const mysql = require('mysql2/promise');
const { Client } = require('ssh2');
const dotenv = require('dotenv');
const path = require('path');

dotenv.config({ path: path.join(__dirname, '../.env') });

// SSH configuration
const sshConfig = {
  host: process.env.PROD_SSH_HOST,
  port: process.env.PROD_SSH_PORT || 22,
  username: process.env.PROD_SSH_USER,
  privateKey: process.env.PROD_SSH_KEY_PATH ? require('fs').readFileSync(process.env.PROD_SSH_KEY_PATH) : undefined
};

// Production database configuration
const prodDbConfig = {
  host: process.env.PROD_DB_HOST || 'localhost',
  user: process.env.PROD_DB_USER,
  password: process.env.PROD_DB_PASSWORD,
  database: process.env.PROD_DB_NAME,
  port: process.env.PROD_DB_PORT || 3306
};

// Local database configuration
const localDbConfig = {
  host: process.env.DB_HOST,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  database: process.env.DB_NAME,
  multipleStatements: true,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0,
  namedPlaceholders: true
};

// Helper function to output progress
function outputProgress(data) {
  process.stdout.write(JSON.stringify(data) + '\n');
}

// Helper function to format duration
function formatDuration(seconds) {
  const hours = Math.floor(seconds / 3600);
  const minutes = Math.floor((seconds % 3600) / 60);
  seconds = Math.floor(seconds % 60);
  
  const parts = [];
  if (hours > 0) parts.push(`${hours}h`);
  if (minutes > 0) parts.push(`${minutes}m`);
  if (seconds > 0 || parts.length === 0) parts.push(`${seconds}s`);
  
  return parts.join(' ');
}

// Helper function to update progress with time estimate
function updateProgress(current, total, operation, startTime) {
  const elapsed = (Date.now() - startTime) / 1000;
  const rate = current / elapsed;
  const remaining = (total - current) / rate;
  
  outputProgress({
    status: 'running',
    operation,
    current,
    total,
    rate,
    elapsed: formatDuration(elapsed),
    remaining: formatDuration(remaining),
    percentage: ((current / total) * 100).toFixed(1)
  });
}

let isImportCancelled = false;

// Add cancel function
function cancelImport() {
  isImportCancelled = true;
  outputProgress({
    status: 'cancelled',
    operation: 'Import cancelled'
  });
}

async function setupSshTunnel() {
  return new Promise((resolve, reject) => {
    const ssh = new Client();

    ssh.on('ready', () => {
      ssh.forwardOut(
        '127.0.0.1',
        0,
        prodDbConfig.host,
        prodDbConfig.port,
        async (err, stream) => {
          if (err) reject(err);
          resolve({ ssh, stream });
        }
      );
    }).connect(sshConfig);
  });
}

async function importCategories(prodConnection, localConnection) {
  outputProgress({
    operation: 'Starting categories import',
    status: 'running'
  });

  const startTime = Date.now();
  const typeOrder = [10, 20, 11, 21, 12, 13];
  let totalInserted = 0;
  let skippedCategories = [];

  try {
    // Process each type in order with its own query
    for (const type of typeOrder) {
      const [categories] = await prodConnection.query(`
        SELECT 
          pc.cat_id,
          pc.name,
          pc.type,
          CASE 
            WHEN pc.type IN (10, 20) THEN NULL  -- Top level categories should have no parent
            WHEN pc.master_cat_id IS NULL THEN NULL
            ELSE pc.master_cat_id
          END as parent_id,
          pc.combined_name as description
        FROM product_categories pc
        WHERE pc.type = ?
        ORDER BY pc.cat_id
      `, [type]);

      if (categories.length === 0) continue;

      console.log(`\nProcessing ${categories.length} type ${type} categories`);

      // For types that can have parents (11, 21, 12, 13), verify parent existence
      let categoriesToInsert = categories;
      if (![10, 20].includes(type)) {
        // Get all parent IDs
        const parentIds = [...new Set(categories.map(c => c.parent_id).filter(id => id !== null))];
        
