Can window-state-change-hook be considered "buffer ranking" hook?

[Jean Louis <bugs@gnu.support>]

I have made this program to rank my buffers by visiting or switching
to them. Each time I switch to buffer, the buffer rank increases and
menu is generated with those buffers mostly visited, but also saved,
etc.

I am using `window-state-change-hook' to "detect" that buffer is used.

I have not found other hooks to be used, so I am asking here if this
approach may be wrong, maybe I should use some other "signal" or
indication that buffer should be ranked.

I like to rank buffers, though I still do not know if this program
will give me what I need, and I need to adapt it. Basically, I am
switching to some buffers for monitoring purposes, and exactly those
where I switched too often, disappeared from main buffer menu, that is
why I am thinking having separate ranking buffer menu.

Each buffer used, saved, to which attention is brought, that shall get
increased rank, and by rank those 10-20 should be displayed in menu.

Question is if I should use maybe some other indication or hook, to
rank the buffer?

;;; rcd-buffer-rank.el --- RCD Buffer Rank  -*- lexical-binding: t; -*-

;; Copyright (C) 2024 by Jean Louis

;; Author: Jean Louis <bugs@gnu.support>
;; Version: 0.1
;; Package-Requires: (rcd-utilities)
;; Keywords: convenience extensions
;; URL:

;; This file is not part of GNU Emacs.

;; This program is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Change Log:

;;; Code:

(defvar-local rcd-buffer-rank 0
  "Buffer rank variable.")
(put 'rcd-buffer-rank 'permanent-local t)
(setq-default rcd-buffer-rank 0)

(defvar rcd-buffer-rank-hash (make-hash-table)
  "Buffer list with ranks.")

(defvar rcd-buffer-rank-exclude '("*Minibuf"))

(defun rcd-buffer-rank-increase ()
  "Increase the rank of the buffer."
  (let* ((buffer (current-buffer))
	 (buffer-name (buffer-name buffer)))
    (unless (string-match-p (rx "*Minibuf") buffer-name)
      (message "CURRENT:%s" buffer)
      (setq rcd-buffer-rank (1+ rcd-buffer-rank))
      (puthash buffer rcd-buffer-rank rcd-buffer-rank-hash)
      (message "Increased rank to %s" rcd-buffer-rank)
      (rcd-buffer-rank-menu-refresh))))

(defun rcd-buffer-rank-switch-to-buffer (name)
  "Switch to buffer, function used in menu."
  (cond ((buffer-live-p (get-buffer name))
	 (switch-to-buffer name))
	(t (rcd-buffer-rank-menu-refresh))))

(defvar rcd-buffer-rank-maximum 10)

(defun rcd-buffer-rank-menu ()
  "Generate menu."
  (let* ((keys (hash-table-keys rcd-buffer-rank-hash))
	 (menu  (list "Buffer by rank"))
	 (keys (sort keys (lambda (a b)
			    (< (gethash a rcd-buffer-rank-hash) 
			       (gethash b rcd-buffer-rank-hash)))))
	 (keys (reverse keys))
	 (max 0))
    (while (and keys (<= max rcd-buffer-rank-maximum))
      (let* ((key (pop keys))
	     (name (buffer-name key)))
	(setq max (1+ max))
	(cond ((not (buffer-live-p key))
	       (remhash key rcd-buffer-rank-hash))

	      ((and (buffer-live-p key) (not (string-match-p (rx "*Minibuf") name)))
	       (setq menu (append menu `([,name (lambda () (interactive) (switch-to-buffer ,name)) t]))))
	      
	      (t (message "Unexpected")))))
    menu))

(defun rcd-buffer-rank-menu-refresh ()
  "Refresh menu."
  (easy-menu-define buffer-rank-menu global-map "Buffers by rank"
    (rcd-buffer-rank-menu)))

(defun rcd-buffer-rank-start ()
  "Start buffer ranking system."
  (interactive)
  (add-hook 'window-state-change-hook 'rcd-buffer-rank-increase)
  ;; on kill, update menu
  (message "Started `rcd-buffer-rank'."))

(defun rcd-buffer-rank-stop ()
  "Stop the buffer ranking system."
  (interactive)
  (remove-hook 'window-state-change-hook 'rcd-buffer-rank-increase)
  (message "Stopped `rcd-buffer-rank'."))

(provide 'rcd-buffer-rank)

;;; rcd-buffer-rank.el ends here