Instead of pinging the API, actually make a short request and use it

vermiculus · vermiculus · commit 295d42403962 · 2017-05-14T08:54:55.000-05:00
GET /rate_limit gives us information on how many requests we have
left.  If we're getting low, warn the user.  If there's nothing
left (or the command times out), ask to go offline.
diff --git a/magithub-core.el b/magithub-core.el
@@ -105,23 +105,30 @@ CAR is a time value; CDR is the cached value.")
   "Non-nil if the API is available.
 
 Pings the API a maximum of once every ten seconds."
+  (magithub-debug-message "checking if the API is available")
   (unless (and (not ignore-offline-mode) (magithub-offline-p))
     (if (and (consp magithub--api-available-p)
              (< (time-to-seconds (time-subtract (current-time) (car magithub--api-available-p))) 10))
         (prog1 (cdr magithub--api-available-p)
-          (when magithub-debug-mode
-            (message "used cached value for api-available-p")))
-      (cdr
-       (setq magithub--api-available-p
-             (cons (current-time)
-                   (with-timeout (1 (ignore (when (y-or-n-p "API is not responding quickly; go offline? ")
-                                              (magithub-go-offline))))
-                     (when magithub-debug-mode
-                       (message "pinging GitHub for api-available-p"))
-                     (let ((magit-git-executable "ping")
-                           (magit-pre-call-git-hook nil)
-                           (magit-git-global-arguments nil))
-                       (= 0 (magit-git-exit-code "-c 1" "-n" "api.github.com"))))))))))
+          (magithub-debug-message "used cached value for api-available-p"))
+      (magithub-debug-message "retrieving new value for api-available-p")
+      (let* ((response (with-timeout (magithub-api-timeout :timeout) (ghub-get "/rate_limit")))
+             (remaining (let-alist response .rate.remaining))
+             status go-offline-message)
+        (magithub-debug-message "new value retrieved for api-available-p: %S" response)
+        (cond
+         ((and (numberp remaining) (< 250 remaining)) (setq status t))
+         ((= 0 remaining) (setq go-offline-message "You're bring rate-limited (no more requests left)"))
+         ((numberp remaining) (setq go-offline-message (format "Only %d requests left" remaining)
+                                    status t))
+         ((eq response :timeout) (setq go-offline-message "API is not responding quickly"))
+         (t (setq go-offline-message "Unknown issue with API access")))
+
+        (setq magithub--api-available-p (cons (current-time) status))
+        (when (and go-offline-message
+                   (y-or-n-p (format "%s; go offline? " go-offline-message)))
+          (magithub-go-offline))
+        status))))
 
 (defun magithub--completing-read (prompt collection &optional format-function predicate require-match default)
   "Using PROMPT, get a list of elements in COLLECTION.