        // Check which parents exist
        const [existingParents] = await localConnection.query(
          'SELECT cat_id FROM categories WHERE cat_id IN (?)',
          [parentIds]
        );
        const existingParentIds = new Set(existingParents.map(p => p.cat_id));

        // Filter categories and track skipped ones
        categoriesToInsert = categories.filter(cat => 
          cat.parent_id === null || existingParentIds.has(cat.parent_id)
        );
        const invalidCategories = categories.filter(cat => 
          cat.parent_id !== null && !existingParentIds.has(cat.parent_id)
        );

        if (invalidCategories.length > 0) {
          const skippedInfo = invalidCategories.map(c => ({
            id: c.id,
            name: c.name,
            type: c.type,
            missing_parent: c.parent_id
          }));
          skippedCategories.push(...skippedInfo);
          
          console.log('\nSkipping categories with missing parents:', 
            invalidCategories.map(c => `${c.id} - ${c.name} (missing parent: ${c.parent_id})`).join('\n')
          );
        }

        if (categoriesToInsert.length === 0) {
          console.log(`No valid categories of type ${type} to insert - all had missing parents`);
          continue;
        }
      }

      console.log(`Inserting ${categoriesToInsert.length} type ${type} categories`);

      const placeholders = categoriesToInsert.map(() => 
        '(?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)'
      ).join(',');

      const values = categoriesToInsert.flatMap(cat => [
        cat.cat_id,
        cat.name,
        cat.type,
        cat.parent_id,
        cat.description,
        'active'
      ]);

      // Insert categories and create relationships in one query to avoid race conditions
      await localConnection.query(`
        INSERT INTO categories (cat_id, name, type, parent_id, description, status, created_at, updated_at)
        VALUES ${placeholders}
        ON DUPLICATE KEY UPDATE
          name = VALUES(name),
          type = VALUES(type),
          parent_id = VALUES(parent_id),
          description = VALUES(description),
          status = VALUES(status),
          updated_at = CURRENT_TIMESTAMP
      `, values);

      totalInserted += categoriesToInsert.length;
      updateProgress(totalInserted, totalInserted, 'Categories import', startTime);
    }

    // After all imports, if we skipped any categories, throw an error
    if (skippedCategories.length > 0) {
      const error = new Error('Categories import completed with errors - some categories were skipped due to missing parents');
      error.skippedCategories = skippedCategories;
      throw error;
    }

    outputProgress({
      status: 'complete',
      operation: 'Categories import completed',
      current: totalInserted,
      total: totalInserted,
      duration: formatDuration((Date.now() - startTime) / 1000)
    });

  } catch (error) {
    console.error('Error importing categories:', error);
    if (error.skippedCategories) {
      console.error('Skipped categories:', JSON.stringify(error.skippedCategories, null, 2));
    }
    throw error;
  }
}

async function importProducts(prodConnection, localConnection) {
  outputProgress({
    operation: 'Starting products import',
    status: 'running'
  });

  const startTime = Date.now();

