Fix and improve indentation management in destination and SOURCE of transcluded content

org-transclusion-indent-mode.el

@@ -22,70 +22,284 @@
 ;;; Commentary:
 ;;  This file is part of Org-transclusion
 ;;  URL: https://github.com/nobiot/org-transclusion
+;;
+;;  This extension ensures org-indent-mode properties are correctly
+;;  applied to transcluded content and refreshed after transclusion
+;;  removal. It also preserves fringe indicators in both source and
+;;  destination buffers when org-indent-mode regenerates line-prefix
+;;  properties.
+;;
+;;  The timing mechanism for synchronizing with org-indent's asynchronous
+;;  initialization is copied from org-modern-indent.
 
 ;;; Code:
 
 (require 'org-indent)
-(declare-function org-transclusion-within-transclusion-p
-                  "org-transclusion")
 
-(add-hook 'org-transclusion-after-add-functions
-          #'org-translusion-indent-add-properties)
+;;;; Variables
+
+(defvar-local org-transclusion-indent--timer nil
+  "Timer for debounced fringe re-application.")
+
+(defvar-local org-transclusion-indent--last-change-tick nil
+  "Buffer modification tick at last fringe application.")
+
+(defvar-local org-transclusion-indent--has-overlays nil
+  "Non-nil if buffer has ever had source overlays.
+Used to prevent premature mode deactivation during buffer refresh.")
+
+(defvar-local org-transclusion-indent--init nil
+  "Initialization state for waiting on org-indent.
+Either nil, t (initialized), or (TIMER ATTEMPT-COUNT).")
+
+;;;; Forward Declarations
+
+;; Silence byte-compiler warnings for functions defined in org-transclusion.el
+(declare-function org-transclusion-prefix-has-fringe-p "org-transclusion" (prefix))
+(declare-function org-transclusion-add-fringe-to-region "org-transclusion" (buffer beg end face))
+(declare-function org-transclusion-remove-fringe-from-region "org-transclusion" (buffer beg end))
+
+
+;; Variable defined by define-minor-mode later in this file
+(defvar org-transclusion-indent-mode)
+
+(defun org-transclusion-indent--find-source-overlays ()
+  "Return list of all transclusion source overlays in current buffer."
+  (seq-filter
+   (lambda (ov) (overlay-get ov 'org-transclusion-by))
+   (overlays-in (point-min) (point-max))))
+
+(defun org-transclusion-indent--reapply-all-fringes ()
+  "Re-apply fringe indicators to all transcluded regions in buffer.
+This function is called after any change that might have removed
+`line-prefix' or `wrap-prefix' properties.
+
+In graphical mode, optimizes by checking only the first line of each
+overlay region, since org-indent regenerates entire subtrees at once.
+
+In terminal mode, always re-applies fringes to all lines, since
+org-indent may regenerate individual lines during typing."
+  (when (buffer-live-p (current-buffer))
+    (let ((current-tick (buffer-modified-tick))
+          (overlays (org-transclusion-indent--find-source-overlays)))
+      ;; Track if we have overlays
+      (when overlays
+        (setq org-transclusion-indent--has-overlays t))
+
+      ;; Only re-apply if buffer actually changed since last application
+      (unless (eq current-tick org-transclusion-indent--last-change-tick)
+        (setq org-transclusion-indent--last-change-tick current-tick)
+        (dolist (ov overlays)
+          (let ((ov-beg (overlay-start ov))
+                (ov-end (overlay-end ov)))
+            (when (and ov-beg ov-end)
+              (if (display-graphic-p)
+                  ;; Graphical mode: optimize by checking only first line
+                  (save-excursion
+                    (goto-char ov-beg)
+                    (let* ((line-beg (line-beginning-position))
+                           (line-prefix (get-text-property line-beg 'line-prefix)))
+                      (when (and line-prefix
+                                 (not (org-transclusion-prefix-has-fringe-p line-prefix)))
+                        (org-transclusion-add-fringe-to-region
+                         (current-buffer) ov-beg ov-end
+                         'org-transclusion-source-fringe))))
+                ;; Terminal mode: always re-apply to all lines
+                (org-transclusion-add-fringe-to-region
+                 (current-buffer) ov-beg ov-end
+                 'org-transclusion-source-fringe)))))))))
+
+(defun org-transclusion-indent--schedule-reapply ()
+  "Schedule fringe re-application after a short delay.
+This debounces rapid changes to avoid excessive processing.
+
+In graphical mode, uses a shorter delay (0.2s) since bitmap rendering
+is fast and flicker-free.  In terminal mode, uses a longer delay (0.7s)
+to reduce visible flicker of ASCII fringe indicators during rapid typing."
+  (when org-transclusion-indent--timer
+    (cancel-timer org-transclusion-indent--timer))
+  (setq org-transclusion-indent--timer
+        (run-with-idle-timer
+         (if (display-graphic-p) 0.2 0.7)  ; Shorter delay for graphical, longer for terminal
+         nil
+         (lambda (buf)
+           (when (buffer-live-p buf)
+             (with-current-buffer buf
+               (org-transclusion-indent--reapply-all-fringes))))
+         (current-buffer))))
+
+(defun org-transclusion-indent--after-change (_beg _end _len)
+  "Schedule fringe re-application after buffer change.
+Added to `after-change-functions' in source buffers."
+  (org-transclusion-indent--schedule-reapply))
+
+(defun org-transclusion-indent--check-and-disable ()
+  "Disable mode if no source overlays remain in buffer.
+Only disables if overlays have been checked and confirmed absent,
+not during temporary states like buffer refresh."
+  (when (and org-transclusion-indent--has-overlays
+             (not (org-transclusion-indent--find-source-overlays)))
+    ;; Wait a bit to ensure this isn't just a temporary state
+    (run-with-idle-timer
+     0.2 nil
+     (lambda (buf)
+       (when (buffer-live-p buf)
+         (with-current-buffer buf
+           (unless (org-transclusion-indent--find-source-overlays)
+             (org-transclusion-indent-mode -1)))))
+     (current-buffer))))
+
+(defun org-transclusion-indent--wait-and-init (buf)
+  "Wait for org-indent to finish initializing BUF, then apply fringes.
+Copied from org-modern-indent's timing mechanism."
+  (if (or (not (bound-and-true-p org-indent-agentized-buffers))
+          (memq buf org-indent-agentized-buffers))
+      ;; org-indent is ready
+      (org-transclusion-indent--init buf)
+    ;; Still waiting
+    (when (buffer-live-p buf)
+      (with-current-buffer buf
+        (if org-transclusion-indent--init
+            (let ((cnt (cl-incf (cadr org-transclusion-indent--init))))
+              (if (> cnt 5)
+                  (progn
+                    (message "org-transclusion-indent-mode: Gave up waiting for %s to initialize" buf)
+                    (setq org-transclusion-indent--init t))
+                (timer-activate
+                 (timer-set-time (car org-transclusion-indent--init)
+                                 (time-add (current-time) 0.2)))))
+          (setq org-transclusion-indent--init
+                (list (run-at-time 0.1 nil #'org-transclusion-indent--wait-and-init buf)
+                      1)))))))
 
