stufflog3/frontend/src/lib/utils/date.ts

const weekDay = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"];
const monthNames = ["January","February","March","April","May","June","july","August","September","October","November","December"]

export function formatFormTime(time: Date | string): string {
  if (!time) {
    return "";
  }
  if (!(time instanceof Date)) {
    time = new Date(time);
  }
  if (Number.isNaN(time.getTime()) || time.getTime() < 86400000) {
    return "";
  }

  return `${time.getFullYear()}-${pad(time.getMonth()+1)}-${pad(time.getDate())}T${pad(time.getHours())}:${pad(time.getMinutes())}`;
}

function pad(n:number) {
  return n < 10 ? '0'+n : n.toString()
};

export function formatTime(time: Date | string): string {
  if (!(time instanceof Date)) {
    time = new Date(time);
  }

  return `${pad(time.getHours())}:${pad(time.getMinutes())}`;
}

export function formatDate(time: Date | string | number): string {
  if (!(time instanceof Date)) {
    time = new Date(time);
  }

  return `${time.getFullYear()}-${pad(time.getMonth()+1)}-${pad(time.getDate())}`;
}

export function formatDateTime(time: Date | string | number): string {
  if (!(time instanceof Date)) {
    time = new Date(time);
  }
  
  return `${formatDate(time)} ${formatTime(time)}`
}

export function formatWeekdayDate(time: Date | string | number): string {
  if (!(time instanceof Date)) {
    time = new Date(time);
  }

  return `${time.getFullYear()}-${pad(time.getMonth()+1)}-${pad(time.getDate())} (${weekDay[time.getDay()]})`;
}

export function formatWeekdayTitle(now: Date, time: Date | string | number): string {
  if (!(time instanceof Date)) {
    time = new Date(time);
  }

  const diff = Math.floor((time.getTime() - now.getTime()) / (86400000));
  console.log(diff);
  if (diff === 0) {
    return "Today"
  } else if (diff === -1) {
    return "Yesterday"
  } else if (diff >= -6) {
    return `${weekDay[time.getDay()]}`;
  } else {
    return formatWeekdayDate(time);
  }
}

export function startOfMonth(now: Date, offset = 0): Date {
  return new Date(now.getFullYear(), now.getMonth() + offset);
}

export function startOfYear(now: Date): Date {
  return new Date(now.getFullYear(), 0, 1);
}

export function endOfYear(now: Date): Date {
  return new Date(new Date(now.getFullYear() + 1, 0, 1).getTime() - 60000);
}

export function endOfMonth(now: Date): Date {
  return new Date(nextMonth(now).getTime() - 60000)
}

export function nextYear(now: Date, n?: number): Date {
  return new Date(now.getFullYear() + (n || 1), now.getMonth(), now.getDate(), now.getHours(), now.getMinutes(), now.getSeconds(), now.getMilliseconds());
}

export function lastYear(now: Date): Date {
  return new Date(now.getFullYear() - 1, now.getMonth(), now.getDate(), now.getHours(), now.getMinutes(), now.getSeconds(), now.getMilliseconds());
}

export function nextMonth(now: Date): Date {
  let result: Date;
  if (now.getMonth() == 11) {
      result = new Date(now.getFullYear() + 1, 0, 1);
  } else {
      result = new Date(now.getFullYear(), now.getMonth() + 1, 1);
  }

  return new Date(result.getTime());
}

export function lastMonth(now: Date): Date {
  let result: Date;
  if (now.getMonth() == 0) {
      result = new Date(now.getFullYear() - 1, 11, 1);
  } else {
      result = new Date(now.getFullYear(), now.getMonth() - 1, 1);
  }

  return new Date(result.getTime());
}

export function startOfWeek(now: Date): Date {
  return new Date(now.getTime() - ((now.getTimezoneOffset() * -60000) + ((now.getTime() + (86400000 * 3)) % (86400000 * 7))));
}

export function endOfWeek(now: Date): Date {
  return new Date(startOfWeek(now).getTime() + (86400000 * 6) + (3600000 * 23) + (60000 * 59))
}

export function startOfDay(now: Date): Date {
  return new Date(Math.floor(now.getTime() / 86400000) * 86400000 - (now.getTimezoneOffset() * -60000));
}

export function endOfDay(now: Date): Date {
  return new Date(startOfDay(now).getTime() + (3600000 * 23) + (60000 * 59))
}

export function monthName(date: Date): string {
  return monthNames[date.getMonth()]
}

export function addDays(date: Date, days: number): Date {
  const newDate = new Date(date.getTime());
  newDate.setDate(newDate.getDate() + days);
  return newDate;
}

export function addMonths(date: Date, months: number): Date {
  const newDate = new Date(date.getTime());
  newDate.setMonth(newDate.getMonth() + months);
  return newDate;
}

export function addYears(date: Date, years: number): Date {
  const newDate = new Date(date.getTime());
  newDate.setFullYear(newDate.getFullYear() + years);
  return newDate;
}

export function formatDays(date: Date, now: Date) {
  const d = startOfDay(date);
  const n = startOfDay(now);
  const diff = Math.round((d.getTime() - n.getTime()) / (86400000));

  if (diff === 0) {
    return "today";
  } else if (diff < 7) {
    return `${diff}d`;
  } else {
    return `${Math.floor(diff / 7)}w${Math.floor(diff % 7)}d`;
  }
}

export function formatPrettyTime(date: Date, now: Date) {
  const d = startOfDay(date);
  const n = startOfDay(now);

  const diff = Math.round((d.getTime() - n.getTime()) / (86400000));
  const hhmm = `${pad(date.getHours())}:${pad(date.getMinutes())}`;

  const dayOfMonth = date.getDate();
  var ordinalDay = dayOfMonth + "th";
  if (dayOfMonth == 1) {
    ordinalDay = dayOfMonth + "st";
  } else if (dayOfMonth == 2) {
    ordinalDay = dayOfMonth + "nd"
  } else if (dayOfMonth == 3) {
    ordinalDay = dayOfMonth + "rd"
  }

  if (diff === 0) {
    return `today at ${hhmm}`;
  } else if (diff === 1) {
    return `tomorrow at ${hhmm}`;
  } else if (diff === -1) {
    return `yesterday at ${hhmm}`;
  } else if (diff > -7 && diff < 7) {
    return `${weekDay[date.getDay()]}, the ${ordinalDay} at ${hhmm}`;
  } else {
    return `${ordinalDay} of ${monthName(date)} at ${hhmm}`;
  }
}