const express = require('express');
const { Pool } = require('pg');
const { v4: uuidv4 } = require('uuid');

const router = express.Router();

// Database pool
const pool = new Pool({
  host: process.env.DB_HOST || 'db',
  port: process.env.DB_PORT || 5432,
  database: process.env.DB_NAME || 'steuer',
  user: process.env.DB_USER || 'app',
  password: process.env.DB_PASSWORD || 'app123',
});

// GET /api/customers - Alle Kunden
router.get('/', async (req, res) => {
  try {
    const { search, limit = 100 } = req.query;
    
    let query = `
      SELECT k.*, 
        (SELECT COUNT(*) FROM rechnungen WHERE kunde = k.name) as rechnungen_count,
        (SELECT COALESCE(SUM(betrag), 0) FROM rechnungen WHERE kunde = k.name AND status = 'bezahlt') as total_umsatz
      FROM kunden k
    `;
    const values = [];
    
    if (search) {
      query += ` WHERE k.name ILIKE $1 OR k.email ILIKE $1 OR k.adresse ILIKE $1`;
      values.push(`%${search}%`);
    }
    
    query += ` ORDER BY k.name ASC LIMIT $${values.length + 1}`;
    values.push(limit);
    
    const result = await pool.query(query, values);
    
    res.json({
      success: true,
      customers: result.rows.map(row => ({
        ...row,
        rechnungen_count: parseInt(row.rechnungen_count) || 0,
        total_umsatz: parseFloat(row.total_umsatz) || 0
      }))
    });
  } catch (error) {
    console.error('Customers List Error:', error);
    res.status(500).json({ success: false, error: error.message });
  }
});

// GET /api/customers/:id - Einzelner Kunde
router.get('/:id', async (req, res) => {
  try {
    const { id } = req.params;
    
    // Kunde + Rechnungen
    const [kundeResult, rechnungenResult] = await Promise.all([
      pool.query('SELECT * FROM kunden WHERE id = $1', [id]),
      pool.query(`
        SELECT * FROM rechnungen 
        WHERE kunde = (SELECT name FROM kunden WHERE id = $1)
        ORDER BY datum DESC
      `, [id])
    ]);
    
    if (kundeResult.rows.length === 0) {
      return res.status(404).json({ success: false, error: 'Kunde nicht gefunden' });
    }
    
    const kunde = kundeResult.rows[0];
    const rechnungen = rechnungenResult.rows;
    
    // Zusammenfassung
    const totalUmsatz = rechnungen.reduce((sum, r) => sum + parseFloat(r.betrag || 0), 0);
    const paidUmsatz = rechnungen
      .filter(r => r.status === 'bezahlt')
      .reduce((sum, r) => sum + parseFloat(r.betrag || 0), 0);
    const openUmsatz = rechnungen
      .filter(r => r.status === 'offen')
      .reduce((sum, r) => sum + parseFloat(r.betrag || 0), 0);
    
    res.json({
      success: true,
      customer: {
        ...kunde,
        rechnungen,
        summary: {
          total_rechnungen: rechnungen.length,
          total_umsatz: totalUmsatz,
          paid_umsatz: paidUmsatz,
          open_umsatz: openUmsatz
        }
      }
    });
  } catch (error) {
    console.error('Customer Detail Error:', error);
    res.status(500).json({ success: false, error: error.message });
  }
});

// POST /api/customers - Kunde erstellen
router.post('/', async (req, res) => {
  try {
    const { name, adresse, plz, ort, email, telefon, notizen } = req.body;
    
    if (!name) {
      return res.status(400).json({ success: false, error: 'Name ist erforderlich' });
    }
    
    const query = `
      INSERT INTO kunden (id, name, adresse, plz, ort, email, telefon, notizen, created_at, updated_at)
      VALUES ($1, $2, $3, $4, $5, $6, $7, $8, NOW(), NOW())
      RETURNING *
    `;
    const values = [uuidv4(), name, adresse || null, plz || null, ort || null, email || null, telefon || null, notizen || null];
    
    const result = await pool.query(query, values);
    
    res.status(201).json({
      success: true,
      customer: result.rows[0]
    });
  } catch (error) {
    console.error('Customer Create Error:', error);
    if (error.code === '23505') {
      return res.status(409).json({ success: false, error: 'Kunde mit diesem Namen existiert bereits' });
    }
    res.status(500).json({ success: false, error: error.message });
  }
});

// PUT /api/customers/:id - Kunde aktualisieren
router.put('/:id', async (req, res) => {
  try {
    const { id } = req.params;
    const { name, adresse, plz, ort, email, telefon, notizen } = req.body;
    
    const query = `
      UPDATE kunden 
      SET 
        name = COALESCE($1, name), 
        adresse = COALESCE($2, adresse), 
        plz = COALESCE($3, plz), 
        ort = COALESCE($4, ort), 
        email = COALESCE($5, email), 
        telefon = COALESCE($6, telefon), 
        notizen = COALESCE($7, notizen),
        updated_at = NOW()
      WHERE id = $8
      RETURNING *
    `;
    const values = [name, adresse, plz, ort, email, telefon, notizen, id];
    
    const result = await pool.query(query, values);
    
    if (result.rows.length === 0) {
      return res.status(404).json({ success: false, error: 'Kunde nicht gefunden' });
    }
    
    res.json({
      success: true,
      customer: result.rows[0]
    });
  } catch (error) {
    console.error('Customer Update Error:', error);
    res.status(500).json({ success: false, error: error.message });
  }
});

// DELETE /api/customers/:id - Kunde löschen
router.delete('/:id', async (req, res) => {
  try {
    const { id } = req.params;
    
    // Prüfe ob Kunde Rechnungen hat
    const checkResult = await pool.query(`
      SELECT COUNT(*) as count FROM rechnungen 
      WHERE kunde = (SELECT name FROM kunden WHERE id = $1)
    `, [id]);
    
    if (parseInt(checkResult.rows[0].count) > 0) {
      return res.status(400).json({ 
        success: false, 
        error: 'Kunde kann nicht gelöscht werden - es existieren Rechnungen' 
      });
    }
    
    const result = await pool.query('DELETE FROM kunden WHERE id = $1 RETURNING *', [id]);
    
    if (result.rows.length === 0) {
      return res.status(404).json({ success: false, error: 'Kunde nicht gefunden' });
    }
    
    res.json({
      success: true,
      message: 'Kunde erfolgreich gelöscht',
      deleted: result.rows[0]
    });
  } catch (error) {
    console.error('Customer Delete Error:', error);
    res.status(500).json({ success: false, error: error.message });
  }
});

module.exports = router;