Implemented async barcode generation using async helpers

ref #13

package.json

@@ -40,6 +40,7 @@
   "license": "CC-BY-NC-SA-4.0",
   "dependencies": {
     "@odit/class-validator-jsonschema": "^2.1.1",
+    "async-helpers": "^0.3.17",
     "axios": "^0.21.1",
     "bwip-js": "^2.0.12",
     "cheerio": "^1.0.0-rc.5",

src/PdfCreator.ts

@@ -1,5 +1,4 @@
 import axios from 'axios';
-import bwipjs from "bwip-js";
 import cheerio from "cheerio";
 import fs from "fs";
 import Handlebars from 'handlebars';
@@ -9,6 +8,7 @@ import mime from "mime-types";
 import path from 'path';
 import { PDFDocument } from 'pdf-lib';
 import puppeteer from "puppeteer";
+import { awaitAsyncHandlebarHelpers, helpers } from './asyncHelpers';
 import { Runner } from './models/Runner';
 import { RunnerGroup } from './models/RunnerGroup';
 
@@ -78,18 +78,13 @@ export class PdfCreator {
                     loadPath: path.join(__dirname, '/locales/{{lng}}.json')
                 }
             });
+
+        await Handlebars.registerHelper(helpers);
         await Handlebars.registerHelper('__',
             function (str) {
                 return i18next.t(str, PdfCreator.interpolations).toString();
             }
         );
-        await Handlebars.registerHelper('--bc',
-            function (str) {
-                //TODO: Fix the async behaviour
-                return "data:image"
-                return PdfCreator.generateBarcode("code39", str.toString());
-            }
-        );
         this.browser = await puppeteer.launch({ headless: true, args: minimal_args });
     }
 
@@ -115,7 +110,8 @@ export class PdfCreator {
         await i18next.changeLanguage(locale);
         const template_source = fs.readFileSync(`${this.templateDir}/sponsoring_contract.html`, 'utf8');
         const template = Handlebars.compile(template_source);
-        const result = template({ runners })
+        let result = template({ runners });
+        result = await awaitAsyncHandlebarHelpers(result);
         const pdf = await this.renderPdf(result, { format: "A5", landscape: true });
         return pdf
     }
@@ -190,25 +186,6 @@ export class PdfCreator {
         return <Buffer>(await mergedPdf.save());
     }
 
-    /**
-     * A simple barcode generation function using default params suitable for usage in pdfs.
-     * Generates the barcodes as base64-encoded png.
-     * @param type Barcode type according to this list: https://github.com/metafloor/bwip-js/wiki/BWIPP-Barcode-Types
-     * @param content Barcode content/text - please remember that some formats only support certain input types.
-     * @returns Barcode image as base64 encoded png string.
-     */
-    public static async generateBarcode(type: string, content: string): Promise<String> {
-        let barcode: Buffer = await bwipjs.toBuffer({
-            bcid: type,
-            text: content,
-            scale: 3,
-            height: 10,
-            includetext: true,
-            textxalign: 'center',
-        });
-        return `data:image/png;base64,${barcode.toString('base64')}`;
-    }
-
     /**
      * Generates a new dummy runner with halfspaces for all strings.
      * Can be used to generate empty sponsoring contracts.

src/asyncHelpers.ts

@@ -0,0 +1,32 @@
+import AsyncHelpers from "async-helpers";
+import bwipjs from "bwip-js";
+
+export const asyncHelpers = new AsyncHelpers();
+async function generateBarcode(str, options, emtpy, cb) {
+    let res = await generateBase64Barcode(options.toString(), str.toString());
+    cb(null, res);
+}
+generateBarcode.async = true;
+asyncHelpers.set('--bc', generateBarcode);
+export const helpers = asyncHelpers.get({ wrap: true });
+
+export async function generateBase64Barcode(type: string, content: string): Promise<String> {
+    let barcode: Buffer = await bwipjs.toBuffer({
+        bcid: type,
+        text: content,
+        scale: 3,
+        height: 10,
+        includetext: true,
+        textxalign: 'center',
+    });
+    return `data:image/png;base64,${barcode.toString('base64')}`;
+}
+
+export async function awaitAsyncHandlebarHelpers(input: string): Promise<string> {
+    return await new Promise((resolve, reject) => {
+        asyncHelpers.resolveIds(input, (err, data) => {
+            if (err) { reject(err) }
+            resolve(data)
+        });
+    });
+}

src/templates/sponsoring_contract.html

@@ -54,7 +54,7 @@
           </div>
         </div>
         <div class="column">
-          <img width="100%" style="vertical-align: revert; margin-top: auto;" src="{{--bc this.id}}" />
+          <img width="100%" style="vertical-align: revert; margin-top: auto;" src="{{--bc this.id 'code39'}}" />
         </div>
       </div>
       <div class="columns" style="padding-top: 1rem;">