// Verstak Bridge — Background Service Worker (Chrome)
// Tracks active tab changes and queues browser events.
// Pushes events to the Verstak HTTP bridge when available.
//
// IMPORTANT: All chrome.* event listeners are registered at global scope,
// NOT inside onInstalled/onStartup. MV3 service workers can be restarted at
// any time; listeners inside lifecycle hooks are lost on restart.
// See: https://developer.chrome.com/docs/extensions/develop/concepts/service-workers/events

const STORAGE_KEY = 'verstak_queue';
const BRIDGE_KEY = 'verstak_bridge_config';
const RECENT_KEY = 'verstak_recent';
const DEFAULT_CONFIG = { port: 9786, secret: '', autoGenPort: false };
const IDLE_RESET_MS = 60_000;

// Session state
let session = {
  url: '',
  title: '',
  domain: '',
  tabId: -1,
  startedAt: null,
};

// --- Global event listeners (registered once at script load) ---

chrome.runtime.onInstalled.addListener(() => {
  setupAlarms();
});

chrome.runtime.onStartup.addListener(() => {
  setupAlarms();
});

// Tab tracking — global scope
chrome.tabs.onActivated.addListener(onTabActivated);
chrome.tabs.onUpdated.addListener(onTabUpdated);
chrome.windows.onFocusChanged.addListener(onWindowFocusChanged);

// Alarm handler — global scope
chrome.alarms.onAlarm.addListener((alarm) => {
  if (alarm.name === 'flushEvents') flushSession();
  if (alarm.name === 'pingBridge') pingBridge();
});

// Message handler — global scope
chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
  if (msg.type === 'FORCE_FLUSH') {
    flushSession();
    flushQueue();
    sendResponse({ ok: true });
  }
  if (msg.type === 'SET_TRACKING') {
    chrome.storage.local.set({ 'verstak_tracking_enabled': msg.enabled });
    sendResponse({ ok: true });
  }
  return true;
});

// --- Alarm setup ---

function setupAlarms() {
  chrome.alarms.create('flushEvents', { periodInMinutes: 0.5 });
  chrome.alarms.create('pingBridge', { periodInMinutes: 1 });
}

// --- Tab tracking ---

function onTabActivated(activeInfo) {
  flushSession();
  startTracking(activeInfo.tabId);
}

function onTabUpdated(tabId, changeInfo, tab) {
  if (changeInfo.status === 'complete' && tab.active) {
    flushSession();
    startTracking(tabId);
  }
}

function onWindowFocusChanged(windowId) {
  if (windowId === chrome.windows.WINDOW_ID_NONE) {
    flushSession();
    session = { url: '', title: '', domain: '', tabId: -1, startedAt: null };
  } else {
    chrome.tabs.query({ active: true, currentWindow: true }, (tabs) => {
      if (tabs && tabs.length > 0) {
        startTracking(tabs[0].id);
      }
    });
  }
}

function startTracking(tabId) {
  chrome.tabs.get(tabId, (tab) => {
    if (chrome.runtime.lastError || !tab || !tab.url) return;
    if (isInternalPage(tab.url)) return;

    session = {
      url: tab.url,
      title: tab.title || '',
      domain: extractDomain(tab.url),
      tabId,
      startedAt: Date.now(),
    };
  });
}

// --- Session flush ---

function flushSession() {
  if (!session.url || !session.startedAt) return;

  const duration = Math.round((Date.now() - session.startedAt) / 1000);
  if (duration < 2) {
    session.startedAt = Date.now();
    return;
  }

  const event = {
    id: generateId(),
    type: 'page_visit',
    url: session.url,
    title: session.title,
    domain: session.domain,
    active_seconds: Math.min(duration, IDLE_RESET_MS / 1000),
    ts_start: new Date(session.startedAt).toISOString(),
    ts_end: new Date().toISOString(),
  };

  queueEvent(event);
  session.startedAt = Date.now();
}

function queueEvent(event) {
  chrome.storage.local.get(STORAGE_KEY, (data) => {
    const queue = data[STORAGE_KEY] || [];
    queue.push(event);

    if (queue.length > 500) {
      queue.splice(0, queue.length - 500);
    }

    chrome.storage.local.set({ [STORAGE_KEY]: queue }, () => {
      if (queue.length >= 5) {
        flushQueue();
      }
    });
  });
}

// --- Bridge communication ---

function flushQueue() {
  chrome.storage.local.get([STORAGE_KEY, BRIDGE_KEY], (data) => {
    const queue = data[STORAGE_KEY] || [];
    if (queue.length === 0) return;

    const config = data[BRIDGE_KEY] || DEFAULT_CONFIG;
    const port = config.port || 9786;
    const secret = config.secret || '';

    const payload = {
      version: 1,
      device_id: 'chrome-' + (config.deviceId || 'unknown'),
      events: queue,
    };

    fetch(`http://127.0.0.1:${port}/api/events`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        'X-Verstak-Secret': secret,
      },
      body: JSON.stringify(payload),
    })
      .then((res) => {
        if (res.ok) {
          for (const ev of queue) {
            updateRecent(ev);
          }
          chrome.storage.local.set({ [STORAGE_KEY]: [] });
          chrome.runtime.sendMessage({ type: 'UI_UPDATE' }).catch(() => {});
        } else if (res.status === 401) {
          console.warn('[verstak] bridge auth failed, check secret');
        }
      })
      .catch(() => {
        // Bridge not available — keep events in queue
      });
  });
}

function pingBridge() {
  chrome.storage.local.get(BRIDGE_KEY, (data) => {
    const config = data[BRIDGE_KEY] || DEFAULT_CONFIG;
    const port = config.port || 9786;

    fetch(`http://127.0.0.1:${port}/api/ping`)
      .then((res) => res.json())
      .then((info) => {
        chrome.storage.local.set({
          [BRIDGE_KEY]: { ...config, ...info, bridgeReachable: true, lastPing: Date.now() }
        });
      })
      .catch(() => {
        chrome.storage.local.set({
          [BRIDGE_KEY]: { ...config, bridgeReachable: false, lastPing: Date.now() }
        });
      });
  });
}

// --- Recent events ---

function updateRecent(event) {
  chrome.storage.local.get(RECENT_KEY, (data) => {
    const recent = data[RECENT_KEY] || [];
    recent.push({
      domain: event.domain,
      title: event.title,
      url: event.url,
      active_seconds: event.active_seconds,
      ts: new Date().toISOString(),
    });
    if (recent.length > 50) {
      recent.splice(0, recent.length - 50);
    }
    chrome.storage.local.set({ [RECENT_KEY]: recent });
  });
}

// --- Helpers ---

function extractDomain(url) {
  try {
    return new URL(url).hostname.replace(/^www\./, '');
  } catch {
    return '';
  }
}

function isInternalPage(url) {
  const internal = [
    'chrome://', 'chrome-extension://', 'about:', 'edge://',
    'file://', 'data:', 'blob:', 'view-source:', 'devtools:',
  ];
  return internal.some((p) => url.startsWith(p));
}

function generateId() {
  const ts = Date.now().toString(36);
  const rand = Math.random().toString(36).substring(2, 8);
  return `evt_${ts}_${rand}`;
}