#!/bin/bash
set -euo pipefail

# Color helpers, logging, variables identical to plasma/xfce scripts

RED='\033[0;31m'; GREEN='\033[0;32m'; YELLOW='\033[0;33m'
CYAN='\033[0;36m'; GRAY='\033[0;37m'; BOLD='\033[1m'; RESET='\033[0m'
[ ! -t 1 ] && RED='' GREEN='' YELLOW='' CYAN='' GRAY='' BOLD='' RESET=''

color_red()    { printf '%b' "$RED"; }
color_green()  { printf '%b' "$GREEN"; }
color_yellow() { printf '%b' "$YELLOW"; }
color_cyan()   { printf '%b' "$CYAN"; }
color_gray()   { printf '%b' "$GRAY"; }
color_reset()  { printf '%b' "$RESET"; }

LOGFILE="${LOGFILE:-/tmp/debian-gnome.log}"
exec > >(tee -a "$LOGFILE") 2>&1

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
OS="${DETECTED_OS:-debian}"
DDE="${DETECTED_DE:-}"
DE="${SELECTED_DE:-none}"
TWM="${SELECTED_TWM:-none}"
INSTALL_LEVEL="${INSTALL_LEVEL:-minimal}"

##########################
# Helper functions
##########################
install_packages() { sudo apt update; sudo apt install -y --no-install-recommends "$@"; }
is_package_installed() { dpkg -s "$1" &>/dev/null; }
detect_de() { command -v gnome-session >/dev/null 2>&1 && echo "gnome" || echo ""; }
detect_display_manager() { [ -f /etc/X11/default-display-manager ] && basename "$(cat /etc/X11/default-display-manager)" || echo ""; }
enable_graphical_target() { sudo systemctl enable sddm; sudo systemctl set-default graphical.target; }

color_yellow; echo "Starting Gnome installation..."; color_reset

CURRENT_DE="$(detect_de)"
CURRENT_DM="$(detect_display_manager)"

if [[ -z "$CURRENT_DE" ]]; then
    color_cyan; echo "No DE detected. Installing Gnome with SDDM..."; color_reset
    install_packages sddm gnome-shell gnome-terminal nautilus gnome-control-center gnome-system-monitor gnome-tweaks network-manager-gnome gnome-keyring gnome-session
    enable_graphical_target
    color_green; echo "Gnome with SDDM installed successfully."; color_reset
else
    color_cyan; echo "Detected existing DE: $CURRENT_DE"; color_reset
    if [[ "$CURRENT_DM" == "lightdm" ]]; then
        color_yellow; echo "Replacing LightDM with SDDM..."; color_reset
        sudo systemctl disable lightdm
        sudo apt purge -y lightdm lightdm-gtk-greeter
        install_packages sddm
        enable_graphical_target
        color_green; echo "LightDM replaced with SDDM."; color_reset
    else
        color_cyan; echo "Current DM: ${CURRENT_DM:-none}, leaving unchanged."; color_reset
    fi
fi