lang/org: add inline base64/http(s) image support

Adds inline image preview support for http/https links, as well as
base64 encode image support with the img protocol. e.g.

Examples:
[[http://domain.com/some/image.png]]
[[https://raw.githubusercontent.com/hlissner/doom-emacs/screenshots/company.png]]
[[img:iVBORw0KGgoAAAANSUhEUgAAACUAAAAuCAAAAACKMo8cAA...]]

modules/lang/org/+attach.el

@@ -63,6 +63,28 @@
   (advice-add #'org-download--fullname
               :filter-return #'+org-attach*download-fullname))
 
+(def-package! org-yt
+  :after org
+  :config
+  (defun +org-inline-data-image (_protocol link _description)
+    "Interpret LINK as base64-encoded image data."
+    (base64-decode-string link))
+
+  (defun +org-image-link (protocol link _description)
+    "Interpret LINK as base64-encoded image data."
+    (when (image-type-from-file-name link)
+      (let ((buf (url-retrieve-synchronously (concat protocol ":" link))))
+        ;; TODO Better error handling
+        (cl-assert buf nil "Download of image \"%s\" failed." link)
+        (with-current-buffer buf
+          (goto-char (point-min))
+          (re-search-forward "\r?\n\r?\n")
+          (buffer-substring-no-properties (point) (point-max))))))
+
+  (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))
+
 
 ;;
 ;; Bootstrap

modules/lang/org/autoload/org.el

@@ -119,8 +119,10 @@ If on a:
        (org-toggle-latex-fragment))
 
       (`link
-       (let ((path (org-element-property :path (org-element-lineage context '(link) t))))
-         (if (and path (image-type-from-file-name path))
+       (let* ((lineage (org-element-lineage context '(link) t))
+              (path (org-element-property :path lineage)))
+         (if (or (equal (org-element-property :type lineage) "img")
+                 (and path (image-type-from-file-name path)))
              (+org/refresh-inline-images)
            (org-open-at-point))))
 

modules/lang/org/packages.el

@@ -15,7 +15,8 @@
   (package! org-pdfview))
 
 (when (featurep! +attach)
-  (package! org-download))
+  (package! org-download)
+  (package! org-yt :recipe (:fetcher github :repo "TobiasZawada/org-yt")))
 
 (when (featurep! +babel)
   (package! ob-mongo)