'use strict';

/*
Cloud provider implementations (Dropbox only as now)

provider Interface:

name: name of the provider
async auth(): authenticate and get access tokens from provider
async save(filename): save map file to provider as filename
async load(filename): load filename from provider
async list(): list available filenames at provider
async getLink(filePath): get shareable link for file
restore(): restore access tokens from storage if possible

*/

window.Cloud = (function () {
  // helpers to use in providers for token handling
  const lSKey = (x) => `auth-${x}`;
  const setToken = (prov, key) => localStorage.setItem(lSKey(prov), key);
  const getToken = (prov) => localStorage.getItem(lSKey(prov));

  /**********************************************************/
  /* Dropbox provider                                       */
  /**********************************************************/

  const DBP = {
    name: 'dropbox',
    clientId: 'pdr9ae64ip0qno4',
    authWindow: undefined,
    token: null, // Access token
    api: null,

    restore() {
      this.token = getToken(this.name);
      if (this.token) this.connect(this.token);
    },

    async call(name, param) {
      try {
        return await this.api[name](param);
      } catch (e) {
        if (e.name !== 'DropboxResponseError') throw e;
        // retry with auth
        await this.auth();
        return await this.api[name](param);
      }
    },

    connect(token) {
      const clientId = this.clientId;
      const auth = new Dropbox.DropboxAuth({clientId});
      auth.setAccessToken(token);
      this.api = new Dropbox.Dropbox({auth});
    },

    async save(fileName, contents) {
      if (!this.api) await this.auth();
      const resp = this.call('filesUpload', {path: '/' + fileName, contents});
      DEBUG && console.log('Dropbox response:', resp);
      return true;
    },

    async load(path) {
      if (!this.api) await this.auth();
      const resp = await this.call('filesDownload', {path});
      const blob = resp.result.fileBlob;
      if (!blob) throw new Error('Invalid response from dropbox.');
      return blob;
    },

    async list() {
      if (!this.api) return null;
      const resp = await this.call('filesListFolder', {path: ''});
      return resp.result.entries.map((e) => ({name: e.name, path: e.path_lower}));
    },

    auth() {
      const url = window.location.origin + window.location.pathname + 'dropbox.html';
      this.authWindow = window.open(url, 'auth', 'width=640,height=480');
      // child window expected to call
      // window.opener.Cloud.providers.dropbox.setDropBoxToken (see below)
      return new Promise((resolve, reject) => {
        const watchDog = () => {
          this.authWindow.close();
          reject(new Error('Timeout. No auth for dropbox.'));
        };
        setTimeout(watchDog, 120 * 1000);
        window.addEventListener('dropboxauth', (e) => {
          clearTimeout(watchDog);
          resolve();
        });
      });
    },

    // Callback function for auth window.
    setDropBoxToken(token) {
      DEBUG && console.log('Access token:', token);
      setToken(this.name, token);
      this.connect(token);
      this.authWindow.close();
      window.dispatchEvent(new Event('dropboxauth'));
    },

    async getLink(path) {
      if (!this.api) await this.auth();
      let resp;

      // already exists?
      resp = await this.call('sharingListSharedLinks', {path});
      if (resp.result.links.length) return resp.result.links[0].url;

      // create new
      resp = await this.call('sharingCreateSharedLinkWithSettings', {
        path,
        settings: {
          require_password: false,
          audience: 'public',
          access: 'viewer',
          requested_visibility: 'public',
          allow_download: true
        }
      });
      DEBUG && console.log('Dropbox link object:', resp.result);
      return resp.result.url;
    }
  };

  // register providers here:
  const providers = {
    dropbox: DBP
  };

  // restore all providers at startup
  for (const p of Object.values(providers)) p.restore();

  return {providers};
})();