export function cx(...classes: Array<string | false | null | undefined>): string {
  return classes.filter(Boolean).join(" ");
}

export function formatDateTime(value?: string | null): string {
  if (!value) return "-";
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return value;
  return date.toLocaleString(undefined, {
    month: "short",
    day: "numeric",
    hour: "2-digit",
    minute: "2-digit",
  });
}

export function makeLocalId(prefix = "local"): string {
  return `${prefix}-${Date.now()}-${Math.random().toString(16).slice(2)}`;
}

export function uniqueById<T extends { id: string }>(items: T[]): T[] {
  const seen = new Set<string>();
  return items.filter((item) => {
    if (seen.has(item.id)) return false;
    seen.add(item.id);
    return true;
  });
}

export function compactQuestions(questions: string[]): string[] {
  return questions.map((q) => q.trim()).filter(Boolean);
}