async Task ShowAsync(HttpContext context, CancellationToken cancellationToken)
{
// generate
var data = new ArraySegment <byte>(new byte[0]);
var size = 300;
var stopwatch = Stopwatch.StartNew();
try
{
// prepare
var query = context.GetRequestUri().ParseQuery();
var value = query.ContainsKey("v") && !string.IsNullOrWhiteSpace(query["v"])
? query["v"].ToBase64(false, true).Decrypt(Global.EncryptionKey)
: query.ContainsKey("d") ? query["d"] : null;
if (string.IsNullOrWhiteSpace(value))
{
throw new InvalidRequestException();
}
if (query.ContainsKey("t"))
{
var timestamp = query["t"].ToBase64(false, true).Decrypt(Global.EncryptionKey).CastAs <long>();
if (DateTime.Now.ToUnixTimestamp() - timestamp > 90)
{
throw new InvalidRequestException();
}
}
size = (query.ContainsKey("s") ? query["s"] : "300").CastAs <int>();
if (!Enum.TryParse(query.ContainsKey("ecl") ? query["ecl"] : "M", out QRCodeGenerator.ECCLevel level))
{
level = QRCodeGenerator.ECCLevel.M;
}
// generate QR code using QRCoder
if ("QRCoder".IsEquals(UtilityService.GetAppSetting("Files:QRCodeProvider")))
{
data = this.Generate(value, size, level);
}
// generate QR code using Google APIs
else
{
try
{
data = (await UtilityService.DownloadAsync($"https://chart.apis.google.com/chart?cht=qr&chs={size}x{size}&chl={value.UrlEncode()}", null, null, cancellationToken).ConfigureAwait(false)).ToArraySegment();
}
catch (Exception ex)
{
await Global.WriteLogsAsync(this.Logger, "Http.QRCodes", $"Error occurred while generating the QR Code by Google Chart APIs: {ex.Message}", ex).ConfigureAwait(false);
data = this.Generate(value, size, level);
}
}
stopwatch.Stop();
if (Global.IsDebugLogEnabled)
{
await Global.WriteLogsAsync(this.Logger, "Http.QRCodes", $"Generate QR Code successful: {value} - [Size: {size} - ECC Level: {level}] - Execution times: {stopwatch.GetElapsedTimes()}").ConfigureAwait(false);
}
}
catch (Exception ex)
{
await Global.WriteLogsAsync(this.Logger, "Http.QRCodes", $"Error occurred while generating the QR Code: {ex.Message}", ex).ConfigureAwait(false);
data = ThumbnailHandler.Generate(ex.Message, size, size, true);
}
// display
context.SetResponseHeaders((int)HttpStatusCode.OK, "image/png", null, 0, "private, no-store, no-cache", TimeSpan.Zero, context.GetCorrelationID());
await context.WriteAsync(data, cancellationToken).ConfigureAwait(false);
}