/**

 * @param fields *(optional)* A list of fields to return in the response.

 * Reference parameters of sub-objects with dot notation.

 *

 * @param exclude_fields *(optional)* A list of fields to exclude from the response.

 * Reference parameters of sub-objects with dot notation. If both `fields` and `exclude_fields`

 * are present, then only `exclude_fields` will be used.

 */

type Mailchimp = {

  api_key: string;

  server: string;

};

export async function main(

  auth: Mailchimp,

  campaign_id: string,

  fields?: string[],

  exclude_fields?: string[],

) {

  const url = new URL(

    `https://${auth.server}.api.mailchimp.com/3.0/reports/${campaign_id}`,

  );

  const params = {

    fields,

    exclude_fields,

  };

  for (const key in params) {

    const value = params[<keyof typeof params>key];

    if (value?.length) {

      url.searchParams.append(key, value.join(","));

    }

  }

  const response = await fetch(url, {

    method: "GET",

    headers: {

      Authorization: `Bearer ${auth.api_key}`,

    },

  });

  if (!response.ok) {

    throw Error(await response.text());

  }

  return await response.json();

}