import type { TZDate } from "@date-fns/tz";
import { format, isSameYear } from "date-fns";

export function formatSize(bytes: number): string {
  const units = ["byte", "kilobyte", "megabyte", "gigabyte", "terabyte"];

  const unitIndex = Math.max(
    0,
    Math.min(Math.floor(Math.log(bytes) / Math.log(1024)), units.length - 1),
  );

  return Intl.NumberFormat("en-US", {
    style: "unit",
    unit: units[unitIndex],
  }).format(+Math.round(bytes / 1024 ** unitIndex));
}

export function formatHoursMinutes(seconds: number) {
  const hours = Math.floor(seconds / 3600);
  const minutes = Math.floor((seconds % 3600) / 60);

  if (hours && minutes) {
    return `${hours}h ${minutes}m`;
  }

  if (hours) {
    return `${hours}h`;
  }

  if (minutes) {
    return `${minutes}m`;
  }

  return "0m";
}

export function formatDate(date: string, dateFormat?: string | null, checkYear = true) {
  if (checkYear && isSameYear(new Date(), new Date(date))) {
    return format(new Date(date), "MMM d");
  }

  return format(new Date(date), dateFormat ?? "P");
}

export function formatNumber(value: number | undefined): string {
  return Intl.NumberFormat("en-US").format(value ?? 0);
}

export function getInitials(value: string) {
  const formatted = value.toUpperCase().replace(/[\s.-]/g, "");

  if (formatted.split(" ").length > 1) {
    return `${formatted.charAt(0)}${formatted.charAt(1)}`;
  }

  if (value.length > 1) {
    return formatted.charAt(0) + formatted.charAt(1);
  }

  return formatted.charAt(0);
}

export function formatDateRange(dates: TZDate[]): string {
  if (!dates.length) return "";

  const formatFullDate = (date: TZDate) => format(date, "MMM d");
  const formatDay = (date: TZDate) => format(date, "d");

  const startDate = dates[0];
  const endDate = dates[1];

  if (!startDate) return "";

  if (dates.length === 1 || !endDate || startDate.getTime() === endDate.getTime()) {
    return formatFullDate(startDate);
  }

  if (startDate.getMonth() === endDate.getMonth()) {
    // Same month
    return `${format(startDate, "MMM")} ${formatDay(startDate)} - ${formatDay(endDate)}`;
  }
  // Different months
  return `${formatFullDate(startDate)} - ${formatFullDate(endDate)}`;
}

export function formatRelativeTime(date: Date): string {
  const now = new Date();
  const diffInSeconds = Math.floor((now.getTime() - date.getTime()) / 1000);

  if (diffInSeconds < 60) {
    return "just now";
  }

  const intervals = [
    { label: "y", seconds: 31536000 },
    { label: "mo", seconds: 2592000 },
    { label: "d", seconds: 86400 },
    { label: "h", seconds: 3600 },
    { label: "m", seconds: 60 },
  ] as const;

  for (const interval of intervals) {
    const count = Math.floor(diffInSeconds / interval.seconds);
    if (count > 0) {
      return `${count}${interval.label} ago`;
    }
  }

  return "just now";
}