  try {
    // Get products from production
    const [rows] = await prodConnection.query(`
      SELECT 
        p.pid AS product_id,
        p.description AS title,
        p.notes AS description,
        p.itemnumber AS SKU,
        p.date_created AS created_at,
        p.datein AS first_received,
        p.location AS location,
        (
          SELECT
            i.available_local - COALESCE(
              (
                SELECT
                  SUM(oi.qty_ordered - oi.qty_placed)
                FROM
                  order_items oi
                  JOIN _order o ON oi.order_id = o.order_id
                WHERE
                  oi.prod_pid = i.pid
                  AND o.date_placed != '0000-00-00 00:00:00'
                  AND o.date_shipped = '0000-00-00 00:00:00'
                  AND oi.pick_finished = 0
                  AND oi.qty_back = 0
                  AND o.order_status != 15
                  AND o.order_status < 90
                  AND oi.qty_ordered >= oi.qty_placed
                  AND oi.qty_ordered > 0
              ),
              0
            ) AS stock_quantity
          FROM
            shop_inventory i
          WHERE
            i.pid = p.pid
            AND i.store = 0
            AND i.show + i.buyable > 0
          LIMIT 1
        ) AS stock_quantity,
        ci.onpreorder AS preorder_count,
        pnb.inventory AS notions_inv_count,
        (
          SELECT
            price_each
          FROM
            product_current_prices
          WHERE
            pid = p.pid
            AND active = 1
          ORDER BY
            qty_buy ASC
          LIMIT 1
        ) AS price,
        p.sellingprice AS regular_price,
        (
          SELECT
            ROUND(AVG(costeach), 5)
          FROM
            product_inventory
          WHERE
            pid = p.pid
            AND COUNT > 0
        ) AS cost_price,
        NULL AS landing_cost_price,
        p.upc AS barcode,
        p.harmonized_tariff_code AS harmonized_tariff_code,
        p.stamp AS updated_at,
        CASE
          WHEN si.show + si.buyable > 0 THEN 1
          ELSE 0
        END AS visible,
        CASE
          WHEN p.reorder >= 0 THEN 1
          ELSE 0
        END AS replenishable,
        s.companyname AS vendor,
        sid.supplier_itemnumber AS vendor_reference,
        sid.notions_itemnumber AS notions_reference,
        CONCAT('https://www.acherryontop.com/shop/product/', p.pid) AS permalink,
        (
          SELECT
            GROUP_CONCAT(pc.name SEPARATOR ', ')
          FROM
            product_category_index pci
            JOIN product_categories pc ON pci.cat_id = pc.cat_id
          WHERE
            pci.pid = p.pid
            AND pc.hidden = 0
        ) AS categories,
        (
          SELECT
            CONCAT('https://sbing.com/i/products/0000/', SUBSTRING(LPAD(p.pid, 6, '0'), 1, 3), '/', p.pid, '-t-', PI.iid, '.jpg')
          FROM
            product_images PI
          WHERE
            PI.pid = p.pid
            AND PI.hidden = 0
          ORDER BY
            PI.order DESC,
            PI.iid
          LIMIT 1
        ) AS image,
        (
          SELECT
            CONCAT('https://sbing.com/i/products/0000/', SUBSTRING(LPAD(p.pid, 6, '0'), 1, 3), '/', p.pid, '-175x175-', PI.iid, '.jpg')
          FROM
            product_images PI
          WHERE
            PI.pid = p.pid
            AND PI.hidden = 0
            AND PI.width = 175
          ORDER BY
            PI.order DESC,
            PI.iid
          LIMIT 1
        ) AS image_175,
        (
          SELECT
            CONCAT('https://sbing.com/i/products/0000/', SUBSTRING(LPAD(p.pid, 6, '0'), 1, 3), '/', p.pid, '-o-', PI.iid, '.jpg')
          FROM
            product_images PI
          WHERE
            PI.pid = p.pid
            AND PI.hidden = 0
          ORDER BY
            PI.width DESC,
            PI.height DESC,
            PI.iid
          LIMIT 1
        ) AS image_full,
        (
          SELECT
            name
          FROM
            product_categories
          WHERE
            cat_id = p.company
        ) AS brand,
        (
          SELECT
            name
          FROM
            product_categories
          WHERE
            cat_id = p.line
        ) AS line,
        (
          SELECT
            name
          FROM
            product_categories
          WHERE
            cat_id = p.subline
        ) AS subline,
        (
          SELECT
            name
          FROM
            product_categories
          WHERE
            cat_id = p.artist
        ) AS artist,
        NULL AS options,
        NULL AS tags,
        COALESCE(
          CASE
            WHEN sid.supplier_id = 92 THEN sid.notions_qty_per_unit
            ELSE sid.supplier_qty_per_unit
          END,
          sid.notions_qty_per_unit
        ) AS moq,
        NULL AS uom,
        p.rating,
        p.rating_votes AS reviews,
        p.weight,
        p.length,
        p.width,
        p.height,
        (
          SELECT
            COUNT(*)
          FROM
            mybasket mb
          WHERE
            mb.item = p.pid
            AND mb.qty > 0
        ) AS baskets,
        (
          SELECT
            COUNT(*)
          FROM
            product_notify pn
          WHERE
            pn.pid = p.pid
        ) AS notifies,
        p.totalsold AS total_sold,
        p.country_of_origin as country_of_origin,
        pls.date_sold as date_last_sold
      FROM
        products p
        LEFT JOIN current_inventory ci ON p.pid = ci.pid
        LEFT JOIN product_notions_b2b pnb ON p.pid = pnb.pid
        LEFT JOIN shop_inventory si ON p.pid = si.pid AND si.store = 0
        LEFT JOIN supplier_item_data sid ON p.pid = sid.pid
        LEFT JOIN suppliers s ON sid.supplier_id = s.supplierid
        LEFT JOIN product_category_index pci ON p.pid = pci.pid
        LEFT JOIN product_categories pc ON pci.cat_id = pc.cat_id
        LEFT JOIN product_last_sold pls ON p.pid = pls.pid
      WHERE p.date_created >= DATE_SUB(CURRENT_DATE, INTERVAL 2 YEAR)
      GROUP BY p.pid
    `);

