(defun hangul-syllables-to-jamo (str)
  "Convert HANGUL SYLLABLES characters in STR to their HANGUL JAMO
equivalents."
  (let ((result "")
	(i 0))
    (while (< i (length str))
      (let ((char (aref str i)))
	(if (and (>= char #xAC00) (<= char #xD7A3))
	    ;; Hangul syllable
	    (let* ((code (- char #xAC00))
		   (lead (/ code (* 21 28)))
		   (medial (/ (% code (* 21 28)) 28))
		   (final (% code 28))
		   (lead-jamo (+ #x1100 lead))
		   (medial-jamo (+ #x1161 medial))
		   (final-jamo (if (> final 0) (+ #x11A7 final) nil)))
	      (setq result
		    (concat result (char-to-string lead-jamo)
			    (char-to-string medial-jamo)
			    (if final-jamo (char-to-string final-jamo) ""))))
	  ;; Not a Hangul syllable
	  (setq result (concat result (char-to-string char)))))
      (setq i (1+ i)))
    result))

(defun hangul-convert-region-to-jamo (beg end)
  (interactive "r")
  (replace-region-contents
   beg end (lambda ()
	     (hangul-syllables-to-jamo (buffer-substring (point-min)
							 (point-max))))))

(defun hangul-convert-buffer-to-jamo ()
  (interactive)
  (hangul-convert-region-to-jamo (point-min) (point-max)))

(require 'dash)

(defconst gf-hangul/choseong
  (cl-loop for i from #x1100 to #x1112 collect i))

(defconst gf-hangul/jungseong
  (cl-loop for i from #x1161 to #x1175 collect i))

(defconst gf-hangul/batchim
  (cl-loop for i from #x11a8 to #x11c2 collect i))

(defun gf-hangul/make-pattern (name seq)
  (format "'%s' : pattern Str = #(%s) ;"
	  name (->> seq
		    (--map (concat "\"" it "\""))
		    (-interpose " | ")
		    (apply #'concat))))

(provide 'helpers)