type ProxyType = "port" | "raw" | "server";

export function parseReq(
  url: string, // with base_path removed (url does start with /)
  remember_me?: string // only impacts the key that is returned
): {
  key: string; // used for caching
  type: ProxyType;
  project_id: string; // the uuid of the target project containing the service being proxied
  port_desc: string; // description of port; "" for raw, or a number or "jupyter"
  internal_url: string | undefined; // url at target of thing we are proxying to; this is ONLY set in case type == 'server'.
} {
  if (url[0] != "/") {
    throw Error(`invalid url -- it should start with / but is "${url}"`);
  }
  const v = url.split("/").slice(1);
  const project_id = v[0];
  if (v[1] != "port" && v[1] != "raw" && v[1] != "server") {
    throw Error(
      `invalid type -- "${v[1]}" must be "port", "raw" or "server" in url="${url}"`
    );
  }
  const type: ProxyType = v[1];
  let internal_url: string | undefined = undefined;
  let port_desc: string;
  if (type == "raw") {
    port_desc = "";
  } else if (type === "port") {
    port_desc = v[2];
  } else if (type === "server") {
    port_desc = v[2];
    internal_url = v.slice(3).join("/");
  } else {
    throw Error(`unknown type "${type}"`);
  }
  let key: string = (remember_me ?? "") + project_id + type + port_desc + internal_url;
  return { key, type, project_id, port_desc, internal_url };
}