(fix): preserve existing description in a roam: link on replace (#1327)

Co-authored-by: Jethro Kuan <jethrokuan95@gmail.com>

CHANGELOG.md

@@ -10,6 +10,7 @@
 - [#1281](https://github.com/org-roam/org-roam/pull/1281) fixed idle-timer not instantiated on `org-roam-mode`
 - [#1308](https://github.com/org-roam/org-roam/pull/1308) fixed file renames corrupting database
 - [#1325](https://github.com/org-roam/org-roam/pull/1325) make titles and tags extracted unique per note
+- [#1327](https://github.com/org-roam/org-roam/pull/1327) preserve existing link description during automatic replacement
 
 ## 1.2.3 (13-11-2020)
 
@@ -70,7 +71,7 @@ This change requires you to set `org-roam-directory` to the resolved path of a f
 - [#974](https://github.com/org-roam/org-roam/pull/974) Protect region targeted by `org-roam-insert`
 - [#994](https://github.com/org-roam/org-roam/pull/994) Simplify org-roam-store-link
 - [#1062](https://github.com/org-roam/org-roam/pull/1062) Variable `org-roam-completions-everywhere` allows for completions everywhere from word at point
-- [#910](https://github.com/org-roam/org-roam/pull/910), [#1105](https://github.com/org-roam/org-roam/pull/1105) Support fuzzy links of the form [[roam:Title]], [[roam:*Headline]] and [[roam:Title*Headline]]
+- [#910](https://github.com/org-roam/org-roam/pull/910), [#1105](https://github.com/org-roam/org-roam/pull/1105) Support fuzzy links of the form `[[roam:Title]]`, `[[roam:*Headline]]` and `[[roam:Title*Headline]]`
 
 ### Bugfixes
 

org-roam-link.el

@@ -71,18 +71,21 @@ noabbrev  Absolute path, no abbreviation of home directory."
 (org-link-set-parameters "roam"
                          :follow #'org-roam-link-follow-link)
 
-(defun org-roam-link-follow-link (path)
+(defun org-roam-link-follow-link (_path)
-  "Navigates to location specified by PATH."
+  "Navigates to location in Org-roam link.
-  (pcase-let ((`(,link-type ,loc ,desc ,mkr) (org-roam-link--get-location path)))
+This function is called by Org when following links of the type
+`roam'. While the path is passed, assume that the cursor is on
+the link."
+  (pcase-let ((`(,link-type ,loc ,desc ,mkr) (org-roam-link--get-location)))
     (when (and org-roam-link-auto-replace loc desc)
       (org-roam-link--replace-link link-type loc desc))
     (pcase link-type
-          ("file"
+      ("file"
-           (if loc
+       (if loc
-               (org-roam--find-file loc)
+           (org-roam--find-file loc)
-             (org-roam-find-file desc nil nil t)))
+         (org-roam-find-file desc nil nil t)))
-          ("id"
+      ("id"
-           (org-goto-marker-or-bmk mkr)))))
+       (org-goto-marker-or-bmk mkr)))))
 
 ;;; Retrieval Functions
 (defun org-roam-link--get-titles ()
@@ -184,43 +187,59 @@ star-idx is the index of the asterisk, if any."
                        (t 'title+headline))))
       (list type title headline star-index))))
 
-(defun org-roam-link--get-location (link)
+(defun org-roam-link--get-location ()
-  "Return the location of Org-roam fuzzy LINK.
+  "Return the location of the Org-roam fuzzy link at point.
 The location is returned as a list containing (link-type loc desc marker).
 nil is returned if there is no matching location.
 
 link-type is either \"file\" or \"id\".
 loc is the target location: e.g. a file path, or an id.
-marker is a marker to the headline, if applicable."
+marker is a marker to the headline, if applicable.
-  (let (mkr link-type desc loc)
+
-    (pcase-let ((`(,type ,title ,headline _) (org-roam-link--split-path link)))
+desc is either the the description of the link under point, or
-      (pcase type
+the target of LINK (title or heading content)."
-        ('title+headline
+  (let ((context (org-element-context))
-         (let ((file (org-roam-link--get-file-from-title title)))
+        mkr link-type desc loc)
-           (if (not file)
+    (pcase (org-element-lineage context '(link) t)
-               (org-roam-message "Cannot find matching file")
+      (`nil (error "Not at an Org link"))
-             (setq mkr (org-roam-link--get-id-from-headline headline file))
+      (link
-             (pcase mkr
+       (if (not (string-equal "roam" (org-element-property :type link)))
-               (`(,marker . ,target-id)
+           (error "Not at Org-roam link")
-                (setq mkr marker
+         (setq desc (and (org-element-property :contents-begin link)
-                      loc target-id
+                         (org-element-property :contents-end link)
-                      link-type "id"
+                         (buffer-substring-no-properties
-                      desc headline))
+                          (org-element-property :contents-begin link)
-               (_ (org-roam-message "cannot find matching id"))))))
+                          (org-element-property :contents-end link))))
-        ('title
+         (pcase-let ((`(,type ,title ,headline _) (org-roam-link--split-path
-         (setq loc (org-roam-link--get-file-from-title title)
+                                                   (org-element-property :path link))))
-               desc title
+           (pcase type
-               link-type "file"))
+             ('title+headline
-        ('headline
+              (let ((file (org-roam-link--get-file-from-title title)))
-         (setq mkr (org-roam-link--get-id-from-headline headline))
+                (if (not file)
-         (pcase mkr
+                    (org-roam-message "Cannot find matching file")
-           (`(,marker . ,target-id)
+                  (setq mkr (org-roam-link--get-id-from-headline headline file))
-            (setq mkr marker
+                  (pcase mkr
-                  loc target-id
+                    (`(,marker . ,target-id)
-                  desc headline
+                     (progn
-                  link-type "id"))
+                       (setq mkr marker
-           (_ (org-roam-message "Cannot find matching headline")))))
+                             loc target-id
-      (list link-type loc desc mkr))))
+                             desc (or desc headline)
+                             link-type "id")))
+                    (_ (org-roam-message "Cannot find matching id"))))))
+             ('title
+              (setq loc (org-roam-link--get-file-from-title title)
+                    link-type "file"
+                    desc (or desc title)))
+             ('headline
+              (setq mkr (org-roam-link--get-id-from-headline headline))
+              (pcase mkr
+                (`(,marker . ,target-id)
+                 (setq mkr marker
+                       loc target-id
+                       link-type "id"
+                       desc (or desc headline)))
+                (_ (org-roam-message "Cannot find matching headline")))))))))
+    (list link-type loc desc mkr)))
 
 ;;; Conversion Functions
 (defun org-roam-link--replace-link (link-type loc &optional desc)
@@ -241,14 +260,11 @@ DESC is the link description."
   (save-excursion
     (goto-char (point-min))
     (while (re-search-forward org-link-bracket-re nil t)
-      (let ((context (org-element-context)))
+      (condition-case nil
-          (pcase (org-element-lineage context '(link) t)
+          (pcase-let ((`(,link-type ,loc ,desc _) (org-roam-link--get-location)))
-            (`nil nil)
+            (when (and link-type loc)
-            (link
+              (org-roam-link--replace-link link-type loc desc)))
-             (when (string-equal "roam" (org-element-property :type link))
+        (error nil)))))
-               (pcase-let ((`(,link-type ,loc ,desc _) (org-roam-link--get-location (org-element-property :path link))))
-                 (when (and link-type loc)
-                   (org-roam-link--replace-link link-type loc desc))))))))))
 
 (defun org-roam-link--replace-link-on-save ()
   "Hook to replace all roam links on save."