import { timingSafeEqual } from "node:crypto";
import { NextResponse } from "next/server";
import { getPayload } from "payload";
import config from "@payload-config";
import { createMeetingToken } from "@/lib/meeting/token";
import { canJoinMeeting, combineDateAndTime, getMeetingStatus } from "@/lib/meeting/status";

export const dynamic = "force-dynamic";

function safeEqual(a: string, b: string): boolean {
  const bufA = Buffer.from(a);
  const bufB = Buffer.from(b);
  if (bufA.length !== bufB.length) return false;
  return timingSafeEqual(bufA, bufB);
}

type Args = { params: Promise<{ slug: string }> };

export async function POST(request: Request, { params }: Args) {
  const { slug } = await params;

  let body: { name?: unknown; password?: unknown };
  try {
    body = await request.json();
  } catch {
    return NextResponse.json({ error: "Ungültige Anfrage." }, { status: 400 });
  }

  const name = typeof body.name === "string" ? body.name.trim() : "";
  const password = typeof body.password === "string" ? body.password.trim() : "";
  if (!name) {
    return NextResponse.json({ error: "Bitte gib deinen Namen ein." }, { status: 400 });
  }

  try {
    const payload = await getPayload({ config });

    const { docs } = await payload.find({
      collection: "events",
      where: { slug: { equals: slug } },
      limit: 1,
    });
    const event = docs[0];
    if (!event || !event.isOnline) {
      return NextResponse.json({ error: "Dieser Online-Termin wurde nicht gefunden." }, { status: 404 });
    }

    const { user } = await payload.auth({ headers: request.headers });
    const isHost = Boolean(user);

    if (!isHost) {
      if (!password) {
        return NextResponse.json({ error: "Bitte gib das Meeting-Passwort ein." }, { status: 400 });
      }
      if (!event.meetingPassword || !safeEqual(password, event.meetingPassword)) {
        return NextResponse.json({ error: "Das Meeting-Passwort ist nicht korrekt." }, { status: 401 });
      }
    }

    const settings = await payload.findGlobal({ slug: "meeting-settings" });
    const start = combineDateAndTime(event.date, event.startTime);
    const end = event.endTime
      ? combineDateAndTime(event.date, event.endTime)
      : new Date(start.getTime() + 60 * 60_000);

    const status = getMeetingStatus({
      start,
      end,
      joinWindowMinutes: isHost ? settings.hostJoinWindowMinutes : settings.participantJoinWindowMinutes,
      closeAfterMinutes: settings.meetingCloseAfterMinutes,
    });

    if (!canJoinMeeting(status)) {
      const message =
        status === "scheduled"
          ? "Dieser Termin ist noch nicht offen. Bitte versuche es näher am Beginn erneut."
          : "Dieser Termin ist bereits beendet.";
      return NextResponse.json({ error: message }, { status: 403 });
    }

    const { token, participantId } = createMeetingToken({
      eventSlug: slug,
      name,
      role: isHost ? "host" : "participant",
    });

    return NextResponse.json({
      token,
      participantId,
      role: isHost ? "host" : "participant",
      eventTitle: event.title,
    });
  } catch (error) {
    console.error("meeting join failed", error);
    return NextResponse.json({ error: "Der Beitritt ist gerade nicht möglich. Bitte versuche es später erneut." }, { status: 500 });
  }
}