const router = require('express').Router();
const { query } = require('../db');

const STATUSES = ['requested', 'translated', 'generated', 'blocked', 'published'];

const STATUS_TIMESTAMP = {
  requested:  'requested_at',
  published:  'published_at',
  blocked:    'blocked_at',
};

// GET /api/words
router.get('/', async (req, res, next) => {
  try {
    const { status, limit = 50, offset = 0 } = req.query;
    const params = [Math.min(parseInt(limit), 500), parseInt(offset)];
    const where = status ? `WHERE w.status = $3` : '';
    if (status) params.push(status);
    const result = await query(
      `SELECT w.*,
        COALESCE(json_agg(DISTINCT p.id) FILTER (WHERE p.id IS NOT NULL), '[]') AS picture_ids,
        COALESCE(json_agg(DISTINCT c.id) FILTER (WHERE c.id IS NOT NULL), '[]') AS category_ids
       FROM words w
       LEFT JOIN word_pictures wp ON wp.word_id = w.id
       LEFT JOIN pictures p ON p.id = wp.picture_id
       LEFT JOIN word_categories wc ON wc.word_id = w.id
       LEFT JOIN categories c ON c.id = wc.category_id
       ${where}
       GROUP BY w.id
       ORDER BY w.created_at DESC
       LIMIT $1 OFFSET $2`,
      params
    );
    res.json(result.rows);
  } catch (err) { next(err); }
});

// GET /api/words/:id
router.get('/:id', async (req, res, next) => {
  try {
    const result = await query(
      `SELECT w.*,
        COALESCE(json_agg(DISTINCT p.id) FILTER (WHERE p.id IS NOT NULL), '[]') AS picture_ids,
        COALESCE(json_agg(DISTINCT c.id) FILTER (WHERE c.id IS NOT NULL), '[]') AS category_ids
       FROM words w
       LEFT JOIN word_pictures wp ON wp.word_id = w.id
       LEFT JOIN pictures p ON p.id = wp.picture_id
       LEFT JOIN word_categories wc ON wc.word_id = w.id
       LEFT JOIN categories c ON c.id = wc.category_id
       WHERE w.id = $1
       GROUP BY w.id`,
      [req.params.id]
    );
    if (!result.rows.length) return res.status(404).json({ error: 'Not found' });
    res.json(result.rows[0]);
  } catch (err) { next(err); }
});

// POST /api/words
router.post('/', async (req, res, next) => {
  try {
    const { titel_de, titel_en, titel_sv, difficulty_level } = req.body;
    const result = await query(
      `INSERT INTO words (titel_de, titel_en, titel_sv, difficulty_level, requested_at)
       VALUES ($1, $2, $3, $4, NOW()) RETURNING *`,
      [titel_de || null, titel_en || null, titel_sv || null, difficulty_level || null]
    );
    res.status(201).json({ ...result.rows[0], picture_ids: [], category_ids: [] });
  } catch (err) { next(err); }
});

// PATCH /api/words/:id
router.patch('/:id', async (req, res, next) => {
  try {
    const allowed = ['titel_de', 'titel_en', 'titel_sv', 'status',
                     'difficulty_level', 'requested_at', 'published_at', 'blocked_at'];
    const fields = Object.keys(req.body).filter(k => allowed.includes(k));
    if (!fields.length) return res.status(400).json({ error: 'No valid fields provided' });

    if (req.body.status && !STATUSES.includes(req.body.status))
      return res.status(400).json({ error: `status must be one of: ${STATUSES.join(', ')}` });

    // Auto-timestamp bei Statuswechsel
    const tsField = STATUS_TIMESTAMP[req.body.status];
    if (tsField && !req.body[tsField]) {
      fields.push(tsField);
      req.body[tsField] = new Date().toISOString();
    }

    const setClauses = fields.map((f, i) => `${f} = $${i + 1}`).join(', ');
    const values = [...fields.map(f => req.body[f]), req.params.id];
    const result = await query(
      `UPDATE words SET ${setClauses} WHERE id = $${fields.length + 1} RETURNING *`,
      values
    );
    if (!result.rows.length) return res.status(404).json({ error: 'Not found' });
    res.json(result.rows[0]);
  } catch (err) { next(err); }
});

// DELETE /api/words/:id
router.delete('/:id', async (req, res, next) => {
  try {
    const result = await query('DELETE FROM words WHERE id = $1 RETURNING id', [req.params.id]);
    if (!result.rows.length) return res.status(404).json({ error: 'Not found' });
    res.status(204).end();
  } catch (err) { next(err); }
});

// POST /api/words/:id/pictures/:pictureId — Bild verknüpfen
router.post('/:id/pictures/:pictureId', async (req, res, next) => {
  try {
    await query(
      `INSERT INTO word_pictures (word_id, picture_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
      [req.params.id, req.params.pictureId]
    );
    res.status(204).end();
  } catch (err) { next(err); }
});

// DELETE /api/words/:id/pictures/:pictureId — Bild-Verknüpfung entfernen
router.delete('/:id/pictures/:pictureId', async (req, res, next) => {
  try {
    await query(
      `DELETE FROM word_pictures WHERE word_id = $1 AND picture_id = $2`,
      [req.params.id, req.params.pictureId]
    );
    res.status(204).end();
  } catch (err) { next(err); }
});

// POST /api/words/:id/categories/:categoryId — Kategorie verknüpfen
router.post('/:id/categories/:categoryId', async (req, res, next) => {
  try {
    await query(
      `INSERT INTO word_categories (word_id, category_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
      [req.params.id, req.params.categoryId]
    );
    res.status(204).end();
  } catch (err) { next(err); }
});

// DELETE /api/words/:id/categories/:categoryId — Kategorie-Verknüpfung entfernen
router.delete('/:id/categories/:categoryId', async (req, res, next) => {
  try {
    await query(
      `DELETE FROM word_categories WHERE word_id = $1 AND category_id = $2`,
      [req.params.id, req.params.categoryId]
    );
    res.status(204).end();
  } catch (err) { next(err); }
});

module.exports = router;