Convert Multiple HTML Pages to PDF in Parallel

using System.Collections.Generic;
using System.Threading.Tasks;
using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Mvc;
using HiQPdf_Next_AspNetDemo.Models;

using HiQPdf.Next;

namespace HiQPdf_Next_AspNetDemo.Controllers
{
    public class ConvertMultipleHtmlToPdfInParallelController : Controller
    {
        public IActionResult Index()
        {
            var model = new ConvertMultipleHtmlToPdfInParallelViewModel();
            return View(model);
        }

        [HttpPost]
        public async Task<ActionResult> ConvertToPdfInParallel(ConvertMultipleHtmlToPdfInParallelViewModel model)
        {
            if (!ModelState.IsValid)
            {
                var errorMessage = ModelStateHelper.GetModelErrors(ModelState);
                throw new ValidationException(errorMessage);
            }

            // Set the serial number received after purchase to use the library in licensed mode; leave it commented for demo mode
            // Licensing.SerialNumber = "your-serial-number";

            // Create PDF merger
            using PdfMerge pdfMerge = new PdfMerge();

            // Set PDF merge options
            SetPdfMergeOptions(pdfMerge, model);

            // Create the list of URLs to convert
            List<string> urlsToConvert = new List<string>() {
                model.Url1,
                model.Url2
            };

            if (model.AsyncParallelConversionEnabled)
            {
                // Parallel conversion using asynchronous methods to convert HTML to PDF

                // List of tasks that will run in parallel
                List<Task<byte[]>> conversionTasks = new List<Task<byte[]>>();

                foreach (string url in urlsToConvert)
                {
                    // Create the HTML to PDF Converter
                    HtmlToPdf htmlToPdfConverter = new HtmlToPdf();

                    // Set the HTML to PDF Converter options
                    SetHtmlToPdfConverterOptions(htmlToPdfConverter, model);

                    // Start async conversion
                    Task<byte[]> convertTask = htmlToPdfConverter.ConvertUrlToMemoryAsync(url);
                    conversionTasks.Add(convertTask);
                }

                // Wait for all conversions to finish
                byte[][] pdfBytesArray = await Task.WhenAll(conversionTasks);

                // Add PDFs in the original order
                foreach (byte[] pdfBytes in pdfBytesArray)
                {
                    pdfMerge.AddPdf(pdfBytes);
                }
            }
            else
            {
                foreach (string url in urlsToConvert)
                {
                    // Create the HTML to PDF Converter
                    HtmlToPdf htmlToPdfConverter = new HtmlToPdf();

                    // Set the HTML to PDF Converter options
                    SetHtmlToPdfConverterOptions(htmlToPdfConverter, model);

                    // Convert HTML to PDF
                    byte[] pdfBytes = htmlToPdfConverter.ConvertUrlToMemory(url);

                    // Add the PDF to the merger
                    int pdfPageCount = pdfMerge.AddPdf(pdfBytes);
                }
            }

            // Merge the PDF documents
            byte[] mergedPdf = pdfMerge.Save();

            // Send the merged PDF file to browser
            FileResult fileResult = new FileContentResult(mergedPdf, "application/pdf");
            fileResult.FileDownloadName = "Convert_Multipe_HTML_in_Parallel.pdf";

            return fileResult;
        }

        private void SetHtmlToPdfConverterOptions(HtmlToPdf htmlToPdfConverter, ConvertMultipleHtmlToPdfInParallelViewModel model)
        {

            // set browser height if specified, otherwise use the default
            if (model.BrowserHeight.HasValue)
                htmlToPdfConverter.BrowserHeight = model.BrowserHeight.Value;

            // Set an additional delay, in seconds, to wait for asynchronous content after the initial load
            // The default value is 0
            htmlToPdfConverter.WaitBeforeConvert = model.WaitTime;

            // Set the maximum time, in seconds, to wait for the HTML page to load
            // The default value is 120 seconds
            htmlToPdfConverter.HtmlLoadedTimeout = model.LoadHtmlTimeout;

            // Set the PDF page margins in points. The default is 0
            htmlToPdfConverter.Document.Margins = new PdfMargins(
                        model.LeftMargin, model.RightMargin,
                        model.TopMargin, model.BottomMargin);

