2 files changed, 169 insertions, 0 deletions
diff --git a/app/javascript/flavours/glitch/service_worker/entry.js b/app/javascript/flavours/glitch/service_worker/entry.js
new file mode 100644
index 000000000..eea4cfc3c
--- /dev/null
+++ b/app/javascript/flavours/glitch/service_worker/entry.js
@@ -0,0 +1,10 @@
+import './web_push_notifications';
+
+// Cause a new version of a registered Service Worker to replace an existing one
+// that is already installed, and replace the currently active worker on open pages.
+self.addEventListener('install', function(event) {
+  event.waitUntil(self.skipWaiting());
+});
+self.addEventListener('activate', function(event) {
+  event.waitUntil(self.clients.claim());
+});
diff --git a/app/javascript/flavours/glitch/service_worker/web_push_notifications.js b/app/javascript/flavours/glitch/service_worker/web_push_notifications.js
new file mode 100644
index 000000000..f63cff335
--- /dev/null
+++ b/app/javascript/flavours/glitch/service_worker/web_push_notifications.js
@@ -0,0 +1,159 @@
+const MAX_NOTIFICATIONS = 5;
+const GROUP_TAG = 'tag';
+
+// Avoid loading intl-messageformat and dealing with locales in the ServiceWorker
+const formatGroupTitle = (message, count) => message.replace('%{count}', count);
+
+const notify = options =>
+  self.registration.getNotifications().then(notifications => {
+    if (notifications.length === MAX_NOTIFICATIONS) {
+      // Reached the maximum number of notifications, proceed with grouping
+      const group = {
+        title: formatGroupTitle(options.data.message, notifications.length + 1),
+        body: notifications
+          .sort((n1, n2) => n1.timestamp < n2.timestamp)
+          .map(notification => notification.title).join('\n'),
+        badge: '/badge.png',
+        icon: '/android-chrome-192x192.png',
+        tag: GROUP_TAG,
+        data: {
+          url: (new URL('/web/notifications', self.location)).href,
+          count: notifications.length + 1,
+          message: options.data.message,
+        },
+      };
+
+      notifications.forEach(notification => notification.close());
+
+      return self.registration.showNotification(group.title, group);
+    } else if (notifications.length === 1 && notifications[0].tag === GROUP_TAG) {
+      // Already grouped, proceed with appending the notification to the group
+      const group = cloneNotification(notifications[0]);
+
+      group.title = formatGroupTitle(group.data.message, group.data.count + 1);
+      group.body  = `${options.title}\n${group.body}`;
+      group.data  = { ...group.data, count: group.data.count + 1 };
+
+      return self.registration.showNotification(group.title, group);
+    }
+
+    return self.registration.showNotification(options.title, options);
+  });
+
+const handlePush = (event) => {
+  const options = event.data.json();
+
+  options.body      = options.data.nsfw || options.data.content;
+  options.dir       = options.data.dir;
+  options.image     = options.image || undefined; // Null results in a network request (404)
+  options.timestamp = options.timestamp && new Date(options.timestamp);
+
+  const expandAction = options.data.actions.find(action => action.todo === 'expand');
+
+  if (expandAction) {
+    options.actions          = [expandAction];
+    options.hiddenActions    = options.data.actions.filter(action => action !== expandAction);
+    options.data.hiddenImage = options.image;
+    options.image            = undefined;
+  } else {
+    options.actions = options.data.actions;
+  }
+
+  event.waitUntil(notify(options));
+};
+
+const cloneNotification = (notification) => {
+  const clone = {  };
+
+  for(var k in notification) {
+    clone[k] = notification[k];
+  }
+
+  return clone;
+};
+
+const expandNotification = (notification) => {
+  const nextNotification = cloneNotification(notification);
+
+  nextNotification.body    = notification.data.content;
+  nextNotification.image   = notification.data.hiddenImage;
+  nextNotification.actions = notification.data.actions.filter(action => action.todo !== 'expand');
+
+  return self.registration.showNotification(nextNotification.title, nextNotification);
+};
+
+const makeRequest = (notification, action) =>
+  fetch(action.action, {
+    headers: {
+      'Authorization': `Bearer ${notification.data.access_token}`,
+      'Content-Type': 'application/json',
+    },
+    method: action.method,
+    credentials: 'include',
+  });
+
+const findBestClient = clients => {
+  const focusedClient = clients.find(client => client.focused);
+  const visibleClient = clients.find(client => client.visibilityState === 'visible');
+
+  return focusedClient || visibleClient || clients[0];
+};
+
+const openUrl = url =>
+  self.clients.matchAll({ type: 'window' }).then(clientList => {
+    if (clientList.length !== 0) {
+      const webClients = clientList.filter(client => /\/web\//.test(client.url));
+
+      if (webClients.length !== 0) {
+        const client       = findBestClient(webClients);
+        const { pathname } = new URL(url);
+
+        if (pathname.startsWith('/web/')) {
+          return client.focus().then(client => client.postMessage({
+            type: 'navigate',
+            path: pathname.slice('/web/'.length - 1),
+          }));
+        }
+      } else if ('navigate' in clientList[0]) { // Chrome 42-48 does not support navigate
+        const client = findBestClient(clientList);
+
+        return client.navigate(url).then(client => client.focus());
+      }
+    }
+
+    return self.clients.openWindow(url);
+  });
+
+const removeActionFromNotification = (notification, action) => {
+  const actions          = notification.actions.filter(act => act.action !== action.action);
+  const nextNotification = cloneNotification(notification);
+
+  nextNotification.actions = actions;
+
+  return self.registration.showNotification(nextNotification.title, nextNotification);
+};
+
+const handleNotificationClick = (event) => {
+  const reactToNotificationClick = new Promise((resolve, reject) => {
+    if (event.action) {
+      const action = event.notification.data.actions.find(({ action }) => action === event.action);
+
+      if (action.todo === 'expand') {
+        resolve(expandNotification(event.notification));
+      } else if (action.todo === 'request') {
+        resolve(makeRequest(event.notification, action)
+          .then(() => removeActionFromNotification(event.notification, action)));
+      } else {
+        reject(`Unknown action: ${action.todo}`);
+      }
+    } else {
+      event.notification.close();
+      resolve(openUrl(event.notification.data.url));
+    }
+  });
+
+  event.waitUntil(reactToNotificationClick);
+};
+
+self.addEventListener('push', handlePush);
+self.addEventListener('notificationclick', handleNotificationClick);