import { sql } from '../../../../lib/sql.js';
import { withAdmin } from '../../../../lib/permission-middleware';
import { checkImportRateLimit } from '../../../../lib/rate-limit.js';

const ALLOWED_UPDATE_FIELDS = new Set([
  'rarity',
  'verified',
  'game',
  'mana_cost',
  'cmc',
  'card_type',
  'edhrec_rank',
  'layout',
  'released_at',
  'reserved',
  'reprint'
]);

const FIELD_VALIDATORS = {
  rarity: (v) => typeof v === 'string' && v.length > 0 && v.length <= 50,
  verified: (v) => typeof v === 'boolean',
  game: (v) => ['mtg', 'pokemon', 'lorcana'].includes(v),
  mana_cost: (v) => v === null || (typeof v === 'string' && v.length <= 50),
  cmc: (v) => v === null || (Number.isInteger(v) && v >= 0 && v <= 20),
  card_type: (v) => v === null || (typeof v === 'string' && v.length <= 255),
  edhrec_rank: (v) => v === null || (Number.isInteger(v) && v >= 0),
  layout: (v) => v === null || (typeof v === 'string' && v.length <= 50),
  released_at: (v) => v === null || (typeof v === 'string' && /^\d{4}-\d{2}-\d{2}$/.test(v)),
  reserved: (v) => typeof v === 'boolean',
  reprint: (v) => typeof v === 'boolean'
};

export default withAdmin(async function handler(req, res, user) {
  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' });
  }

  const { allowed, reset } = await checkImportRateLimit(req, user.userId);
  if (!allowed) {
    res.setHeader('Retry-After', Math.ceil((reset - Date.now()) / 1000));
    return res.status(429).json({ error: 'Too many attempts. Try again later.' });
  }

  try {
    const { cardIds, updates } = req.body;

    if (!Array.isArray(cardIds) || cardIds.length === 0) {
      return res.status(400).json({ error: 'cardIds array is required' });
    }

    if (!updates || typeof updates !== 'object') {
      return res.status(400).json({ error: 'updates object is required' });
    }

    // Validate and filter allowed fields
    const validUpdates = {};
    const errors = [];

    for (const [field, value] of Object.entries(updates)) {
      if (!ALLOWED_UPDATE_FIELDS.has(field)) {
        errors.push(`Field '${field}' is not allowed for batch update`);
        continue;
      }
      const validator = FIELD_VALIDATORS[field];
      if (validator && !validator(value)) {
        errors.push(`Invalid value for field '${field}'`);
        continue;
      }
      validUpdates[field] = value;
    }

    if (errors.length > 0) {
      return res.status(400).json({ error: 'Validation failed', details: errors });
    }

    if (Object.keys(validUpdates).length === 0) {
      return res.status(400).json({ error: 'No valid fields to update' });
    }

    // Safety cap
    if (cardIds.length > 1000) {
      return res.status(400).json({ error: 'Maximum 1000 cards per batch operation' });
    }

    // Build dynamic update query
    const setClauses = [];
    const values = [];
    let paramIdx = 1;

    for (const [field, value] of Object.entries(validUpdates)) {
      setClauses.push(`${field} = $${paramIdx}`);
      values.push(value);
      paramIdx++;
    }

    // Add updated_at
    setClauses.push(`updated_at = CURRENT_TIMESTAMP`);

    const placeholders = cardIds.map((_, i) => `$${paramIdx + i}`).join(',');
    values.push(...cardIds);

    const query = `
      UPDATE cards
      SET ${setClauses.join(', ')}
      WHERE id IN (${placeholders})
    `;

    const result = await sql.query(query, values);

    // Log the batch edit for audit
    console.log(`[admin batch edit] User ${user.email} updated ${result.rowCount} cards:`, validUpdates);

    res.status(200).json({
      success: true,
      updated: result.rowCount,
      fields: Object.keys(validUpdates)
    });

  } catch (error) {
    console.error('Error in batch edit:', error);
    res.status(500).json({
      success: false,
      error: 'Internal server error',
      message: error.message
    });
  }
});