            // Set the page layout: how the width at which the HTML is laid out relates to the PDF page width
            PdfPageSize pageSize = GetSelectedPageSize(model.PageSize);
            PdfPageOrientation pageOrientation = GetSelectedPageOrientation(model.PageOrientation);

            switch (model.PageLayout)
            {
                case "FitBrowserWindowToPage":
                    // Fixed page size: the HTML is laid out as in a browser window of the given width and the result
                    // is scaled to the content width of the page, so a responsive site keeps its desktop layout.
                    // This is the default layout of the converter, with an A4 page and a 1024 pixel window
                    htmlToPdfConverter.FitBrowserWindowToPage(pageSize, pageOrientation, windowWidth: model.BrowserWidth);
                    break;

                case "LayoutAtPageWidth":
                    // Fixed page size: the HTML is laid out at the content width of the page, one CSS pixel
                    // being 0.75 points. For HTML templates designed for the paper size
                    htmlToPdfConverter.LayoutAtPageWidth(pageSize, pageOrientation);
                    break;

                default:
                    // The PDF page width follows the browser window width and the HTML is drawn 1:1;
                    // the page height comes from the page size and the orientation
                    htmlToPdfConverter.PageWidthFromBrowserWindow(model.BrowserWidth, singlePage: false, zoom: model.BrowserZoom);
                    htmlToPdfConverter.Document.PageSize = pageSize;
                    htmlToPdfConverter.Document.PageOrientation = pageOrientation;
                    break;
            }

            // Enable the creation of a hierarchy of bookmarks from H1 to H6 tags
            htmlToPdfConverter.Document.GenerateDocumentOutline = model.AutoBookmarks;
        }

        private void SetPdfMergeOptions(PdfMerge pdfMerge, ConvertMultipleHtmlToPdfInParallelViewModel model)
        {
            // set the document security
            pdfMerge.Security.OpenPassword = model.OpenPassword;
            pdfMerge.Security.AllowPrinting = model.AllowPrinting;
        }

        private PdfPageSize GetSelectedPageSize(string pageSize)
        {
            switch (pageSize)
            {
                case "A0":
                    return PdfPageSize.A0;
                case "A1":
                    return PdfPageSize.A1;
                case "A10":
                    return PdfPageSize.A10;
                case "A2":
                    return PdfPageSize.A2;
                case "A3":
                    return PdfPageSize.A3;
                case "A4":
                    return PdfPageSize.A4;
                case "A5":
                    return PdfPageSize.A5;
                case "A6":
                    return PdfPageSize.A6;
                case "A7":
                    return PdfPageSize.A7;
                case "A8":
                    return PdfPageSize.A8;
                case "A9":
                    return PdfPageSize.A9;
                case "ArchA":
                    return PdfPageSize.ArchA;
                case "ArchB":
                    return PdfPageSize.ArchB;
                case "ArchC":
                    return PdfPageSize.ArchC;
                case "ArchD":
                    return PdfPageSize.ArchD;
                case "ArchE":
                    return PdfPageSize.ArchE;
                case "B0":
                    return PdfPageSize.B0;
                case "B1":
                    return PdfPageSize.B1;
                case "B2":
                    return PdfPageSize.B2;
                case "B3":
                    return PdfPageSize.B3;
                case "B4":
                    return PdfPageSize.B4;
                case "B5":
                    return PdfPageSize.B5;
                case "Flsa":
                    return PdfPageSize.Flsa;
                case "HalfLetter":
                    return PdfPageSize.HalfLetter;
                case "Ledger":
                    return PdfPageSize.Ledger;
                case "Legal":
                    return PdfPageSize.Legal;
                case "Letter":
                    return PdfPageSize.Letter;
                case "Letter11x17":
                    return PdfPageSize.Letter11x17;
                case "Note":
                    return PdfPageSize.Note;
                default:
                    return PdfPageSize.A4;
            }
        }

        private PdfPageOrientation GetSelectedPageOrientation(string pageOrientation)
        {
            return pageOrientation == "Portrait" ?
                PdfPageOrientation.Portrait : PdfPageOrientation.Landscape;
        }
    }
}