PDFEngineAPI/BlackRock.Reporting.API/Controllers/PDFGeneratorController.cs

using System.Web;
using Microsoft.AspNetCore.Mvc;
using PuppeteerSharp;

namespace BlackRock.Reporting.API.Controllers
{
    [Route("api/[controller]")]
    public class PDFGeneratorController: Controller
    {
        private readonly IHostEnvironment host;

        public PDFGeneratorController(IHostEnvironment host)
        {
            this.host = host;
        }
        // Pristize URL adresa izvora web stranice koju treba eksportovati u PDF fajl
        [HttpGet("{url}")]
        public async Task<IActionResult> Get(string url= "http://localhost:3000/#/dashboard")
        {
//          Service ima endpint na koji stize zahtev sa urlom strance koju treba eksportovati u PDF
            if (string.IsNullOrEmpty(url))
                return BadRequest();

            var result = HttpUtility.UrlDecode(url);
            // Temporary name of file which will be downloaded
            var fileName = Guid.NewGuid().ToString() + ".pdf";
            // Path to wwwroot folder combined with name of pdf file
            string path = Path.Combine(host.ContentRootPath, $"wwwroot/pdfs/{fileName}");
            // string path = Path.Combine(host.WebRootPath, fileName);
            // Generate PDF file in wwwroot
//          Service obradjuje zahtev
//          U pozadini se podize chromium koji cemo koristiti za print
//          Pupeter otvara stranicu sa zadatim urlom
//          Pokrece se Engine Modul i priprema za procesiranje strance
//          Transformacija stranice u print ready stranicu
//          Daje se instrukija pupeteru da pokrene print nad print ready stranicom
            await GeneratePdf(result, path);
            // Prepare PDF file to download
//          Generisani PDF fails se vraca kao rezultat obrade zahteva
            FileStream stream = new FileStream(path, FileMode.Open);
            
            return File(stream, "application/pdf", fileName);
        }
        
        private async Task GeneratePdf(string url, string path)
        {
            await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultRevision);
            var options = new LaunchOptions
            {
                Headless = true
            };
            using (var browser = await Puppeteer.LaunchAsync(options))
            using (var page = await browser.NewPageAsync())
            {
                await page.GoToAsync(url, WaitUntilNavigation.DOMContentLoaded);


                var allResultsSelector = ".chartjs-render-monitor";
                await page.WaitForSelectorAsync(allResultsSelector);
                await EvaluateScript(page, "dist/main.js");
                // Transform HTML page before printing in PDF
                // TODO: Find solution to import some JS library
                // await page.EvaluateFunctionAsync("() => {document.getElementsByTagName('p')[0].style.display = 'none'}");
                //await page.EvaluateFunctionAsync("() => metoda()");
                //await page.ClickAsync("button#prepare");
                // Ne moze da radi jer Puppeteer ne pristupa skrivenim elementima
                //await page.ClickAsync("button#modify");
                // Resenje evaluate JS
                //await EvaluateScript(page, "transform.js");
                //string present = await CheckIfTransformExists(page);
                //// provera da li je transformacija vec odradjena
                //if (string.IsNullOrEmpty(present))
                //{
                //    await EvaluateScript(page, "transform.js");
                //}

                //await EvaluateScript(page, "modify.js");

                //await page.EvaluateFunctionAsync("() => document.querySelector('#modify').click()");
                await page.PdfAsync(path, new PdfOptions() { PrintBackground = true });

            }
        }

        // private async Task<string> CheckIfTransformExists(Page page)
        // {
        //     string path4 = Path.Combine(host.WebRootPath, "check.js");
        //     FileStream fs4 = new FileStream(path4, FileMode.Open);
        //     StreamReader streamReader4 = new StreamReader(fs4);
        //     string result4 = "";
        //     while (!streamReader4.EndOfStream)
        //     {
        //         result4 += (streamReader4.ReadLine() + Environment.NewLine);
        //     }
        //     fs4.Close();
        //     var present = await page.EvaluateFunctionAsync<string>(result4);
        //     return present;
        // }

        private async Task EvaluateScript(Page page,string fileName)
        {
            string path2 = Path.Combine(host.ContentRootPath, fileName);
            var result = await System.IO.File.ReadAllTextAsync(path2);
            await page.EvaluateExpressionAsync(result);
        }
    }
}