    let current = 0;
    const total = rows.length;

    // Process products in batches
    const BATCH_SIZE = 100;
    for (let i = 0; i < rows.length; i += BATCH_SIZE) {
      const batch = rows.slice(i, i + BATCH_SIZE);
      
      console.log(`Inserting ${batch.length} products`);

      // First insert the products
      const values = batch.flatMap(r => [
        r.product_id, r.title, r.description, r.SKU, r.created_at, r.first_received,
        r.stock_quantity, r.preorder_count, r.notions_inv_count, r.price, r.regular_price,
        r.cost_price, r.landing_cost_price, r.barcode, r.harmonized_tariff_code,
        r.updated_at, r.visible, 1, r.replenishable, r.vendor,
        r.vendor_reference, r.notions_reference, r.permalink,
        r.image, r.image_175, r.image_full, r.brand, r.line, r.subline, r.artist,
        r.options, r.tags, r.moq, r.uom, r.rating, r.reviews, r.weight, r.length,
        r.width, r.height, r.country_of_origin, r.location, r.total_sold,
        r.baskets, r.notifies, r.date_last_sold
      ]);

      // Get the number of columns from the first row's values
      const columnsPerRow = values.length / batch.length;
      const placeholders = batch.map(() => 
        `(${Array(columnsPerRow).fill('?').join(',')})`
      ).join(',');

      const sql = `INSERT INTO products (
        pid, title, description, SKU, created_at, first_received,
        stock_quantity, preorder_count, notions_inv_count, price, regular_price,
        cost_price, landing_cost_price, barcode, harmonized_tariff_code,
        updated_at, visible, managing_stock, replenishable, vendor,
        vendor_reference, notions_reference, permalink,
        image, image_175, image_full, brand, line, subline, artist,
        options, tags, moq, uom, rating, reviews, weight, length,
        width, height, country_of_origin, location, total_sold,
        baskets, notifies, date_last_sold
      )
      VALUES ${placeholders}
      ON DUPLICATE KEY UPDATE
        title = VALUES(title),
        description = VALUES(description),
        stock_quantity = VALUES(stock_quantity),
        preorder_count = VALUES(preorder_count),
        notions_inv_count = VALUES(notions_inv_count),
        price = VALUES(price),
        regular_price = VALUES(regular_price),
        cost_price = VALUES(cost_price),
        landing_cost_price = VALUES(landing_cost_price),
        barcode = VALUES(barcode),
        harmonized_tariff_code = VALUES(harmonized_tariff_code),
        updated_at = VALUES(updated_at),
        visible = VALUES(visible),
        replenishable = VALUES(replenishable),
        vendor = VALUES(vendor),
        vendor_reference = VALUES(vendor_reference),
        notions_reference = VALUES(notions_reference),
        permalink = VALUES(permalink),
        image = VALUES(image),
        image_175 = VALUES(image_175),
        image_full = VALUES(image_full),
        brand = VALUES(brand),
        line = VALUES(line),
        subline = VALUES(subline),
        artist = VALUES(artist),
        options = VALUES(options),
        tags = VALUES(tags),
        moq = VALUES(moq),
        uom = VALUES(uom),
        rating = VALUES(rating),
        reviews = VALUES(reviews),
        weight = VALUES(weight),
        length = VALUES(length),
        width = VALUES(width),
        height = VALUES(height),
        country_of_origin = VALUES(country_of_origin),
        location = VALUES(location),
        total_sold = VALUES(total_sold),
        baskets = VALUES(baskets),
        notifies = VALUES(notifies),
        date_last_sold = VALUES(date_last_sold)`;

      await localConnection.query(sql, values);

