sparebank1_actual_budget_integration/src/bank/sparebank1Api.ts

import { BANK_OAUTH_CLIENT_ID, BANK_OAUTH_CLIENT_SECRET } from "../../config.ts"
import { OAuthTokenResponse } from "@/bank/sparebank1.ts"
import logger from "@/logger.ts"

const baseUrl = "https://api.sparebank1.no"

type Success<T> = { status: "success"; data: T }
type Failure<T> = { status: "failure"; data: T }
type Result<OK, Err> = Success<OK> | Failure<Err>

function success<T>(data: T): Success<T> {
  return { status: "success", data: data }
}

function failure<T>(data: T): Failure<T> {
  return { status: "failure", data: data }
}

export async function refreshToken(
  refreshToken: string,
): Promise<Result<OAuthTokenResponse, string>> {
  const queries = new URLSearchParams({
    client_id: BANK_OAUTH_CLIENT_ID,
    client_secret: BANK_OAUTH_CLIENT_SECRET,
    refresh_token: refreshToken,
    grant_type: "refresh_token",
  })
  const url = `${baseUrl}/oauth/token?${queries}`
  logger.debug("Sending POST request to url: '%s'", url)
  const response = await fetch(url, {
    method: "post",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
    },
  })
  logger.debug(`Received response with status '${response.status}'`)
  if (!response.ok) {
    return failure(await response.text())
  }
  return success(await response.json())
}