Auto blog post addition.

build.el

@@ -13,15 +13,76 @@
       "<nav>
   <a href=\"/\">Home</a>
   <a href=\"/about.html\">About</a>
+  <a href=\"/blog.html\">Blog</a>
 </nav>")
 
+(defun blog-extract-title (file)
+  "Extract #+TITLE: value from FILE."
+  (with-temp-buffer
+    (insert-file-contents file)
+    (goto-char (point-min))
+    (if (re-search-forward "^#\\+TITLE:[ \t]*\\(.+\\)$" nil t)
+        (string-trim (match-string 1))
+      (file-name-base file))))
+
+(defun blog-extract-excerpt (file &optional max-chars)
+  "Extract first body paragraph from FILE, up to MAX-CHARS characters."
+  (let ((max (or max-chars 250)))
+    (with-temp-buffer
+      (insert-file-contents file)
+      (goto-char (point-min))
+      ;; Skip metadata lines and headings
+      (while (and (not (eobp))
+                  (looking-at "^\\(#\\+\\|\\*\\|[ \t]*$\\)"))
+        (forward-line 1))
+      (let ((start (point)))
+        ;; Collect lines until blank line or heading
+        (while (and (not (eobp))
+                    (not (looking-at "^\\(\\*\\|[ \t]*$\\)")))
+          (forward-line 1))
+        (let ((text (string-trim (buffer-substring-no-properties start (point)))))
+          ;; Collapse whitespace
+          (setq text (replace-regexp-in-string "[ \t\n]+" " " text))
+          (if (> (length text) max)
+              (concat (substring text 0 max) "...")
+            text))))))
+
+(defun blog-generate-listings (_project)
+  "Scan content/blog/ and generate recent-posts.org and all-posts.org."
+  (let* ((blog-dir "./content/blog")
+         (gen-dir "./content/generated")
+         (pattern (concat blog-dir "/[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]-*.org"))
+         (files (sort (file-expand-wildcards pattern t)
+                      (lambda (a b) (string> (file-name-base a)
+                                             (file-name-base b)))))
+         (make-entry
+          (lambda (file)
+            (let* ((base (file-name-base file))
+                   (date (substring base 0 10))
+                   (title (blog-extract-title file))
+                   (excerpt (blog-extract-excerpt file))
+                   (link (concat "file:../blog/" base ".org")))
+              (concat
+               "*[[" link "][" title "]]* — " date "\n\n"
+               excerpt "\n\n"
+               "[[" link "][Read more →]]\n\n"
+               "-----\n\n")))))
+    (make-directory gen-dir t)
+    (with-temp-file (concat gen-dir "/recent-posts.org")
+      (dolist (file (seq-take files 3))
+        (insert (funcall make-entry file))))
+    (with-temp-file (concat gen-dir "/all-posts.org")
+      (dolist (file files)
+        (insert (funcall make-entry file))))))
 (setq org-publish-project-alist
       `(("site-pages"
          :base-directory "./content"
          :base-extension "org"
          :publishing-directory "./public"
          :recursive t
+         :exclude "generated/"
          :publishing-function org-html-publish-to-html
+         :preparation-function blog-generate-listings
          :html-head-include-default-style nil
          :html-head-include-scripts nil
          :html-head "<link rel=\"stylesheet\" href=\"/style.css\"><script src=\"/animation.js\" defer></script>"