(feat): rename file on title change (#1073)

Adds `org-roam-title-change-hook`. This now contains two functions:

1. `org-roam--update-links-on-title-change`: updates the link
description of all files that link to the current file.
2. `org-roam--update-file-name-on-title-change`: updates the current
buffer's filename to reflect the updated title.

CHANGELOG.md

@@ -10,6 +10,7 @@ In this release we support fuzzy links of the form `[[Title]]`, `[[*Headline]]`
 
 ### Features
  
+- [#1073](https://github.com/org-roam/org-roam/pull/1073) Rename file on title change, when `org-roam-rename-file-on-title-change` is non-nil.
 - [#1071](https://github.com/org-roam/org-roam/pull/1071) Update link descriptions on title changes, and clean-up rename file advice
 - [#1061](https://github.com/org-roam/org-roam/pull/1061) Speed up the extraction of file properties, headlines, and titles
 - [#1046](https://github.com/org-roam/org-roam/pull/1046) New user option to exclude files from Org-roam

org-roam-db.el

@@ -461,12 +461,15 @@ connections, nil is returned."
       (org-roam-db--insert-headlines headlines))))
 
 (defun org-roam-db--update-file (&optional file-path)
-  "Update Org-roam cache for FILE-PATH."
-  (when (org-roam--org-roam-file-p file-path)
-    (let ((buf (or (and file-path
-                        (find-file-noselect file-path t))
-                   (current-buffer))))
-      (with-current-buffer buf
+  "Update Org-roam cache for FILE-PATH.
+If the file does not exist anymore, remove it from the cache.
+If the file exists, update the cache with information."
+  (setq file-path (or file-path
+                      (buffer-file-name (buffer-base-buffer))))
+  (cond ((not (file-exists-p file-path))
+         (org-roam-db--clear-file file-path))
+        ((org-roam--org-roam-file-p file-path)
+         (with-current-buffer (find-file-noselect file-path t)
            (org-with-wide-buffer
             (emacsql-with-transaction (org-roam-db)
               (org-roam-db--update-meta)
@@ -475,8 +478,7 @@ connections, nil is returned."
               (org-roam-db--update-refs)
               (when org-roam-enable-headline-linking
                 (org-roam-db--update-headlines))
-           (org-roam-db--update-links)))
-        (org-roam-buffer--update-maybe :redisplay t)))))
+              (org-roam-db--update-links)))))))
 
 (defun org-roam-db-build-cache (&optional force)
   "Build the cache for `org-roam-directory'.

org-roam.el

@@ -1527,23 +1527,45 @@ replaced links are made relative to the current buffer."
               (replace-match (concat type ":" new-path)
                              nil t nil 1))))))))
 
+(defcustom org-roam-rename-file-on-title-change t
+  "If non-nil, alter the filename on title change.
+The new title is converted into a slug using
+`org-roam-title-to-slug-function', and compared with the current
+filename."
+  :group 'org-roam
+  :type 'boolean)
+
+(defcustom org-roam-title-change-hook '(org-roam--update-file-name-on-title-change
+                                        org-roam--update-links-on-title-change)
+  "Hook run after detecting a title change.
+Each hook is passed two arguments: the old title, and new title
+respectively."
+  :group 'org-roam
+  :type 'hook)
+
 (defvar-local org-roam-current-title nil
   "The current title of the Org-roam file.")
 
+(defun org-roam--handle-title-change ()
+  "Detect a title change, and run `org-roam-title-change-hook'."
+  (let ((new-title (car (org-roam--extract-titles)))
+        (old-title org-roam-current-title))
+    (unless (string-equal old-title new-title)
+      (run-hook-with-args 'org-roam-title-change-hook old-title new-title)
+      (setq-local org-roam-current-title new-title))))
+
 (defun org-roam--setup-title-auto-update ()
   "Setup automatic link description update on title change."
   (setq-local org-roam-current-title (car (org-roam--extract-titles)))
-  (add-hook 'after-save-hook #'org-roam--update-links-on-title-change nil t))
+  (add-hook 'after-save-hook #'org-roam--handle-title-change nil t))
 
-(defun org-roam--update-links-on-title-change ()
-  "Update the link description of other Org-roam files on title change.
-This function is to be called in `after-save-hook'. If the title
-of the Org-roam file has changed, it will iterate over all
-Org-roam files that link to the current file, and replace the
-link descriptions with the new title if applicable."
-  (let ((new-title (car (org-roam--extract-titles)))
-        (old-title org-roam-current-title))
-    (unless (string-equal old-title new-title)
+(defun org-roam--update-links-on-title-change (old-title new-title)
+  "Update the link description of other Org-roam files.
+Iterate over all Org-roam files that have link description of
+OLD-TITLE, and replace the link descriptions with the NEW-TITLE
+if applicable.
+
+To be added to `org-roam-title-change-hook'."
   (let* ((current-path (file-truename (buffer-file-name)))
          (files-affected (org-roam-db-query [:select :distinct [from]
                                              :from links
@@ -1554,7 +1576,26 @@ link descriptions with the new title if applicable."
                                (find-file-noselect (car file)))
         (org-roam--replace-link current-path current-path old-title new-title)
         (save-buffer)))))
-    (setq-local org-roam-current-title new-title)))
+
+(defun org-roam--update-file-name-on-title-change (old-title new-title)
+  "Update the file name on title change.
+The slug is computed from OLD-TITLE using
+`org-roam-title-to-slug-function'. If the slug is part of the
+current filename, the new slug is computed with NEW-TITLE, and
+that portion of the filename is renamed.
+
+To be added to `org-roam-title-change-hook'."
+  (when org-roam-rename-file-on-title-change
+    (let* ((old-slug (funcall org-roam-title-to-slug-function old-title))
+           (file (buffer-file-name (buffer-base-buffer)))
+           (file-name (file-name-nondirectory file)))
+      (when (string-match-p old-slug file-name)
+        (let* ((new-slug (funcall org-roam-title-to-slug-function new-title))
+               (new-file-name (replace-regexp-in-string old-slug new-slug file-name)))
+          (rename-file file-name new-file-name)
+          (set-visited-file-name new-file-name t t)
+          (add-to-list 'org-roam--file-update-queue new-file-name)
+          (org-roam-message "File moved to %S" (abbreviate-file-name new-file-name)))))))
 
 (defun org-roam--rename-file-advice (old-file new-file-or-dir &rest _args)
   "Rename backlinks of OLD-FILE to refer to NEW-FILE-OR-DIR.