import { NextRequest } from "next/server";
import { prisma } from "@/lib/db";
import { storage } from "@/lib/storage";

export const dynamic = "force-dynamic";

/**
 * Stream an episode's MP3 to anonymous visitors, authorized purely by a valid,
 * still-enabled public `shareId` (NOT a session). Returns 404 when the share is
 * disabled or the audio is missing so we never disclose private episode state.
 *
 * Supports HTTP Range requests so the audio element can seek/scrub.
 */
export async function GET(
  req: NextRequest,
  { params }: { params: Promise<{ shareId: string }> }
) {
  const { shareId } = await params;

  const episode = await prisma.episode.findUnique({
    where: { shareId },
    select: { audioAsset: { select: { storageKey: true } } },
  });
  const key = episode?.audioAsset?.storageKey;
  if (!key) return new Response("Not found", { status: 404 });

  if (!(await storage().exists(key))) return new Response("Not found", { status: 404 });

  const data = await storage().get(key);
  const total = data.byteLength;
  const contentType = "audio/mpeg";

  const range = req.headers.get("range");
  if (range) {
    const match = /bytes=(\d+)-(\d*)/.exec(range);
    if (match) {
      const start = Number(match[1]);
      const end = match[2] ? Math.min(Number(match[2]), total - 1) : total - 1;
      if (start <= end && start < total) {
        const chunk = data.subarray(start, end + 1);
        return new Response(chunk as BodyInit, {
          status: 206,
          headers: {
            "Content-Type": contentType,
            "Content-Length": String(chunk.byteLength),
            "Content-Range": `bytes ${start}-${end}/${total}`,
            "Accept-Ranges": "bytes",
            "Cache-Control": "public, max-age=3600",
          },
        });
      }
    }
  }

  return new Response(data as BodyInit, {
    headers: {
      "Content-Type": contentType,
      "Content-Length": String(total),
      "Accept-Ranges": "bytes",
      "Cache-Control": "public, max-age=3600",
    },
  });
}