open-in-repo.el

(defun get-repo-url (arg)
  (let* ((remote (if arg "upstream" (nth 2 (s-split "/" (magit-get-tracked-ref)))))
         (remote-url (magit-get "remote" remote "url"))
         (fragments (s-split "[:/@]/?/?" (s-chop-suffix ".git" remote-url))))
    (concat "http://" (s-join "/" (cdr fragments)))))

(defun open-in-repo (arg)
  (interactive "P")
  (let* ((url (get-repo-url arg))
         (branch (if arg "master" (magit-get-current-branch)))
         (file (buffer-file-name (current-buffer)))
         (fragment (if file "blob" "tree"))
         (path (magit-file-relative-name (or file default-directory)))
         (line (if file (concat "#L" (number-to-string (line-number-at-pos))) "")))
    (browse-url (concat (s-join "/" (list url fragment branch path)) line))))