using_type_guards.ts

class Invoice {
  public amount: number;
  public description: string;
  country: string;
}

class SalesInvoices extends Invoice {
  products: Array<string> = [];
}

class PurchaseInvoice extends Invoice {
  tax: number;
}

const invoicesToProcess: Array<Invoice> = [];

function createInvoice(
  description: string | number,
  amount: number,
  country
): Invoice {
  const descriptionValue =
    typeof description === "number" ? `${description}` : description;
  return {
    description: descriptionValue,
    amount,
    country,
  };
}

const invoiceWithNumber = createInvoice(1231321, 120, "ES");
const invoIceWithString = createInvoice("Bananana", 90, "USA");

console.log(invoIceWithString, invoiceWithNumber);
console.clear();
const salesInvoice = new SalesInvoices();
salesInvoice.amount = 130;
salesInvoice.country = "ES";

const basicInvoice = new Invoice();
basicInvoice.amount = 90;
basicInvoice.country = "USA";

function addInvoiceToProcess(invoice: Invoice) {
  if (invoice instanceof SalesInvoices) {
    invoicesToProcess.push(invoice);
  }
}

addInvoiceToProcess(basicInvoice);
addInvoiceToProcess(salesInvoice);

console.log(invoicesToProcess);
console.clear();

interface ValidInvoice {}

function isValidInvoice(invoice: Invoice): invoice is SalesInvoices {
  return invoice.amount > 100 && invoice.country === "ES";
}

invoicesToProcess.forEach((invoice) => {
  if (isValidInvoice(invoice)) {
    console.log(invoice);
  }
});