[elpa] externals/denote 9d8748c382 022/355: Add proof-of-concept backlink (lots of TODO)

[ELPA Syncer]

branch: externals/denote
commit 9d8748c3820d53661ac198b37a32e5020da7a97f
Author: Protesilaos Stavrou <info@protesilaos.com>
Commit: Protesilaos Stavrou <info@protesilaos.com>

    Add proof-of-concept backlink (lots of TODO)
---
 denote.el | 48 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 8 deletions(-)

diff --git a/denote.el b/denote.el
index 7bd2367277..1414082ffe 100644
--- a/denote.el
+++ b/denote.el
@@ -92,6 +92,14 @@ define."
   :type 'string
   :group 'denote)
 
+(defcustom denote-link-insert-functions
+  (list #'denote-write-backlink)
+  "Functions that run after `denote-link'.
+Each function accepts a TARGET-FILE and an ORIGIN-LINK argument.
+Both are supplied by `denote-link'."
+  :type 'hook
+  :group 'denote)
+
 ;;; Main variables
 
 ;; TODO 2022-06-04: Can we make the entire file name format a defcustom?
@@ -386,6 +394,9 @@ sample template.  We will eventually have a manual."
 (defvar denote--link-format "[[denote:%s][%s (%s)]]"
   "Format of Org link to note.")
 
+(defvar denote--backlink-format "[[denote:%s][backlink: %s (%s)]]"
+  "Format of Org link to note.")
+
 (defun denote--retrieve-value (note regexp)
   "Return REGEXP value from NOTE."
   (let ((default-directory (denote--directory)))
@@ -399,15 +410,36 @@ sample template.  We will eventually have a manual."
                   nil t nil #'file-regular-p))
 
 ;;;###autoload
-(defun denote-link (note)
-  "Create Org link to NOTE in `denote-directory'."
+(defun denote-link (target)
+  "Create Org link to TARGET note in `denote-directory'.
+Run `denote-link-insert-functions' afterwards."
   (interactive (list (denote--read-file-prompt)))
-  (let ((identifier (cdr (denote--retrieve-value note 
denote--identifier-regexp)))
-        (filename (string-remove-prefix
-                   (denote--directory)
-                   (cdr (denote--retrieve-value note 
denote--filename-regexp))))
-        (title (cdr (denote--retrieve-value note denote--title-regexp))))
-    (insert (format denote--link-format filename title identifier))))
+  (let* ((target-id (cdr (denote--retrieve-value target 
denote--identifier-regexp)))
+         (target-name (string-remove-prefix
+                    (denote--directory)
+                    (cdr (denote--retrieve-value target 
denote--filename-regexp))))
+         (target-title (cdr (denote--retrieve-value target 
denote--title-regexp)))
+         (target-link (format denote--link-format target-name target-title 
target-id))
+         (origin-note (buffer-file-name))
+         (origin-id (cdr (denote--retrieve-value origin-note 
denote--identifier-regexp)))
+         (origin-name (string-remove-prefix
+                    (denote--directory)
+                    (cdr (denote--retrieve-value origin-note 
denote--filename-regexp))))
+         (origin-title (cdr (denote--retrieve-value origin-note 
denote--title-regexp)))
+         (origin-link (format denote--backlink-format origin-name origin-title 
origin-id)))
+    (insert target-link)
+    (run-hook-with-args 'denote-link-insert-functions target origin-link)))
+
+;; NOTE 2022-06-05: A proof-of-concept.  We need to: (i) have a
+;; Backlinks headeding, (ii) delete duplicates, (iii) ensure one
+;; backlink per line, (iv) have a `denote-unlink' command or a
+;; `denote-clean-backlinks' for invalid links.
+(defun denote-write-backlink (target-file origin-link)
+  "Insert ORIGIN-LINK to TARGET-FILE."
+  (let ((default-directory (denote--directory)))
+    (with-current-buffer (find-file-noselect target-file)
+      (goto-char (point-max))
+      (insert origin-link))))
 
 (provide 'denote)
 ;;; denote.el ends here