import { NextRequest } from "next/server";

// Server-side URL of the K-TV backend (never exposed to the browser).
// Falls back to the public URL if the internal one isn't set.
const API_URL =
  process.env.API_URL ??
  process.env.NEXT_PUBLIC_API_URL ??
  "http://localhost:4000/api/v1";

/**
 * GET /api/stream/[channelId]?token=<bearer>
 *
 * Resolves the backend's 307 stream redirect and returns the final
 * Jellyfin URL as JSON. Browsers can't read the Location header from a
 * redirected fetch, so this server-side route does it for them.
 *
 * Returns:
 *   200 { url: string }  — stream URL ready to use as <video src>
 *   204                  — channel is in a gap (no-signal)
 *   401                  — missing token
 *   502                  — backend error
 */
export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ channelId: string }> },
) {
  const { channelId } = await params;
  const token = request.nextUrl.searchParams.get("token");
  const channelPassword = request.nextUrl.searchParams.get("channel_password");
  const blockPassword = request.nextUrl.searchParams.get("block_password");
  const quality = request.nextUrl.searchParams.get("quality");

  let res: Response;
  try {
    const headers: Record<string, string> = {};
    if (token) headers["Authorization"] = `Bearer ${token}`;
    if (channelPassword) headers["X-Channel-Password"] = channelPassword;
    if (blockPassword) headers["X-Block-Password"] = blockPassword;
    const backendParams = new URLSearchParams();
    if (quality) backendParams.set("quality", quality);
    const backendQuery = backendParams.toString() ? `?${backendParams}` : "";
    res = await fetch(`${API_URL}/channels/${channelId}/stream${backendQuery}`, {
      headers,
      redirect: "manual",
    });
  } catch {
    return new Response(null, { status: 502 });
  }

  if (res.status === 204) {
    return new Response(null, { status: 204 });
  }

  if (res.status === 401 || res.status === 403) {
    const body = await res.json().catch(() => ({}));
    return Response.json(body, { status: res.status });
  }

  if (res.status === 307 || res.status === 302 || res.status === 301) {
    const location = res.headers.get("Location");
    if (location) {
      return Response.json({ url: location });
    }
  }

  return new Response(null, { status: 502 });
}