R/ct_build_request.R

In ChrisMuir/comtradr: Interface with the United Nations Comtrade API

#' Build a valid request object from the checked parameters
#'
#' This is an internal function takes the necessary parameters
#' from `ct_check_params()` and creates a httr2 request to be performed.
#' This request can then be used in a second function, `ct_perform_request()`
#' to actually return the data. It is called internally ct `ct_get_data()` and
#' `ct_get_bulk`.
#'
#' @param params a named vector of parameters for the comtrade request,
#' result from `ct_check_params()`.
#'
#' @noRd
#' @returns a httr2 request object
#' @inheritParams ct_get_data
ct_build_request <- function(params,
                             primary_token = NULL,
                             file_hash = NA,
                             reporter_code = NA,
                             verbose = FALSE,
                             bulk) {
  ## if the file_hash is missing we know that this is about the standard API
  if(is.na(file_hash)){
    query_params <- params$query_params

    extra_params <- params$extra_params |>
      purrr::map(unlist) |>
      purrr::pluck(1) |>
      as.list()
    query_params <- c(query_params, extra_params)
    type <- params$url_params$type

    freq <- params$url_params$freq

    clCode <- params$url_params$clCode

    if(bulk){
      base_url <- "https://comtradeapi.un.org/bulk/v1/get/"
    } else {
      base_url <- "https://comtradeapi.un.org/data/v1/get/"
    }

    req <-
      httr2::request(base_url) |>
      httr2::req_url_path_append(type) |>
      httr2::req_url_path_append(freq) |>
      httr2::req_url_path_append(clCode) |>
      httr2::req_headers(`Ocp-Apim-Subscription-Key` = primary_token) |>
      httr2::req_url_query(!!!query_params)

    if (stringr::str_length(req$url) > 4095) {
      rlang::abort("Your request exceeds 4KB or 4096 characters, which is the upper limit of the Comtrade API.") # nolint
    }

    if (verbose) {
      cli::cli_inform(c("i" = paste0("URL that will be queried: ", req$url)))
    }

  } else {
    ## in this case here we are constructing a special request for a bulk file
    req <- httr2::request("https://comtradeapi.un.org/bulk/v1/file/") |>
      httr2::req_url_path_append(list(reporter_code, file_hash)) |>
      httr2::req_url_query(format = "json") |>
      httr2::req_headers(`Ocp-Apim-Subscription-Key` = primary_token)

    if (stringr::str_length(req$url) > 4095) {
      rlang::abort("Your request exceeds 4KB or 4096 characters, which is the upper limit of the Comtrade API.") # nolint
    }
  }


  return(req)
}