#!/bin/bash

# Exit out if the same script is already running in the background
pidof -sq -o %PPID -x "$(basename "$0")" && exit

# Set the directory/file paths
flatpak_themes_dir="$HOME/.themes"
flatpak_icons_dir="$HOME/.icons"
profile="$HOME/.profile"

# Create flatpak icons & themes directories if they don't exist
mkdir -p "$flatpak_themes_dir" "$flatpak_icons_dir" ||
	{ echo "failed to make directories $flatpak_themes_dir & $flatpak_icons_dir"; exit 1; }

# Enable option for syncing the current theme with XFWM theme if not already enabled
[ "$(xfconf-query -c xsettings -p /Xfce/SyncThemes)" != 'true' ] && xfconf-query -c xsettings -p /Xfce/SyncThemes -n -t bool -s true

xdg_directory_lookup() {
	# Go through each item in $XDG_DATA_DIRS and find the subdirectory $1
	while read -r dir; do
		subdir="${dir%/}/$1"
		if [ -d "$subdir" ]; then
			echo "$subdir"
			break
		fi
	done < <(printf '%s:%s\n' "$HOME/.local/share" "$XDG_DATA_DIRS" | tr ':' '\n')
}

# Function for setting variables in ~/.profile
profile_set_variable() {
	# Return if the variable is already set to the correct value
	grep -xq "\s*export\s\+$1=$2\s*" "$profile" && return
	# If the variable is set to a different value then remove that line
	grep -q "^\s*export\s\+$1=" "$profile" && sed -i "/^\s*export\s\+$1=/d" "$profile"

	# Set the variable to the correct value under a comment mentioning this script
	if grep -xq '\s*#\s*Values set by the fix-theming script\s*' "$profile"; then
		sed -i "/^\s*#\s*Values set by the fix-theming script\s*$/a export $1=$2" "$profile"
	elif grep -q '\s' "$profile"; then
		tail -n1 "$profile" | grep -qx '\s*' && begin='' || begin='\n'
		printf '%b# Values set by the fix-theming script\nexport %s=%s\n' "$begin" "$1" "$2" >> "$profile"
	else
		printf '# Values set by the fix-theming script\nexport %s=%s\n' "$1" "$2" > "$profile"
	fi
	# Set variable logout_required to true
	logout_required='true'
}

hdpi_theme_fix() {
	# Get the current window scaling factor (highDPI setting)
	current_scaling=$(xfconf-query -c xsettings -p /Gdk/WindowScalingFactor)
	# Get the current XFWM theme
	current_xfwm_theme=$(xfconf-query -c xfwm4 -p /general/theme)
	# Get the current mouse cursor size
	cursor_size=$(xfconf-query -c xsettings -p /Gtk/CursorThemeSize)

