import { escapeRegExp } from '@lendi-ui/commons/utils';

const formatToCurrency = (_value: string) => {
  const decimalSeparator = '.';

  if (_value === '' || _value === undefined) {
    return '';
  }

  const value = decimalSeparator !== '.' ? replaceDecimalSeparator(_value, decimalSeparator) : _value;

  // This is somewhat of an overkill way to do currency formatting,
  // but it covers some interesting edge cases like if there's a decimal number (123.10)
  // and you delete the 123, it will magically replace it with a 0 to ensure proper format (0.10)
  const numberFormatter = new Intl.NumberFormat('en-AU', {
    minimumFractionDigits: 0,
    maximumFractionDigits: 20,
  });

  let formatted = numberFormatter.format(Number(value));

  // Include decimal separator if user input ends with decimal separator
  const includeDecimalSeparator = _value.slice(-1) === decimalSeparator ? decimalSeparator : '';

  const [, decimals] = value.match(RegExp('\\d+\\.(\\d+)')) ?? [];

  // Keep original decimal padding if no decimalScale
  if (decimals && decimalSeparator) {
    if (formatted.includes(decimalSeparator)) {
      formatted = formatted.replace(RegExp(`(\\d+)(${escapeRegExp(decimalSeparator)})(\\d+)`, 'g'), `$1$2${decimals}`);
    } else {
      formatted = `${formatted}${decimalSeparator}${decimals}`;
    }
  }

  return [formatted, includeDecimalSeparator].join('');
};

/**
 * Before converting to Number, decimal separator has to be .
 */
const replaceDecimalSeparator = (value: string, decimalSeparator: '.'): string => {
  let newValue = value;
  if (decimalSeparator && decimalSeparator !== '.') {
    newValue = newValue.replace(RegExp(escapeRegExp(decimalSeparator), 'g'), '.');
  }
  return newValue;
};

export default formatToCurrency;