R/exercise.R

In zevross-spatial/rstudio-conf2020-spatial-ex: Exercises and Solutions for Spatial Data with R Workshop (Part 1)

#' Open an exercise
#'
#' Open an exercise file. A new file is created in your working directory unless
#' you specify the `dir` argument.
#'
#' @param number A number specifying which exercise to open.
#'
#' @param overwrite If you want to overwrite the exercise file you already
#'   opened use overwrite = TRUE, default to `FALSE`.
#'
#' @param suffix If you do not want to overwrite your previous exercise file
#'   but want to open another version you can specify text that will get
#'   appended to the filename.
#'
#'   For example, if `suffix` is `"attempt-2"` and `exercise` is 0 the new file
#'   would be `exercise-0-attempt-2.R`.
#'
#' @param dir A character string specifying the directory where the exercise
#'   file will be created, defaults to `getwd()`, the current working directory.
#'
#' @export
open_exercise <- function(number, overwrite = FALSE, suffix = NULL,
                          dir = getwd()) {
  dir_exercises <- system.file("exercises", package = "zrsaSpatialWorkshop")

  exercise_name <- paste("exercise", number, sep = "-")
  exercise_file <- paste0(exercise_name, ".R")

  if (Sys.getenv("RSTUDIO") == 1) {
    editor <- rstudioapi::navigateToFile
  } else {
    editor <- file.edit
  }
  
  
  if (!file.exists(file.path(dir_exercises, exercise_file)) ||
        number < 1 || number > 7) {
    stop(
      "could not find exercise number ", '"', number , '"',
      call. = FALSE
    )
  }

  path_exercise <- file.path(dir_exercises, exercise_file)

  exercise_new <- paste(c(exercise_name, suffix), collapse = "-")
  path_new <- file.path(dir, paste0(exercise_new, ".R"))

  if (file.exists(path_new) && !isTRUE(overwrite)) {
    editor(path_new)
    stop(
      "A file already exists for exercise ", number, ".",
      "\n\n",
      "If you want to overwrite this file please specify `overwrite = TRUE`.",
      "\n\n",
      "If you prefer to create a new exercise file you can specify `suffix`, ",
      "see ?zrsaSpatialWorkshop::open_exercise",
      call. = FALSE
    )
  }

  file.copy(path_exercise, path_new, copy.mode = FALSE, overwrite = TRUE)

  editor(path_new)
}