tvl-depot/fun/elblog/blog.el

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;;; blog.el --- A simple org-mode & elnode blog software.
;;; -*- lexical-binding: t; -*-
(require 'dash)
(require 'elnode)
(require 'f)
(require 'ht)
;; Definition of customization options
(defgroup elblog nil
"Configuration for the Emacs Lisp blog software"
:link '(url-link "https://github.com/tazjin/elblog"))
(defcustom elblog-port 8010
"Port to run elblog's HTTP server on"
:group 'elblog
:type 'integer)
(defcustom elblog-host "localhost"
"Host for elblog's HTTP server to listen on"
:group 'elblog
:type 'string)
(defcustom elblog-title "Elblog"
"Title text for this elblog instance"
:group 'elblog
:type 'string)
(defcustom elblog-article-directory nil
"Directory in which elblog articles are stored"
:group 'elblog
:type 'string)
(defcustom elblog-additional-routes '()
"Additional Elnode routes to register in the Elblog instance"
:group 'elblog
:type '(alist :key-type regexp :value-type function))
;; Declare user-configurable variables needed at runtime.
(defvar elblog-articles (ht-create)
"A hash-table of blog articles. This is used for looking up articles from
URL fragments as well as for rendering the index.")
;; HTML templating setup
(defun template-preamble ()
"Templates the preamble snippet with the correct blog title."
(format (f-read-text "preamble.html") elblog-title))
(defun configure-org-html-export ()
"Configure org-mode settings for elblog's HTML templating to work correctly."
(setq org-html-postamble t)
(setq org-html-doctype "html5")
(setq org-html-head-include-scripts nil)
(setq org-html-style-default (f-read-text "blog.css"))
(setq org-html-preamble-format `(("en" ,(template-preamble))))
(setq org-html-postamble-format `(("en" ,(f-read-text "postamble.html")))))
;; Article fetching & rendering functions
(defun render-org-buffer (input-buffer &optional force)
"Renders an org-mode buffer as HTML and returns the name of the output buffer."
(letrec ((output-buffer (concat (buffer-name input-buffer) "-rendered"))
;; Don't re-render articles unless forced.
(must-render (or force
(not (get-buffer output-buffer)))))
(if (and input-buffer must-render)
(with-current-buffer input-buffer
(org-export-to-buffer 'html output-buffer nil nil t)))
(if input-buffer output-buffer nil)))
(defun get-buffer-string (buffer)
"Returns the contents of the specified buffer as a string."
(with-current-buffer (get-buffer buffer)
(buffer-string)))
(defvar-local article-not-found
'(404 . "<html><body><p>Oh no, the article was not found.</p></body></html>"))
(defvar-local text-html '("Content-Type" . "text/html"))
(defun render-article (article)
"Renders an article, if it exists."
(letrec ((rendered (-some->>
(ht-get elblog-articles article)
(concat elblog-article-directory)
(find-file)
(render-org-buffer))))
(if rendered `(200 . ,(get-buffer-string rendered))
article-not-found)))
(defun blog-post-handler (httpcon)
"This handler servers a blog post from the configured blog post directory."
(let ((response (render-article (elnode-http-mapping httpcon 1))))
(elnode-http-start httpcon (car response) text-html)
(elnode-http-return httpcon (cdr response))))
;; Web server implementation
(defvar elblog-routes
'(("^.*//\\(.*\\)" . blog-post-handler))
"The default routes available in elblog. They can be extended by the user
by setting the elblog-additional-routes customize option.")
(defun elblog-handler (httpcon)
(elnode-hostpath-dispatcher
httpcon
(-concat elblog-additional-routes elblog-routes)))
(defun start-elblog ()
(interactive)
(configure-org-html-export)
(elnode-start 'elblog-handler
:port elblog-port
:host elblog-host))
(defun stop-elblog ()
(interactive)
(elnode-stop elblog-port))
(provide 'elblog)