      // Then insert the category relationships for this batch
      const categoryPromises = batch.map(async product => {
        // Get the category IDs from the production query
        const [categoryRows] = await prodConnection.query(`
          SELECT DISTINCT cat_id 
          FROM product_category_index 
          WHERE pid = ? AND cat_id IN (
            SELECT cat_id FROM product_categories WHERE hidden = 0
          )
        `, [product.product_id]);

        return categoryRows.map(row => [row.cat_id, product.product_id]);
      });

      const categoryResults = await Promise.all(categoryPromises);
      const categoryRelationships = categoryResults.flat();

      if (categoryRelationships.length > 0) {
        const catPlaceholders = categoryRelationships.map(() => '(?, ?)').join(',');
        await localConnection.query(`
          INSERT INTO product_categories (cat_id, pid)
          VALUES ${catPlaceholders}
          ON DUPLICATE KEY UPDATE cat_id = VALUES(cat_id)
        `, categoryRelationships.flat());
      }

      current += batch.length;
      updateProgress(current, total, 'Products import', startTime);
    }

    outputProgress({
      status: 'complete',
      operation: 'Products import completed',
      current: total,
      total,
      duration: formatDuration((Date.now() - startTime) / 1000)
    });
  } catch (error) {
    console.error('Error importing products:', error);
    throw error;
  }
}

async function importProductCategories(prodConnection, localConnection) {
  outputProgress({
    operation: 'Starting product categories import',
    status: 'running'
  });

  const startTime = Date.now();

  try {
    // Get product category relationships from production
    const [rows] = await prodConnection.query(`
      SELECT DISTINCT
        pci.pid,
        pci.cat_id
      FROM
        product_category_index pci
        JOIN product_categories pc ON pci.cat_id = pc.cat_id
      WHERE
        pc.hidden = 0
    `);

    let current = 0;
    const total = rows.length;

    // Process in batches
    const BATCH_SIZE = 500;
    for (let i = 0; i < rows.length; i += BATCH_SIZE) {
      const batch = rows.slice(i, i + BATCH_SIZE);
      
      // Create placeholders for batch insert
      const placeholders = batch.map(() => '(?, ?)').join(',');

      // Flatten values for batch insert
      const values = batch.flatMap(row => [row.cat_id, row.pid]);

      await localConnection.query(`
        INSERT INTO product_categories (cat_id, pid)
        VALUES ${placeholders}
        ON DUPLICATE KEY UPDATE
          cat_id = VALUES(cat_id)
      `, values);

      current += batch.length;
      updateProgress(current, total, 'Product categories import', startTime);
    }

    outputProgress({
      status: 'complete',
      operation: 'Product categories import completed',
      current: total,
      total,
      duration: formatDuration((Date.now() - startTime) / 1000)
    });
  } catch (error) {
    console.error('Error importing product categories:', error);
    throw error;
  }
}

async function importOrders(prodConnection, localConnection) {
  outputProgress({
    operation: 'Starting orders import',
    status: 'running'
  });

  const startTime = Date.now();