-(defun org-translusion-indent-add-properties (beg end)
-  "BEG END."
+(defun org-transclusion-indent--init (buf)
+  "Initialize indent mode in BUF after org-indent completes.
+To be added to `org-indent-post-buffer-init-functions'."
+  (when (buffer-live-p buf)
+    (with-current-buffer buf
+      (setq org-transclusion-indent--init t)
+      (org-transclusion-indent--reapply-all-fringes))))
+
+(defun org-transclusion-indent--auto-enable-maybe ()
+  "Auto-enable indent mode if source overlays are detected.
+Added to `post-command-hook' in `org-mode' buffers with `org-indent-mode'."
+  (when (and (not org-transclusion-indent-mode)
+             (org-transclusion-indent--find-source-overlays))
+    (org-transclusion-indent-mode +1)))
+
+;;;; Destination Buffer Support
+
+(defun org-transclusion-indent--add-properties-and-fringes (beg __end)
+  "Ensure org-indent properties and fringe indicators in transcluded region.
+BEG and END are approximate bounds; we find actual bounds from text properties.
+
+When org-indent-mode is active, `org-indent-add-properties' overwrites
+the uniform `line-prefix' and `wrap-prefix' properties set by the main
+package, removing fringe indicators. This function re-applies fringes
+by appending them to org-indent's indentation prefixes."
   (when org-indent-mode
-    (advice-add #'org-indent-set-line-properties
-                :override
-                #'org-transclusion-indent-set-line-properties-ad)
-    (org-indent-add-properties beg end)
-    (advice-remove #'org-indent-set-line-properties
-                   #'org-transclusion-indent-set-line-properties-ad)))
-
-(defun org-transclusion-indent-set-line-properties-ad (level indentation &optional heading)
-  "Set prefix properties on current line an move to next one.
-
-LEVEL is the current level of heading.  INDENTATION is the
-expected indentation when wrapping line.
-
-When optional argument HEADING is non-nil, assume line is at
-a heading.  Moreover, if it is `inlinetask', the first star will
-have `org-warning' face."
-
-  (let* ((line (aref (pcase heading
-                       (`nil org-indent--text-line-prefixes)
-                       (`inlinetask org-indent--inlinetask-line-prefixes)
-                       (_ org-indent--heading-line-prefixes))
-                     level))
-         (wrap
-          (org-add-props
-              (concat line
-                      (if heading (concat (make-string level ?*) " ")
-                        (make-string indentation ?\s)))
-              nil 'face 'org-indent)))
-
-    ;; Org-transclusion's addition begin
-    (when (org-transclusion-within-transclusion-p)
-      (setq line
-            (concat line
-                    (propertize
-                     "x"
-                     'display
-                     '(left-fringe org-transclusion-fringe-bitmap
-                                   org-transclusion-fringe))))
-      (setq wrap
-            (concat line
-                    (propertize
-                     "x"
-                     'display
-                     '(left-fringe org-transclusion-fringe-bitmap
-                                   org-transclusion-fringe)))))
-    ;; Org-transclusion's addition end
-
-    ;; Add properties down to the next line to indent empty lines.
-    (add-text-properties (line-beginning-position) (line-beginning-position 2)
-                         `(line-prefix ,line wrap-prefix ,wrap)))
-  (forward-line))
+    ;; Find actual transclusion bounds using text properties
+    ;; The transclusion that was just added should be at or near BEG
+    (save-excursion
+      (goto-char beg)
+      ;; Search forward for org-transclusion-type property
+      (when-let* ((match (text-property-search-forward 'org-transclusion-type))
+                  (actual-beg (prop-match-beginning match))
+                  (actual-end (prop-match-end match)))
+        ;; Apply org-indent properties and fringes to actual bounds
+        (org-indent-add-properties actual-beg actual-end)
+        (org-transclusion-add-fringe-to-region
