import {
  createError,
  defineEventHandler,
  getRouterParam,
  sendStream,
  setHeaders,
} from "h3";
import { dropStore, DropStoreError } from "../../../../utils/drop-store";
import { bearerToken, publicHeaders } from "../../../../utils/http";

export default defineEventHandler(async (event) => {
  publicHeaders(event);
  const token = bearerToken(event);
  if (!token)
    throw createError({
      statusCode: 403,
      statusMessage: "A valid lease is required.",
    });
  const id = String(getRouterParam(event, "id") || "").toUpperCase();
  let handle:
    | Awaited<ReturnType<typeof dropStore.readChunk>>["handle"]
    | undefined;
  let stream:
    | ReturnType<NonNullable<typeof handle>["createReadStream"]>
    | undefined;
  let closed = false;
  const close = async () => {
    if (closed) return;
    closed = true;
    stream?.destroy();
    await handle?.close().catch(() => undefined);
  };
  const abort = () => {
    if (!event.node.res.writableEnded && stream && !stream.destroyed)
      stream.destroy(new Error("Client disconnected."));
    void close();
  };
  try {
    const chunk = await dropStore.readChunk(
      id,
      Number(getRouterParam(event, "index")),
      token,
    );
    handle = chunk.handle;
    stream = handle.createReadStream();
    event.node.res.once("close", abort);
    event.node.res.once("finish", close);
    setHeaders(event, {
      "content-type": "application/octet-stream",
      "content-length": chunk.size,
      "cache-control": "private, no-store",
    });
    return await sendStream(event, stream);
  } catch (error) {
    await close();
    if (error instanceof DropStoreError)
      throw createError({
        statusCode:
          error.code === "expired"
            ? 410
            : error.code === "not-found"
              ? 404
              : 403,
        statusMessage: error.message,
      });
    throw error;
  } finally {
    event.node.res.off("close", abort);
    event.node.res.off("finish", close);
    await close();
  }
});