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