import type { NextApiRequest, NextApiResponse } from 'next';
import mysql from 'mysql2/promise';
import { resolveImageUrl } from '../../../lib/images';

interface ProductVariant {
  id: number;
  name: string;
  volume: string;
  volumeMl: number;
  currentPrice: number;
  kind: 'SAMPLE' | 'BOTTLE' | 'OTHER';
  sku: string;
  stock: number;
}

interface ProductResponse {
  id: number;
  slug: string;
  name: string;
  description: string;
  brandName: string;
  primaryImage: string;
  stock: number;
  sortOrder: number;
  variants: ProductVariant[];
}

interface CategoryResponse {
  id: number;
  name: string;
  slug: string;
  products: ProductResponse[];
}

interface ErrorResponse {
  error: string;
}

const pool = mysql.createPool({
  host: process.env.DB_HOST || 'localhost',
  user: process.env.DB_USER || 'root',
  password: process.env.DB_PASSWORD || '',
  database: process.env.DB_NAME || 'perfume_shop',
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0,
});

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse<CategoryResponse | ErrorResponse>
) {
  if (req.method !== 'GET') {
    return res.status(405).json({ error: 'Method not allowed' });
  }

  const { slug } = req.query;

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

  try {
    const connection = await pool.getConnection();

    // Get category info
    const [categoryRows] = await connection.query(
      `SELECT
        c.id,
        c.name,
        c.slug
      FROM categories c
      WHERE c.slug = ? AND c.active = 1`,
      [slug]
    );

    if (!Array.isArray(categoryRows) || categoryRows.length === 0) {
      connection.release();
      return res.status(404).json({ error: 'Category not found' });
    }

    const category = (categoryRows as any[])[0];

    // Get category's products with variants
    const [productRows] = await connection.query(
      `SELECT
        p.id AS product_id,
        p.name AS product_name,
        p.slug AS product_slug,
        p.description,
        b.name AS brand_name,
        img.url AS image_url,
        COALESCE(ps.stock, 0) AS stock,
        COALESCE(psort.s_id, 999999) AS sort_order,
        pv.id AS variant_id,
        pv.label,
        pv.volume_ml,
        pv.kind,
        pv.sku,
        pv.stock AS variant_stock,
        pr.price
      FROM products p
      JOIN brands b ON b.id = p.brand_id
      JOIN product_variants pv
        ON pv.product_id = p.id
       AND pv.is_active = 1
      JOIN prices pr
        ON pr.variant_id = pv.id
       AND pr.valid_to IS NULL
      LEFT JOIN product_images img
        ON img.product_id = p.id
       AND img.is_primary = 1
      LEFT JOIN product_stock ps ON ps.product_id = p.id
      LEFT JOIN product_sort psort ON psort.product_id = p.id
      JOIN product_category pc
        ON pc.product_id = p.id
      WHERE pc.category_id = ? AND p.type = 'perfume' AND p.is_active = 1
        AND EXISTS (
          SELECT 1 FROM product_variants available_variant
          WHERE available_variant.product_id = p.id
            AND available_variant.is_active = 1
            AND (
              (available_variant.kind = 'SAMPLE' AND COALESCE(ps.stock, 0) >= available_variant.volume_ml)
              OR (available_variant.kind <> 'SAMPLE' AND available_variant.stock > 0)
            )
        )
      ORDER BY sort_order ASC, p.id ASC, pv.volume_ml`,
      [category.id]
    );

    connection.release();

    // Group variants by product
    const productsMap = new Map<number, ProductResponse>();

    for (const row of (productRows as any[])) {
      if (!productsMap.has(row.product_id)) {
        productsMap.set(row.product_id, {
          id: row.product_id,
          slug: row.product_slug,
          name: row.product_name,
          description: row.description || '',
          brandName: row.brand_name || 'Unknown Brand',
          primaryImage: resolveImageUrl(row.image_url),
          stock: row.stock || 0,
          sortOrder: Number(row.sort_order) || 0,
          variants: [],
        });
      }

      if (row.variant_id) {
        const product = productsMap.get(row.product_id)!;
        product.variants.push({
          id: row.variant_id,
          name: row.label || '',
          volume: row.volume_ml ? `${row.volume_ml} ml` : '',
          volumeMl: row.volume_ml || 0,
          currentPrice: Number(row.price) || 0,
          kind: row.kind || 'SAMPLE',
          sku: row.sku || `VYS-${row.variant_id}`,
          stock: Number(row.variant_stock) || 0,
        });
      }
    }

    const response: CategoryResponse = {
      id: category.id,
      name: category.name,
      slug: category.slug,
      products: Array.from(productsMap.values()),
    };

    res.status(200).json(response);
  } catch (error) {
    res.status(500).json({ error: 'Failed to fetch category' });
  }
}