import express from 'express';
import { pool } from '../db.js';
import { requireAuth } from '../middleware/auth.js';

const router = express.Router();
router.use(requireAuth);

const STATUSES = new Set([
  'Neu',
  'Kontaktiert',
  'Qualifiziert',
  'Angebot',
  'Gewonnen',
  'Verloren',
]);

// Felder, die per API gesetzt werden duerfen. owner_id/created_by werden
// separat behandelt, alles andere ist nicht beschreibbar.
const TEXT_FIELDS = [
  'salutation',
  'first_name',
  'last_name',
  'company',
  'position',
  'email',
  'phone',
  'mobile',
  'linkedin',
  'website',
  'street',
  'zip',
  'city',
  'country',
  'source',
  'notes',
  'avatar',
];

function emptyToNull(value) {
  if (value === null || value === undefined) return null;
  const text = String(value).trim();
  return text === '' ? null : text;
}

function parseTags(raw) {
  if (!raw) return [];
  try {
    const parsed = JSON.parse(raw);
    return Array.isArray(parsed) ? parsed.filter((t) => typeof t === 'string') : [];
  } catch {
    return [];
  }
}

function serializeTags(value) {
  if (!Array.isArray(value)) return null;
  const tags = [...new Set(value.map((t) => String(t).trim()).filter(Boolean))];
  return JSON.stringify(tags);
}

function mapLead(row) {
  return { ...row, tags: parseTags(row.tags), owner_id: row.owner_id, created_by: row.created_by };
}

const SELECT_LEADS = `
  SELECT l.*,
         creator.name AS created_by_name,
         owner.name   AS owner_name
  FROM crm_leads l
  LEFT JOIN crm_users creator ON creator.id = l.created_by
  LEFT JOIN crm_users owner   ON owner.id   = l.owner_id
`;

async function fetchLead(id) {
  const [rows] = await pool.query(`${SELECT_LEADS} WHERE l.id = ? LIMIT 1`, [id]);
  return rows[0] ? mapLead(rows[0]) : null;
}

/** Prueft, ob eine uebergebene Benutzer-ID existiert. */
async function userExists(id) {
  if (id === null) return true;
  const [rows] = await pool.query('SELECT id FROM crm_users WHERE id = ? LIMIT 1', [id]);
  return Boolean(rows[0]);
}

// GET /api/leads
router.get('/', async (req, res, next) => {
  try {
    const [rows] = await pool.query(`${SELECT_LEADS} ORDER BY l.updated_at DESC, l.id DESC`);
    res.json(rows.map(mapLead));
  } catch (err) {
    next(err);
  }
});

// POST /api/leads
router.post('/', async (req, res, next) => {
  const firstName = emptyToNull(req.body?.first_name);
  const lastName = emptyToNull(req.body?.last_name);
  if (!firstName || !lastName) {
    return res.status(400).json({ error: 'Vorname und Nachname sind erforderlich.' });
  }

  const status = STATUSES.has(req.body?.status) ? req.body.status : 'Neu';
  const ownerId =
    req.body?.owner_id === undefined || req.body.owner_id === null || req.body.owner_id === ''
      ? req.user.id
      : Number(req.body.owner_id);

  if (Number.isNaN(ownerId) || !(await userExists(ownerId))) {
    return res.status(400).json({ error: 'Zustaendiger Benutzer existiert nicht.' });
  }

  const columns = [...TEXT_FIELDS, 'status', 'tags', 'owner_id', 'created_by'];
  const values = [
    ...TEXT_FIELDS.map((field) =>
      field === 'first_name' ? firstName : field === 'last_name' ? lastName : emptyToNull(req.body?.[field])
    ),
    status,
    serializeTags(req.body?.tags) ?? '[]',
    ownerId,
    req.user.id,
  ];

  try {
    const [result] = await pool.query(
      `INSERT INTO crm_leads (${columns.join(', ')})
       VALUES (${columns.map(() => '?').join(', ')})`,
      values
    );
    res.status(201).json(await fetchLead(result.insertId));
  } catch (err) {
    next(err);
  }
});

// PATCH /api/leads/:id
router.patch('/:id', async (req, res, next) => {
  const id = Number(req.params.id);
  if (!Number.isInteger(id)) return res.status(400).json({ error: 'Ungueltige Lead-ID.' });

  const fields = [];
  const values = [];

  for (const field of TEXT_FIELDS) {
    if (req.body?.[field] === undefined) continue;
    const value = emptyToNull(req.body[field]);
    if ((field === 'first_name' || field === 'last_name') && !value) {
      return res.status(400).json({ error: 'Vorname und Nachname duerfen nicht leer sein.' });
    }
    fields.push(`${field} = ?`);
    values.push(value);
  }

  if (req.body?.status !== undefined) {
    if (!STATUSES.has(req.body.status)) return res.status(400).json({ error: 'Ungueltiger Status.' });
    fields.push('status = ?');
    values.push(req.body.status);
  }

  if (req.body?.tags !== undefined) {
    fields.push('tags = ?');
    values.push(serializeTags(req.body.tags) ?? '[]');
  }

  if (req.body?.owner_id !== undefined) {
    const ownerId =
      req.body.owner_id === null || req.body.owner_id === '' ? null : Number(req.body.owner_id);
    if (ownerId !== null && (Number.isNaN(ownerId) || !(await userExists(ownerId)))) {
      return res.status(400).json({ error: 'Zustaendiger Benutzer existiert nicht.' });
    }
    fields.push('owner_id = ?');
    values.push(ownerId);
  }

  if (fields.length === 0) return res.status(400).json({ error: 'Keine Aenderungen uebergeben.' });

  try {
    values.push(id);
    const [result] = await pool.query(
      `UPDATE crm_leads SET ${fields.join(', ')} WHERE id = ?`,
      values
    );
    if (result.affectedRows === 0) return res.status(404).json({ error: 'Lead nicht gefunden.' });
    res.json(await fetchLead(id));
  } catch (err) {
    next(err);
  }
});

// DELETE /api/leads/:id  - Verbindungen entfernt die DB per ON DELETE CASCADE
router.delete('/:id', async (req, res, next) => {
  const id = Number(req.params.id);
  if (!Number.isInteger(id)) return res.status(400).json({ error: 'Ungueltige Lead-ID.' });

  try {
    const [result] = await pool.query('DELETE FROM crm_leads WHERE id = ?', [id]);
    if (result.affectedRows === 0) return res.status(404).json({ error: 'Lead nicht gefunden.' });
    res.json({ ok: true });
  } catch (err) {
    next(err);
  }
});

export default router;