Post subscription items

type Stripe = {

  token: string;

};

/**

 * Post subscription items

 * Adds a new item to an existing subscription. No existing items will be changed or replaced.

 */

export async function main(

  auth: Stripe,

  body: {

    billing_thresholds?: { usage_gte: number; [k: string]: unknown } | "";

    expand?: string[];

    metadata?: { [k: string]: string };

    payment_behavior?:

      | "allow_incomplete"

      | "default_incomplete"

      | "error_if_incomplete"

      | "pending_if_incomplete";

    price?: string;

    price_data?: {

      currency: string;

      product: string;

      recurring: {

        interval: "day" | "month" | "week" | "year";

        interval_count?: number;

        [k: string]: unknown;

      };

      tax_behavior?: "exclusive" | "inclusive" | "unspecified";

      unit_amount?: number;

      unit_amount_decimal?: string;

      [k: string]: unknown;

    };

    proration_behavior?: "always_invoice" | "create_prorations" | "none";

    proration_date?: number;

    quantity?: number;

    subscription: string;

    tax_rates?: string[] | "";

  }

) {

  const url = new URL(`https://api.stripe.com/v1/subscription_items`);

  const response = await fetch(url, {

    method: "POST",

    headers: {

      "Content-Type": "application/x-www-form-urlencoded",

      Authorization: "Bearer " + auth.token,

    },

    body: encodeParams(body),

  });

  if (!response.ok) {

    const text = await response.text();

    throw new Error(`${response.status} ${text}`);

  }

  return await response.json();

}

function encodeParams(o: any) {

  function iter(o: any, path: string) {

    if (Array.isArray(o)) {

      o.forEach(function (a) {

        iter(a, path + "[]");

      });

      return;

    }

    if (o !== null && typeof o === "object") {

      Object.keys(o).forEach(function (k) {

        iter(o[k], path + "[" + k + "]");

      });

      return;

    }

    data.push(path + "=" + o);

  }

  const data: string[] = [];

  Object.keys(o).forEach(function (k) {

    if (o[k] !== undefined) {

      iter(o[k], k);

    }

  });

  return new URLSearchParams(data.join("&"));

}