const express = require('express');
const router = express.Router();
const db = require('../database');

// Get cashback summary by month/year with optional filters
router.get('/:year/:month', (req, res) => {
  const { year, month } = req.params;
  const { card_id, category_id } = req.query;
  
  let query = `
    SELECT 
      c.id as card_id,
      c.name as card_name,
      c.bank,
      cat.id as category_id,
      cat.name as category_name,
      mc.cashback_percent,
      COALESCE(SUM(t.amount), 0) as total_spent,
      COALESCE(SUM(t.cashback_amount), 0) as total_cashback,
      COUNT(t.id) as transaction_count
    FROM monthly_categories mc
    JOIN cards c ON mc.card_id = c.id
    JOIN categories cat ON mc.category_id = cat.id
    LEFT JOIN transactions t ON t.card_id = mc.card_id 
      AND t.category_id = mc.category_id 
      AND strftime('%Y', t.date) = ? 
      AND strftime('%m', t.date) = ?
    WHERE mc.year = ? AND mc.month = ?
  `;
  
  const queryParams = [year, month.toString().padStart(2, '0'), year, month];
  
  // Add filters
  if (card_id) {
    query += ' AND c.id = ?';
    queryParams.push(card_id);
  }
  
  if (category_id) {
    query += ' AND cat.id = ?';
    queryParams.push(category_id);
  }
  
  query += ' GROUP BY c.id, cat.id ORDER BY c.name, cat.name';
  
  db.all(query, queryParams, (err, rows) => {
    if (err) {
      console.error(err);
      res.status(500).json({ error: 'Database error' });
    } else {
      // Calculate totals
      const totalSpent = rows.reduce((sum, row) => sum + row.total_spent, 0);
      const totalCashback = rows.reduce((sum, row) => sum + row.total_cashback, 0);
      const totalTransactions = rows.reduce((sum, row) => sum + row.transaction_count, 0);
      
      res.json({
        summary: {
          total_spent: totalSpent,
          total_cashback: totalCashback,
          total_transactions: totalTransactions,
          average_cashback_rate: totalSpent > 0 ? (totalCashback / totalSpent) * 100 : 0
        },
        details: rows
      });
    }
  });
});

// Get overall cashback statistics
router.get('/stats/overview', (req, res) => {
  const query = `
    SELECT 
      COUNT(DISTINCT c.id) as total_cards,
      COUNT(DISTINCT cat.id) as total_categories,
      COALESCE(SUM(t.amount), 0) as lifetime_spent,
      COALESCE(SUM(t.cashback_amount), 0) as lifetime_cashback,
      COUNT(t.id) as lifetime_transactions
    FROM cards c
    CROSS JOIN categories cat
    LEFT JOIN transactions t ON 1=1
  `;
  
  db.get(query, (err, row) => {
    if (err) {
      console.error(err);
      res.status(500).json({ error: 'Database error' });
    } else {
      res.json(row);
    }
  });
});

module.exports = router;