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

const router = express.Router();

// Helper: find or insert a tarifoptionen row matching the new structure's option.
// Used by the /multi endpoints to keep the old tarifoptionen table in sync.
async function syncLegacyOption(anbieter_id, tarif_id, name, code, provision_euro, beschreibung) {
    try {
        await db.run(
            `INSERT OR IGNORE INTO tarifoptionen (anbieter_id, tarif_id, name, code, provision_euro, beschreibung)
             VALUES (?, ?, ?, ?, ?, ?)`,
            [anbieter_id, tarif_id, name, code || null, provision_euro || 0, beschreibung || null]
        );
    } catch (err) {
        console.error('Legacy tarifoption sync failed:', err.message);
    }
}

// --- Legacy single-tariff API (per-(anbieter,tarif) options) ---

router.get('/', asyncHandler(async (req, res) => {
    const rows = await db.all(
        `SELECT t.*, a.name AS anbieter_name, ta.name AS tarif_name
         FROM tarifoptionen t
         JOIN anbieter a ON t.anbieter_id = a.id
         LEFT JOIN tarife ta ON t.tarif_id = ta.id
         WHERE t.aktiv = 1
         ORDER BY a.name, t.tarif_id IS NULL DESC, COALESCE(ta.name, ''), t.name`
    );
    res.json(rows);
}));

router.post('/', asyncHandler(async (req, res) => {
    const { anbieter_id, tarif_id, name, code, provision_euro, beschreibung } = req.body || {};
    if (!anbieter_id && !tarif_id) {
        return res.status(400).json({ error: 'Entweder Anbieter oder Tarif muss angegeben werden' });
    }
    if (!name || !name.trim()) {
        return res.status(400).json({ error: 'Name ist erforderlich' });
    }

    let resolvedAnbieterId = anbieter_id;
    if (tarif_id && !resolvedAnbieterId) {
        const tarif = await db.get('SELECT anbieter_id FROM tarife WHERE id = ?', [tarif_id]);
        if (!tarif) return res.status(404).json({ error: 'Tarif nicht gefunden' });
        resolvedAnbieterId = tarif.anbieter_id;
    }

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

router.put('/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const { name, provision_euro } = req.body || {};
    if (!name) return res.status(400).json({ error: 'Tarifoption-Name ist erforderlich' });
    const result = await db.run(
        'UPDATE tarifoptionen SET name = ?, provision_euro = ? WHERE id = ?',
        [name, provision_euro || 0, id]
    );
    if (result.changes === 0) return res.status(404).json({ error: 'Tarifoption nicht gefunden' });
    res.json({ message: 'Tarifoption erfolgreich aktualisiert' });
}));

router.delete('/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const result = await db.run('DELETE FROM tarifoptionen WHERE id = ?', [id]);
    if (result.changes === 0) return res.status(404).json({ error: 'Tarifoption nicht gefunden' });
    res.json({ message: 'Tarifoption erfolgreich gelöscht' });
}));

// --- Multi-tariff API (tarifoptionen_new + tarifoptionen_tarife) ---

router.get('/multi', asyncHandler(async (req, res) => {
    const rows = await db.all(
        `SELECT tn.id, tn.name, tn.code, tn.provision_euro, tn.beschreibung, tn.aktiv, tn.created_at,
                GROUP_CONCAT(t.name || ' (' || a.name || ')') AS tarif_names,
                GROUP_CONCAT(t.id) AS tarif_ids
         FROM tarifoptionen_new tn
         LEFT JOIN tarifoptionen_tarife tt ON tn.id = tt.tarifoption_id
         LEFT JOIN tarife t ON tt.tarif_id = t.id
         LEFT JOIN anbieter a ON t.anbieter_id = a.id
         WHERE tn.aktiv = 1
         GROUP BY tn.id, tn.name, tn.code, tn.provision_euro, tn.beschreibung, tn.aktiv, tn.created_at
         ORDER BY tn.created_at DESC`
    );
    res.json(rows);
}));

router.post('/multi', asyncHandler(async (req, res) => {
    const { anbieter_id, tarif_ids = [], is_anbieter_weit = false, name, code, provision_euro, beschreibung } = req.body || {};
    if (!anbieter_id || !name) return res.status(400).json({ error: 'Anbieter und Name sind erforderlich' });
    if (!is_anbieter_weit && (!tarif_ids || tarif_ids.length === 0)) {
        return res.status(400).json({ error: 'Bei tarif-spezifischen Optionen müssen Tarife ausgewählt werden' });
    }

