const express = require('express');
const router = express.Router();
const { calculateNetHours } = require('../utils/timeCalculator');

/**
 * Initialize export routes with database instance
 * @param {Database} db - SQLite database instance
 * @returns {Router} - Configured Express router
 */
function createExportRouter(db) {
  /**
   * GET /api/export?from=YYYY-MM-DD&to=YYYY-MM-DD
   * Export entries as CSV
   */
  router.get('/', (req, res) => {
    try {
      const { from, to } = req.query;
      
      let query = 'SELECT * FROM entries';
      const params = [];
      
      if (from && to) {
        query += ' WHERE date >= ? AND date <= ?';
        params.push(from, to);
      } else if (from) {
        query += ' WHERE date >= ?';
        params.push(from);
      } else if (to) {
        query += ' WHERE date <= ?';
        params.push(to);
      }
      
      query += ' ORDER BY date ASC, start_time ASC';
      
      const stmt = db.prepare(query);
      const entries = stmt.all(...params);
      
      // Generate CSV with German formatting
      let csv = 'Datum,Startzeit,Endzeit,Pause in Minuten,Gesamtstunden\n';
      
      entries.forEach(entry => {
        const calculated = calculateNetHours(entry.start_time, entry.end_time, entry.pause_minutes);
        
        // Format date as DD.MM.YYYY
        const [year, month, day] = entry.date.split('-');
        const formattedDate = `${day}.${month}.${year}`;
        
        // Use comma as decimal separator for hours
        const netHoursFormatted = calculated.netHours.toFixed(2).replace('.', ',');
        
        csv += `${formattedDate},${entry.start_time},${entry.end_time},${entry.pause_minutes},${netHoursFormatted}\n`;
      });
      
      res.setHeader('Content-Type', 'text/csv; charset=utf-8');
      res.setHeader('Content-Disposition', 'attachment; filename="zeiterfassung.csv"');
      res.send(csv);
    } catch (error) {
      console.error('Error exporting entries:', error);
      res.status(500).json({ error: 'Failed to export entries' });
    }
  });

  return router;
}

module.exports = createExportRouter;