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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) |