export function interpolate(
  message: string,
  username: string,
  serverNickname: string | null,
  globalNickname: string | null,
  aliases: string[]
): string {
  const displayName = serverNickname ?? globalNickname ?? username;
  const dt = getNow();

  let result = message
    .replace(/\{username\}/g,        username)
    .replace(/\{server_nickname\}/g,  serverNickname ?? displayName)
    .replace(/\{nickname\}/g,         globalNickname ?? username)
    .replace(/\{alias\[random\]\}/g,  () =>
      aliases.length > 0 ? aliases[Math.floor(Math.random() * aliases.length)] : displayName
    )
    .replace(/\{alias\[(\d+)\]\}/g,   (_, i: string) => aliases[parseInt(i)] ?? displayName)
    .replace(/\{alias\}/g,            aliases[0] ?? displayName)
    .replace(/\{DAY\}/g,   dt.dayName.toUpperCase())
    .replace(/\{Day\}/g,   dt.dayName.charAt(0).toUpperCase() + dt.dayName.slice(1))
    .replace(/\{day\}/g,   dt.dayName)
    .replace(/\{MONTH\}/g, dt.monthName.toUpperCase())
    .replace(/\{Month\}/g, dt.monthName.charAt(0).toUpperCase() + dt.monthName.slice(1))
    .replace(/\{month\}/g, dt.monthName)
    .replace(/\{month_num\}/g, String(dt.monthNum).padStart(2, "0"))
    .replace(/\{date_full\}/g, `${String(dt.dayNum).padStart(2,"0")}-${String(dt.monthNum).padStart(2,"0")}-${dt.yearNum}`)
    .replace(/\{date\}/g,      dt.dateKey)
    .replace(/\{day_num\}/g,   String(dt.dayNum).padStart(2, "0"));

  return resolveEmojiTokens(result);
}