
//we can clean up OLD captcha images using a background service later
//await _imageFileService.DeleteImage(imageId);//might fail, does not matter
}
return(new RServiceResult <bool>(bRes));
}
catch (Exception exp)
{
return(new RServiceResult <bool>(false, exp.ToString()));
}
}
/// <summary>
/// Generate Captcha
/// </summary>
/// <returns></returns>
public async Task <RServiceResult <RImage> > Generate()
{
try
{
string value = $"{(new Random(DateTime.Now.Millisecond)).Next(0, 99999)}".PadLeft(5, '0');
using (Image img = new Bitmap(_CaptchaWidth, _CaptchaHeight))
{
using (Graphics g = Graphics.FromImage(img))
{
g.FillRectangle(Brushes.White, 0, 0, _CaptchaWidth, _CaptchaHeight);
using (Font fnt = new Font(_FontName, _FontSize))
{
SizeF sz = g.MeasureString(value, fnt);
g.DrawString(value, fnt, Brushes.Black, new PointF((_CaptchaWidth - sz.Width) / 2, (_CaptchaHeight - sz.Height) / 2));
}
}
using (MemoryStream ms = new MemoryStream())
{
img.Save(ms, ImageFormat.Png);
ms.Position = 0;
RServiceResult <RImage> image = await _imageFileService.Add(null, ms, $"{$"{(new Random(DateTime.Now.Millisecond)).Next(0, 99999)}".PadLeft(5, '0')}-{Guid.NewGuid()}.png", "Captcha");
if (!string.IsNullOrEmpty(image.ExceptionString))
{
return(new RServiceResult <RImage>(null, image.ExceptionString));
}
RCaptchaImage captcha = new RCaptchaImage()
{
Value = value,
DateTime = DateTime.Now,
RImage = image.Result
};
await _context.CaptchaImages.AddAsync(captcha);
await _context.SaveChangesAsync();
return(image);
}
}
}
catch (Exception exp)
{
return(new RServiceResult <RImage>(null, exp.ToString()));
}
}