+         (current-buffer) actual-beg actual-end 'org-transclusion-fringe)))))
+
+(defun org-transclusion-indent--refresh-source-region (src-buf src-beg src-end)
+  "Refresh org-indent properties in source region after transclusion removal.
+SRC-BUF is the source buffer, SRC-BEG and SRC-END are the region bounds.
+
+For `org-mode' buffers with `org-indent-mode', refreshes indentation properties.
+For non-org buffers, removes fringe indicators that were added during
+transclusion."
+  (with-current-buffer src-buf
+    (if (buffer-local-value 'org-indent-mode src-buf)
+        ;; Org buffer with indent-mode: refresh properties
+        (progn
+          (org-indent-add-properties src-beg src-end)
+          (when (and (boundp 'org-transclusion-indent-mode)
+                     org-transclusion-indent-mode)
+            (org-transclusion-indent--check-and-disable)))
+      ;; Non-org buffer or org buffer without indent-mode: just remove fringes
+      (org-transclusion-remove-fringe-from-region src-buf src-beg src-end))))
+
+;;;; Minor Mode Definition
+
+;;;###autoload
+(define-minor-mode org-transclusion-indent-mode
+  "Minor mode for org-indent-mode support in org-transclusion.
+
+This mode serves two purposes:
+
+1. In destination buffers: ensures org-indent properties are applied
+   and fringe indicators are preserved when org-indent overwrites them.
+
+2. In source buffers: preserves fringe indicators when org-indent-mode
+   regenerates `line-prefix' properties.
+
+The mode auto-activates in source buffers when transclusion source
+overlays are detected, and auto-deactivates when all transclusions
+are removed."
+  :init-value nil
+  :lighter " OT-Indent"
+  :group 'org-transclusion
+  (if org-transclusion-indent-mode
+      (progn
+        ;; Install hooks for source buffer fringe preservation
+        (add-hook 'after-change-functions
+                  #'org-transclusion-indent--after-change nil t)
+
+        ;; Register with org-indent or wait for it
+        (cond
+         ;; Already initialized before, just toggle
+         ((or (called-interactively-p 'any) org-transclusion-indent--init)
+          (org-transclusion-indent--init (current-buffer)))
+         ;; Register with buffer init hook if available
+         ((boundp 'org-indent-post-buffer-init-functions)
+          (add-hook 'org-indent-post-buffer-init-functions
+                    #'org-transclusion-indent--init nil t))
+         ;; Fallback: wait for org-indent
+         (t (org-transclusion-indent--wait-and-init (current-buffer)))))
+
+    ;; Cleanup
+    (remove-hook 'after-change-functions
+                 #'org-transclusion-indent--after-change t)
+    (when (boundp 'org-indent-post-buffer-init-functions)
+      (remove-hook 'org-indent-post-buffer-init-functions
+                   #'org-transclusion-indent--init t))
+    (when org-transclusion-indent--timer
+      (cancel-timer org-transclusion-indent--timer)
+      (setq org-transclusion-indent--timer nil))
+    (when (and (listp org-transclusion-indent--init)
+               (timerp (car org-transclusion-indent--init)))
+      (cancel-timer (car org-transclusion-indent--init)))
+    (setq org-transclusion-indent--has-overlays nil
+          org-transclusion-indent--init nil)))
+
+;;;###autoload
+(defun org-transclusion-indent-mode-setup ()
+  "Set up auto-activation of `indent mode' in `org-mode' buffers.
+Adds `post-command-hook' to detect when source overlays appear."
+  (when (and (derived-mode-p 'org-mode)
+             (bound-and-true-p org-indent-mode))
+    (add-hook 'post-command-hook
+              #'org-transclusion-indent--auto-enable-maybe nil t)))
+
+;; Auto-setup in org-mode buffers - add late to hook like org-modern-indent
+(add-hook 'org-mode-hook #'org-transclusion-indent-mode-setup 90)
+
+;;;; Hook Registration
+
+(add-hook 'org-transclusion-after-add-functions
+          #'org-transclusion-indent--add-properties-and-fringes)
+(add-hook 'org-transclusion-after-remove-functions
+          #'org-transclusion-indent--refresh-source-region)
 
 (provide 'org-transclusion-indent-mode)