const getClientLocale = (): string => {
  return navigator.languages.length > 0 ? navigator.languages[0] : "en-US";
};

const getAge = (dateOfBirth: Date): number => {
  const today = new Date();

  const thisYear = today.getFullYear();
  const thisMonth = today.getMonth();
  const thisDay = today.getDate();

  const dobYear = dateOfBirth.getFullYear();
  const dobMonth = dateOfBirth.getMonth();
  const dobDay = dateOfBirth.getDate();

  let age = thisYear - dobYear;

  if (thisMonth < dobMonth) age--;
  if (thisMonth === dobMonth && thisDay < dobDay) age--;

  return age;
};

const toImperial = (cm: number): string => {
  const realFeet = (cm * 0.3937) / 12;
  const feet = Math.floor(realFeet);
  const inches = Math.round((realFeet - feet) * 12);

  return `${feet}'${inches}"`;
};

const toInch = (cm: number): string => {
  return `${Math.round(cm / 2.45)} in`;
};

const toLbs = (kg: number): number => {
  const nearExact = kg / 0.45359237;
  const lbs = Math.floor(nearExact);

  return lbs;
};

const toFahrenheit = (celsius: number): number => {
  return celsius * 1.8 + 32;
};

const dateFormat = new Intl.DateTimeFormat(getClientLocale(), {
  year: "numeric",
  month: "long",
  day: "2-digit",
});

export {
  getClientLocale,
  getAge,
  toImperial,
  toInch,
  toLbs,
  toFahrenheit,
  dateFormat,
};