Initial commit: SyncWatch Chrome extension + WebSocket server

2026-05-23 22:22:19 -04:00
commit 24d88f4754
8 changed files with 649 additions and 0 deletions
--- a/extension/background.js
+++ b/extension/background.js
@@ -0,0 +1,127 @@
+let ws = null;
+let roomCode = null;
+let serverUrl = null;
+let connectState = 'disconnected'; // 'disconnected' | 'connecting' | 'connected'
+
+function send(msg) {
+  if (ws && ws.readyState === WebSocket.OPEN) {
+    ws.send(JSON.stringify(msg));
+  }
+}
+
+function notifyPopup(msg) {
+  chrome.runtime.sendMessage(msg).catch(() => {});
+}
+
+function notifyAllTabs(msg) {
+  chrome.tabs.query({}, (tabs) => {
+    for (const tab of tabs) {
+      chrome.tabs.sendMessage(tab.id, msg).catch(() => {});
+    }
+  });
+}
+
+function connect(url) {
+  if (ws) {
+    ws.close();
+    ws = null;
+  }
+  serverUrl = url;
+  connectState = 'connecting';
+
+  try {
+    ws = new WebSocket(url);
+  } catch {
+    connectState = 'disconnected';
+    notifyPopup({ type: 'ws_status', status: 'error' });
+    return;
+  }
+
+  ws.onopen = () => {
+    connectState = 'connected';
+    notifyPopup({ type: 'ws_status', status: 'connected' });
+  };
+
+  ws.onclose = () => {
+    connectState = 'disconnected';
+    roomCode = null;
+    notifyPopup({ type: 'ws_status', status: 'disconnected' });
+  };
+
+  ws.onerror = () => {
+    connectState = 'disconnected';
+    notifyPopup({ type: 'ws_status', status: 'error' });
+  };
+
+  ws.onmessage = (event) => {
+    let msg;
+    try { msg = JSON.parse(event.data); } catch { return; }
+
+    switch (msg.type) {
+      case 'created':
+      case 'joined':
+        roomCode = msg.code;
+        notifyPopup(msg);
+        break;
+      case 'error':
+      case 'peer_joined':
+      case 'peer_left':
+        notifyPopup(msg);
+        break;
+      case 'sync':
+        notifyAllTabs({ type: 'apply_sync', action: msg.action, time: msg.time });
+        break;
+    }
+  };
+}
+
+// Keep service worker alive and reconnect if needed
+chrome.alarms.create('keepalive', { periodInMinutes: 0.4 });
+
+chrome.alarms.onAlarm.addListener((alarm) => {
+  if (alarm.name !== 'keepalive') return;
+  if (ws && ws.readyState === WebSocket.OPEN) {
+    send({ type: 'ping' });
+  } else if (serverUrl && connectState !== 'connecting') {
+    connect(serverUrl);
+  }
+});
+
+chrome.runtime.onMessage.addListener((msg, _sender, sendResponse) => {
+  switch (msg.type) {
+    case 'connect':
+      chrome.storage.local.set({ serverUrl: msg.url });
+      connect(msg.url);
+      sendResponse({ ok: true });
+      break;
+    case 'disconnect':
+      serverUrl = null;
+      roomCode = null;
+      if (ws) ws.close();
+      sendResponse({ ok: true });
+      break;
+    case 'create_room':
+      send({ type: 'create' });
+      sendResponse({ ok: true });
+      break;
+    case 'join_room':
+      send({ type: 'join', code: msg.code });
+      sendResponse({ ok: true });
+      break;
+    case 'media_event':
+      if (roomCode) {
+        send({ type: 'sync', action: msg.action, time: msg.time });
+      }
+      sendResponse({ ok: true });
+      break;
+    case 'get_state':
+      sendResponse({ connectState, roomCode });
+      break;
+  }
+  return true;
+});
+
+// Restore WS connection on service worker restart
+chrome.storage.local.get(['serverUrl'], ({ serverUrl: saved }) => {
+  if (saved) connect(saved);
+});