R/cran-versions.R

In ErdaradunGaztea/woodendesc: Find Packages and Their Dependencies in Any 'R' Repository

#' Get all package versions on CRAN
#'
#' @description This function queries CRAN for the codes of all available
#' package versions, both current and archived, for a given package.
#'
#' @template package
#'
#' @return A character vector of version codes.
#'
#' @examplesIf !woodendesc:::is_cran_check()
#' wood_cran_versions("versionsort")
#'
#' @family cran
#' @family versions
#' @export
wood_cran_versions <- function(package) {
  assert_param_package(package)

  cran_versions_cache(package)
}

cran_versions_cache <- function(package) {
  cache_file <- cache_path("versions", "CRAN", package)

  # Return usable cache if exists
  if (is_cache_usable(cache_file)) {
    return(readRDS(cache_file))
  }

  # Return "expired" cache if no new version was published in the meantime
  if (file.exists(cache_file)) {
    version_codes <- readRDS(cache_file)
    if (versionsort::ver_latest(version_codes) == wood_cran_latest(package)) {
      return(version_codes)
    }
  }

  # Download new data and cache it
  desc <- rlang::try_fetch({
    httr2::request("http://crandb.r-pkg.org") |>
      httr2::req_url_path_append("-", "allall") |>
      httr2::req_url_query(start_key = sprintf("\"%s\"", package), limit = 1) |>
      httr2::req_perform() |>
      httr2::resp_body_json()
  }, httr2_http_404 = function(cnd) {
    rlang::abort(
      sprintf("Can't find package `%1$s` on CRAN.", package, version),
      parent = cnd
    )
  })

  validate_cran_package(package, desc)

  # Extract all cacheable data
  versions <- desc[[package]][["versions"]]
  version_codes <- names(versions)
  latest <- desc[[package]][["latest"]]

  # Save cache
  saveRDS(versions, cache_path("descriptions", "CRAN", package))
  saveRDS(version_codes, cache_file)
  saveRDS(latest, cache_path("latest", "CRAN", package))

  # Return value
  version_codes
}