(defun wg-workgroup-kill-saved-wconfig (workgroup wconfig-or-name)

  "Delete WCONFIG-OR-NAME from WORKGROUP's saved wconfigs.

WCONFIG-OR-NAME is resolved with `wg-workgroup-get-saved-wconfig'."

  (wg-when-let ((wconfig (wg-workgroup-get-saved-wconfig

                          workgroup wconfig-or-name)))

    (wg-asetf (wg-workgroup-saved-wconfigs workgroup) (remq wconfig it)

              (wg-workgroup-modified workgroup) t)))

;;; garbage collection

;; update buf list

(defun wg-update-buffer-in-buf-list (&optional buffer)

  "Update BUFFER's corresponding buf in `wg-buf-list'.

BUFFER nil defaults to `current-buffer'."

  (let ((buffer (or buffer (current-buffer))))

    (wg-when-let ((uid (wg-buffer-uid buffer))

                  (old-buf (wg-find-buf-by-uid uid))

                  (new-buf (wg-buffer-to-buf buffer)))

      (setf (wg-buf-uid new-buf) (wg-buf-uid old-buf))

      (wg-asetf (wg-buf-list) (cons new-buf (remove old-buf it))))))

(defun wg-update-buf-list (&optional buffer-list)

  "Update all bufs in `wg-buf-list' corresponding to buffers in BUFFER-LIST."

  (mapc 'wg-update-buffer-in-buf-list (or buffer-list (buffer-list))))

;; gc buf uids

(defun wg-workgroup-gc-buf-uids (workgroup)

  "Remove buf uids from WORKGROUP that have no referent in `wg-buf-list'."

  (wg-asetf (wg-workgroup-strong-buf-uids workgroup)

            (cl-remove-if-not 'wg-find-buf-by-uid it)

            (wg-workgroup-weak-buf-uids workgroup)

            (cl-remove-if-not 'wg-find-buf-by-uid it)))

(defun wg-gc-buf-uids ()

  "Remove from all workgroups those buf uids that have no referent in `wg-buf-list'."

  (mapc 'wg-workgroup-gc-buf-uids (wg-workgroup-list)))

;; gc bufs

(defun wg-wtree-buf-uids (wtree)

  (wg-flatten-wtree wtree 'wg-win-buf-uid))

(defun wg-wtree-unique-buf-uids (wtree)

  (cl-remove-duplicates (wg-wtree-buf-uids wtree) :test 'string=))

(defun wg-wconfig-buf-uids (wconfig)

  "Return WCONFIG's wtree's `wg-wtree-buf-uids'."

  (wg-wtree-unique-buf-uids (wg-wconfig-wtree wconfig)))

(defun wg-workgroup-base-wconfig-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's working wconfig."

  (wg-wconfig-buf-uids (wg-workgroup-base-wconfig workgroup)))

(defun wg-workgroup-saved-wconfigs-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's base wconfig."

  (cl-reduce 'wg-string-list-union

          (wg-workgroup-saved-wconfigs workgroup)

          :key 'wg-wconfig-buf-uids))

(defun wg-workgroup-all-wconfig-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's wconfigs."

  (cl-union (wg-workgroup-base-wconfig-buf-uids workgroup)

         (wg-workgroup-saved-wconfigs-buf-uids workgroup)

         :test 'string=))

(defun wg-workgroup-all-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP."

  (cl-reduce 'wg-string-list-union

          (list (wg-workgroup-base-wconfig-buf-uids workgroup)

                (wg-workgroup-saved-wconfigs-buf-uids workgroup)

                (if wg-restore-associated-buffers

                    (wg-workgroup-associated-buf-uids workgroup))

                )))

(defun wg-session-all-buf-uids (&optional session)

  "Return a new list of all unique buf uids in SESSION.

SESSION nil defaults to `wg-current-session'."

  (cl-reduce 'wg-string-list-union

          (wg-session-workgroup-list (or session (wg-current-session)))

          :key 'wg-workgroup-all-buf-uids))

(defun wg-buffer-list-all-uids (&optional buffer-list)

  "Return a list of the uids of all buffers in BUFFER-LIST in

which `wg-buffer-uid' is locally bound.

BUFFER-LIST nil defaults to `buffer-list'."

  (delq nil (mapcar 'wg-buffer-uid (or buffer-list (buffer-list)))))

(defun wg-all-buf-uids (&optional session buffer-list)

  "Return the union of `wg-session-all-buf-uids' and `wg-buffer-list-all-uids'."

  (cl-union (wg-session-all-buf-uids session)

         (wg-buffer-list-all-uids buffer-list)

         :test 'string=))

(defun wg-gc-bufs ()

  "gc bufs from `wg-buf-list' that are no longer needed."