#!/bin/bash
[[ $EUID -eq 0 ]] || {
	echo "root access required" >&2
	exit 1
}

MAX_CHARGE_THRESHOLD=$1
[ "$MAX_CHARGE_THRESHOLD" ] \
	|| MAX_CHARGE_THRESHOLD=75

DEVICE_SETTING_FILE=/sys/class/power_supply/BAT1/charge_control_end_threshold

[ "$MAX_CHARGE_THRESHOLD" ] && [[ $MAX_CHARGE_THRESHOLD -ge 40 ]] && [[ $MAX_CHARGE_THRESHOLD -le 100 ]] || {
	echo -e "Value '$MAX_CHARGE_THRESHOLD' is invalid. If you REALLY want to do this, overwrite the setting yourself\n$DEVICE_SETTING_FILE" >&2
	exit 2
}

echo "$MAX_CHARGE_THRESHOLD" > "$DEVICE_SETTING_FILE"