Rewrite custom org link types

This should fix a few issues with links (like org-download links)
resolving to the incorrect org-directory or org-id-attach-dir (because
it's resolved too early).

I've also simplified and refactored the API to make it easier to grok.

modules/lang/org/autoload/org-link.el

@@ -1,43 +1,59 @@
 ;;; lang/org/autoload/org-link.el -*- lexical-binding: t; -*-
 
-(defun +org--relpath (path root)
+(defun +org--relative-path (path root)
   (if (and buffer-file-name (file-in-directory-p buffer-file-name root))
       (file-relative-name path)
     path))
 
+(defun +org--read-link-path (key dir &optional fn)
+  (let ((file (funcall (or fn #'read-file-name) (format "%s: " (capitalize key)) dir)))
+    (format "%s:%s" key (file-relative-name file dir))))
+
 ;;;###autoload
-(defun +org-def-link (key dir)
-  (org-link-set-parameters
+(defun +org-define-basic-link (key dir-var &rest plist)
+  "Define a link with some basic completion & fontification.
+
+KEY is the name of the link type. DIR-VAR is the directory variable to resolve
+links relative to. PLIST is passed to `org-link-set-parameters' verbatim.
+
+Links defined with this will be rendered in the `error' face if the file doesn't
+exist, and `org-link' otherwise."
+  (declare (indent 2))
+  (let ((requires (plist-get plist :requires)))
+    (apply #'org-link-set-parameters
            key
-   :complete (lambda () (+org--relpath (+org-link-read-file key dir) dir))
-   :follow   (lambda (link) (find-file (expand-file-name link dir)))
+           :complete (lambda ()
+                       (if requires (mapc #'require (doom-enlist requires)))
+                       (+org--relative-path (+org--read-link-path key (symbol-value dir-var))
+                                            (symbol-value dir-var)))
+           :follow   (lambda (link) (find-file (expand-file-name link (symbol-value dir-var))))
            :face     (lambda (link)
-               (if (file-exists-p (expand-file-name link dir))
+                       (if (file-exists-p (expand-file-name link (symbol-value dir-var)))
                            'org-link
-                 'error))))
+                         'error))
+           (doom-plist-delete plist :requires))))
+
+
+;;
+;;; Image data functions (for custom inline images)
 
 ;;;###autoload
-(defun +org-link-read-file (key dir)
-  (let ((file (read-file-name (format "%s: " (capitalize key)) dir)))
-    (format "%s:%s"
-            key
-            (file-relative-name file dir))))
+(defun +org-image-file-data-fn (protocol link _description)
+  "Intepret LINK as an image file path and return its data."
+  (when (and (file-exists-p link)
+             (image-type-from-file-name link))
+    (with-temp-buffer
+      (insert-file-contents-literally link)
+      (buffer-string))))
 
 ;;;###autoload
-(defun +org-link-read-directory (key dir)
-  (let ((file (read-directory-name (format "%s: " (capitalize key)) dir)))
-    (format "%s:%s"
-            key
-            (file-relative-name file dir))))
-
-;;;###autoload
-(defun +org-inline-data-image (_protocol link _description)
+(defun +org-inline-image-data-fn (_protocol link _description)
   "Interpret LINK as base64-encoded image data."
   (base64-decode-string link))
 
 ;;;###autoload
-(defun +org-image-link (protocol link _description)
-  "Interpret LINK as base64-encoded image data."
+(defun +org-http-image-data-fn (protocol link _description)
+  "Interpret LINK as an URL to an image file."
   (when (image-type-from-file-name link)
     (if-let* ((buf (url-retrieve-synchronously (concat protocol ":" link))))
         (with-current-buffer buf

modules/lang/org/config.el

@@ -397,15 +397,15 @@ underlying, modified buffer. This fixes that."
             '("wolfram"     . "https://wolframalpha.com/input/?i=%s")
             '("doom-repo"   . "https://github.com/hlissner/doom-emacs/%s"))
 
-  (+org-def-link "org" org-directory)
-  (+org-def-link "doom" doom-emacs-dir)
-  (+org-def-link "doom-docs" doom-docs-dir)
-  (+org-def-link "doom-modules" doom-modules-dir)
+  (+org-define-basic-link "org" 'org-directory)
+  (+org-define-basic-link "doom" 'doom-emacs-dir)
+  (+org-define-basic-link "doom-docs" 'doom-docs-dir)
+  (+org-define-basic-link "doom-modules" 'doom-modules-dir)
 
   ;; Allow inline image previews of http(s)? urls or data uris
-  (org-link-set-parameters "http"  :image-data-fun #'+org-image-link)
-  (org-link-set-parameters "https" :image-data-fun #'+org-image-link)
-  (org-link-set-parameters "img"   :image-data-fun #'+org-inline-data-image)
+  (org-link-set-parameters "http"  :image-data-fun #'+org-http-image-data-fn)
+  (org-link-set-parameters "https" :image-data-fun #'+org-http-image-data-fn)
+  (org-link-set-parameters "img"   :image-data-fun #'+org-inline-image-data-fn)
 
   ;; Add support for youtube links + previews
   (require 'org-yt nil t))

modules/lang/org/contrib/dragndrop.el

@@ -16,12 +16,14 @@
 
   (after! org
     ;; A shorter link to attachments
-    (+org-def-link "download" org-attach-id-dir)
-    (setf (alist-get "download" org-link-abbrev-alist nil nil #'equal)
-          (abbreviate-file-name org-attach-id-dir)))
+    (+org-define-basic-link "download" 'org-attach-id-dir
+      :image-data-fun #'+org-image-file-data-fn
+      :requires 'org-download))
   :config
-  (setq org-download-image-dir org-attach-id-dir
-        org-download-link-format "[[download:%s]]\n"
+  (unless org-download-image-dir
+    (setq org-download-image-dir (expand-file-name (or org-attach-id-dir "")
+                                                   org-directory)))
+  (setq org-download-link-format "[[download:%s]]\n"
         org-download-method 'attach
         org-download-heading-lvl nil
         org-download-timestamp "_%Y%m%d_%H%M%S"