import { createClient } from '@supabase/supabase-js';

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

const supabase = createClient(SUPABASE_URL, SUPABASE_KEY);

export default async function handler(req, res) {
  if (!SUPABASE_KEY) return res.status(500).json({ error: 'Service key missing' });

  try {
    console.log('Starting migration to shift indices...');
    
    // 1. Migrate 'products' table
    const { data: products } = await supabase
      .from('products')
      .select('product_id, data')
      .eq('status', 'edited'); // Only migrated ones need shifting
    
    let pCount = 0;
    if (products) {
      for (const p of products) {
        if (p.data.length >= 13 && (typeof p.data[12] === 'number' || (typeof p.data[12] === 'string' && /^[0-9.]+$/.test(p.data[12])))) {
          const newData = [...p.data];
          newData.splice(12, 0, ''); // Insert empty PM Classification
          await supabase.from('products').update({ data: newData }).eq('product_id', p.product_id);
          pCount++;
        }
      }
    }

    // 2. Migrate 'products_history' table (optional but good for consistency)
    const { data: history } = await supabase
      .from('products_history')
      .select('id, old_data, new_data');
    
    let hCount = 0;
    if (history) {
      for (const h of history) {
        let changed = false;
        let nOld = h.old_data;
        let nNew = h.new_data;

        if (nOld && nOld.length >= 13 && (typeof nOld[12] === 'number' || (typeof nOld[12] === 'string' && /^[0-9.]+$/.test(nOld[12])))) {
          nOld = [...nOld];
          nOld.splice(12, 0, '');
          changed = true;
        }
        if (nNew && nNew.length >= 13 && (typeof nNew[12] === 'number' || (typeof nNew[12] === 'string' && /^[0-9.]+$/.test(nNew[12])))) {
          nNew = [...nNew];
          nNew.splice(12, 0, '');
          changed = true;
        }

        if (changed) {
          await supabase.from('products_history').update({ old_data: nOld, new_data: nNew }).eq('id', h.id);
          hCount++;
        }
      }
    }

    return res.json({
      success: true,
      productsMigrated: pCount,
      historyMigrated: hCount,
      message: 'Migration completed successfully. Indices >= 12 shifted by +1.'
    });
  } catch (err) {
    return res.status(500).json({ error: err.message });
  }
}