const express = require('express');
const router = express.Router();

// GET /api/hts-lookup?search=term
// Finds matching products and groups them by harmonized tariff code
router.get('/', async (req, res) => {
  const searchTerm = typeof req.query.search === 'string' ? req.query.search.trim() : '';

  if (!searchTerm) {
    return res.status(400).json({ error: 'Search term is required' });
  }

  try {
    const pool = req.app.locals.pool;
    const likeTerm = `%${searchTerm}%`;

    const { rows } = await pool.query(
      `
      WITH matched_products AS (
        SELECT 
          pid,
          title,
          sku,
          barcode,
          brand,
          vendor,
          harmonized_tariff_code,
          NULLIF(
            LOWER(
              REGEXP_REPLACE(
                COALESCE(NULLIF(TRIM(harmonized_tariff_code), ''), ''),
                '[^0-9A-Za-z]',
                '',
                'g'
              )
            ),
            ''
          ) AS normalized_code
        FROM products
        WHERE visible = TRUE
          AND (
            title ILIKE $1
            OR sku ILIKE $1
            OR barcode ILIKE $1
            OR vendor ILIKE $1
            OR brand ILIKE $1
            OR vendor_reference ILIKE $1
            OR harmonized_tariff_code ILIKE $1
          )
      ),
      grouped AS (
        SELECT 
          COALESCE(NULLIF(TRIM(harmonized_tariff_code), ''), 'Unspecified') AS harmonized_tariff_code,
          normalized_code,
          COUNT(*)::INT AS product_count,
          json_agg(
            json_build_object(
              'pid', pid,
              'title', title,
              'sku', sku,
              'barcode', barcode,
              'brand', brand,
              'vendor', vendor
            )
            ORDER BY title
          ) AS products
        FROM matched_products
        GROUP BY 
          COALESCE(NULLIF(TRIM(harmonized_tariff_code), ''), 'Unspecified'),
          normalized_code
      ),
      hts_lookup AS (
        SELECT 
          h."HTS Number" AS hts_number,
          h."Indent" AS indent,
          h."Description" AS description,
          h."Unit of Quantity" AS unit_of_quantity,
          h."General Rate of Duty" AS general_rate_of_duty,
          h."Special Rate of Duty" AS special_rate_of_duty,
          h."Column 2 Rate of Duty" AS column2_rate_of_duty,
          h."Quota Quantity" AS quota_quantity,
          h."Additional Duties" AS additional_duties,
          NULLIF(
            LOWER(
              REGEXP_REPLACE(
                COALESCE(h."HTS Number", ''),
                '[^0-9A-Za-z]',
                '',
                'g'
              )
            ),
            ''
          ) AS normalized_hts_number
        FROM htsdata h
      )
      SELECT 
        g.harmonized_tariff_code,
        g.product_count,
        g.products,
        hts.hts_details
      FROM grouped g
      LEFT JOIN LATERAL (
        SELECT json_agg(
          json_build_object(
            'hts_number', h.hts_number,
            'indent', h.indent,
            'description', h.description,
            'unit_of_quantity', h.unit_of_quantity,
            'general_rate_of_duty', h.general_rate_of_duty,
            'special_rate_of_duty', h.special_rate_of_duty,
            'column2_rate_of_duty', h.column2_rate_of_duty,
            'quota_quantity', h.quota_quantity,
            'additional_duties', h.additional_duties
          )
          ORDER BY LENGTH(COALESCE(h.normalized_hts_number, '')) ASC NULLS LAST,
                   NULLIF(h.indent, '')::INT NULLS LAST
        ) AS hts_details
        FROM hts_lookup h
        WHERE COALESCE(g.normalized_code, '') <> ''
          AND COALESCE(h.normalized_hts_number, '') <> ''
          AND (
            g.normalized_code LIKE h.normalized_hts_number || '%'
            OR h.normalized_hts_number LIKE g.normalized_code || '%'
          )
      ) hts ON TRUE
      ORDER BY g.product_count DESC, g.harmonized_tariff_code ASC
      `,
      [likeTerm]
    );

    const totalMatches = rows.reduce((sum, row) => sum + (parseInt(row.product_count, 10) || 0), 0);

    res.json({
      search: searchTerm,
      total: totalMatches,
      results: rows.map(row => ({
        harmonized_tariff_code: row.harmonized_tariff_code,
        product_count: parseInt(row.product_count, 10) || 0,
        hts_details: Array.isArray(row.hts_details)
          ? row.hts_details.map(detail => ({
              hts_number: detail.hts_number,
              indent: detail.indent,
              description: detail.description,
              unit_of_quantity: detail.unit_of_quantity,
              general_rate_of_duty: detail.general_rate_of_duty,
              special_rate_of_duty: detail.special_rate_of_duty,
              column2_rate_of_duty: detail.column2_rate_of_duty,
              quota_quantity: detail.quota_quantity,
              additional_duties: detail.additional_duties
            }))
          : [],
        products: Array.isArray(row.products)
          ? row.products.map(product => ({
              pid: product.pid,
              title: product.title,
              sku: product.sku,
              barcode: product.barcode,
              brand: product.brand,
              vendor: product.vendor
            }))
          : []
      }))
    });
  } catch (error) {
    console.error('Error performing HTS lookup:', error);
    res.status(500).json({ error: 'Failed to lookup HTS codes' });
  }
});

module.exports = router;