  try {
    // Get orders from production
    const [rows] = await prodConnection.query(`
      SELECT
        oi.order_id AS order_number,
        oi.prod_pid AS product_id,
        oi.prod_itemnumber AS SKU,
        o.date_placed_onlydate AS date,
        oi.prod_price_reg AS price,
        oi.qty_ordered AS quantity,
        (oi.prod_price_reg - oi.prod_price) AS discount,
        COALESCE((
          SELECT
            otp.item_taxes_to_collect
          FROM
            order_tax_info oti
            JOIN order_tax_info_products otp ON oti.taxinfo_id = otp.taxinfo_id
          WHERE
            oti.order_id = o.order_id
            AND otp.pid = oi.prod_pid
          ORDER BY
            oti.stamp DESC
          LIMIT 1
        ), 0) AS tax,
        0 AS tax_included,
        COALESCE(ROUND(
          ((o.summary_shipping - COALESCE(o.summary_discount_shipping, 0)) * 
          (oi.prod_price * oi.qty_ordered) / NULLIF(o.summary_subtotal, 0)), 2
        ), 0) as shipping,
        o.order_cid AS customer,
        CONCAT(COALESCE(u.firstname, ''), ' ', COALESCE(u.lastname, '')) AS customer_name,
        CASE
          WHEN o.order_status = 15 THEN 1
          ELSE 0
        END AS canceled
      FROM
        _order o
        JOIN order_items oi ON o.order_id = oi.order_id
        LEFT JOIN users u ON o.order_cid = u.cid
      WHERE
        o.order_status >= 15
        AND o.date_placed_onlydate >= DATE_SUB(CURRENT_DATE, INTERVAL 2 YEAR)
      ORDER BY
        o.date_placed_onlydate DESC
    `);

    let current = 0;
    const total = rows.length;

    // Process in batches
    const BATCH_SIZE = 500;
    for (let i = 0; i < rows.length; i += BATCH_SIZE) {
      const batch = rows.slice(i, i + BATCH_SIZE);
      
      // Create placeholders for batch insert
      const placeholders = batch.map(() => 
        '(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)'
      ).join(',');

      // Flatten values for batch insert
      const values = batch.flatMap(row => [
        row.order_number,
        row.product_id,
        row.SKU,
        row.date,
        row.price,
        row.quantity,
        row.discount,
        row.tax,
        row.tax_included,
        row.shipping,
        row.customer,
        row.customer_name,
        row.canceled
      ]);

      await localConnection.query(`
        INSERT INTO orders (
          order_number, product_id, SKU, date, price, quantity, discount,
          tax, tax_included, shipping, customer, customer_name, canceled
        )
        VALUES ${placeholders}
        ON DUPLICATE KEY UPDATE
          price = VALUES(price),
          quantity = VALUES(quantity),
          discount = VALUES(discount),
          tax = VALUES(tax),
          tax_included = VALUES(tax_included),
          shipping = VALUES(shipping),
          customer_name = VALUES(customer_name),
          canceled = VALUES(canceled)
      `, values);

      current += batch.length;
      updateProgress(current, total, 'Orders import', startTime);
    }

    outputProgress({
      status: 'complete',
      operation: 'Orders import completed',
      current: total,
      total,
      duration: formatDuration((Date.now() - startTime) / 1000)
    });
  } catch (error) {
    console.error('Error importing orders:', error);
    throw error;
  }
}

async function importPurchaseOrders(prodConnection, localConnection) {
  outputProgress({
    operation: 'Starting purchase orders import',
    status: 'running'
  });

  const startTime = Date.now();

  try {
    // Get purchase orders from production
    const [rows] = await prodConnection.query(`
      SELECT 
        po.po_id,
        s.companyname as vendor,
        po.date_ordered as date,
        po.date_estin as expected_date,
        pop.pid as product_id,
        p.itemnumber as sku,
        COALESCE(rp.cost_each, pop.cost_each, 0) as cost_price,
        CASE 
          WHEN po.status = 0 THEN 'canceled'
          WHEN po.status = 1 THEN 'created'
          WHEN po.status = 10 THEN 'electronically_ready_send'
          WHEN po.status = 11 THEN 'ordered'
          WHEN po.status = 12 THEN 'preordered'
          WHEN po.status = 13 THEN 'electronically_sent'
          WHEN po.status = 15 THEN 'receiving_started'
          WHEN po.status = 50 THEN 'closed'
          ELSE 'unknown'
        END as status,
        NULLIF(CONCAT_WS(' ', NULLIF(po.short_note, ''), NULLIF(po.notes, '')), '') as notes,
        pop.qty_each as ordered,
        COALESCE(rp.received_qty, 0) as received,
        rp.received_date,
        rp.received_by
      FROM po
      JOIN po_products pop ON po.po_id = pop.po_id
      JOIN products p ON pop.pid = p.pid
      JOIN suppliers s ON po.supplier_id = s.supplierid
      LEFT JOIN receivings r ON po.po_id = r.po_id
      LEFT JOIN receivings_products rp ON r.receiving_id = rp.receiving_id 
          AND pop.pid = rp.pid
      WHERE
        po.date_ordered >= DATE_SUB(CURRENT_DATE, INTERVAL 2 YEAR)
      ORDER BY
        po.date_ordered DESC
    `);

    let current = 0;
    const total = rows.length;

