#!/usr/bin/env bash
set -e

# use_nix.sh - Script to update NixOS configuration
# Usage: use_nix.sh [--rebuild] [--first-run]

function check_root() {
    if [[ $EUID -ne 0 ]]; then
        echo "This script must be run as root" >&2
        exit 1
    fi
}

function show_usage() {
    echo "Usage: $0 [--rebuild] [--first-run]"
    echo "  --rebuild    Automatically run nixos-rebuild after copying files"
    echo "  --first-run  Indicate this is the first system configuration"
}

AUTO_REBUILD=0
FIRST_RUN=0

# Parse arguments
for arg in "$@"; do
    case $arg in
        --rebuild) AUTO_REBUILD=1 ;;
        --first-run) FIRST_RUN=1 ;;
        --help|-h) show_usage; exit 0 ;;
        *) echo "Unknown option: $arg"; show_usage; exit 1 ;;
    esac
done

check_root

# Check if source directory exists
if [[ ! -d "root-conf/nixos" ]]; then
    echo "Error: Source directory 'root-conf/nixos' not found!" >&2
    exit 1
fi

# Backup existing configuration
if [[ -d /etc/nixos ]]; then
    echo "Backing up existing configuration to /etc/nixos.bak"
    rm -rf /etc/nixos.bak 2>/dev/null || true
    cp -r /etc/nixos /etc/nixos.bak
    rm -rf /etc/nixos/*
else
    mkdir -p /etc/nixos
fi

# Copy new configuration
echo "Copying files to /etc/nixos/"
cp -r root-conf/nixos/* /etc/nixos/
ls -l /etc/nixos/

# Rebuild if requested
if [[ $AUTO_REBUILD -eq 1 ]]; then
    echo "Running nixos-rebuild switch..."
    if [[ $FIRST_RUN -eq 1 ]]; then
        echo "First run: running nixos-rebuild with --upgrade"
        nixos-rebuild switch --upgrade
    else
        echo "Running nixos-rebuild switch with flake"
        nixos-rebuild switch --flake /etc/nixos
    fi
fi

echo "Done!"