sale-calculator-strategy/src/SaleCalculator.js

Sales calculation engine

let products = {};
let productTaxes = {};
let taxes = {};
let wholesaleLevels = {};
let settings = {};

/**
 * Sales Calculation Engine (V1)
 * @author softseti 
 * 
 * Core logic for calculating sale totals with support for:
 * - Wholesale pricing levels
 * - Product-specific and general taxes
 * - Deal/discount allocations
 */

// ==============================================
// INITIALIZATION
// ==============================================

/**
 * Initializes the calculator with indexed data
 * @param {Object} params - Data collections:
 *   - products: {id: Product} 
 *   - product_taxes: {product_id: TaxAssociation[]}
 *   - taxes: {id: Tax}
 *   - wholesale_levels: {product_id: WholesaleLevel[]}
 *   - settings: GlobalSettings
 */

function init(params) {
  products = params.products || {};
  productTaxes = params.product_taxes || {};
  taxes = params.taxes || {};
  wholesaleLevels = params.wholesale_levels || {};
  settings = params.settings || {};
}

// ==============================================
// CORE CALCULATION ENGINE (V2 SCOPE)
// ==============================================

function calcTotal(sale) {
  validateSaleStructure(sale);
  sale = preprocessSale(sale);

  return sale.dwSaleProducts.reduce((total, product) => {
    const discount = calcDwSaleProductDiscount(product, sale);
    const productSum = calcDwSaleProductSum(product, sale) - discount; 
    const taxes = getApplicableProductTaxes(product, productSum, sale);
    return total + productSum + taxes;
  }, 0);
}

function preprocessSale(sale) {
  if (sale.dwSaleDeals) {
    sale.dwSaleDeals = sale.dwSaleDeals.map(deal => ({
      ...deal,
      sum: deal.amount * -1 
    }));
  }
  return sale;
}

function calcDwSaleProductSum(saleProduct, sale) {
  const product = products[saleProduct.product_id];
  if (!product) {
    throw new Error(`Product ${saleProduct.product_id} not found`);
  }

  const price = saleProduct.custom_price ?? calcDwSaleProductPrice(saleProduct, sale);
  return (saleProduct.quantity * price) / product.quantity;
}


function calcDwSaleProductPrice(saleProduct, sale) { 
  const product = products[saleProduct.product_id];
  const wholeSaleLevel = getProductWholesaleLevel(saleProduct, sale); 
  return wholeSaleLevel?.price ?? product.original_public_price;
}

function getProductWholesaleLevel(saleProduct, sale) {
  const product = products[saleProduct.product_id];
  const quantity = settings.wholesale_level_quantity_restriction === 'sale'
    ? sumProductQuantity(sale.dwSaleProducts, product.id)
    : saleProduct.quantity;

  const levels = wholesaleLevels[product.id] || [];
  return levels.find(l => 
    quantity >= l.quantity_min && 
    quantity <= l.quantity_max
  ) || null;
}

function calcDwSaleProductDiscount(product, sale) {
  const discount = sale.dwSaleDeals.reduce((total, deal) => total + Math.abs(deal.sum), 0);
  const subtotal = calcSubtotal(sale) + discount;
  const productSum = calcDwSaleProductSum(product, sale);
  const productPercent = (productSum * 100) / subtotal;
  return (productPercent / 100) * discount;
}

function calcSubtotal(sale) {
  const productSum = sale.dwSaleProducts.reduce(
    (sum, saleProduct) => sum + calcDwSaleProductSum(saleProduct, sale), 0);
  const dealsSum = sale.dwSaleDeals.reduce((sum, d) => sum + d.sum, 0);
  return productSum + dealsSum;
}

function getApplicableProductTaxes(saleProduct, productSum, sale) {
  const specificTaxes = getProductSpecificTaxes(saleProduct, sale);
  const generalTaxes = getGeneralTaxes(sale);
  return [...specificTaxes, ...generalTaxes].reduce(
    (total, tax) => total + (productSum * (tax.rate / 100)),
    0
  );
}

function getProductSpecificTaxes(saleProduct, sale) {
  const taxReceiptTypeKey = getTaxReceiptTypeKey(sale.receipt_type_key);
  const associations = productTaxes[saleProduct.product_id] || [];
  const taxMap = {};

  associations.forEach(({ tax_id }) => {
    const tax = taxes[tax_id];
    if (tax && !tax.general && tax[taxReceiptTypeKey]) {
      taxMap[getTaxIndex(tax)] = tax;
    }
  });

  return Object.values(taxMap);
}

function getGeneralTaxes(sale) {
  const taxReceiptTypeKey = getTaxReceiptTypeKey(sale.receipt_type_key);
  return Object.values(taxes).filter(t => 
    t.active && 
    t.general && 
    t[taxReceiptTypeKey]
  );
}

// ==============================================
// HELPERS
// ==============================================

function validateSaleStructure(sale) {
  const required = ['receipt_type_key', 'company_id', 'branch_id', 'dwSaleProducts'];
  if (required.some(field => !sale[field])) {
    throw new Error("Estructura de venta inválida");
  }
  if (Object.keys(products).length === 0) {
    throw new Error("Productos no cargados");
  }
}

function sumProductQuantity(products, productId) {
  return products.filter(p => p.product_id === productId)
    .reduce((sum, p) => sum + p.quantity, 0);
}

function getTaxIndex(tax) {
  return `${tax.abbreviation.toLowerCase()}${tax.rate.toFixed(6).replace('.', '')}`;
}

function getTaxReceiptTypeKey(receiptType) { 
  return receiptType === 'note' ? 'sales_note' : receiptType; 
}

module.exports = {
  init,
  calcTotal,
  _internals: {
    calcDwSaleProductSum,
    calcDwSaleProductDiscount,
    getApplicableProductTaxes
  }
};