#!/bin/bash
set -euo pipefail

# Map the exported variables to your local names with fallbacks to satisfy set -u
OS="${DETECTED_OS:-fedora}"
DE="${SELECTED_DE:-none}"
TWM="${SELECTED_TWM:-none}"
INSTALL_LEVEL="${INSTALL_LEVEL:-full}"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

echo
color_cyan "Starting Fedora Full setup..."
echo

#------------------------------------------
# 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)"

# Add Terra repo
add_terra_repo() {
    if [ ! -f /etc/yum.repos.d/terra.repo ]; then
        say_yellow "Adding Terra repository for Noctalia Shell..."

        TMP_FILE="/tmp/terra.repo"

        curl -fsSL https://github.com/terrapkg/subatomic-repos/raw/main/terra.repo -o "$TMP_FILE" &&
        sudo mv "$TMP_FILE" /etc/yum.repos.d/terra.repo

        say_yellow "Clearing DNF cache..."
        sudo dnf clean metadata
    else
        say_gray "Terra repository already configured."
    fi
}

pause_if_debug

# Core components for Niri & Noctalia setup
NIRI_PACKAGES=(niri fuzzel swaybg swaylock noctalia-shell)

if [[ -z "$CURRENT_DE" || "$CURRENT_DE" == "none" || "$CURRENT_DE" == "sway" ]]; then
    say_cyan "No Desktop Environment detected. Installing Niri + Noctalia Shell..."

    # 1. Add the repo first
    add_terra_repo

    # 2. Install everything
    install_packages sddm "${NIRI_PACKAGES[@]}"
    switch_display_manager "sddm"

    say_green "Niri, Noctalia, and SDDM installed successfully."

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

pause_if_debug

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