import { Router } from 'express';
import { z } from 'zod';
import db from '../db/index.js';
import { HttpError } from '../middleware/errorHandler.js';

const router = Router();
// Toutes ces routes sont montées sous requireAdmin dans server.js

/* GET /api/ref-categories — liste complète */
router.get('/', (_req, res) => {
  const rows = db.prepare(`
    SELECT c.id, c.nom,
           COUNT(rc.referentiel_id) AS nb_utilises
    FROM categories_inv c
    LEFT JOIN referentiel_categories_inv rc ON rc.categorie_id = c.id
    GROUP BY c.id
    ORDER BY c.nom
  `).all();
  res.json(rows);
});

/* POST /api/ref-categories — créer */
router.post('/', (req, res, next) => {
  try {
    const { nom } = z.object({ nom: z.string().min(1).max(200) }).parse(req.body);
    const exists = db.prepare('SELECT id FROM categories_inv WHERE nom = ?').get(nom.trim());
    if (exists) throw new HttpError(409, `La catégorie "${nom.trim()}" existe déjà.`);
    const r = db.prepare('INSERT INTO categories_inv (nom) VALUES (?)').run(nom.trim());
    res.status(201).json({ id: r.lastInsertRowid, nom: nom.trim(), nb_utilises: 0 });
  } catch (e) { next(e); }
});

/* PUT /api/ref-categories/:id — renommer (propage automatiquement) */
router.put('/:id', (req, res, next) => {
  try {
    const { nom } = z.object({ nom: z.string().min(1).max(200) }).parse(req.body);
    const row = db.prepare('SELECT id, nom FROM categories_inv WHERE id = ?').get(req.params.id);
    if (!row) throw new HttpError(404, 'Catégorie introuvable');
    const dup = db.prepare('SELECT id FROM categories_inv WHERE nom = ? AND id != ?').get(nom.trim(), row.id);
    if (dup) throw new HttpError(409, `La catégorie "${nom.trim()}" existe déjà.`);
    db.prepare('UPDATE categories_inv SET nom = ? WHERE id = ?').run(nom.trim(), row.id);
    const nb = db.prepare('SELECT COUNT(*) AS n FROM referentiel_categories_inv WHERE categorie_id = ?').get(row.id).n;
    res.json({ id: row.id, nom: nom.trim(), nb_utilises: nb });
  } catch (e) { next(e); }
});

/* DELETE /api/ref-categories/:id — supprimer si non utilisée */
router.delete('/:id', (req, res, next) => {
  try {
    const row = db.prepare('SELECT id FROM categories_inv WHERE id = ?').get(req.params.id);
    if (!row) throw new HttpError(404, 'Catégorie introuvable');
    const nb = db.prepare('SELECT COUNT(*) AS n FROM referentiel_categories_inv WHERE categorie_id = ?').get(row.id).n;
    if (nb > 0) throw new HttpError(409, `Catégorie utilisée par ${nb} référentiel(s) — retirez-la d'abord.`);
    db.prepare('DELETE FROM categories_inv WHERE id = ?').run(row.id);
    res.status(204).end();
  } catch (e) { next(e); }
});

/* POST /api/ref-categories/:id/merge — fusionner dans une autre catégorie */
router.post('/:id/merge', (req, res, next) => {
  try {
    const { target_id } = z.object({ target_id: z.number().int() }).parse(req.body);
    const source = db.prepare('SELECT id, nom FROM categories_inv WHERE id = ?').get(req.params.id);
    if (!source) throw new HttpError(404, 'Catégorie source introuvable');
    const target = db.prepare('SELECT id, nom FROM categories_inv WHERE id = ?').get(target_id);
    if (!target) throw new HttpError(404, 'Catégorie cible introuvable');
    if (source.id === target.id) throw new HttpError(400, 'Source et cible identiques');

    const result = db.transaction(() => {
      const refs = db.prepare(
        'SELECT referentiel_id FROM referentiel_categories_inv WHERE categorie_id = ?'
      ).all(source.id);
      let added = 0, skipped = 0;
      for (const { referentiel_id } of refs) {
        const exists = db.prepare(
          'SELECT 1 FROM referentiel_categories_inv WHERE referentiel_id = ? AND categorie_id = ?'
        ).get(referentiel_id, target.id);
        if (!exists) {
          db.prepare(
            'INSERT INTO referentiel_categories_inv (referentiel_id, categorie_id) VALUES (?, ?)'
          ).run(referentiel_id, target.id);
          added++;
        } else {
          skipped++;
        }
      }
      db.prepare('DELETE FROM referentiel_categories_inv WHERE categorie_id = ?').run(source.id);
      db.prepare('DELETE FROM categories_inv WHERE id = ?').run(source.id);
      return { added, skipped, total: refs.length };
    })();

    res.json({ ok: true, ...result,
      message: `Fusion terminée : ${result.added} lien(s) ajouté(s), ${result.skipped} déjà présent(s). "${source.nom}" supprimée.` });
  } catch (e) { next(e); }
});

export default router;