Added pdf merging for big requests (over 100 runners)

ref #5

package.json

@@ -52,6 +52,7 @@
     "i18next": "^19.8.7",
     "i18next-fs-backend": "^1.0.8",
     "mime-types": "^2.1.28",
+    "pdf-lib": "^1.16.0",
     "puppeteer": "^7.0.1",
     "reflect-metadata": "^0.1.13",
     "routing-controllers": "^0.9.0-alpha.6",
@@ -81,4 +82,4 @@
       "publish": false
     }
   }
-}
+}

src/PdfCreator.ts

@@ -6,6 +6,7 @@ import i18next from "i18next";
 import Backend from 'i18next-fs-backend';
 import mime from "mime-types";
 import path from 'path';
+import { PDFDocument } from 'pdf-lib';
 import puppeteer from "puppeteer";
 import { Runner } from './models/Runner';
 import { RunnerGroup } from './models/RunnerGroup';
@@ -45,7 +46,7 @@ export class PdfCreator {
                 return i18next.t(str, PdfCreator.interpolations).toString();
             }
         );
-        this.browser = await puppeteer.launch({ headless: true });
+        this.browser = await puppeteer.launch({ headless: true, args: ['--disable-dev-shm-usage', '--shm-size=10gb'] });
     }
 
     /**
@@ -57,6 +58,15 @@ export class PdfCreator {
         if (runners.length == 1 && Object.keys(runners[0]).length == 0) {
             runners[0] = this.generateEmptyRunner();
         }
+        if (runners.length > 100) {
+            let pdfs: Buffer[] = new Array<Buffer>();
+            let i, j;
+            for (i = 0, j = runners.length; i < j; i += 100) {
+                let chunk = runners.slice(i, i + 100);
+                pdfs.push(await this.generateSponsoringContract(chunk, locale));
+            }
+            return await this.mergePdfs(pdfs);
+        }
         await i18next.changeLanguage(locale);
         const template_source = fs.readFileSync(`${this.templateDir}/sponsoring_contract.html`, 'utf8');
         const template = Handlebars.compile(template_source);
@@ -112,6 +122,25 @@ export class PdfCreator {
         return pdf;
     }
 
+    /**
+     * Merges multiple pdfs into one.
+     * @param pdfs The pdfs you want to merge as an buffer array.
+     * @returns The merged pdf as a buffer.
+     */
+    private async mergePdfs(pdfs: Buffer[]): Promise<Buffer> {
+        const mergedPdf = await PDFDocument.create();
+
+        for (const pdfBuffer of pdfs) {
+            const pdf = await PDFDocument.load(pdfBuffer);
+            const copiedPages = await mergedPdf.copyPages(pdf, pdf.getPageIndices());
+            copiedPages.forEach((page) => {
+                mergedPdf.addPage(page);
+            });
+        }
+
+        return <Buffer>(await mergedPdf.save());
+    }
+
     /**
      * Generates a new dummy runner with halfspaces for all strings.
      * Can be used to generate empty sponsoring contracts.