next-learn/dashboard/15-final/app/lib/utils.ts

import { Invoice, Revenue, Customer } from './definitions';

export const formatCurrency = (amount: number) => {
  return (amount / 100).toLocaleString('en-US', {
    style: 'currency',
    currency: 'USD',
  });
};

export const formatDateToLocal = (
  dateStr: string,
  locale: string = 'en-US',
) => {
  const date = new Date(dateStr);
  const options: Intl.DateTimeFormatOptions = {
    day: 'numeric',
    month: 'short',
    year: 'numeric',
  };
  const formatter = new Intl.DateTimeFormat(locale, options);
  return formatter.format(date);
};

export function findLatestInvoices(invoices: Invoice[], customers: Customer[]) {
  // Sort the invoices by date in descending order and take the top 5
  const latestInvoices = [...invoices]
    .sort((a, b) => new Date(b.date).getTime() - new Date(a.date).getTime())
    .slice(0, 5);

  // Find corresponding customers for the latest 5 invoices
  const latestInvoicesWithCustomerInfo = latestInvoices.map((invoice) => {
    const customer = customers.find(
      (customer) => customer.id === invoice.customer_id,
    );

    // Format the amount to USD
    const formattedAmount = invoice.amount.toLocaleString('en-US', {
      style: 'currency',
      currency: 'USD',
    });

    return {
      id: invoice.id,
      name: customer?.name,
      image_url: customer?.image_url,
      email: customer?.email,
      amount: formattedAmount,
    };
  });

  return latestInvoicesWithCustomerInfo;
}

export const calculateInvoicesByStatus = (
  invoices: Invoice[],
  status: 'pending' | 'paid',
) => {
  return invoices
    .filter((invoice) => !status || invoice.status === status)
    .reduce((total, invoice) => total + invoice.amount / 100, 0)
    .toLocaleString('en-US', {
      style: 'currency',
      currency: 'USD',
    });
};

export const calculateCustomerInvoices = (
  invoices: Invoice[],
  status: 'pending' | 'paid',
  customerId: number,
) => {
  return invoices
    .filter((invoice) => invoice.customer_id === customerId)
    .filter((invoice) => !status || invoice.status === status)
    .reduce((total, invoice) => total + invoice.amount / 100, 0)
    .toLocaleString('en-US', {
      style: 'currency',
      currency: 'USD',
    });
};

export const countCustomerInvoices = (
  invoices: Invoice[],
  customerId: number,
) => {
  return invoices.filter((invoice) => invoice.customer_id === customerId)
    .length;
};

export const generateYAxis = (revenue: Revenue[]) => {
  // Calculate what labels we need to display on the y-axis
  // based on highest record and in 1000s
  const yAxisLabels = [];
  const highestRecord = Math.max(...revenue.map((month) => month.revenue));
  const topLabel = Math.ceil(highestRecord / 1000) * 1000;

  for (let i = topLabel; i >= 0; i -= 1000) {
    yAxisLabels.push(`$${i / 1000}K`);
  }

  return { yAxisLabels, topLabel };
};