    // Process in batches
    const BATCH_SIZE = 500;
    for (let i = 0; i < rows.length; i += BATCH_SIZE) {
      const batch = rows.slice(i, i + BATCH_SIZE);
      
      // Create placeholders for batch insert
      const placeholders = batch.map(() => 
        '(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)'
      ).join(',');

      // Flatten values for batch insert
      const values = batch.flatMap(row => [
        row.po_id,
        row.vendor,
        row.date,
        row.expected_date,
        row.product_id,
        row.sku,
        row.cost_price,
        row.status,
        row.notes,
        row.ordered,
        row.received,
        row.received_date,
        row.received_by
      ]);

      await localConnection.query(`
        INSERT INTO purchase_orders (
          po_id, vendor, date, expected_date, product_id, sku,
          cost_price, status, notes, ordered, received, received_date, received_by
        )
        VALUES ${placeholders}
        ON DUPLICATE KEY UPDATE
          vendor = VALUES(vendor),
          expected_date = VALUES(expected_date),
          cost_price = VALUES(cost_price),
          status = VALUES(status),
          notes = VALUES(notes),
          ordered = VALUES(ordered),
          received = VALUES(received),
          received_date = VALUES(received_date),
          received_by = VALUES(received_by)
      `, values);

      current += batch.length;
      updateProgress(current, total, 'Purchase orders import', startTime);
    }

    outputProgress({
      status: 'complete',
      operation: 'Purchase orders import completed',
      current: total,
      total,
      duration: formatDuration((Date.now() - startTime) / 1000)
    });
  } catch (error) {
    console.error('Error importing purchase orders:', error);
    throw error;
  }
}

// Modify main function to handle cancellation and avoid process.exit
async function main() {
  let ssh;
  let prodConnection;
  let localConnection;

  try {
    outputProgress({
      status: 'running',
      operation: 'Starting import process',
      message: 'Setting up connections...'
    });

    // Set up connections
    const tunnel = await setupSshTunnel();
    ssh = tunnel.ssh;
    
    prodConnection = await mysql.createConnection({
      ...prodDbConfig,
      stream: tunnel.stream
    });

    localConnection = await mysql.createPool(localDbConfig);

    if (isImportCancelled) throw new Error('Import cancelled');

    // First import all categories
    await importCategories(prodConnection, localConnection);
    if (isImportCancelled) throw new Error('Import cancelled');
    
    // Then import products
    await importProducts(prodConnection, localConnection);
    if (isImportCancelled) throw new Error('Import cancelled');
    
    // Then import product-category relationships
    await importProductCategories(prodConnection, localConnection);
    if (isImportCancelled) throw new Error('Import cancelled');
    
    await importOrders(prodConnection, localConnection);
    if (isImportCancelled) throw new Error('Import cancelled');
    
    await importPurchaseOrders(prodConnection, localConnection);
    if (isImportCancelled) throw new Error('Import cancelled');

    outputProgress({
      status: 'complete',
      operation: 'Import process completed'
    });

  } catch (error) {
    console.error('Error during import process:', error);
    outputProgress({
      status: error.message === 'Import cancelled' ? 'cancelled' : 'error',
      operation: 'Import process',
      error: error.message
    });
    throw error;
  } finally {
    if (prodConnection) await prodConnection.end();
    if (localConnection) await localConnection.end();
    if (ssh) ssh.end();
  }
}

// Run the import only if this is the main module
if (require.main === module) {
  main().catch(error => {
    console.error('Unhandled error in main process:', error);
    process.exit(1);
  });
}

// Export the functions needed by the route
module.exports = {
  main,
  outputProgress,
  cancelImport
};