;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/meta.el

(require 'cl-lib)

(defun meta--count-list (l)
  (cl-loop
    with res
    with done
    for e in l
    do (unless (member e done)
         (push (list (cl-count e l :test #'equal) e) res)
         (push e done))
    finally return (cl-sort res #'>= :key #'car)))

(defun meta--result-list (l)
  (cl-loop
    with biggest = (length (number-to-string (caar l)))
    with num-len = (length (number-to-string (length l)))
    with longest = (apply #'max (cl-mapcar (lambda (e) (length (cadr e))) l))
    for (n lib) in l
    for i from 1
    for str = (concat str
                (format (concat (format "%%%dd. " num-len)
                                (format "%%-%ds " longest)
                                (format "%%%dd"   biggest)
                                "\n")
                        i lib n))
    finally (insert "\n" str)))

(defun meta--funs (&optional n pred label)
  (or n (setq n 20))
  (or pred (setq pred #'functionp))
  (or label (setq label (symbol-name pred)))
  (let ((num 0)
        (libs)
        (str)
        (dash)
        (par))
    (mapatoms (lambda (e) (when (funcall pred e)
                            (setq str  (symbol-name e))
                            (setq dash (string-match "-" str))
                            (setq par  (string-match "(" str))
                            (unless par
                              (cl-incf num)
                              (when dash
                                (push (substring str 0 dash) libs))))))
    (with-help-window "*meta*"
      (insert (format "%s: %d\n" label num))
      (let* ((clst (meta--count-list libs))
             (len  (length clst)))
        (meta--result-list (cl-subseq clst 0 (min n (1- len))))))))

;; (meta--funs   10 nil "functions")
;; (meta--funs  nil nil "functions")
;; (meta--funs  100 nil "functions")
;; (meta--funs 1000 nil "functions")

;; (meta--funs   10 #'boundp "variables")
;; (meta--funs  nil #'boundp "variables")
;; (meta--funs  100 #'boundp "variables")
;; (meta--funs 1000 #'boundp "variables")

;; (meta--funs   10 #'facep "faces")
;; (meta--funs  nil #'facep "faces")
;; (meta--funs  100 #'facep "faces")
;; (meta--funs 1000 #'facep "faces")

(provide 'meta)