Support timestring.el

Quickly access strings that encode time is various formats. See the module docs
in timestring.el for more information.

emacs/.emacs.d/init.el

@@ -28,6 +28,7 @@
 ;; TODO: Consider renaming entr.el.
 (require 'entr)
 (require 'scrot)
+(require 'timestring)
 
 ;; TODO: Remove path once published to MELPA.
 ;; TODO: How can I package this using Nix?

emacs/.emacs.d/wpc/timestring.el

@@ -0,0 +1,71 @@
+;;; timestring.el --- Quickly access timestamps in different formats -*- lexical-binding: t -*-
+
+;; Author: William Carroll <wpcarro@gmail.com>
+;; Version: 0.0.1
+;; Package-Requires: ((ts "0.2") (emacs "25.1"))
+;; Homepage: https://user.git.corp.google.com/wpcarro/briefcase
+
+;;; Commentary:
+
+;; I was making some API calls where a URL needed a `since` parameter that of an
+;; RFC 3339 encoded string.
+;;
+;; Because I didn't know what a RFC 3339 encoded
+;; string was at the time, and because I didn't know what its format was
+;; according to strftime, and because I'm most likely to forget both of these
+;; things by the next time that I need something similar, I decided to write
+;; this package so that I can accumulate a list of common time encodings.
+;;
+;; Thank you, Emacs.
+;;
+;; p.s. - I may turn this into a proper module and publish it.  But not today.
+
+;;; Code:
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 'ts)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defcustom timestring-supported-encodings
+  '(("RFC 3339" . "%Y-%m-%dT%H:%M:%SZ")
+    ;; Does anyone recognize this format?
+    ("IDK" . "%Y-%m-%d %H:%M:%S %z"))
+  "Mapping of encoding names to their format strings.")
+
+(defcustom timestring-supported-times
+  '(("yesterday" . timestring--yesterday)
+    ("now" . ts-now)
+    ("tomorrow" . timestring--tomorrow))
+  "Mapping of a labels to the functions that create those time objects.")
+
+(defun timestring--yesterday ()
+  "Return a time object for yesterday."
+  (ts-adjust 'day -1 (ts-now)))
+
+(defun timestring--tomorrow ()
+  "Return a time object for yesterday."
+  (ts-adjust 'day +1 (ts-now)))
+
+(defun timestring--completing-read (label xs)
+  "Call `completing-read' with LABEL over the collection XS."
+  (alist-get (completing-read label xs) xs nil nil #'equal))
+
+(defun timestring-copy-encoded-time ()
+  "Select a common time and then select an encoding.  The selected time will be
+encoded using the selected encoding and copied onto your clipboard."
+  (interactive)
+  (let ((time (funcall (timestring--completing-read
+                        "Time: " timestring-supported-times)))
+        (fmt (timestring--completing-read
+              "Encoding: " timestring-supported-encodings)))
+    (kill-new (ts-format fmt time))
+    (message "Copied!")))
+
+(provide 'timestring)
+;;; timestring.el ends here