Initial commit: LinkedIn Analyzer with Gemini 2.5 Flash and PHP Backend

background.js

@@ -0,0 +1,176 @@
+// background.js — Service Worker
+// Handles all Gemini API calls (avoids CORS issues from content scripts)
+
+const GEMINI_MODEL = 'gemini-2.5-flash';
+const GEMINI_URL = `https://generativelanguage.googleapis.com/v1beta/models/${GEMINI_MODEL}:generateContent`;
+
+// ─── Message listener ────────────────────────────────────────────────────────
+
+chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
+  if (message.type === 'GEMINI_REQUEST') {
+    handleGeminiRequest(message.payload)
+      .then(result => sendResponse({ success: true, data: result }))
+      .catch(err => sendResponse({ success: false, error: err.message }));
+    return true; // Keep message channel open for async
+  }
+});
+
+// ─── Core API call ───────────────────────────────────────────────────────────
+
+async function handleGeminiRequest({ apiKey, prompt, tab }) {
+  // Rate limit check
+  const canProceed = await checkRateLimit();
+  if (!canProceed) {
+    throw new Error('Daily limit reached (1,000 requests). Resets at midnight PT.');
+  }
+
+  // Check cache (keyed by tab + prompt hash — different jobs produce different hashes)
+  const cacheKey = `cache_${tab}_${hashString(prompt)}`;
+  const cached = await getCached(cacheKey);
+  if (cached) {
+    return { text: cached, fromCache: true };
+  }
+
+  // Truncate prompt if too long (free tier has strict TPM limits)
+  const maxPromptChars = 6000;
+  const trimmedPrompt = prompt.length > maxPromptChars
+    ? prompt.substring(0, maxPromptChars) + '\n\n[Description truncated for length]'
+    : prompt;
+
+  // Retry logic (up to 3 attempts with LONG backoff for free tier)
+  const MAX_RETRIES = 3;
+  const RETRY_DELAYS = [2000, 20000, 30000]; // 2s, 20s, 30s
+  let lastError = '';
+
+  for (let attempt = 0; attempt < MAX_RETRIES; attempt++) {
+    await delay(RETRY_DELAYS[attempt]);
+
+    try {
+      const response = await fetch(`${GEMINI_URL}?key=${apiKey}`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          contents: [{ parts: [{ text: trimmedPrompt }] }],
+          generationConfig: {
+            temperature: 0.7,
+            maxOutputTokens: 2048,
+            topP: 0.9
+          }
+        })
+      });
+
+      if (response.ok) {
+        const data = await response.json();
+        const text = data.candidates?.[0]?.content?.parts?.[0]?.text;
+        if (!text) {
+          lastError = 'Empty response from Gemini.';
+          continue;
+        }
+
+        await incrementUsage();
+        await setCached(cacheKey, text);
+        return { text, fromCache: false };
+      }
+
+      const status = response.status;
+      const errData = await response.json().catch(() => ({}));
+      const errMsg = errData.error?.message || '';
+
+      if (status === 429 || status === 503) {
+        lastError = `API quota limit (${status}): ${errMsg || 'Too many tokens'}. Waiting before retry...`;
+        continue;
+      } else if (status === 400) {
+        throw new Error('Request error: ' + (errMsg || 'Bad request'));
+      } else if (status === 403) {
+        throw new Error('Access denied. Check your API key in settings.');
+      } else {
+        throw new Error(`API Error (${status}): ${errMsg || 'Unknown'}`);
+      }
+
+    } catch (e) {
+      if (e.message.startsWith('Request error') || e.message.startsWith('Access denied') || e.message.startsWith('API Error')) {
+        throw e;
+      }
+      lastError = e.message || 'Network error';
+      if (attempt === MAX_RETRIES - 1) throw new Error(`Failed after ${MAX_RETRIES} attempts: ${lastError}`);
+    }
+  }
+
+  throw new Error(`API busy. ${lastError}. Please wait 1-2 minutes and try again.`);
+}
+
+// ─── Rate Limiting ───────────────────────────────────────────────────────────
+
+async function checkRateLimit() {
+  const today = new Date().toDateString();
+  const data = await storageGet(['usageDate', 'usageCount']);
+
+  if (data.usageDate !== today) return true; // New day, reset
+  return (data.usageCount || 0) < 1000;
+}
+
+async function incrementUsage() {
+  const today = new Date().toDateString();
+  const data = await storageGet(['usageDate', 'usageCount']);
+
+  if (data.usageDate !== today) {
+    await storageSet({ usageDate: today, usageCount: 1 });
+  } else {
+    await storageSet({ usageCount: (data.usageCount || 0) + 1 });
+  }
+}
+
+// ─── Cache ───────────────────────────────────────────────────────────────────
+
+async function getCached(key) {
+  const data = await storageGet(['analysisCache']);
+  const cache = data.analysisCache || {};
+  const entry = cache[key];
+  if (!entry) return null;
+
+  // Expire after 24 hours
+  if (Date.now() - entry.timestamp > 24 * 60 * 60 * 1000) {
+    return null;
+  }
+  return entry.value;
+}
+
+async function setCached(key, value) {
+  const data = await storageGet(['analysisCache']);
+  const cache = data.analysisCache || {};
+
+  // Keep max 50 entries
+  const keys = Object.keys(cache);
+  if (keys.length >= 50) {
+    // Remove oldest
+    const oldest = keys.sort((a, b) => cache[a].timestamp - cache[b].timestamp)[0];
+    delete cache[oldest];
+  }
+
+  cache[key] = { value, timestamp: Date.now() };
+  await storageSet({ analysisCache: cache });
+}
+
+// ─── Utilities ───────────────────────────────────────────────────────────────
+
+function delay(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+
+function hashString(str) {
+  let hash = 0;
+  for (let i = 0; i < Math.min(str.length, 200); i++) {
+    const char = str.charCodeAt(i);
+    hash = ((hash << 5) - hash) + char;
+    hash = hash & hash;
+  }
+  return Math.abs(hash).toString(36);
+}
+
+function storageGet(keys) {
+  return new Promise(resolve => chrome.storage.local.get(keys, resolve));
+}
+
+function storageSet(data) {
+  return new Promise(resolve => chrome.storage.local.set(data, resolve));
+}