1 files changed, 46 insertions, 21 deletions

@@ -1,4 +1,13 @@
-;;; dawn.el --- Do things at dawn (and dusk) -*- lexical-binding: t; -*-
+;;; dawn.el --- Lightweight dawn/dusk task scheduling -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2022 Case Duckworth
+
+;; Author: Case Duckworth
+;; Maintainer: Case Duckworth <acdw@acdw.net>
+;; URL: https://codeberg.org/acdw/dusk.el
+;; Version: 0.3.0
+;; Keywords: calendar, themes, convenience
+;; Package-Requires: ((emacs "24.3"))
 
 ;;; Commentary:
 
@@ -12,6 +21,8 @@
 (require 'cl-lib)
 (require 'solar)
 
+;;; Timers
+
 (defvar dawn--dawn-timer nil
   "Timer for dawn-command.")
 
@@ -21,16 +32,19 @@
 (defvar dawn--reset-timer nil
   "Timer to reset dawn at midnight.")
 
+;;; Functions
+
 (defun dawn-encode-time (f)
-  "Encode fractional time F."
-  (let ((hhmm (cl-floor f))
-        (date (cdddr (decode-time))))
-    (encode-time
-     (append (list 0
-                   (round (* 60 (cadr hhmm)))
-                   (car hhmm)
-                   )
-             date))))
+  "Encode fractional time F.
+If F is nil, return nil."
+  (when f
+    (let ((hhmm (cl-floor f))
+          (date (cdddr (decode-time))))
+      (encode-time
+       (append (list 0
+                     (round (* 60 (cadr hhmm)))
+                     (car hhmm))
+               date)))))
 
 (defun dawn-midnight ()
   "Return the time of the /next/ midnight."
@@ -46,22 +60,34 @@
   "Return the time of today's sunset."
   (dawn-encode-time (caadr (solar-sunrise-sunset (calendar-current-date)))))
 
+;;; Interface
+
+;;;###autoload
 (defun dawn-schedule (dawn-command dusk-command)
   "Run DAWN-COMMAND at sunrise, and DUSK-COMMAND at dusk.
-RESET is an argument for internal use."
+Requires `calendar-longitude' and `calendar-latitude' to be set;
+if they're not, it will prompt the user for them or error."
   (when (or (null calendar-longitude)
-            (null calendar-latitude))
-    (user-error "`dawn' won't work without setting %s!"
-                (cond ((and (null calendar-longitude)
-                            (null calendar-latitude))
-                       "`calendar-longitude' and `calendar-latitude'")
-                      ((null calendar-longitude)
-                       "`calendar-longitude'")
-                      ((null calendar-latitude)
-                       "`calendar-latitude'"))))
+            (null calendar-latitude))
+    (or (solar-setup)
+        (user-error "`dawn' won't work without setting %s!"
+                    (cond ((and (null calendar-longitude)
+                                (null calendar-latitude))
+                           "`calendar-longitude' and `calendar-latitude'")
+                          ((null calendar-longitude)
+                           "`calendar-longitude'")
+                          ((null calendar-latitude)
+                           "`calendar-latitude'")))))
   (let ((dawn (dawn-sunrise))
         (dusk (dawn-sunset)))
     (cond
+     ((or (null dawn) (null dusk))
+      ;; There is no sunrise or sunset, due to how close we are to the poles.
+      ;; In this case, we must figure out whether it's day or night.
+      (pcase (caddr (solar-sunrise-sunset (calendar-current-date)))
+        ("0:00" (funcall dusk-command))  ; 0 hours of daylight
+        ("24:00" (funcall dawn-command)) ; 24 hours of daylight
+        ))
      ((time-less-p nil dawn)
       ;; If it isn't dawn yet, it's still dark.  Run DUSK-COMMAND and schedule
       ;; DAWN-COMMAND and DUSK-COMMAND for later.
@@ -76,7 +102,6 @@ RESET is an argument for internal use."
      (t ;; Otherwise, it's past dusk, so run DUSK-COMMAND.
       (funcall dusk-command)))
     ;; Schedule a reset at midnight, to re-calculate dawn/dusk times.
-    ;(unless reset)
     (run-at-time (dawn-midnight) nil
                  #'dawn-schedule dawn-command dusk-command)))