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);
});