change-theme-on-brightness

#!/bin/bash

# Variables
ADB="adb -s 52105802eed17447"
THRESHOLD=35
INTERVAL=1
INTERVAL_ERROR=300
GTK3_SETTINGS="$HOME/.config/gtk-3.0/settings.ini"
GTK3_OPTION="gtk-application-prefer-dark-theme"
GTK4_OPTION="org.gnome.desktop.interface color-scheme"

# Functions
set_gtk3 () {
    [[ "$CUR_GTK3" == "$1" ]] && return 0
    sed -i 's/^'${GTK3_OPTION}'=[0-1]$/'${GTK3_OPTION}'='${1}'/' $GTK3_SETTINGS &>/dev/null
    CUR_GTK3="$1"
}
set_gtk4 () {
    [[ "$CUR_GTK4" == "$1" ]] && return 0
    gsettings set $GTK4_OPTION "prefer-${1}"
    CUR_GTK4="$1"
}
set_theme () { 
    [[ "$1" == 0 ]] && THEME=light || THEME=dark
    set_gtk3 $1
    set_gtk4 $THEME
}

# Get the current values ( ran only once at the start of the script )
CUR_GTK3=$(grep "$GTK3_OPTION" "$GTK3_SETTINGS" | grep -o "[0-1]$")
CUR_GTK4=$(gsettings get $GTK4_OPTION | tr -d "'" | cut -d'-' -f2)

while true ; do
    # Executed every $INTERVAL second(s)
    BRIGHTNESS="$($ADB shell cat /sys/class/sensors/light_sensor/lux | cut -d',' -f4)" || (sleep $INTERVAL_ERROR ; continue)
    if [ "$BRIGHTNESS" -gt "$THRESHOLD" ] ; then
        set_theme 0 # Light
    else
        set_theme 1 # Dark
    fi
    sleep $INTERVAL
done