const express = require('express');
const db = require('../db');
const asyncHandler = require('../middleware/asyncHandler');

const router = express.Router();

function validateAmount(amount) {
    return amount === null || amount === undefined || (Number.isFinite(parseFloat(amount)) && parseFloat(amount) >= 0);
}

router.get('/', asyncHandler(async (req, res) => {
    const rows = await db.all(
        `SELECT t.*, a.name AS anbieter_name
         FROM tarife t
         JOIN anbieter a ON t.anbieter_id = a.id
         ORDER BY a.name, t.name`
    );
    res.json(rows);
}));

router.get('/:anbieter_id', asyncHandler(async (req, res) => {
    const { anbieter_id } = req.params;
    const rows = await db.all('SELECT * FROM tarife WHERE anbieter_id = ? ORDER BY name', [anbieter_id]);
    res.json(rows);
}));

router.post('/', asyncHandler(async (req, res) => {
    const { name, anbieter_id, provision_euro, beschreibung } = req.body || {};

    if (!name || !name.trim()) {
        return res.status(400).json({ error: 'Tarifname ist erforderlich' });
    }
    if (!anbieter_id) {
        return res.status(400).json({ error: 'Anbieter ist erforderlich' });
    }
    if (!validateAmount(provision_euro)) {
        return res.status(400).json({ error: 'Provision muss eine positive Zahl sein' });
    }

    try {
        const result = await db.run(
            `INSERT INTO tarife (name, anbieter_id, provision_euro, beschreibung) VALUES (?, ?, ?, ?)`,
            [name.trim(), anbieter_id, provision_euro || 0, beschreibung || null]
        );
        res.json({
            id: result.lastID,
            name: name.trim(),
            anbieter_id,
            provision_euro: provision_euro || 0,
            beschreibung: beschreibung || null,
        });
    } catch (err) {
        if (/UNIQUE/.test(err.message)) {
            return res.status(400).json({ error: 'Tarif mit diesem Namen existiert bereits für diesen Anbieter' });
        }
        throw err;
    }
}));

router.put('/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const { name, provision_euro, beschreibung } = req.body || {};
    if (!name) return res.status(400).json({ error: 'Tarif-Name ist erforderlich' });
    if (!validateAmount(provision_euro)) {
        return res.status(400).json({ error: 'Provision muss eine positive Zahl sein' });
    }
    const result = await db.run(
        `UPDATE tarife SET name = ?, provision_euro = ?, beschreibung = ? WHERE id = ?`,
        [name, provision_euro || 0, beschreibung || null, id]
    );
    if (result.changes === 0) return res.status(404).json({ error: 'Tarif nicht gefunden' });
    res.json({ message: 'Tarif erfolgreich aktualisiert' });
}));

router.delete('/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const used = await db.get(
        'SELECT EXISTS(SELECT 1 FROM schaltungen WHERE tarif_id = ?) AS has_schaltungen',
        [id]
    );
    if (used.has_schaltungen) {
        return res.status(400).json({ error: 'Tarif kann nicht gelöscht werden: Tarif wird in Schaltungen verwendet' });
    }
    const result = await db.run('DELETE FROM tarife WHERE id = ?', [id]);
    if (result.changes === 0) return res.status(404).json({ error: 'Tarif nicht gefunden' });
    res.json({ message: 'Tarif erfolgreich gelöscht' });
}));

router.get('/:tarif_id/tarifoptionen', asyncHandler(async (req, res) => {
    const { tarif_id } = req.params;
    const rows = await db.all(
        'SELECT * FROM tarifoptionen WHERE tarif_id = ? AND aktiv = 1 ORDER BY name',
        [tarif_id]
    );
    res.json(rows);
}));

router.get('/:id/provisionsregeln', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const rows = await db.all(
        `SELECT pr.*, t.name AS tarif_name, a.name AS anbieter_name
         FROM provisionsregeln pr
         JOIN tarife t ON pr.tarif_id = t.id
         JOIN anbieter a ON t.anbieter_id = a.id
         WHERE pr.tarif_id = ? AND pr.aktiv = 1
         ORDER BY pr.gueltig_ab DESC`,
        [id]
    );
    res.json(rows);
}));

router.put('/:id/mitarbeiter-provision', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const { mitarbeiter_provision } = req.body || {};
    const result = await db.run(
        'UPDATE tarife SET mitarbeiter_provision = ? WHERE id = ?',
        [mitarbeiter_provision || 0, id]
    );
    if (result.changes === 0) return res.status(404).json({ error: 'Tarif nicht gefunden' });
    res.json({ message: 'Mitarbeiter-Provision erfolgreich aktualisiert' });
}));

module.exports = router;