const express = require('express');
const cors = require('cors');
const fetch = require('node-fetch');
const bodyParser = require('body-parser');

const app = express();
const PORT = 7860; // Default port for Hugging Face Spaces

// --- CONFIGURATION ---
// These tokens must be set in your Space Settings -> Variables and secrets
const STORAGE_POOLS = [
  { 
    repo: "abhy60098/MY-STORAGE", 
    token: process.env.HF_TOKEN_1 
  },
  { 
    repo: "sushmasinharnc/MY-STORAGE", 
    token: process.env.HF_TOKEN_2 
  },
  { 
    repo: "shuarya2011/MY-STORAGE", 
    token: process.env.HF_TOKEN_3 
  }
];

const DB_FILE = "db.json";

// --- MIDDLEWARE ---
app.use(cors()); // Allows any website to connect
app.use(bodyParser.json({ limit: '50mb' })); // Allows large image uploads

// --- ROUTES ---

// 1. Health Check / Home Page
app.get('/', (req, res) => {
  res.send(`
    <div style="font-family: sans-serif; text-align: center; margin-top: 50px;">
      <h1>🚀 Distributed Storage API is Online</h1>
      <p>Status: <b>Connected to ${STORAGE_POOLS.length} Storage Pools</b></p>
      <p>Use <code>/posts</code> (GET) to fetch data and <code>/posts</code> (POST) to upload.</p>
    </div>
  `);
});

// 2. GET: Fetch data from all 3 datasets and merge them
app.get('/posts', async (req, res) => {
  try {
    const allResults = await Promise.all(STORAGE_POOLS.map(async (pool) => {
      // We check if the token exists before calling
      if (!pool.token) return [];

      const url = `https://huggingface.co/api/datasets/${pool.repo}/raw/main/${DB_FILE}`;
      const response = await fetch(url, { 
        headers: { Authorization: `Bearer ${pool.token}` } 
      });

      if (response.ok) {
        const data = await response.json();
        return data.posts || [];
      }
      return []; // Return empty if file doesn't exist yet
    }));

    // Flatten the array of arrays and sort by ID (timestamp) descending
    const mergedPosts = allResults.flat().sort((a, b) => b.id - a.id);
    res.json(mergedPosts);
  } catch (err) {
    console.error("GET Error:", err);
    res.status(500).json({ error: "Failed to fetch posts from pools." });
  }
});

// 3. POST: Upload image and update database in a random pool
app.post('/posts', async (req, res) => {
  try {
    const { username, caption, imageBase64, fileName } = req.body;

    if (!imageBase64 || !username) {
      return res.status(400).json({ error: "Missing required fields (username or image)." });
    }

    // Pick a random pool to distribute storage usage
    const pool = STORAGE_POOLS[Math.floor(Math.random() * STORAGE_POOLS.length)];
    
    if (!pool.token) {
      return res.status(500).json({ error: "Storage pool token not configured in Secrets." });
    }

    const timestamp = Date.now();
    const imagePath = `uploads/${timestamp}-${fileName}`;

    // A. Upload the Image file
    const uploadImageUrl = `https://huggingface.co/api/datasets/${pool.repo}/upload/main/${imagePath}`;
    const imageUploadRes = await fetch(uploadImageUrl, {
      method: 'POST',
      headers: { 
        Authorization: `Bearer ${pool.token}`, 
        'Content-Type': 'application/json' 
      },
      body: JSON.stringify({
        content: imageBase64, // Expecting raw base64 string
        message: `Upload image from ${username}`
      })
    });

    if (!imageUploadRes.ok) {
      const errorText = await imageUploadRes.text();
      throw new Error(`Image Upload Failed: ${errorText}`);
    }

    const finalImageUrl = `https://huggingface.co/datasets/${pool.repo}/resolve/main/${imagePath}`;

    // B. Fetch existing db.json from the SAME pool
    const dbUrl = `https://huggingface.co/api/datasets/${pool.repo}/raw/main/${DB_FILE}`;
    const dbRes = await fetch(dbUrl, { 
      headers: { Authorization: `Bearer ${pool.token}` } 
    });
    
    let db = { posts: [] };
    if (dbRes.ok) {
      db = await dbRes.json();
    }

    // C. Add new post to the beginning of the list
    db.posts.unshift({
      id: timestamp,
      username,
      caption,
      imageUrl: finalImageUrl,
      pool: pool.repo
    });

    // D. Upload the updated db.json back to Hugging Face
    const updateDbUrl = `https://huggingface.co/api/datasets/${pool.repo}/upload/main/${DB_FILE}`;
    const dbUploadRes = await fetch(updateDbUrl, {
      method: 'POST',
      headers: { 
        Authorization: `Bearer ${pool.token}`, 
        'Content-Type': 'application/json' 
      },
      body: JSON.stringify({
        content: Buffer.from(JSON.stringify(db, null, 2)).toString('base64'),
        message: "Update database JSON"
      })
    });

    if (!dbUploadRes.ok) throw new Error("Database update failed.");

    res.status(201).json({ success: true, imageUrl: finalImageUrl });
  } catch (err) {
    console.error("POST Error:", err);
    res.status(500).json({ error: err.message });
  }
});

// Start the server
app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});