fix arch xfce + add arch plasma

v2/arch-xfce.sh

@@ -70,28 +70,42 @@ say_yellow -e "Starting XFCE installation..."
 CURRENT_DE="$(detect_de)"
 CURRENT_DM="$(detect_display_manager)"
 
-if [[ -z "$CURRENT_DE" ]]; then
-    say_cyan -e "No Desktop Environment detected. Installing XFCE (light setup with SDDM)..."
+if [[ -z "$CURRENT_DE" || "$CURRENT_DE" != "xfce" ]]; then
+    say_cyan -e "XFCE4 not detected. Installing XFCE (light setup with SDDM)..."
 
     install_packages sddm xfce4 xfce4-goodies
     enable_graphical_target
 
     say_green -e "XFCE with SDDM installed successfully. You can reboot now to start XFCE."
 else
-    say_cyan -e "Detected existing Desktop Environment: $CURRENT_DE"
+    say_cyan -e "Detected existing Desktop Environment: $CURRENT_DE. Checking Display Manager..."
 
-    if [[ "$CURRENT_DM" == "lightdm" ]]; then
-        say_yellow -e "LightDM is currently active. Replacing with SDDM..."
+    # Check and replace other Display Managers if they conflict with the preferred SDDM setup
+    if [[ "$CURRENT_DM" != "sddm" ]]; then
+        say_yellow -e "Display manager **$CURRENT_DM** is currently active. Replacing with **SDDM**, the default for KDE Plasma..."
 
-        sudo systemctl disable lightdm
-        sudo apt purge -y lightdm lightdm-gtk-greeter
+        # Attempt to disable the old DM if detected
+        if [ ! -z "$CURRENT_DM" ]; then
+            sudo systemctl disable "$CURRENT_DM" || true
+        fi
+        
+        # Remove common alternative DMs if they exist to prevent conflicts
+        if is_package_installed lightdm; then
+            say_gray -e "Removing lightdm..."
+            remove_packages lightdm lightdm-gtk-greeter || true
+        fi
+        if is_package_installed gdm; then
+            say_gray -e "Removing gdm..."
+            remove_packages gdm || true
+        fi
 
+        # Ensure SDDM is installed and enabled
         install_packages sddm
         enable_graphical_target
 
-        say_green -e "LightDM removed and replaced with SDDM."
+        say_green -e "Old display manager removed and replaced with SDDM."
     else
-        say_cyan -e "Current display manager: ${CURRENT_DM:-none}. Leaving unchanged."
+        say_cyan -e "Current display manager is already **SDDM**. Leaving unchanged."
     fi
 fi