const express = require('express');
const sqlite3 = require('sqlite3').verbose();
const cors = require('cors');
const path = require('path');
const multer = require('multer');
const fs = require('fs');

const app = express();

// Use DATA_DIR env var if set, otherwise use local "data" folder
const DATA_DIR = process.env.DATA_DIR || path.join(__dirname, 'data');

const dbPath = path.join(DATA_DIR, 'db.sqlite');
const db = new sqlite3.Database(dbPath);
const upload = multer({ dest: path.join(DATA_DIR, 'uploads/') });
app.use(cors());
app.use(express.json());
app.use('/uploads', express.static(path.join(DATA_DIR, 'uploads')));

// Create uploads directory if it doesn't exist
fs.mkdirSync(path.join(DATA_DIR, 'uploads'), { recursive: true });

// Initialize database and ensure counters table exists
db.serialize(() => {
  db.run(`CREATE TABLE IF NOT EXISTS counters (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    value INTEGER NOT NULL DEFAULT 0,
    name TEXT NOT NULL DEFAULT 'Counter',
    image TEXT
  )`);
});

// Get all counters
app.get('/api/counters', (req, res) => {
  db.all('SELECT * FROM counters', (err, rows) => {
    if (err) return res.status(500).json({ error: err.message });
    // Ensure id and value are numbers
    const counters = rows.map(row => ({
      ...row,
      id: Number(row.id),
      value: Number(row.value)
    }));
    res.json(counters);
  });
});

// Create a new counter with image
app.post('/api/counters', upload.single('image'), (req, res) => {
  const { name = 'Counter', value = 0 } = req.body;
  const image = req.file ? `/uploads/${req.file.filename}` : null;
  db.run('INSERT INTO counters (name, value, image) VALUES (?, ?, ?)', [name, value, image], function (err) {
    if (err) return res.status(500).json({ error: err.message });
    res.json({ id: Number(this.lastID), name, value: Number(value), image });
  });
});

// Update a counter (now supports image upload)
app.put('/api/counters/:id', upload.single('image'), (req, res) => {
  const { name, value } = req.body;
  const id = req.params.id;
  let image = null;

  // If a new image is uploaded, get its path
  if (req.file) {
    image = `/uploads/${req.file.filename}`;
    // Optionally, delete the old image file
    db.get('SELECT image FROM counters WHERE id = ?', [id], (err, row) => {
      if (row && row.image) {
        const oldImagePath = path.join(__dirname, '..', row.image);
        fs.unlink(oldImagePath, () => { }); // Ignore errors
      }
    });
  }

  // Build dynamic SQL and params
  let fields = [];
  let params = [];
  if (name !== undefined) { fields.push('name = ?'); params.push(name); }
  if (value !== undefined) { fields.push('value = ?'); params.push(value); }
  if (image !== null) { fields.push('image = ?'); params.push(image); }
  if (fields.length === 0) return res.status(400).json({ error: 'No valid fields to update.' });

  params.push(id);
  const sql = `UPDATE counters SET ${fields.join(', ')} WHERE id = ?`;

  db.run(sql, params, function (err) {
    if (err) return res.status(500).json({ error: err.message });
    res.json({ updated: this.changes });
  });
});

// Delete a counter
app.delete('/api/counters/:id', (req, res) => {
  db.run('DELETE FROM counters WHERE id = ?', [req.params.id], function (err) {
    if (err) return res.status(500).json({ error: err.message });
    res.json({ deleted: this.changes });
  });
});

// Serve static frontend files
const clientBuildPath = path.join(__dirname, '..', 'frontend', 'dist');
app.use(express.static(clientBuildPath));

// For SPA: serve index.html for any unknown route (after API and uploads)
app.get('/*path', (req, res) => {
  if (req.path.startsWith('/api') || req.path.startsWith('/uploads')) return res.status(404).end();
  res.sendFile(path.join(clientBuildPath, 'index.html'));
});

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`API server running on http://localhost:${PORT}`);
});

process.on('SIGTERM', () => {
  console.log('SIGTERM received, shutting down gracefully...');
  db.close(() => {
    console.log('Database connection closed.');
    process.exit(0);
  });
});