Fixed double-sided printing

ref #14

src/PdfCreator.ts

@@ -129,10 +129,11 @@ export class PdfCreator {
             const pdfs = await Promise.all(pdf_promises);
             return await this.mergePdfs(pdfs);
         }
+        const cards_swapped = this.swapArrayPairs(cards);
         await i18next.changeLanguage(locale);
         const template_source = fs.readFileSync(`${this.templateDir}/runner_card.html`, 'utf8');
         const template = Handlebars.compile(template_source);
-        const result = template({ cards, eventname: "LfK! 2069" })
+        const result = template({ cards, cards_swapped, eventname: "LfK! 2069" })
         const pdf = await this.renderPdf(result, { format: "A4", landscape: false });
         return pdf
     }
@@ -220,4 +221,22 @@ export class PdfCreator {
         runner.group = group;
         return runner;
     }
+
+    /**
+     * Swaps pairs (0/1, 2/3, ...) of elements in an array recursively.
+     * If the last element has no partner it inserts an empty element at the end and swaps the two
+     * This is needed to generate pdfs with front- and backside that get printet on one paper.
+     * @param array The array which's pairs shall get switched.
+     * @returns Array with swapped pairs,
+     */
+    private swapArrayPairs(array): Array<any> {
+        if (array.length == 1) {
+            return [null, array[0]];
+        }
+        if (array.length == 0) {
+            return null;
+        }
+
+        return [array[1], array[0]].concat(this.swapArrayPairs(array.slice(2)));
+    }
 }

src/templates/runner_card.html

@@ -46,19 +46,18 @@
           </div>
         </div>
         <p>{{this.runner.lastname}}, {{this.runner.firstname}} {{this.runner.middlename}}</p>
-        <p>{{this.runner.group.name}}</p>
+        <p>{{this.runner.group.name}} {{this.id}}</p>
       </div>
       {{/each}}
     </div>
   </div>
   <div class="sheet">
     <div class="columns is-multiline">
-      {{#each cards}}
+      {{#each cards_swapped}}
       <div class="column is-half runnercard">
+        <p>{{this.id}}</p>
         <!--SPONSOR LOGO FIRST-->
-        <img src="https://odit.services/assets/img/profile-pic-no_bg.hash.0c81702a.png" height="2cm" />
         <!--BARCODE SECOND-->
-        <img src="https://odit.services/assets/img/profile-pic-no_bg.hash.0c81702a.png" height="3.5cm" />
       </div>
       {{/each}}
     </div>