Enable very minimal update checking on Linux

app/src/browser/linux-updater-adapter.es6

@@ -1,6 +1,7 @@
 import {EventEmitter} from 'events';
-// import request from 'request';
-import _ from 'underscore';
+import https from 'https';
+import shell from 'electron';
+import url from 'url';
 
 /*
 Currently, this class doesn't do much. We don't display update notices within
@@ -8,26 +9,61 @@ the app because we can't provide a consistent upgrade path for linux users.
 However, we still want the app to report to our autoupdate service so we know
 how many Linux users exist.
 */
-class LinuxUpdaterAdapter {
-
+class LinuxUpdaterAdapter extends EventEmitter {
   setFeedURL(feedURL) {
     this.feedURL = feedURL;
+    this.downloadURL = null;
+  }
+
+  onError = (err) => {
+    this.emit('error', err.toString());
   }
 
   checkForUpdates() {
     if (!this.feedURL) {
       return;
     }
-    // TODO BG I removed request!
-    request(this.feedURL, () => {
+
+    this.emit('checking-for-update');
+
+    const feedHost = url.parse(this.feedURL).hostname;
+    const feedPath = this.feedURL.split(feedHost).pop();
+
+    // Hit the feed URL ourselves and see if an update is available.
+    // On linux we can't autoupdate, but we can still show the "update available" bar.
+    https.get({ host: feedHost, path: feedPath }, (res) => {
+      console.log(`Manual update check returned ${res.statusCode}`);
+
+      if (res.statusCode === 204) {
+        this.emit('update-not-available');
+        return;
+      }
+
+      let data = '';
+      res.on('error', this.onError);
+      res.on('data', (chunk) => { data += chunk; });
+      res.on('end', () => {
+        try {
+          const json = JSON.parse(data);
+          console.log(JSON.stringify(json, null, 2));
+          if (!json.url) {
+            this.onError(new Error(`Autoupdater response did not include URL: ${data}`));
+            return;
+          }
+          this.downloadURL = url;
+          this.emit('update-downloaded', 'Click to download.', null);
+        } catch (err) {
+          this.onError(err);
+        }
+      });
     });
   }
 
   quitAndInstall() {
-
+    if (this.downloadURL) {
+      shell.openExternal(this.downloadURL);
+    }
   }
 }
 
-Object.assign(LinuxUpdaterAdapter.prototype, EventEmitter.prototype);
-const adapter = new LinuxUpdaterAdapter();
-export default adapter
+export default new LinuxUpdaterAdapter()

app/src/browser/mailspring-protocol-handler.es6

@@ -13,7 +13,7 @@ import path from 'path';
 //   * <config-dir>/packages
 //   * RESOURCE_PATH/node_modules
 //
-export default class NylasProtocolHandler {
+export default class MailspringProtocolHandler {
   constructor({configDirPath, resourcePath, safeMode}) {
     this.loadPaths = [];
 
@@ -23,13 +23,14 @@ export default class NylasProtocolHandler {
     this.loadPaths.push(path.join(configDirPath, 'packages'));
     this.loadPaths.push(path.join(resourcePath, 'internal_packages'));
 
-    this.registerNylasProtocol();
+    this.registerProtocol();
   }
 
-  // Creates the 'Nylas' custom protocol handler.
-  registerNylasProtocol() {
-    protocol.registerFileProtocol('mailspring', (request, callback) => {
-      const relativePath = path.normalize(request.url.substr(7));
+  // Creates the 'Mailspring' custom protocol handler.
+  registerProtocol() {
+    const scheme = 'mailspring'
+    protocol.registerFileProtocol(scheme, (request, callback) => {
+      const relativePath = path.normalize(request.url.substr(scheme.length + 1));
 
       let filePath = null;
       for (const loadPath of this.loadPaths) {