DE Night Mode scripts

DE Night mode

An often-requested feature is the possibility to change DE theme automatically, shifting from a light one during the day, to a dark one, during the night.

While Clight won't add support for DE-specific code, the feature can be achieved quite easily through its bus api: you can listen on "Time" PropertiesChanged signal that is emitted at Sunrise and Sunset.
Such a script could look like:

1. KDE
2. Gnome
3. Cinnamon
4. Xfce

KDE

#!/usr/bin/env python

import dbus
import subprocess
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop

old_time = -1; # 0 -> day, 1 -> night

def handle_time_change(*args):
    global old_time
    if 'DayTime' in args[1] and old_time != args[1]['DayTime']:
        if args[1]['DayTime'] == 1:
            subprocess.Popen(["lookandfeeltool", "-a", "org.kde.breezedark.desktop"])
        elif args[1]['DayTime'] == 0:
            subprocess.Popen(["lookandfeeltool", "-a", "org.kde.breeze.desktop"])
        old_time = args[1]['DayTime']

DBusGMainLoop(set_as_default=True)
bus = dbus.SessionBus()
bus.add_signal_receiver(
    handle_time_change,
    'PropertiesChanged',
    'org.freedesktop.DBus.Properties',
    path='/org/clight/clight'
)

loop = GLib.MainLoop().run()

Gnome

#!/usr/bin/env python

import dbus
import subprocess
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop

old_time = -1; # 0 -> day, 1 -> night

def handle_time_change(*args):
    global old_time
    if 'DayTime' in args[1] and old_time != args[1]['DayTime']:
        if args[1]['DayTime'] == 1:
			# Applications
			subprocess.Popen(["gsettings set org.gnome.desktop.interface gtk-theme", "Matcha-dark-sea"])
			# Cursor
			subprocess.Popen(["gsettings set org.gnome.desktop.interface cursor-theme", "xcursor-breeze-snow"])
			# Icons
			subprocess.Popen(["gsettings set org.gnome.desktop.interface icon-theme", "Papirus-Dark-Maia"])
			# Shell
			subprocess.Popen(["gsettings set org.gnome.shell.extensions.user-theme name", "Matcha-dark-sea"])
        elif args[1]['DayTime'] == 0:
			# Applications
			subprocess.Popen(["gsettings set org.gnome.desktop.interface gtk-theme", "Matcha-sea"])
			# Cursor
			subprocess.Popen(["gsettings set org.gnome.desktop.interface cursor-theme", "xcursor-breeze"])
			# Icons
			subprocess.Popen(["gsettings set org.gnome.desktop.interface icon-theme", "Papirus-Maia"])
			# Shell
			subprocess.Popen(["gsettings set org.gnome.shell.extensions.user-theme name", "Matcha-sea"])
        old_time = args[1]['DayTime']

DBusGMainLoop(set_as_default=True)
bus = dbus.SessionBus()
bus.add_signal_receiver(
    handle_time_change,
    'PropertiesChanged',
    'org.freedesktop.DBus.Properties',
    path='/org/clight/clight'
)

loop = GLib.MainLoop().run()

Cinnamon

#!/usr/bin/env python

import dbus
import subprocess
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop

old_time = -1; # 0 -> day, 1 -> night

def handle_time_change(*args):
    global old_time
    if 'DayTime' in args[1] and old_time != args[1]['DayTime']:
        if args[1]['DayTime'] == 1:
			# Window borders
			subprocess.Popen(["gsettings set org.cinnamon.desktop.wm.preferences theme", "Matcha-dark-sea"])
			# Icons
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface icon-theme", "Papirus-Dark-Maia"])
			# Controls
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface gtk-theme", "Matcha-dark-sea"])
			# Mouse Pointer
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface cursor-theme", "xcursor-breeze-snow"])
			# Desktop
			subprocess.Popen(["gsettings set org.cinnamon.theme name", "Matcha-dark-sea"])
        elif args[1]['DayTime'] == 0:
			# Window borders
			subprocess.Popen(["gsettings set org.cinnamon.desktop.wm.preferences theme", "Matcha-sea"])
			# Icons
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface icon-theme", "Papirus-Maia"])
			# Controls
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface gtk-theme", "Matcha-sea"])
			# Mouse Pointer
			subprocess.Popen(["gsettings set org.cinnamon.desktop.interface cursor-theme", "xcursor-breeze"])
			# Desktop
			subprocess.Popen(["gsettings set org.cinnamon.theme name", "Matcha-sea"])
        old_time = args[1]['DayTime']

DBusGMainLoop(set_as_default=True)
bus = dbus.SessionBus()
bus.add_signal_receiver(
    handle_time_change,
    'PropertiesChanged',
    'org.freedesktop.DBus.Properties',
    path='/org/clight/clight'
)

loop = GLib.MainLoop().run()

Xfce

#!/usr/bin/env python

import dbus
import subprocess
from gi.repository import GLib
from dbus.mainloop.glib import DBusGMainLoop

old_time = -1; # 0 -> day, 1 -> night

def handle_time_change(*args):
    global old_time
    if 'Time' in args[1] and old_time != args[1]['Time']:
        if args[1]['Time'] == 1:
            # GTK theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Net/ThemeName -s", "Matcha-dark-sea"])
            # Xfwm4 theme
            subprocess.Popen(["xfconf-query -c xfwm4 -p /general/theme -s", "Matcha-dark-sea"])
            # Cursor theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Gtk/CursorThemeName -s", "xcursor-breeze-snow"])
            # Icon theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Net/IconThemeName -s", "Papirus-Dark-Maia"])
        elif args[1]['Time'] == 0:
            # GTK theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Net/ThemeName -s", "Matcha-sea"])
            # Xfwm4 theme
            subprocess.Popen(["xfconf-query -c xfwm4 -p /general/theme -s", "Matcha-sea"])
            # Cursor theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Gtk/CursorThemeName -s", "xcursor-breeze"])
            # Icon theme
            subprocess.Popen(["xfconf-query -c xsettings -p /Net/IconThemeName -s", "Papirus-Maia"])
        old_time = args[1]['Time']

DBusGMainLoop(set_as_default=True)
bus = dbus.SessionBus()
bus.add_signal_receiver(
    handle_time_change,
    'PropertiesChanged',
    'org.freedesktop.DBus.Properties',
    path='/org/clight/clight'
)

loop = GLib.MainLoop().run()

Thanks @yochananmarqos for Gnome and Cinnamon scripts!
You can even just change your wallpaper with similar scripts, or whatever you'll come up with!
Happy scripting!