// index.js
const functions = require("firebase-functions");
const admin = require("firebase-admin");
const { GoogleGenerativeAI } = require("@google/generative-ai");

// Load .env only for local testing
if (process.env.NODE_ENV !== "production") {
  require("dotenv").config();
}

// Initialize Firebase Admin
// In production (Firebase Functions), this uses default credentials
// For local testing, it uses the service account file
if (!admin.apps.length) {
  if (process.env.NODE_ENV !== "production") {
    const serviceAccount = require("./firebase-service-account.json");
    admin.initializeApp({
      credential: admin.credential.cert(serviceAccount),
    });
  } else {
    admin.initializeApp();
  }
}

// Get API key from environment
// In Firebase Functions, set this using: firebase functions:config:set gemini.api_key="YOUR_KEY"
// For local testing, use .env file
const api_key =
  process.env.GOOGLE_AI_API_KEY || functions.config().gemini?.api_key;

const MODEL_NAME = "gemini-2.5-flash";

/**
 * Fetches an image from a public URL and returns base64 + mimeType.
 * This helper can be reused inside a Firebase Function later.
 */
const fetch_image_as_base64 = async (image_url) => {
  const response = await fetch(image_url);

  if (!response.ok) {
    throw new Error(
      `Failed to fetch image: ${response.status} ${response.statusText}`,
    );
  }

  const array_buffer = await response.arrayBuffer();
  const base64_data = Buffer.from(array_buffer).toString("base64");
  const mime_type = response.headers.get("content-type") || "image/jpeg";

  return { base64_data, mime_type };
};

/**
 * Fetches categories from Firestore and returns them in a format
 * that Gemini can use to assign a category ID.
 * Only returns categories where visible = true.
 */
const fetch_categories_from_firestore = async () => {
  const db = admin.firestore();
  const categories_snapshot = await db
    .collection("categories")
    .where("visible", "==", true)
    .get();

  const categories = [];
  categories_snapshot.forEach((doc) => {
    let cat_data = doc.data();
    cat_data.id = doc.id;
    categories.push(cat_data);
  });

  return categories;
};

/**
 * Main logic: takes an image URL, calls Gemini, and returns the description text.
 * This function is what we'll later call from Firebase Functions.
 */
const describe_image_from_url = async (image_url) => {
  if (!api_key) {
    throw new Error("Missing Gemini API key");
  }

  // Initialize Gemini
  const gen_ai = new GoogleGenerativeAI(api_key);
  const model = gen_ai.getGenerativeModel({ model: MODEL_NAME });

  // Fetch categories from Firestore
  const categories = await fetch_categories_from_firestore();

  // Format categories for the prompt
  const categories_list = categories
    .map((cat) => `${cat.id}: ${cat.name}`)
    .join(", ");

  const { base64_data, mime_type } = await fetch_image_as_base64(image_url);

  const prompt = `Analyze this rental item for marketplace listing with value estimation. Return raw JSON only, no markdown:
    {
        "title": "Clear, concise title (max 50 chars)",
        "description": "Detailed description (2-3 sentences)",
        "categoryId": "Category ID from this list: [${categories_list}]. If none match, leave this field as an empty string",
        "condition": "One of: New, Like New, Good, Fair, Poor",
        "suggestedDailyPrice": 15.99,
        "suggestedWeeklyPrice": 89.99,
        "suggestedMonthlyPrice": 299.99,
        "estimatedValue": 599.99,
        "brand": "Brand name if identifiable",
        "model": "Model if identifiable",
        "features": ["Key feature 1", "Feature 2", "Feature 3"],
        "targetAudience": ["Students", "Professionals", "Families"],
        "seasonality": "One of: Year-round, Summer, Winter, Spring, Fall, Holiday",
        "insuranceRecommended": true,
        "depositSuggestion": 100.00
    }`;

  const result = await model.generateContent({
    contents: [
      {
        role: "user",
        parts: [
          { text: prompt },
          {
            inlineData: {
              data: base64_data,
              mimeType: mime_type,
            },
          },
        ],
      },
    ],
  });

  return result.response.text();
};

/**
 * CLI entrypoint for local testing:
 *   node index.js https://example.com/image.jpg
 */
const main = async () => {
  const image_url = process.argv[2];

  if (!image_url) {
    console.error("Usage: node index.js <image_url>");
    process.exit(1);
  }

  try {
    // First, fetch categories from Firestore
    console.log("Fetching categories from Firestore...");
    const categories = await fetch_categories_from_firestore();
    console.log("Categories found:", categories);
    console.log("");

    console.log("Fetching and describing image from:", image_url);
    const description = await describe_image_from_url(image_url);

    console.log("\n=== GEMINI DESCRIPTION ===\n");
    console.log(description);
    console.log("\n==========================\n");
  } catch (err) {
    console.error("Error describing image:", err);
  }
};

// Run main only if called directly: `node index.js ...`
if (require.main === module) {
  main();
}

// Firebase Cloud Function
// Call this from your Flutter app
exports.analyzeRentalItem = functions.https.onRequest(async (req, res) => {
  // Enable CORS
  res.set("Access-Control-Allow-Origin", "*");

  if (req.method === "OPTIONS") {
    res.set("Access-Control-Allow-Methods", "POST");
    res.set("Access-Control-Allow-Headers", "Content-Type");
    res.set("Access-Control-Max-Age", "3600");
    return res.status(204).send("");
  }

  if (req.method !== "POST") {
    return res.status(405).json({ error: "Method not allowed" });
  }

  try {
    const { imageUrl } = req.body;

    if (!imageUrl) {
      return res.status(400).json({ error: "Missing imageUrl in request body" });
    }

    const result = await describe_image_from_url(imageUrl);

    // Parse the JSON response from Gemini
    const parsed_result = JSON.parse(result);

    return res.status(200).json({
      success: true,
      data: parsed_result,
    });
  } catch (error) {
    console.error("Error analyzing rental item:", error);
    return res.status(500).json({
      success: false,
      error: error.message,
    });
  }
});

// Export helper function for local testing
module.exports.describe_image_from_url = describe_image_from_url;