From 3167e1e9e2389e0b17435c6fd336acd3c02ef5cc Mon Sep 17 00:00:00 2001
From: Florian Obser <fobser@ripe.net>
Date: Wed, 5 Apr 2023 18:17:33 +0200
Subject: [PATCH] I wrote some code to find and read IETF documents in Emacs.

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+#+TITLE: Emacs IETF
+#+DATE: 2023-04-05
+* Prologue
+Some years ago I discovered [[https://github.com/paulehoffman/ietf-cli][ietf-cli]] in OpenBSD ports. It creates a
+local mirror of IETF drafts, RFCs and other files and makes them
+accessible from the command line. I have it configured to use
+Emacs for the pager[fn::Like normal people... I uses emacsclient for
+performance reasons.].
+
+I was never too happy about the cli interface though. While it is open
+source I never got around to hack on it or to send feature
+requests. These are the things I do not like. Most of them are a
+question of work flow more than limitations of the =ietf= tool:
+1. I never figured out how to configure tab-completion in my shell for it.
+2. I am not yet running a shell inside of Emacs, so it breaks my
+   work flow when reading a draft and I want to quickly open an RFC
+   for reference.
+3. The tool is pretty opinionated. You need to call just so for it do
+   what you ask. To open an RFC you need to type =ietf rfc 1925=. It
+   will not accept =ietf RFC1925= or =ietf rfc1925=. That means that
+   copy & paste does not work most of the time.
+
+More recently I discovered the [[https://github.com/minad/vertico][vertico]] completion extension combined
+with [[https://github.com/oantolin/orderless][orderless]] completion. Those two extensions provide the kind of
+completion I want for RFCs and even more so for drafts:
+#+begin_quote
+[Orderless] divides the pattern into space-separated components, and
+matches candidates that match all of the components in any order.
+#+end_quote
+* Emacs-lisp
+The =ietf= tool provides the =mirror= command that rsyncs the IETF
+documents to a configurable folder. Reading an RFC or draft then
+comes down to opening the correct file. So we can copy the code of
+=find-file=, change =default-directory= and we are good to go:
+
+#+begin_src emacs-lisp
+  ;; were ietf mirror stores the local mirror
+  (setq ietf-mirror "~/ietf-mirror/")
+
+  ;; look for drafts in the 'short-id/' sub-directory and make sure the
+  ;; buffer is a read-only text buffer.
+
+  (defun ietf-draft (filename &optional wildcards)
+    (interactive
+     (let
+         ((default-directory (concat ietf-mirror "short-id/")))
+       (find-file-read-args "Find file: "
+                            (confirm-nonexistent-file-or-buffer))))
+    (let ((value (find-file-noselect filename nil nil wildcards)))
+      (if (listp value)
+          (mapcar 'pop-to-buffer-same-window (nreverse value))
+        (pop-to-buffer-same-window value))
+      (read-only-mode)
+      (text-mode)))
+
+  ;; RFCs are stored in 'in-notes/'
+  (defun ietf-rfc (filename &optional wildcards)
+    (interactive
+     (let
+         ((default-directory (concat ietf-mirror "in-notes/"))
+          (completion-ignored-extensions
+           '("/" ".html" ".json" ".pdf" ".ps" ".tar" ".xml" ".xsd")))
+       (find-file-read-args "Find file: "
+                            (confirm-nonexistent-file-or-buffer))))
+    (let ((value (find-file-noselect filename nil nil wildcards)))
+      (if (listp value)
+          (mapcar 'pop-to-buffer-same-window (nreverse value))
+        (pop-to-buffer-same-window value))
+      (read-only-mode)
+      (text-mode)))
+#+end_src
+
+Setting a global key binding lets us open RFCs and drafts from
+anywhere within Emacs:
+#+begin_src emacs-lisp
+  (global-set-key (kbd "C-c i d") 'ietf-draft)
+  (global-set-key (kbd "C-c i r") 'ietf-rfc)
+#+end_src
+* Epilogue
+The =ietf= tool has many more options that I have not explored or used
+yet. =rfc= and =draft= are the two main commands I am using and on
+occasion I am using the diff tool.
+
+I will keep the tool around to keep the mirror up2date and for the
+occasional use of =diff=. Having moved the functionality I use most
+often into Emacs and making it behave like I want it is a huge
+improvement.