Capacitorjs save blob as pdf in android

[GorillaWarHead]

i'm trying to get a blob file from Rest Api and save it as pdf in android using capacitor js but nothing happens. im using capacitor filesystem plugin

here is the code :

import { Filesystem, Directory } from '@capacitor/filesystem';

const blobToBase64 = (blob) => {
    const reader = new FileReader();
    reader.readAsDataURL(blob);
    return new Promise((resolve) => {
      reader.onloadend = () => {
        resolve(reader.result);
      };
    });
  };

savePDF() {
    return HTTP()
      .get(`/vendorprintfacture`, {
        params: {
          path: state.pagePath,
          id: state.factureDetails.id,
        },
        responseType: 'arraybuffer',
      })
      .then(async (res) => {
        const blob = new Blob([res.data], { type: 'application/pdf' });
        
        blobToBase64(blob).then(async (res) => {
          try {
            Filesystem.writeFile({
              path: `pdf/${new Date()}.pdf`,
              data: res,
              directory: Directory.Documents,
            });
          } catch (e) {
            console.error('Unable to write file', e);
          }
        });

      
      })
      .catch((e) => {
      
        console.log(e);
      })
  }