First commit

extension/background.js

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+/**
+ * @name Preso extension
+ *
+ * This script, as part of a Chrome extension, allows the refreshing and looping
+ * of Google Slides documents (without having to resort to "Publishing to web").
+ *
+ * See: https://plemont.github.io for details.
+ */
+const PRESO_REGEX = /^https:\/\/docs\.google\.com\/presentation\/d\/[^/]+\/present(.*)$/;
+
+function fullscreenAndLoop(tab) {
+  chrome.windows.getCurrent(win =>
+    chrome.windows.update(win.id, {state: 'fullscreen'}));
+  let nextUrl = calculateNextSlideUrl(tab.url);
+  setTimeout(createReload(tab.id, nextUrl), 10000);
+}
+
+function calculateNextSlideUrl(url) {
+  let [hostPath, parts] = url.split('?');
+  let params = extractParamsDictionary(parts);
+  let slideId = params.slide;
+  let matches;
+  if (slideId) {
+    let idRegex = /^(id\..*)_(\d+)_(\d+)$/;
+    if ((matches = idRegex.exec(slideId)) !== null) {
+      let currentPage = +matches[2];
+      let totalPages = +matches[3];
+      let newSlide = [matches[1], (currentPage + 1) % totalPages,
+          totalPages].join('_');
+      return hostPath + '?loop=1&slide=' + newSlide;
+    }
+  }
+  return url;
+}
+
+function createReload(tabId, nextUrl) {
+  return function() {
+    chrome.tabs.query({
+      active: true,
+      lastFocusedWindow: true
+    }, function(tabs) {
+      let url = tabs[0].url;
+      let matches = PRESO_REGEX.exec(url);
+      if (matches) {
+        chrome.tabs.update(tabId, {url: nextUrl});
+      }
+    });
+  };
+}
+
+function extractParamsDictionary(parts) {
+  let params = {};
+  parts.split('&').forEach(part => {
+    let [key, value] = part.split('=');
+    params[key] = value;
+  });
+  return params;
+}
+
+function checkForValidUrl(tabId, changeInfo, tab) {
+  // Only process events that are completions, not loading events.
+  if (changeInfo.status !== 'complete') {
+    return;
+  }
+  let matches;
+  if ((matches = PRESO_REGEX.exec(tab.url)) !== null) {
+    let args = matches[1];
+    if (args.startsWith('?')) {
+      let parts = args.substr(1);
+      let params = extractParamsDictionary(parts);
+
+      // If there is a loop parameter, then just prepare for the next page.
+      if (params.loop) {
+        fullscreenAndLoop(tab);
+      } else {
+        // if no loop parameter, highlight the pageAction button.
+        chrome.pageAction.show(tab.id);
+      }
+    }
+  }
+}
+
+chrome.pageAction.onClicked.addListener(() => {
+  chrome.tabs.query({
+    active: true,
+    lastFocusedWindow: true
+  }, function(tabs) {
+    let url = tabs[0].url;
+    let matches = PRESO_REGEX.exec(url);
+    if (matches) {
+      fullscreenAndLoop(tabs[0]);
+    }
+  });
+});
+
+// Listen for any changes to the URL of any tab.
+chrome.tabs.onUpdated.addListener(checkForValidUrl);

extension/manifest.json

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+{
+  "name": "Preso",
+  "version": "0.0.1",
+  "manifest_version": 2,
+  "description": "Refresh'n'loop presentations",
+  "homepage_url": "https://plemont.github.io",
+  "background": {
+    "scripts": [
+      "background.js"
+    ],
+    "persistent": true
+  },
+  "page_action": {
+    "default_title": "Present'n'loop"
+  },
+  "permissions": [
+    "tabs",
+    "webNavigation",
+    "activeTab"
+  ]
+}

generate_refresh.js

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+var CLIENT_ID = 'INSERT_CLIENT_ID';
+var CLIENT_SECRET = 'INSERT_CLIENT_SECRET';
+
+/**
+ * This script allows the stepping through of the Authorization Code Grant in
+ * order to obtain a refresh token.
+ *
+ * This script uses the out-of-band redirect URI, which is not part of the
+ * OAuth2 standard, to allow not redirecting the user. If this does not work
+ * with your API, try instead the OAuth playground:
+ * https://developers.google.com/oauthplayground/
+ *
+ * Execute script twice:
+ * Execution 1, will result in a URL, which when placed in the browser will
+ * issue a code.
+ * Execution 2: place the code in "CODE" below and execute. If successful a
+ * refresh token will be printed to the console.
+ */
+
+// Enter required scopes, e.g. ['https://www.googleapis.com/auth/drive']
+var SCOPES = ['https://www.googleapis.com/auth/presentations',
+              'https://www.googleapis.com/auth/drive'];
+
+// Auth URL, e.g. https://accounts.google.com/o/oauth2/auth
+var AUTH_URL = 'https://accounts.google.com/o/oauth2/auth';
+// Token URL, e.g. https://accounts.google.com/o/oauth2/token
+var TOKEN_URL = 'https://accounts.google.com/o/oauth2/token';
+
+var CODE = '';
+
+function main() {
+  if (CODE) {
+    generateRefreshToken();
+  } else {
+    generateAuthUrl();
+  }
+}
+
+/**
+ * Creates the URL for pasting in the browser, which will generate the code
+ * to be placed in the CODE variable.
+ */
+function generateAuthUrl() {
+  var payload = {
+    scope: SCOPES.join(' '),
+    // Specify that no redirection should take place
+    // This is Google-specific and not part of the OAuth2 specification.
+    redirect_uri: 'urn:ietf:wg:oauth:2.0:oob',
+    response_type: 'code',
+    access_type: 'offline',
+    client_id: CLIENT_ID
+  };
+  var options = {payload: payload};
+  var request = UrlFetchApp.getRequest(AUTH_URL, options);
+  Logger.log(
+      'Browse to the following URL: ' + AUTH_URL + '?' + request.payload);
+}
+
+/**
+ * Generates a refresh token given the authorization code.
+ */
+function generateRefreshToken() {
+  var payload = {
+    code: CODE,
+    client_id: CLIENT_ID,
+    client_secret: CLIENT_SECRET,
+    // Specify that no redirection should take place
+    // This is Google-specific and not part of the OAuth2 specification.
+    redirect_uri: 'urn:ietf:wg:oauth:2.0:oob',
+    grant_type: 'authorization_code'
+  };
+  var options = {method: 'POST', payload: payload};
+  var response = UrlFetchApp.fetch(TOKEN_URL, options);
+  var data = JSON.parse(response.getContentText());
+  if (data.refresh_token) {
+    var msg = 'Success! Refresh token: ' + data.refresh_token +
+      '\n\nThe following may also be a useful format for pasting into your script:\n\n' +
+      'var CLIENT_ID = \'' + CLIENT_ID + '\';\n' +
+      'var CLIENT_SECRET = \'' + CLIENT_SECRET + '\';\n' +
+      'var REFRESH_TOKEN = \'' + data.refresh_token + '\';\n';
+    Logger.log(msg);
+  } else {
+    Logger.log(
+        'Error, failed to generate Refresh token: ' +
+        response.getContentText());
+  }
+}