;;; fontset/fc-util.el --- functions for parsing ttf charset output from `fc-query'

;; Author: Noah Friedman <friedman@splode.com>
;; Created: 2019-08-06
;; Public domain.

;; $Id: fc-util.el,v 1.1 2019/08/28 02:02:56 friedman Exp $

;;; Commentary:

;; charset from: fc-query /usr/share/fonts/google-noto-emoji/NotoEmoji-Regular.ttf
;;
;; (let ((parsed (fc-parse-charmap "
;; 0000: 00000000 03ff0009 00000000 00000000 00000000 00004201 00000000 00000000
;; 0020: 00000000 10000000 00000200 00000000 00000000 00000000 00000000 00000008
;; 0021: 00000000 02000004 00000000 00000000 03f00000 00000600 00000000 00000000
;; 0023: 0c000000 00000000 00000000 00000000 00000000 00000000 00000000 00091e00
;; 0024: 00000000 00000000 00000000 00000000 00000000 00000000 00000004 00000000
;; 0025: 00000000 00000000 00000000 00000000 00000000 00400c00 00000401 78000000
;; 0026: 20324003 04000000 000fff00 88000169 00080000 60000c03 00104030 242c0400
;; 0027: 00549f24 00180100 00b85090 00000010 00e00000 80010002 00000000 00000000
;; 0029: 00000000 00300000 00000000 00000000 00000000 00000000 00000000 00000000
;; 002b: 180000e0 00000000 00210000 00000000 00000000 00000000 00000000 00000000
;; 0030: 00000000 20010000 00000000 00000000 00000000 00000000 00000000 00000000
;; 0032: 00000000 00000000 00000000 00000000 02800000 00000000 00000000 00000000
;; 00fe: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 80000000
;; 01f0: 00000010 00000000 00000000 00000000 00000000 00000000 00008000 00000000
;; 01f1: 00000000 00000000 00000000 c0030000 07fe4000 00000000 00000000 ffffffc0
;; 01f2: 04000006 07fc8000 00030000 00000000 00000000 00000000 00000000 00000000
;; 01f3: ffffffff ffbf0001 ffffffff 1fffffff 000fffff ffffffff 000007df 0001ffff
;; 01f4: ffffffff 7ffffbff fffffffd ffffffff ffffffff ffffffff ffffffff 1effffff
;; 01f5: ffffffff 3fffffff ffff0000 000000ff 00000000 00000000 00000000 f8000000
;; 01f6: ffffffff ffffffff 0000ffe1 00000000 feffffff ffffffff 0000003f 00000000
;; 0fe4: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00007fe0
;; 0fe8: 00000000 00ffd000 00000000 00000000 00000000 00000000 00000000 00000000")))
;;    (list (fc-make-char-by-plane parsed)
;;          (fc-make-printable-fontset-charmap parsed)))

;;; Code:

(require 'xsd-regexp)

(defun fc-parse-charmap (strblock)
  (mapcar (lambda (row)
            (let ((charset)
                  (i 0))
              (mapc (lambda (n)
                      (let ((j 32))
                        (while (not (zerop j))
                          (unless (zerop (logand n 1))
                            (push i charset))
                          (setq i (1+ i)
                                j (1- j)
                                n (lsh n -1)))))
                (mapcar (lambda (bitmap)
                          (string-to-number bitmap 16))
                        (cdr row)))
              (cons (car row) charset)))

          (mapcar (lambda (line)
                    (let* ((s1 (split-string line ":" t "\\s-+"))
                           (upper (string-to-number (car s1) 16))
                           (bitmaps (split-string (cadr s1) " " t)))
                      (cons upper bitmaps)))
                  (split-string strblock "\n" t "\\s-+"))))

(defun fc-format-range (range)
  (if (consp range)
      (if (= (1+ (car range)) (cdr range))
          (format "%02x %02x" (car range) (cdr range))
        (format "%02x-%02x" (car range) (cdr range)))
    (format "%02x" range)))

(defun fc-make-char-by-plane (parsed)
  (mapconcat 'identity
             (mapcar (lambda (row)
                       (format "%04x: %s"
                               (car row)
                               (mapconcat 'fc-format-range
                                          ;; destructively modifies list, so copy
                                          (xsdre-make-range-list (copy-sequence (cdr row)))
                                          " ")))
                     parsed)
             "\n"))

(defun fc-make-fontset-charmap (parsed)
  (apply 'nconc
         (mapcar (lambda (elt)
                   (xsdre-make-range-list (copy-sequence elt)))
                 (mapcar (lambda (row)
                           (let ((upper (lsh (car row) 8)))
                             (mapcar (lambda (n)
                                       (logior upper n))
                                     (cdr row))))
                         parsed))))

(defun fc-make-printable-fontset-charmap (parsed)
  (with-temp-buffer
    (pp (fc-make-fontset-charmap parsed) (current-buffer))
    (goto-char (point-min))
    (while (re-search-forward "\\([0-9]+\\)" nil t)
      (replace-match (format "#x%02X" (string-to-number (matching-substring 1)))))
    (buffer-string)))

(provide 'fontset/fc-util)

;;; fc-util.el ends here.