import { applyCors, isAllowedOrigin } from './_cors.js';
import { createClient } from '@supabase/supabase-js';

const SUPABASE_URL = process.env.SUPABASE_URL || 'https://hwithddwaapyhnfwcesj.supabase.co';
const SUPABASE_KEY = process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.SUPABASE_SERVICE_KEY || 'sb_publishable_fGXkh0bSrAOqSk2jWKAzSg_NJD9YPCv';

const supabase = createClient(SUPABASE_URL, SUPABASE_KEY);

function setCors(req, res) {
  applyCors(req, res, 'POST, OPTIONS');
}

export default async function handler(req, res) {
  setCors(req, res);

  if (req.method === 'OPTIONS') {
    return res.status(204).end();
  }

  const origin = req.headers.origin;
  if (origin && !isAllowedOrigin(origin)) {
    return res.status(403).json({ error: 'Forbidden' });
  }

  try {
    if (req.method !== 'POST') {
      return res.status(405).json({ error: 'Method not allowed' });
    }

    const { rows } = req.body;

    if (!rows || !Array.isArray(rows)) {
      return res.status(400).json({ error: 'Missing rows data' });
    }

    const articleNoIdx = 0;
    // Fetch current product rows so we can preserve internal-only columns
    // that do not exist in the live Dropbox workbook.
    const { data: existingProducts } = await supabase
      .from('products')
      .select('product_id, data, status');
    const existingProductMap = new Map((existingProducts || []).map(p => [p.product_id, p]));
    const productsToUpsert = [];

    for (const row of rows) {
      const productId = String(row[articleNoIdx]);
      if (!productId || productId.trim() === '') continue;

      const existing = existingProductMap.get(productId);
      const dbRowData = existing?.data;

      if (dbRowData && Array.isArray(dbRowData)) {
        const mergedData = [...row];
        while (mergedData.length < dbRowData.length) {
          mergedData.push(null);
        }

        for (let i = 100; i < dbRowData.length; i++) {
          const internalValue = dbRowData[i];
          if (internalValue !== undefined && internalValue !== null && internalValue !== '') {
            mergedData[i] = internalValue;
          }
        }

        productsToUpsert.push({
          product_id: productId,
          data: mergedData,
          status: existing?.status || 'excel',
          updated_at: new Date().toISOString()
        });
      } else {
        // Normal excel sync
        productsToUpsert.push({
          product_id: productId,
          data: row,
          status: 'excel',
          updated_at: new Date().toISOString()
        });
      }
    }

    console.log('Upserting/updating', productsToUpsert.length, 'products in Supabase...');

    // Chunk upsert updates to avoid payload sizes or API limits
    const CHUNK_SIZE = 100;
    for (let i = 0; i < productsToUpsert.length; i += CHUNK_SIZE) {
      const chunk = productsToUpsert.slice(i, i + CHUNK_SIZE);
      const { error } = await supabase
        .from('products')
        .upsert(chunk, { onConflict: 'product_id' });

      if (error) {
        console.error('Supabase upsert error in chunk:', error);
        return res.status(500).json({ error: error.message, detail: 'Failed to upsert products chunk' });
      }
    }

    return res.json({
      success: true,
      syncedCount: productsToUpsert.length
    });
  } catch (err) {
    console.error('Handler error:', err);
    res.status(500).json({ error: err.message });
  }
}