import { berlinParts, berlinWallTimeToUTC } from "@/lib/calendar/timezone";

export type MeetingStatus = "scheduled" | "open" | "live" | "ended";

/**
 * Payload's "time only" date fields still store a full ISO timestamp, just
 * with an arbitrary date portion — this combines the real event date with
 * the hour/minute from a time-only field into one correct Date.
 */
export function combineDateAndTime(dateISO: string, timeISO?: string | null): Date {
  const date = new Date(dateISO);
  if (!timeISO) return date;
  const time = new Date(timeISO);
  if (Number.isNaN(date.getTime()) || Number.isNaN(time.getTime())) return new Date(NaN);
  const dateParts = berlinParts(date);
  const timeParts = berlinParts(time);
  return berlinWallTimeToUTC(dateParts, timeParts.hour, timeParts.minute);
}

export type MeetingWindow = {
  start: Date;
  end: Date;
  joinWindowMinutes: number;
  closeAfterMinutes: number;
  now?: Date;
};

export function getMeetingStatus({
  start,
  end,
  joinWindowMinutes,
  closeAfterMinutes,
  now = new Date(),
}: MeetingWindow): MeetingStatus {
  const openAt = start.getTime() - joinWindowMinutes * 60_000;
  const closeAt = end.getTime() + closeAfterMinutes * 60_000;
  const t = now.getTime();

  if (t >= closeAt) return "ended";
  if (t >= start.getTime()) return "live";
  if (t >= openAt) return "open";
  return "scheduled";
}

export function canJoinMeeting(status: MeetingStatus): boolean {
  return status === "open" || status === "live";
}

export const statusLabel: Record<MeetingStatus, string> = {
  scheduled: "Online-Termin",
  open: "Termin beginnt bald",
  live: "Jetzt teilnehmen",
  ended: "Termin beendet",
};