feat: ✨ added functions to get R and Rstudio versions

Closes #49 closes #3 closes #1

R/get-versions.R

@@ -0,0 +1,50 @@
+#' Get a list of the allowed R versions for the rostools courses.
+#'
+#' The allowed versions are those that are at maximum a year old from today,
+#' sorted by the oldest first.
+#'
+#' @return A character vector of allowed R versions.
+#' @export
+#'
+#' @examples
+#' get_allowed_r_versions()
+get_allowed_r_versions <- function() {
+  rversions::r_versions() |>
+    dplyr::filter(
+      date >= one_year_ago()
+    ) |>
+    dplyr::pull(version)
+}
+
+#' Get a list of the allowed RStudio versions for the rostools courses.
+#'
+#' The versions are those that are at a maximum one year old from today,
+#' sorted by the oldest first.
+#'
+#' @return A character vector of allowed RStudio versions.
+#' @export
+#'
+#' @examples
+#' get_allowed_rstudio_versions()
+get_allowed_rstudio_versions <- function() {
+  versions <- gh::gh("/repos/:owner/:repo/tags", owner = "rstudio", repo = "rstudio") |>
+    purrr::map_chr("name") |>
+    stringr::str_subset("\\d{4}\\.\\d{2}")
+
+  tibble::tibble(
+    version = versions,
+    date = versions |>
+      stringr::str_extract("\\d{4}\\.\\d{2}") |>
+      stringr::str_c(".01") |>
+      lubridate::as_date()
+  ) |>
+    dplyr::filter(
+      date >= one_year_ago()
+    ) |>
+    dplyr::arrange(date) |>
+    dplyr::pull(version)
+}
+
+one_year_ago <- function() {
+  lubridate::today() - lubridate::years(1)
+}