R/npi_handle_requests.R

In frankfarach/npi: Access the U.S. National Provider Identifier Registry API

#' Send API requests
#'
#' Sends API requests and stores the responses in a list.
#'
#' @param results A list of query results.
#' @return A list of API results.
#' @noRd
npi_get_results <- function(results = list(), ...) {
  msg <- glue::glue(
    "Requesting records {...$skip}-{...$skip + ...$limit}..."
  )
  rlang::inform("status_pre_request", message = msg)

  result <- npi_get(npi_url(), query = ...)
  append(results, list(result))
}



#' @noRd
calc_results_stats <- function(results, user_n) {
  # Determine how many records were returned and how many are left
  last_n_returned <- ifelse(rlang::is_empty(results),
    0L,
    length(utils::tail(results, 1)[[1]])
  )
  tot_n_returned <- sum(vapply(results, length, integer(1L)))
  n_remaining <- user_n - tot_n_returned

  # Return stats needed for error control and params for the next query
  list(
    last_n_returned = last_n_returned,
    n_remaining = n_remaining,
    params = list(
      skip = tot_n_returned,
      limit = ifelse(
        n_remaining < MAX_N_PER_REQUEST,
        n_remaining,
        MAX_N_PER_REQUEST
      )
    )
  )
}



#' Page API requests
#'
#' Gets the maximum number of records allowed by the API in the fewest number
#' of requests.
#'
#' @param params A list of query parameters.
#' @param user_n A scalar integer representing the maximum number of records
#'   the user requested.
#' @param results A list of request results
#' @return A final list of API results.
#' @noRd
npi_control_requests <- function(params, user_n, results = list()) {
  result_stats <- calc_results_stats(results = results, user_n = user_n)

  # Avoid an endless loop when the API returns no records
  if (!rlang::is_empty(results) && result_stats[["last_n_returned"]] == 0L) {
    return(tibble::tibble())
  }

  # Return `results` when either (1) we have `user_n` number of records, or
  # (2) there were some records in the last result but not the max possible.
  if (result_stats[["n_remaining"]] == 0L ||
    (result_stats[["last_n_returned"]] > 0L &&
      result_stats[["last_n_returned"]] < MAX_N_PER_REQUEST)) {
    return(results)
  }

  query <- utils::modifyList(params, result_stats[["params"]])
  results <- npi_get_results(results = results, query = query)
  Sys.sleep(1.5)
  npi_control_requests(params = params, user_n = user_n, results = results)
}