.diff(other: FduInstance, unit?: UnitType): number

import { fdu } from '@pyyupsk/fdu';

const date1 = fdu('2024-01-15');
const date2 = fdu('2024-01-20');

// Days
date1.diff(date2, 'day');     // -5
date2.diff(date1, 'day');     // 5

// Default (milliseconds)
date1.diff(date2);            // -432000000

const start = fdu('2024-01-01');
const end = fdu('2024-03-15');

end.diff(start, 'year');      // 0 (less than a year)
end.diff(start, 'month');     // 2 (2 months and 14 days)
end.diff(start, 'week');      // 10 (10 full weeks)
end.diff(start, 'day');       // 74

const morning = fdu('2024-01-15T09:00:00');
const afternoon = fdu('2024-01-15T14:30:00');

afternoon.diff(morning, 'hour');      // 5
afternoon.diff(morning, 'minute');    // 330 (5.5 hours = 330 minutes)
afternoon.diff(morning, 'second');    // 19800

const date1 = fdu('2024-01-15');
const date2 = fdu('2025-01-10');

// Year difference (calendar years)
date2.diff(date1, 'year');    // 1 (different calendar years)

const date3 = fdu('2024-01-15');
const date4 = fdu('2024-03-20');

// Month difference (calendar months)
date4.diff(date3, 'month');   // 2 (from January to March)

const birthdate = fdu('1990-05-15');
const today = fdu();

const age = today.diff(birthdate, 'year');
console.log(`Age: ${age} years`);

const event = fdu('2024-12-25');
const now = fdu();

const daysUntil = event.diff(now, 'day');
console.log(`${daysUntil} days until Christmas`);

const start = fdu('2024-01-15T09:00:00');
const end = fdu('2024-01-15T14:30:45');

const hours = end.diff(start, 'hour');
const minutes = end.diff(start, 'minute');
const seconds = end.diff(start, 'second');

console.log(`Elapsed: ${hours}h ${minutes % 60}m ${seconds % 60}s`);
// Elapsed: 5h 30m 45s

function formatDuration(start: FduInstance, end: FduInstance): string {
  const days = end.diff(start, 'day');
  const hours = end.diff(start, 'hour') % 24;
  const minutes = end.diff(start, 'minute') % 60;

  return `${days}d ${hours}h ${minutes}m`;
}

const start = fdu('2024-01-15T09:00:00');
const end = fdu('2024-01-17T14:30:00');

formatDuration(start, end);  // '2d 5h 30m'

function getRelativeTime(date: FduInstance): string {
  const now = fdu();
  const diffMinutes = now.diff(date, 'minute');

  if (diffMinutes < 1) return 'just now';
  if (diffMinutes < 60) return `${diffMinutes} minutes ago`;

  const diffHours = now.diff(date, 'hour');
  if (diffHours < 24) return `${diffHours} hours ago`;

  const diffDays = now.diff(date, 'day');
  if (diffDays < 7) return `${diffDays} days ago`;

  const diffWeeks = now.diff(date, 'week');
  if (diffWeeks < 4) return `${diffWeeks} weeks ago`;

  const diffMonths = now.diff(date, 'month');
  return `${diffMonths} months ago`;
}

const pastDate = fdu('2024-01-10');
getRelativeTime(pastDate);  // e.g., '5 days ago'

const deadline = fdu('2024-12-31');
const now = fdu();

const daysRemaining = deadline.diff(now, 'day');

if (daysRemaining < 0) {
  console.log(`Overdue by ${Math.abs(daysRemaining)} days`);
} else if (daysRemaining < 7) {
  console.log(`Urgent: ${daysRemaining} days remaining`);
} else {
  console.log(`${daysRemaining} days until deadline`);
}

const clockIn = fdu('2024-01-15T09:00:00');
const clockOut = fdu('2024-01-15T17:30:00');

const hoursWorked = clockOut.diff(clockIn, 'hour');
const minutesWorked = clockOut.diff(clockIn, 'minute') % 60;

console.log(`Worked: ${hoursWorked} hours ${minutesWorked} minutes`);
// Worked: 8 hours 30 minutes

const subscriptionStart = fdu('2023-01-15');
const now = fdu();

const monthsSubscribed = now.diff(subscriptionStart, 'month');
const daysSubscribed = now.diff(subscriptionStart, 'day');

console.log(`Subscribed for ${monthsSubscribed} months (${daysSubscribed} days)`);

const date1 = fdu('2023-12-31');
const date2 = fdu('2024-01-01');

date2.diff(date1, 'year');   // 1 (different calendar years)
date2.diff(date1, 'day');    // 1 (actual days)