import { useEffect, useState } from 'react';

export function useRealtimeNow(intervalMs = 1000): number {
  const [now, setNow] = useState(() => Date.now());

  useEffect(() => {
    const timer = window.setInterval(() => {
      setNow(Date.now());
    }, intervalMs);

    return () => window.clearInterval(timer);
  }, [intervalMs]);

  return now;
}

export function formatCountdown(targetIso: string, now = Date.now()): string {
  const diffMs = new Date(targetIso).getTime() - now;
  if (diffMs <= 0) return 'due';

  let remainingSeconds = Math.floor(diffMs / 1000);
  const days = Math.floor(remainingSeconds / 86_400);
  remainingSeconds -= days * 86_400;
  const hours = Math.floor(remainingSeconds / 3_600);
  remainingSeconds -= hours * 3_600;
  const minutes = Math.floor(remainingSeconds / 60);
  const seconds = remainingSeconds - minutes * 60;

  if (days > 0) return `${days}d ${hours}h ${minutes}m ${seconds}s`;
  if (hours > 0) return `${hours}h ${minutes}m ${seconds}s`;
  if (minutes > 0) return `${minutes}m ${seconds}s`;
  return `${seconds}s`;
}

export function formatPastTime(iso: string, now = Date.now()): string {
  const diff = Math.max(0, now - new Date(iso).getTime());
  const minutes = Math.round(diff / 60_000);
  if (minutes < 1) return 'just now';
  if (minutes < 60) return `${minutes}m ago`;
  const hours = Math.round(minutes / 60);
  if (hours < 24) return `${hours}h ago`;
  return `${Math.round(hours / 24)}d ago`;
}