export function GetNumber(value: any, defaultValue: number = 0): number {
    return (value == undefined || value == null || isNaN(value)) ? defaultValue : Number(value);
}

export function IsNull(value: unknown): boolean {
    // return value === null || typeof value === 'undefined';
    return value === null || value === undefined;
}

export function IsNotNull(value: unknown): boolean {
    return !IsNull(value);
}


/**
* Returns age as a human-readable string in years, months, weeks and days.
* E.g. "10 years, 5 months, 1 week, 2 days".
* If DOB is in the future or invalid, returns "0 days".
*
* @param DOB           Date or parsable date-string of birth
* @param referenceDate Date to calculate age against (default: now)
*/
export function GetAgeString(
  DOB: Date | string,
  referenceDate: Date = new Date()
): string {
  // 1) Parse & validate DOB
  const birthDate = DOB instanceof Date
    ? new Date(DOB.getTime())
    : new Date(DOB);
  if (isNaN(birthDate.getTime())) {
    // invalid date
    return '0 days';
  }
 
  // 2) Normalize both dates to UTC midnight (avoid DST/timezone issues)
  function toUtcMidnight(d: Date) {
    return new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
  }
  const start = toUtcMidnight(birthDate);
  const end   = toUtcMidnight(referenceDate);
 
  // 3) Prevent negative intervals
  if (start > end) {
    return '0 days';
  }
 
  // 4) Calculate full years
  let years = end.getUTCFullYear() - start.getUTCFullYear();
  // “Anniversary” = birthday + years
  let anniversary = new Date(Date.UTC(
    start.getUTCFullYear() + years,
    start.getUTCMonth(),
    start.getUTCDate()
  ));
  if (anniversary > end) {
    years--;
    anniversary = new Date(Date.UTC(
      start.getUTCFullYear() + years,
      start.getUTCMonth(),
      start.getUTCDate()
    ));
  }
 
  // 5) Calculate full months since last anniversary
  let temp = new Date(anniversary);
  let months = 0;
  while (true) {
    const next = new Date(Date.UTC(
      temp.getUTCFullYear(),
      temp.getUTCMonth() + 1,
      temp.getUTCDate()
    ));
    if (next <= end) {
      months++;
      temp = next;
    } else {
      break;
    }
  }
 
  // 6) Calculate remaining days → weeks + days
  const msPerDay = 24 * 60 * 60 * 1000;
  const daysTotal = Math.floor((end.getTime() - temp.getTime()) / msPerDay);
  const weeks = Math.floor(daysTotal / 7);
  const days = daysTotal % 7;
 
  // 7) Build the output, skipping zero-valued units
  const parts: string[] = [];
  if (years)  parts.push(`${years} year${years > 1 ? 's' : ''}`);
  if (months) parts.push(`${months} month${months > 1 ? 's' : ''}`);
  if (weeks)  parts.push(`${weeks} week${weeks > 1 ? 's' : ''}`);
  if (days)   parts.push(`${days} day${days > 1 ? 's' : ''}`);
 
  // 8) Fallback
  if (parts.length === 0) {
    return '0 days';
  }
 
  return parts.join(', ');
}