extension/background.js

// ── AI Detector · background.js (service worker) ─────────────────────────
//
// Responsibilities:
//   1. Keep a canonical scan-result cache (in-memory + storage)
//   2. Handle OPEN_SIDE_PANEL messages from popup
//   3. Relay GET_SCAN_RESULT / CLEAR_SCAN_RESULT messages to side panel
// ── Init side panel on action click ───────────────────────────────────────
chrome.runtime.onInstalled.addListener(() => {
  chrome.sidePanel.setPanelBehavior({ openPanelOnActionClick: true }).catch((error) => console.error(error));
});

// ── In-memory result cache ────────────────────────────────────────────────
// Survives for the lifetime of the service worker (typically a few minutes
// of inactivity). chrome.storage.local is the durable fallback.
let cachedResult = null;

const activeScans = new Set();

chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {

  // Orchestrate scan logic globally to avoid duplication and sync state
  if (msg.type === "START_SCAN") {
    const tabId = msg.tabId;
    if (activeScans.has(tabId)) {
      sendResponse({ ok: false });
      return false;
    }
    activeScans.add(tabId);
    console.log("SCAN_STARTED");

    cachedResult = { status: "scanning", tabId, timestamp: Date.now() };
    chrome.storage.local.set({ scanResult: cachedResult, lastScreenshot: msg.screenshot }).catch(()=>{});

    chrome.scripting.executeScript({
      target: { tabId },
      files: ["content.js"]
    }).then(() => {
      const timeoutPromise = new Promise((_, reject) => setTimeout(() => reject(new Error("Scan timed out after 90 seconds")), 90000));
      const scanPromise = new Promise((resolve, reject) => {
        chrome.tabs.sendMessage(tabId, { type: "SCAN_IMAGES", screenshot: msg.screenshot }, (resp) => {
          if (chrome.runtime.lastError) reject(new Error(chrome.runtime.lastError.message));
          else resolve(resp);
        });
      });
      return Promise.race([scanPromise, timeoutPromise]);
    }).then((response) => {
      if (!response) throw new Error("No response from content script");
      
      let finalResult;
      if (response.stopped) {
        finalResult = { status: "stopped", risk: 0, count: 0, explanation: null, tabId, timestamp: Date.now() };
      } else if (response.done) {
        const risk = typeof response.risk === "number" ? response.risk : 0;
        const count = typeof response.count === "number" ? response.count : 0;
        const explanation = response.explanation || null;
        const rawConfidence = typeof response.rawConfidence === "number" ? response.rawConfidence : risk / 100;
        finalResult = { status: "done", risk, count, explanation, rawConfidence, tabId, timestamp: Date.now() };
      } else {
        throw new Error(response.error || "Unexpected response");
      }
      
      console.log("SCAN_COMPLETED");
      cachedResult = finalResult;
      chrome.storage.local.set({ scanResult: finalResult }).catch(()=>{});
    }).catch(err => {
      console.warn("SCAN_ERROR:", err.message);
      const errResult = { status: "error", error: err.message, tabId, timestamp: Date.now() };
      cachedResult = errResult;
      chrome.storage.local.set({ scanResult: errResult }).catch(()=>{});
    }).finally(() => {
      activeScans.delete(tabId);
    });

    sendResponse({ ok: true });
    return false;
  }

  if (msg.type === "STOP_SCAN") {
    console.log("SCAN_STOPPED");
    chrome.tabs.sendMessage(msg.tabId, { type: "STOP_SCAN" }, () => {
      void chrome.runtime.lastError;
    });
    sendResponse({ ok: true });
    return false;
  }

  // Side panel → background: retrieve latest scan result
  if (msg.type === "GET_SCAN_RESULT") {
    if (cachedResult) {
      sendResponse({ result: cachedResult });
      return false;
    }
    // Fall back to storage (service worker may have been restarted)
    chrome.storage.local.get("scanResult", (data) => {
      if (chrome.runtime.lastError) {
        console.warn("[BG] storage read error:", chrome.runtime.lastError.message);
        sendResponse({ result: null });
        return;
      }
      cachedResult = data.scanResult || null;
      sendResponse({ result: cachedResult });
    });
    return true; // async response
  }


  // Popup or side panel: clear stored result
  if (msg.type === "CLEAR_SCAN_RESULT") {
    cachedResult = null;
    chrome.storage.local.remove("scanResult");
    sendResponse({ ok: true });
    return false;
  }
});