import { clsx, type ClassValue } from "clsx";
import { twMerge } from "tailwind-merge";

/** Merge conditional class names and resolve Tailwind conflicts. */
export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs));
}

/** Human-readable file size, e.g. 1536 -> "1.5 KB". */
export function formatBytes(bytes: number): string {
  if (!bytes || bytes < 0) return "0 B";
  const units = ["B", "KB", "MB", "GB", "TB"];
  const i = Math.min(
    units.length - 1,
    Math.floor(Math.log(bytes) / Math.log(1024)),
  );
  const value = bytes / Math.pow(1024, i);
  return `${value.toFixed(i === 0 ? 0 : 1)} ${units[i]}`;
}

/** Locale-aware date for the Vietnamese UI, e.g. "2 thg 6, 2026 14:30". */
export function formatDateTime(iso: string): string {
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return "—";
  return new Intl.DateTimeFormat("vi-VN", {
    day: "numeric",
    month: "short",
    year: "numeric",
    hour: "2-digit",
    minute: "2-digit",
  }).format(d);
}

/** Compact relative-ish label used in lists, e.g. "Hôm nay 14:30". */
export function formatDate(iso: string): string {
  const d = new Date(iso);
  if (Number.isNaN(d.getTime())) return "—";
  return new Intl.DateTimeFormat("vi-VN", {
    day: "numeric",
    month: "short",
    year: "numeric",
  }).format(d);
}