require('dotenv').config();
const express = require('express');
const cors = require('cors');
const { Pool } = require('pg');

const app = express();
const port = process.env.PORT || 3000;

app.use(cors());
app.use(express.json());

const pool = new Pool({
  host: process.env.DB_HOST || 'db',
  port: process.env.DB_PORT || 5432,
  user: process.env.POSTGRES_USER,
  password: process.env.POSTGRES_PASSWORD,
  database: process.env.POSTGRES_DB,
});

async function initDatabase() {
  await pool.query(`
    CREATE TABLE IF NOT EXISTS attendance (
      id SERIAL PRIMARY KEY,
      student_name VARCHAR(80) NOT NULL,
      arrival_time TIME NOT NULL,
      created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
    );
  `);
}

app.get('/api/health', (req, res) => {
  res.json({ status: 'ok', service: 'attendance-backend' });
});

app.get('/api/attendance', async (req, res) => {
  try {
    const result = await pool.query('SELECT * FROM attendance ORDER BY created_at DESC, id DESC');
    res.json(result.rows);
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to load attendance entries' });
  }
});

app.post('/api/attendance', async (req, res) => {
  try {
    const { student_name, arrival_time } = req.body;
    if (!student_name || !arrival_time) {
      return res.status(400).json({ error: 'student_name and arrival_time are required' });
    }
    const result = await pool.query(
      'INSERT INTO attendance (student_name, arrival_time) VALUES ($1, $2) RETURNING *',
      [student_name, arrival_time]
    );
    res.status(201).json(result.rows[0]);
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to create attendance entry' });
  }
});

app.delete('/api/attendance/:id', async (req, res) => {
  try {
    await pool.query('DELETE FROM attendance WHERE id = $1', [req.params.id]);
    res.json({ deleted: true });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to delete attendance entry' });
  }
});

initDatabase()
  .then(() => app.listen(port, () => console.log(`Attendance API running on port ${port}`)))
  .catch((error) => {
    console.error('Database initialization failed:', error);
    process.exit(1);
  });