Add hypo-delete-last

This commit changes the workings of the `hypo--collect-url' function to
store the hash of the last uploaded file or snippet. This is then used
by `hypo-delete-last' to delete that same url.

NEWS

@@ -0,0 +1,5 @@
+# -*- mode: org; -*-
+* v0.2.0
+
+  - Add =hypo-delete-last=, which deletes the last posted item of the
+    current session.

hypo.el

@@ -31,10 +31,17 @@
 (autoload 'beginning-of-sexp "thingatpt")
 (autoload 'end-of-sexp "thingatpt")
 
+(defvar hypo--last-post nil
+  "The hash of the last snippet sent to hypo.
+
+Will be used for certain commands that operate on the last thing
+sent to hypo.")
+
 (defun hypo--collect-url ()
   "Collect the returned url."
   (let* ((start (search-forward "\n\n"))
          (end (1- (search-forward "\n"))))
+    (setq hypo--last-post (buffer-substring-no-properties (- end 7) end))
     (copy-region-as-kill start end)))
 
 (defun hypo--collect-and-kill (status)
@@ -96,5 +103,14 @@ STATUS is ignored."
                  (progn (end-of-sexp) (point))
                  filename)))
 
+(defun hypo-delete-last ()
+  "Delete the last thing sent to hypo."
+  (interactive)
+  (unless hypo--last-post (error "Nothing posted this session"))
+  (let ((url-request-method "DELETE"))
+    (url-retrieve (concat "https://ryuslash.org/hypo/" hypo--last-post)
+                  #'ignore)
+    (setq hypo--last-post nil)))
+
 (provide 'hypo)
 ;;; hypo.el ends here