Copy and set your current GTK3 theme over another's Flatpak theme

flatpak-theme-takeover.sh

#!/bin/bash

# Copy and set your current GTK3 theme over another's Flatpak theme.
# It's like a raider takeover of some Flatpak theme 😁 🙃.
# NOTICE: some Flatpak theme must be already installed.
#
# What if you set your custom GTK3 theme for your desktop and want it for Flatpak?
# Use this script to takeover of another's Flatpak theme and set it!

USAGE(){
    echo "Copy and set your current GTK3 theme over the chosen Flatpak installed theme:"
    echo "   ${0##*/} [OPTIONS] choose.the.Gtk3Flatpak.Theme"
    echo
    echo " Options:"
    echo "   -t Theme-Name   Specify theme name (Use it if you want to set other than your current theme)."
    echo "   -o              Make flatpak overrides in userspace dir (set global override for env and for themes)."
    echo "   -O              Make flatpak overrides in system dir (set global override for env and for themes)."
    echo "   -u              Use it if your host theme is in the userspace directory (~/.themes "
    echo "                    or ~/.local/share/themes), otherwise it assume to be in the system directory."
    echo "   -h              This help."
    echo " Examples:"
    echo "   Set your current theme over SomeFlatpakTheme:"
    echo "     ${0##*/} -o org.gtk.Gtk3theme.SomeFlatpakTheme"
    echo "   If you want to set another than current theme, e.g. 'Theme-Name':"
    echo "     ${0##*/} -o -t Theme-Name org.gtk.Gtk3theme.SomeFlatpakTheme"
    echo
    echo "   Don't forget to install some Flatpak theme before run."
    exit $1
}

# Set variables defaults
override=false;userspace=false;xfce=false;fuserspace=true;

# Command line options
while getopts "ht:oOu\?" opt; do
	case "$opt" in
		h ) USAGE 1;                                  ;;
		t ) host_theme_name="$OPTARG";                ;;
		o ) override=true;                            ;;
		O ) override=true; fuserspace=false;          ;;
		u ) userspace=true;                           ;;
		\?) USAGE 1;                                  ;;
		* ) echo "Unknown option '$opt'"; USAGE 1;    ;;
	esac
done
shift $(($OPTIND -1))

# Set variables
user_confdir="${XDG_CONFIG_HOME:-$HOME/.config}"
user_themes_dir="${XDG_DATA_HOME:-$HOME/.local/share}"/themes
[ -d "$user_themes_dir" ] || user_themes_dir="${HOME}/.themes"
sys_themes_dir="/usr/share/themes"
if [ -z "$host_theme_name" ]; then
    xfconf-query -V >& /dev/null
    hasxfce=$?
    if ! ((hasxfce == 127)); then
        xfce=true
        host_theme_name="$(xfconf-query -c xsettings -p /Net/ThemeName -n)"
    elif [ -f "${user_confdir}/gtk-3.0/settings.ini" ]; then
        host_theme_name="$(cat "$user_confdir"/gtk-3.0/settings.ini | grep -m1 "^ *\?gtk-theme-name=" | cut -d = -f 2)"
    else
        host_theme_name="$(gsettings get org.gnome.desktop.interface gtk-theme|cut -d \' -f 2)"
    fi
fi
if [ -z "$host_theme_name" ]; then
    echo "Specify you current theme with: -t Theme-Name"
    USAGE 1
fi

if $userspace; then
    host_theme_dir="$user_themes_dir"/"$host_theme_name"
else
    host_theme_dir="$sys_themes_dir"/"$host_theme_name"
fi

flat_theme_name="${1##*.}"
flat_theme_dir="$(flatpak info --show-location ${1} 2>/dev/null)"
if [ -z "$flat_theme_dir" ]; then
    echo -e "${1} not installed\nAborting."
    exit 1
fi

# Overwrite Flatpak theme
expr "$flat_theme_dir" : '^/home' >& /dev/null && cp_cmd="cp" || cp_cmd="sudo cp"
if [ -d "$host_theme_dir" ]; then
    if [ -e "$host_theme_dir"/gtk-3.0/gtk.css ]; then
            $cp_cmd "$(readlink -f "$host_theme_dir"/gtk-3.0/gtk.css)" "$flat_theme_dir"/files/gtk.css
    else
            echo -e "No such file "$host_theme_dir"/gtk-3.0/gtk.css\nAborting."
            exit 1
    fi
    if [ -e "$host_theme_dir"/gtk-3.0/assets ]; then
        $cp_cmd -r "$(readlink -f "$host_theme_dir"/gtk-3.0/assets)" "$flat_theme_dir"/files/; fi
    if [ -e "$host_theme_dir"/gtk-3.0/gtk.gresource ]; then
        $cp_cmd "$(readlink -f "$host_theme_dir"/gtk-3.0/gtk.gresource)" "$flat_theme_dir"/files/; fi
else
    echo -e "No such directory ${host_theme_dir}\nAborting."
    exit 1
fi

# Override Flatpak stuff
if $override; then
    if $fuserspace; then
        # Override to ~/.local/share/flatpak/overrides/global
        echo " override: env: GTK_THEME=${flat_theme_name}"
        flatpak -u override --env=GTK_THEME="$flat_theme_name"
        echo " override: filesystem: xdg-data/themes"
        flatpak -u override --filesystem=xdg-data/themes
    else
        # Override to /var/lib/flatpak/overrides/global
        echo " override: env: GTK_THEME=${flat_theme_name}"
        sudo flatpak override --env=GTK_THEME="$flat_theme_name"
        echo " override: filesystem: xdg-data/themes"
        sudo flatpak override --filesystem=xdg-data/themes
    fi
fi
    
# Set taken over theme for apps
for dir in ${HOME}/.var/app/*; do
    flat_confdir="${dir}/config/gtk-3.0"
    mkdir -p "$flat_confdir"
    cp "${user_confdir}/gtk-3.0/settings.ini" "${flat_confdir}"/
    sed -ri "\:^\s*?gtk-theme-name=:s/(gtk-theme-name=).*/\1"$flat_theme_name"/" "$flat_confdir"/settings.ini

    if $xfce; then
        flat_xfconfdir="${dir}/config/xfce4/xfconf/xfce-perchannel-xml"
        mkdir -p "$flat_xfconfdir"
        cp "${user_confdir}/xfce4/xfconf/xfce-perchannel-xml/xsettings.xml" "$flat_xfconfdir"/
        sed -ri '\:name="ThemeName":s/(value=)".+?"/\1"'$flat_theme_name'"/' "$flat_xfconfdir"/xsettings.xml
    fi
    flatpak info "${dir##*/}" >& /dev/null && \
        flatpak run --command=bash<<<"gsettings set org.gnome.desktop.interface gtk-theme $flat_theme_name" "${dir##*/}"
done