dotfiles/home/.local/bin/scripts/brightness

#!/bin/sh

BRIGHTNESS_FILE="/sys/class/backlight/intel_backlight/brightness"
BRIGHTNESS_MAX=937

function change_brightness() {
    BRIGHTNESS=$(cat $BRIGHTNESS_FILE)

    change_value=$2

    # If we're dealing with percentages, convert to absolutes
    if [ $3 == "%" ]; then
        change_value=$((($BRIGHTNESS_MAX / 100) * $change_value))
    elif [ $3 == "#" ]; then
        change_value=$change_value
    else
        echo "Invalid unit, options: [% - percent, # - absolute], default: %"
        exit 1
    fi

    # Increment or decrement based on first arg
    if [ $1 == "+" ]; then
        new_brightness=$(($BRIGHTNESS + $change_value))
    elif [ $1 == "-" ]; then
        new_brightness=$(($BRIGHTNESS - $change_value))
    else
        echo "Invalid operator, options: [+, -]"
        exit 1
    fi

    # Make sure we respect min/max boundaries
    if [ $new_brightness -lt 0 ]; then
        new_brightness=0
    elif [ $new_brightness -gt $BRIGHTNESS_MAX ]; then
        new_brightness=$BRIGHTNESS_MAX
    fi

    # Write the brightness (sudo shouldn't require password here)
    echo $new_brightness | sudo tee $BRIGHTNESS_FILE
}

if [ $# -ge 1 ] && [ "$1" == "+" ] || [ "$1" == "-" ]; then
    if [ $# -lt 2 ]; then
        change_value=5 # Default to 5%
    else
        change_value=$2
    fi

    if [ $# -lt 3 ]; then
        unit="%"
    else
        unit=$3
    fi
    change_brightness $1 $change_value $unit > /dev/null
fi

# Display new brightness

BRIGHTNESS=$(cat $BRIGHTNESS_FILE)
BRIGHTNESS_PERCENT=$(echo "($BRIGHTNESS / $BRIGHTNESS_MAX) * 100" | bc -l)
BRIGHTNESS_PERCENT=$(printf "%.2f" $BRIGHTNESS_PERCENT)

echo "Brightness: ${BRIGHTNESS_PERCENT}% (absolute: $BRIGHTNESS)"