(use-package persp-mode
  :ensure t
  :diminish persp-mode
  
  :init
  (setq wg-morph-on nil ;; switch off animation
        persp-add-buffer-on-after-change-major-mode t
        persp-auto-resume-time -1
        persp-autokill-buffer-on-remove 'kill-weak
        persp-save-dir (expand-file-name "persp-confs/" !/savefile-dir))

  (add-hook 'after-init-hook (lambda () (persp-mode 1)))
  
  :config
  (defvar !//persp-last-selected-perspective persp-nil-name
    "Previously selected perspective.")
  (defun !//persp-save-last-selected-perspective (_ _ &optional _)
    (setq !//persp-last-selected-perspective persp-last-persp-name))
  (advice-add 'persp-activate :before #'!//persp-save-last-selected-perspective))

;; from: https://github.com/Bad-ptr/persp-mode.el/issues/93#issuecomment-392282950
(with-eval-after-load "persp-mode"
  (defvar persp-indirrect-buffers-to-restore nil)
  
  (persp-def-buffer-save/load
   :tag-symbol 'def-indirect-buffer
   :predicate #'buffer-base-buffer
   :save-function
   #'(lambda (buf tag vars)
       (list tag (buffer-name buf) vars
             (buffer-name (buffer-base-buffer))))
   :load-function
   #'(lambda (savelist)
       (destructuring-bind
           (buf-name vars base-buf-name &rest _rest) (cdr savelist)
         (push (cons buf-name base-buf-name)
               persp-indirrect-buffers-to-restore)
         nil)))

  (add-hook 'persp-after-load-state-functions
            #'(lambda (&rest _args)
                (dolist (ibc persp-indirrect-buffers-to-restore)
                  (let* ((nbn (car ibc))
                         (bbn (cdr ibc))
                         (bb (get-buffer bbn)))
                    (when bb
                      (when (get-buffer nbn)
                        (setq nbn (generate-new-buffer-name nbn)))
                      (make-indirect-buffer bb nbn t))))
                (setq persp-indirrect-buffers-to-restore nil))))