public static class PdfHelper
    {
        private static async Task<byte[]> GetPdfFromHtmlString(string content, string id)
        {
            var path = GetExecutingDirectory();
            var exePath = Path.Join(path, "wkhtmltopdf.exe");
            var inputPath = Path.Join(path, $"{id}.html");
            var outputPath = Path.Join(path, $"{id}.pdf");

            await File.WriteAllTextAsync(inputPath, content);

            // https://stackoverflow.com/questions/6057781/wkhtmltopdf-with-full-page-background
            var arguments = $" -T 0 -B 0 -L 0 -R 0 --dpi 300 --page-size A4 --disable-smart-shrinking --print-media-type \"{inputPath}\" \"{outputPath}\"";
            await RunProcessAsync(exePath, arguments);

            var bytes = await File.ReadAllBytesAsync(outputPath);

            File.Delete(inputPath);
            File.Delete(outputPath);

            return bytes;
        }

        private static string GetExecutingDirectory()
        {
            var location = new Uri(Assembly.GetExecutingAssembly().GetName().CodeBase);
            return new FileInfo(location.AbsolutePath)?.Directory?.FullName;
        }

        private static void RunProcess(string fileName, string arguments, string workingDirectory)
        {
            var process = new Process
            {
                StartInfo = { FileName = fileName, Arguments = arguments, WorkingDirectory = workingDirectory }
            };
            process.Start();
        }

        private static Task<int> RunProcessAsync(string fileName, string arguments)
        {
            var tcs = new TaskCompletionSource<int>();

            var process = new Process
            {
                StartInfo = { FileName = fileName, Arguments = arguments, WorkingDirectory = GetExecutingDirectory() },
                EnableRaisingEvents = true
            };

            process.Exited += (sender, args) =>
            {
                tcs.SetResult(process.ExitCode);
                process.Dispose();
            };

            process.Start();

            return tcs.Task;
        }

        public static async Task<byte[]> GetOrderConfirmation(string template, string id)
        {
            var stream = await GetPdfFromHtmlString(template, id);
            return stream;
        }

        public static async Task<string> GetOrderConfirmationTemplate(CustomerOrder customerOrder)
        {
            var template = await DotLiquidHelper
                .GetTemplate("orderConfirmation.html");

            return template.Render(Hash.FromAnonymousObject(new { data = new OrderConfirmationDrop(customerOrder) }));
        }
    }

public static class DotLiquidHelper
    {
        private static async Task<string> GetTemplateAsString(string filename)
        {
            var path = Path.Join(ConfigurationHelper.GetExecutingDirectory(), $"\\Templates\\{filename}");

            using (var streamReader = new StreamReader(path, Encoding.UTF8))
            {
                return await streamReader.ReadToEndAsync();
            }
        }

        public static async Task<Template> GetTemplate(string fileName)
        {
            Template.NamingConvention = new CSharpNamingConvention();

            var templateString = await GetTemplateAsString(fileName);
            var template = Template.Parse(templateString);

            template.MakeThreadSafe();

            return template;
        }
    }