Create Billing Meter

//native

/**

 * Create Billing Meter

 * Create a billing meter for usage-based prices. Meter events with `event_name` are aggregated by `aggregation_formula`; `value_payload_key` names the payload field holding the value (default `value`) and `customer_payload_key` the one holding the customer id (default `stripe_customer_id`).

 */

export async function main(

  auth: RT.Stripe,

  display_name: string,

  event_name: string,

  aggregation_formula: "count" | "sum" | "last",

  value_payload_key: string | undefined,

  customer_payload_key: string | undefined,

  event_time_window: "day" | "hour" | undefined

) {

  const response = await fetch(`https://api.stripe.com/v1/billing/meters`, {

    method: "POST",

    headers: {

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

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

      Accept: "application/json",

      "Stripe-Version": "2025-03-31.basil",

    },

    body: toForm({

      display_name,

      event_name,

      default_aggregation: { formula: aggregation_formula },

      value_settings: { event_payload_key: value_payload_key },

      customer_mapping: customer_payload_key

        ? { type: "by_id", event_payload_key: customer_payload_key }

        : undefined,

      event_time_window,

    }),

  })

  if (!response.ok) {

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

  }

  return await response.json()

}

// Stripe takes form-encoded params with bracketed nesting: metadata[key]=v, items[0][price]=p

function toForm(

  params: { [key: string]: any },

  prefix = "",

  out = new URLSearchParams()

) {

  for (const [key, value] of Object.entries(params)) {

    if (value == null || value === "") continue

    const name = prefix ? `${prefix}[${key}]` : key

    if (typeof value === "object") toForm(value, name, out)

    else out.append(name, String(value))

  }

  return out

}