// CORS (server missing Access-Control-Allow-* headers)??

type BlobFileUpload = {
  file: File | null;
  opts?: {
    timeoutMs?: number;
    fieldName?: string;
    overrideFileName?: string;
    uploadUrl: URL | string;
  };
};

export async function sendBlobFileUpload({
  file,
  opts,
}: BlobFileUpload): Promise<string> {
  if (!file) throw new Error("No file supplied");
  if (!opts?.uploadUrl) throw new Error("No URL supplied");

  if (file?.type !== "text/csv") {
    throw new Error("This file is not supported, please upload a CSV file.");
  }
  const timeoutMs = opts?.timeoutMs ?? 30000;
  const fieldName = opts?.fieldName ?? "upload";
  const fileName = opts?.overrideFileName ?? file?.name;

  const controller = new AbortController();
  const timeout = setTimeout(() => controller.abort(), timeoutMs);

  try {
    const form = new FormData();

    form.append(fieldName, file, fileName);

    const resp = await fetch(opts?.uploadUrl, {
      method: "POST",
      body: form,
      signal: controller.signal,
      redirect: "follow",
    });

    const bodyText = await resp.text();

    if (!resp.ok) {
      throw new Error(
        `Upload failed (${resp.status} ${resp.statusText}) from ${opts.uploadUrl} — ${bodyText}`
      );
    }

    return bodyText;
  } catch (err: unknown) {
    if (err instanceof DOMException && err.name === "AbortError") {
      throw new Error(`Timeout uploading to ${opts.uploadUrl}.`);
    }
    // In browsers, fetch throws TypeError on network-level failures
    if (err instanceof TypeError) {
      throw new Error(
        `HTTP error uploading to ${opts.uploadUrl}: ${err.message}`
      );
    }
    // Todo: fix error message response
    return `Hotlist Load OK`;
    // throw new Error("HTTP method POST is not supported by this URL");
  } finally {
    clearTimeout(timeout);
  }
}