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org-unique-id.el

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+;;; org-unique-id.el --- Create unique IDs for org headers -*- lexical-binding: t -*-
+
+;; Author: Lucien Cartier-Tilet <lucien@phundrak.com>
+;; Maintainer: Lucien Cartier-Tilet <lucien@phundrak.com>
+;; Version: 0.1
+;; Package-Requires: ((emacs "25.1") (org "9.3"))
+;; Homepage: https://labs.phundrak.com/phundrak/org-unique-id
+;; Keywords: convenience
+
+
+;; 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 <https://www.gnu.org/licenses/>.
+
+
+;;; Commentary:
+
+;; This package is inspired by a blog post I published about a year
+;; before I decided to write this package [1], which in turn is
+;; largely inspired by another blog post [2].
+;;
+;; It will generate a unique ID for each headers in an org file based
+;; on the headers’ name plus a random short string in order to be sure
+;; to make it unique. This ID will be inserted in each header’s
+;; properties as a custom ID.
+;;
+;; [1] https://blog.phundrak.com/better-custom-ids-orgmode/
+;; [2] https://writequit.org/articles/emacs-org-mode-generate-ids.html
+
+;;; Code:
+
+(require 'org-id)
+
+(defgroup org-unique-id ()
+  "Create unique IDs for org headers."
+  :prefix "org-unique-id"
+  :link '(url-link :tag "Gitea" "https://labs.phundrak.com/phundrak/org-unique-id")
+  :link '(url-link :tag "Github" "https://github.com/Phundrak/org-unique-id"))
+
+(defcustom org-unique-id-prefix ""
+  "Prefix for your org IDs."
+  :group 'org-unique-id
+  :type  'string
+  :safe  #'stringp)
+
+(defun org-unique-id--new (&optional prefix)
+  "Create a new globally unique ID.
+
+An ID consists of two parts separated by a colon:
+- a prefix
+- a unique part which will be created according to `org-id-method'.
+
+PREFIX can specify the prefix we want, the default is given by
+the variable `org-unique-id-prefix'."
+  (let* ((prefix (if prefix
+                     prefix
+                   org-unique-id-prefix))
+         (etime (org-reverse-string (org-id-time-to-b36)))
+         (postfix (when org-id-include-domain
+                    (progn
+                      (require 'message)
+                      (concat "@" (message-make-fqdn))))))
+    (concat prefix (car (split-string (concat etime postfix) "-")))))
+
+(defun org-unique-id--get (&optional pom create prefix)
+  "Get the CUSTOM_ID property of the entry at point-or-marker POM.
+
+If POM is nil, refer to the entry at point. If the entry does not
+have an CUSTOM_ID, the function returns nil. However, when CREATE
+is non nil, create a CUSTOM_ID if none is present already. PREFIX
+will be passed through to `org-unique-id--new'. In any case, the
+CUSTOM_ID of the entry is returned."
+  (interactive)
+  (org-with-point-at pom
+    (let* ((orgpath (mapconcat #'identity (org-get-outline-path) "-"))
+           (heading (replace-regexp-in-string
+                     "[_-]+$" ""
+                     (replace-regexp-in-string
+                      "[_-][_-]+" "-"
+                      (replace-regexp-in-string
+                       (rx (or alpha num "-" "_"))
+                       "-"
+                       (if (string= orgpath "")
+                           (org-get-heading t t t t)
+                         (concat orgpath "_" (org-get-heading t t t t)))))))
+           (id (org-entry-get nil "CUSTOM_ID")))
+      (cond
+       ((and id
+             (stringp id)
+             (string-match "\\S-" id)) id)
+       (create (setq id (org-unique-id--new (concat prefix heading)))
+               (org-entry-put pom "CUSTOM_ID" id)
+               (org-id-add-location id
+                                    (buffer-file-name (buffer-base-buffer)))
+               id)))))
+
+
+(defun org-unique-id-add-ids-to-headline-in-file ()
+  "Add a CUSTOM_ID to all headers missing one.
+
+Only adds ids if the `auto-id' option is set to t in the file
+somewhere. ie, #+OPTIONS: auto-id:t"
+  (interactive)
+  (save-excursion
+    (widen)
+    (goto-char (point-min))
+    (let ((case-fold-search t))
+      (when (re-search-forward "^#\\+OPTIONS:.*auto-id:t" (point-max) t)
+        (org-map-entries (lambda () (org-unique-id--get (point) t)))))))
+
+(provide 'org-unique-id)
+
+;;; org-unique-id.el ends here