Cloud functions query data based on DateTime

const functions = require('firebase-functions');
const admin = require('firebase-admin');

exports.calculateSalesByDate = functions.https.onCall(async (data, context) => {
  try {
    if (!context.auth.uid) {
      return;
    }

    const shopId = data.shopId;
    const selectedDate = data.selectedDate;
    const firestore = admin.firestore();

    // Query the productRegister collection to get all products and sort by name A-Z. 
    const productRegisterQuery = firestore.collection('productRegister')
      .where('shopId', '==', shopId)
      .orderBy('ProductName', 'asc'); // Sort by name A-Z
    const productRegisterSnapshot = await productRegisterQuery.get();

    const products = [];

    // Use Promise.all to parallelize the fetching of shopStockSnapshot
    await Promise.all(productRegisterSnapshot.docs.map(async (productDoc) => {
      const productData = productDoc.data();
      const productId = "productRegister/" + productDoc.id;
      const productRef = productDoc.ref;

      // Initialize quantities for each product with default values of 0 if null.
      let purchasedQuantity = productData.purchasedQuantity || 0;
      let grandTotalSales = productData.grandTotalSales || 0;

      // Handle null values for blurHash and ProductImage.
      const blurHash = productData.blurHash || 'LyPjx{v%~9P8m.WVb]oe?ETHIqv%';
      const productImage = productData.ProductImage || 'https://firebasestorage.googleapis.com/v0/b/898798768.appspot.com/o/icons/default.png?';

      // Query the "purchasedProducts" subcollection for the current product based on productRef.
      const purchasedProductsQuery = firestore.collectionGroup('purchasedProducts')
        .where('productRef', '==', productRef)
        .where('date', '==', selectedDate)
        .get();

      const purchasedProductsSnapshot = await purchasedProductsQuery;

      // Sum the quantities in purchasedProducts.
      purchasedProductsSnapshot.forEach((productPurchasedDoc) => {
        const productPurchasedData = productPurchasedDoc.data();
        purchasedQuantity += productPurchasedData.quantity;
        grandTotalSales += productPurchasedData.totalPrice;
      });

      // Add the product details along with PurchasePrice,SellingPrice, and availableStockValue to the result array.
      products.push({
        id: productId,
        name: productData.ProductName,
        unit: productData.ProductUnit,
        productId: productData.ProductId,
        blurHash,
        productImage,
        shopId: productData.shopId,
        purchasedQuantity,
        grandTotalSales,
      });
    }));

    // Return the products array as the result.
    return products;
  } catch (error) {
    // Handle any errors that occur during execution.
    console.error('An error occurred:', error);
    throw new functions.https.HttpsError('internal', 'An error occurred.');
  }
});