nyaa

battery.scm

@@ -0,0 +1,56 @@
+;;; Battery monitoring daemon script.
+
+(import shell)
+
+(import srfi-1)
+
+;;; Constant values.
+
+;;; Battery level control interval, in seconds.
+
+(define +check-interval+ 5) 
+
+;;; Path to the virtual file containing the battery percentage number.
+
+(define +capacity-path+ "/sys/class/power_supply/BAT1/capacity")
+
+;;; Association list of threshold levels and formatting functions.
+
+(define +thresholds+
+  `((20 . ,(lambda (battery-level)
+	     (string-append "Battery level low: " (number->string battery-level) "%.")))
+    (5 . ,(lambda (battery-level)
+	    (string-append "Battery level critical: " (number->string battery-level) "%.")))))
+
+;;; Utility functions.
+
+;;; Get the battery level, return it as a number.
+
+(define (get-battery-level)
+  (with-input-from-file +capacity-path+ read))
+
+;;; Method to display a notification dialog.
+
+(define (user-notify message)
+  (run ("notify-send '" ,message "'")))
+
+;;; Core daemon loop.
+
+(define (core previous-level)
+  (let ((current-level (get-battery-level)))
+    (let ((crossed-thresholds
+	   (filter (lambda (n)
+		     (and (>= n current-level)
+			  (< n previous-level)))
+		   (map car +thresholds+))))
+      (if (not (null? crossed-thresholds))
+	  (user-notify ((cdr (assoc (last crossed-thresholds) +thresholds+)) current-level))))
+    (sleep +check-interval+)
+    (core current-level)))
+
+;;; Entry point of the program.
+
+(define (main)
+  (core 100))
+
+(main)