web-wallet-sample/assets/scripts/libs/google.client.js

const scripts = ['https://apis.google.com/js/api.js', 'https://accounts.google.com/gsi/client'];
const DISCOVERY_DOC = 'https://www.googleapis.com/discovery/v1/apis/drive/v3/rest';
const CLIENT_ID = '53206975661-ih3r0ubph3rqejdq97b029difbrk2bqj.apps.googleusercontent.com';

// Authorization scopes required by the API; multiple scopes can be included, separated by spaces.
const SCOPES = 'openid email profile';
const SCOPES_DRIVE = 'https://www.googleapis.com/auth/drive.appdata';

export class GoogleClient {
  async initGApi() {
    return new Promise((resolve, reject) => {
      gapi.load('client', async () => {
        await gapi.client.init({ discoveryDocs: [DISCOVERY_DOC] });
        resolve();
      });
    });
  }
  initTokenClient(scopes, cb) {
    this.tokenClient = google.accounts.oauth2.initTokenClient({
      client_id: CLIENT_ID,
      scope: scopes,
      callback: cb // defined later
    });
    console.log('google client init success');
  }
  async initGoolgeClient() {
    await loadScripts(scripts.map((script) => [script]));
    await this.initGApi();
    this.initTokenClient(SCOPES);
  }
  login(funid) {
    this.tokenClient.callback = async (resp) => {
      if (resp.error !== undefined) {
        throw resp;
      }
      console.log('token: ', gapi.client.getToken());
      this.access_token = gapi.client.getToken().access_token;
      let result = {
        data: gapi.client.getToken().access_token,
        errcode: 0,
      };
      jc.wallet.nativeSvr.handleNativeCallback(funid, JSON.stringify(result));
    };

    if (gapi.client.getToken() === null) {
      // Prompt the user to select a Google Account and ask for consent to share their data
      // when establishing a new session.
      this.tokenClient.requestAccessToken({ prompt: 'consent' });
    } else {
      // Skip display of account chooser and consent dialog for an existing session.
      this.tokenClient.requestAccessToken({ prompt: '' });
    }
  }
  generateCfgName(key) {
    return `wallet_${key}.json`;
  }
  hasDriveScope() {
    return google.accounts.oauth2.hasGrantedAnyScope(gapi.client.getToken(), SCOPES_DRIVE);
  }
  async requestDriveScope() {
    return new Promise((resolve, reject) => {
      this.initTokenClient(SCOPES + " " + SCOPES_DRIVE, (resp) => {
        if (resp.error !== undefined) {
          throw resp;
        }
        resolve(); 
      });
      this.tokenClient.requestAccessToken({ prompt: 'consent' });
    });
  }
  async listFiles() {
    return gapi.client.drive.files.list({
      spaces: 'appDataFolder',
      fields: 'files(id, name)',
    });
  }
  async downloadCfg(key) {
    if (!this.hasDriveScope()) {
      await this.requestDriveScope();
    }
    let fileName = this.generateCfgName(key)
    let files = await this.listFiles();
    let file = files.result.files.find((file) => file.name.toLowerCase()  === fileName.toLowerCase());
    if (file) {
      let fileId = file.id;
      let info = await gapi.client.drive.files.get({
        fileId: fileId,
        alt: 'media',
      });
      return info.result;
    }
  }
  async uploadOneFile(content, fileName) {
    return new Promise((resolve, reject) => {
      var file = new Blob([JSON.stringify(content)], {type: 'application/json'});
      var metadata = {
        'name': fileName, // Filename at Google Drive
        'mimeType': 'application/json', // mimeType at Google Drive
        'parents': ['appDataFolder'], // Folder ID at Google Drive
      };

      var accessToken = gapi.auth.getToken().access_token; // Here gapi is used for retrieving the access token.
      var form = new FormData();
      form.append('metadata', new Blob([JSON.stringify(metadata)], {type: 'application/json'}));
      form.append('file', file);

      var xhr = new XMLHttpRequest();
      xhr.open('post', 'https://www.googleapis.com/upload/drive/v3/files?uploadType=multipart&fields=id');
      xhr.setRequestHeader('Authorization', 'Bearer ' + accessToken);
      xhr.responseType = 'json';
      xhr.onload = () => {
        console.log(xhr.response.id); // Retrieve uploaded file ID.
        resolve && resolve(xhr.response);
      };
      xhr.send(form);
    });
  }
  async uploadCfg(key, pass) {
    if (!this.hasDriveScope()) {
      await this.requestDriveScope();
    }
    let fileName = this.generateCfgName(key);
    let files = await this.listFiles();
    let file = files.result.files.find((file) => file.name.toLowerCase()  === fileName.toLowerCase());
    if (!file) {
      let res = await this.uploadOneFile({pass}, fileName);
      return res;
    } else {
      return file;
    }
  }
}