    const newId = await db.transaction(async () => {
        const inserted = await db.run(
            'INSERT INTO tarifoptionen_new (name, code, provision_euro, beschreibung) VALUES (?, ?, ?, ?)',
            [name, code || null, provision_euro || 0, beschreibung || null]
        );
        const tarifoptionId = inserted.lastID;

        let targetTarifIds = tarif_ids;
        if (is_anbieter_weit) {
            const tarifs = await db.all('SELECT id FROM tarife WHERE anbieter_id = ?', [anbieter_id]);
            targetTarifIds = tarifs.map(t => t.id);
        }

        for (const tarifId of targetTarifIds) {
            await db.run(
                'INSERT INTO tarifoptionen_tarife (tarifoption_id, tarif_id) VALUES (?, ?)',
                [tarifoptionId, tarifId]
            );
            await syncLegacyOption(anbieter_id, tarifId, name, code, provision_euro, beschreibung);
        }
        return { id: tarifoptionId, count: targetTarifIds.length };
    });

    res.json({ id: newId.id, message: 'Tarifoption erfolgreich erstellt', assignments: newId.count });
}));

router.put('/multi/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const { name, code, provision_euro, beschreibung, anbieter_id, is_anbieter_weit, tarif_ids } = req.body || {};
    if (!name) return res.status(400).json({ error: 'Tarifoption-Name ist erforderlich' });

    await db.transaction(async () => {
        const upd = await db.run(
            'UPDATE tarifoptionen_new SET name = ?, code = ?, provision_euro = ?, beschreibung = ? WHERE id = ?',
            [name, code || null, provision_euro || 0, beschreibung || null, id]
        );
        if (upd.changes === 0) {
            const e = new Error('Tarifoption nicht gefunden');
            e.status = 404;
            throw e;
        }
        await db.run('DELETE FROM tarifoptionen_tarife WHERE tarifoption_id = ?', [id]);
        // Best-effort cleanup of legacy rows that may have been synced under this name/code.
        await db.run(
            'DELETE FROM tarifoptionen WHERE name = ? AND (code = ? OR (code IS NULL AND ? IS NULL))',
            [name, code || null, code || null]
        );

        let targetTarifIds = tarif_ids || [];
        if (is_anbieter_weit && anbieter_id) {
            const tarifs = await db.all('SELECT id FROM tarife WHERE anbieter_id = ?', [anbieter_id]);
            targetTarifIds = tarifs.map(t => t.id);
        }

        for (const tarifId of targetTarifIds) {
            await db.run(
                'INSERT INTO tarifoptionen_tarife (tarifoption_id, tarif_id) VALUES (?, ?)',
                [id, tarifId]
            );
            const tarif = await db.get('SELECT anbieter_id FROM tarife WHERE id = ?', [tarifId]);
            if (tarif) {
                await syncLegacyOption(tarif.anbieter_id, tarifId, name, code, provision_euro, beschreibung);
            }
        }
    });
    res.json({ message: 'Tarifoption erfolgreich aktualisiert' });
}));

router.delete('/multi/:id', asyncHandler(async (req, res) => {
    const { id } = req.params;
    const option = await db.get('SELECT name, code FROM tarifoptionen_new WHERE id = ?', [id]);
    if (!option) return res.status(404).json({ error: 'Tarifoption nicht gefunden' });

    await db.transaction(async () => {
        await db.run('DELETE FROM tarifoptionen_tarife WHERE tarifoption_id = ?', [id]);
        await db.run(
            'DELETE FROM tarifoptionen WHERE name = ? AND (code = ? OR (code IS NULL AND ? IS NULL))',
            [option.name, option.code, option.code]
        );
        await db.run('DELETE FROM tarifoptionen_new WHERE id = ?', [id]);
    });
    res.json({ message: 'Tarifoption erfolgreich gelöscht' });
}));

// Tariff-specific tarifoption list (used by frontend when adding options to a schaltung)
router.get('/tarif/:tarif_id', 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);
}));

module.exports = router;