// Supplier product and inventory schema
interface SupplierProduct {
  supplierId: string;
  supplierSku: string;       // supplier's own SKU
  internalProductId: string; // your product ID
  costPriceCents: number;    // what you pay the supplier
  stockQty: number;
  lastSyncedAt: Date;
}

// Route an order line to the best available supplier
async function selectBestSupplier(
  productId: string,
  requiredQty: number
): Promise<SupplierProduct | null> {
  // Pick the cheapest in-stock supplier with enough quantity
  return db.supplierProducts.findOne({
    internal_product_id: productId,
    stock_qty: { gte: requiredQty },
    is_active: true,
  }, { orderBy: ['cost_price_cents', 'asc'] });
}

// Sync supplier inventory from CSV feed
async function syncSupplierInventoryFromCsv(
  supplierId: string,
  csvContent: string
): Promise<void> {
  const rows = parseCsv(csvContent); // [{sku, qty, cost}]
  for (const row of rows) {
    await db.supplierProducts.upsert({
      supplier_id: supplierId,
      supplier_sku: row.sku,
      stock_qty: parseInt(row.qty),
      cost_price_cents: Math.round(parseFloat(row.cost) * 100),
      last_synced_at: new Date(),
    });
  }
  // Zero out SKUs not in the feed (discontinued)
  const activeSKUs = new Set(rows.map(r => r.sku));
  const allProducts = await db.supplierProducts.findBySupplierId(supplierId);
  for (const sp of allProducts) {
    if (!activeSKUs.has(sp.supplier_sku)) {
      await db.supplierProducts.update(sp.id, { stock_qty: 0 });
    }
  }
}

// Submit a dropship order to a supplier API
async function submitDropshipOrder(params: {
  supplierApiEndpoint: string;
  supplierApiKey: string;
  orderReference: string;
  shippingAddress: Address;
  items: { supplierSku: string; quantity: number }[];
}): Promise<string> {
  const response = await fetch(params.supplierApiEndpoint + '/orders', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${params.supplierApiKey}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      reference: params.orderReference,
      ship_to: params.shippingAddress,
      items: params.items,
    }),
  });
  if (!response.ok) throw new Error(`Supplier API error: ${response.status}`);
  const result = await response.json();
  return result.order_id; // supplier's order reference
}