	unset logout_required

	if [ "$current_scaling" -eq '2' ]; then
		# Increase mouse cursor size if it's equal to 25
		if [ "$cursor_size" -eq 25 ]; then
			xfconf-query -c xsettings -p /Gtk/CursorThemeSize -s '45'
			notify-send 'Mouse cursor size increased to 45' "Changed to a larger mouse cursor because you've enabled highDPI on your system"
		fi
		# Increase scaling for QT apps
		for var in QT_SCALE_FACTOR QT_AUTO_SCREEN_SCALE_FACTOR QT_ENABLE_HIGHDPI_SCALING; do
			profile_set_variable "$var" 2
		done
		for variant in xhdpi hdpi; do
			# If this variant of the theme is already enabled then break out of the loop
			[ "${current_xfwm_theme##*-}" = "$variant" ] && break
			# Store the name for this variant of the theme in highDPI_theme variable
			highDPI_theme=$current_xfwm_theme-$variant
			# Find the directory where highDPI_theme is stored
			highDPI_theme_dir=$(xdg_directory_lookup "themes/$highDPI_theme")
			# If this directory exists then change to that theme for XFWM
			if [ -d "$highDPI_theme_dir" ]; then
				xfconf-query -c xfwm4 -p /general/theme -n -t string -s "$highDPI_theme"
				[ "$1" != 'no_hdpi_notification' ] && notify-send "XFWM theme changed to $highDPI_theme" "Changed to the highDPI variant of your chosen theme because you've enabled highDPI on your system"
				break
			fi
		done
	else
		# Decrease mouse cursor size if it's equal to 45
		if [ "$cursor_size" -eq 45 ]; then
			xfconf-query -c xsettings -p /Gtk/CursorThemeSize -s '25'
			notify-send 'Mouse cursor size decreased to 25' "Changed to a smaller mouse cursor because you've disabled highDPI on your system"
		fi
		# Decrease scaling for QT apps
		unset logout_required
		for var in QT_SCALE_FACTOR QT_AUTO_SCREEN_SCALE_FACTOR QT_ENABLE_HIGHDPI_SCALING; do
			profile_set_variable "$var" 1
		done
		for variant in xhdpi hdpi; do
			# Continue looping if this (highDPI) variant of the theme is not enabled
			[ "${current_xfwm_theme##*-}" != "$variant" ] && continue
			# Store the name for the normal variant of this theme in normal_theme variable
			normal_theme=${current_xfwm_theme%-"$variant"}
			# Find the directory where normal_theme is stored
			normal_theme_dir=$(xdg_directory_lookup "themes/$normal_theme")
			# If this directory exists then change to that theme for XFWM
			if [ -d "$normal_theme_dir" ]; then
				xfconf-query -c xfwm4 -p /general/theme -n -t string -s "$normal_theme"
				notify-send "XFWM theme changed to $normal_theme" "Changed to the normal variant of your chosen theme because you've disabled highDPI on your system"
				break
			fi
		done
	fi
	# Show popup menu about logout if it's required
	[ "$logout_required" = 'true' ] &&
		yad  --image "dialog-question" --title "Alert" --buttons-layout=center --text-align=center --button=yad-yes:0 --button=yad-no:1 --text 'Logout is required in order to apply the DPI preferences to the QT apps.\nWould you like to logout now?' &&
		xfce4-session-logout --logout
}

sync_theme() {
	# Get the current system theme
	current_theme=$(xfconf-query -c xsettings -p /Net/ThemeName)

	# Apply the current theme with gsettings
	gsettings set org.gnome.desktop.interface gtk-theme "$current_theme"

	# Apply the current theme for GTK and Libadwaita apps on flatpak
	flatpak override --user --env=GTK_THEME="$current_theme"

	# Apply the current theme for XFWM
	xfconf-query -c xfwm4 -p /general/theme -n -t string -s "$current_theme"

	# Change XFWM theme and mouse cursor size according to the user's highDPI setting
	hdpi_theme_fix 'no_hdpi_notification'

	# Cleanup flatpak_themes_dir
	rm -rf "${flatpak_themes_dir:?}"/*

	# Find the directory where the current theme is stored
	current_theme_dir=$(xdg_directory_lookup "themes/$current_theme")
	# Copy/sync current_theme_dir to flatpak_themes_dir
	[ -d "$current_theme_dir" ] &&
		rsync -av --delete --progress "$current_theme_dir" "$flatpak_themes_dir"
}

sync_font() {
	# Get the current system font
	font=$(xfconf-query -c xsettings -p /Gtk/FontName)
	# Apply the same font for the title of xfce windows
	xfconf-query -c xfwm4 -p /general/title_font -n -t string -s "$font"
}

# Initial synchronization
sync_theme
sync_font

# Monitor when the user changes their system theme or icons or font in XFCE and sync them as needed
while read -r line; do
	case "$line" in
		'set: /Net/ThemeName') sync_theme ;;
		'set: /Gdk/WindowScalingFactor') hdpi_theme_fix ;;
		'set: /Gtk/FontName') sync_font ;;
	esac
done < <(xfconf-query -c xsettings -m)