#!/bin/bash
set -euo pipefail

##########################
# Color helpers (printf-safe, no tput)
##########################
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"

# Disable colors if output is not a terminal
if [ ! -t 1 ]; then
    RED="" GREEN="" YELLOW="" CYAN="" GRAY="" BOLD="" RESET=""
fi

say_red()    { printf "\n"; printf "%b%s%b\n" "$RED" "$*" "$RESET"; }
say_green()    { printf "\n"; printf "%b%s%b\n" "$GREEN" "$*" "$RESET"; }
say_yellow()   { printf "\n"; printf "%b%s%b\n" "$YELLOW" "$*" "$RESET"; }
say_cyan()     { printf "\n"; printf "%b%s%b\n" "$CYAN" "$*" "$RESET"; }
say_gray()     { printf "\n"; printf "%b%s%b\n" "$GRAY" "$*" "$RESET"; }
say_bold()     { printf "\n"; printf "%b%s%b\n" "$BOLD" "$*" "$RESET"; }

##########################
# Use exported variables from main detection script
##########################
OS="${DETECTED_OS:-fedora}"
DDE="${DETECTED_DE:-none}"
DE="${SELECTED_DE:-none}"
TWM="${SELECTED_TWM:-none}"
INSTALL_LEVEL="${INSTALL_LEVEL:-minimal}"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

##########################
# Helper functions
##########################
install_packages() { sudo dnf install -y "$@"; }
is_package_installed() { rpm -q "$@" &>/dev/null; }

detect_de() {
    # Check if a desktop session is currently running or XFCE is available
    if [ "${XDG_CURRENT_DESKTOP:-}" ]; then
        echo "${XDG_CURRENT_DESKTOP,,}" # lowercase the output
    elif command -v xfce4-session >/dev/null 2>&1; then
        echo "xfce"
    else
        echo ""
    fi
}

detect_display_manager() {
    # Fedora/Systemd way to check the active DM symlink
    if [ -L /etc/systemd/system/display-manager.service ]; then
        basename "$(readlink /etc/systemd/system/display-manager.service)" | sed 's/\.service//'
    else
        echo ""
    fi
}

switch_display_manager() {
    local target_dm="$1"
    local current_dm
    current_dm=$(detect_display_manager)

    if [[ "$current_dm" != "$target_dm" ]]; then
        if [[ -n "$current_dm" ]]; then
            say_yellow "Disabling existing display manager: $current_dm"
            sudo systemctl disable "$current_dm"
        fi
        say_yellow "Enabling $target_dm..."
        sudo systemctl enable "$target_dm"
    fi
    sudo systemctl set-default graphical.target
}

#########################
# Start installation
##########################
say_yellow "Starting Niri setup..."

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

# Core components for Niri (Fedora package names)
# Note: Ensure noctalia-shell and xwayland-satellite are available in your enabled Copr/repos
NIRI_PACKAGES=(niri fuzzel swaybg swaylock) 

if [[ -z "$CURRENT_DE" || "$CURRENT_DE" == "none" ]]; then
    say_cyan "No Desktop Environment detected. Installing Niri (light setup with SDDM)..."

    install_packages sddm "${NIRI_PACKAGES[@]}"
    switch_display_manager "sddm"

    say_green "Niri with SDDM installed successfully. You can reboot now to start Niri."
else
    say_cyan "Detected existing Desktop Environment: $CURRENT_DE"
    
    # Always install the window manager packages
    install_packages "${NIRI_PACKAGES[@]}"

    if [[ "$CURRENT_DM" == "lightdm" ]]; then
        say_yellow "LightDM is currently active. Replacing with SDDM..."

        # Fedora equivalent to purge lightdm safely
        sudo dnf remove -y lightdm lightdm-gtk

        install_packages sddm
        switch_display_manager "sddm"

        say_green "LightDM removed and replaced with SDDM."
    else
        say_cyan "Current display manager: ${CURRENT_DM:-none}. Leaving it to handle Niri login sessions."
    fi
fi

# End of script
say_green "Niri / SDDM setup completed."