Better messaging and logic when installing gathertweet

R/install.R

 install_gathertweet <- function(
   location = "/usr/local/bin"
 ) {
+  only_know_unix()
   if (!dir_exists(location)) {
-    log_fatal("Location {location} does not exist")
+    log_fatal("Location {location} does not exist, please create it and try again.")
   }
   if (!fs::file_access(location, "write")) {
-    log_fatal("You do not have write permissions for {location}")
+    log_fatal("You do not have write permissions for {location}\n",
+              "Try installing gathertweet to a local directory, such as $HOME/.local/bin")
   }
   log_info("Creating link to gathertweet at {location}/gathertweet")
   fs::link_create(
     system.file("gathertweet.R", package = "gathertweet"),
     path(location, "gathertweet")
   )
+  instructions_run_gathertweet(location)
+}
+
+only_know_unix <- function() {
+  if (.Platform$OS.type == "unix") return(invisible(TRUE))
+  msg <- glue::glue(
+    "I'm sorry, but I don't know how to install executable scripts on your ",
+    "platform ({.Platform$OS.type}), so you'll have to do this manually. ",
+    "Copy the gathertweet executable script from the location below ",
+    "to a place where you can run it.\n",
+    "{system.file('gathertweet.R', package='gathertweet')}"
+  )
+  rlang::abort(msg)
+}
+
+instructions_run_gathertweet <- function(location) {
+  which_gathertweet <- tryCatch(
+    system2("which", "gathertweet2", stdout = TRUE),
+    error = function(e) "",
+    warning = function(w) ""
+  )
+  if (which_gathertweet == "") {
+    log_warn("gathertweet may not be installed in a location visible to your system path")
+    log_warn("You may need to fully specify `{location}/gathertweet` to run gathertweet")
+  } else {
+    log_info("You can now call gathertweet from the command line")
+  }
+  log_info("In CRON jobs, use `{location}/gathertweet`")
 }