# vm.nix
let
  pkgs = import <nixpkgs> {};
in

let
  # 1. SOURCE YOUR DEBIAN IMAGE
  debianImage = pkgs.fetchurl {
    name = "debian-13-genericcloud-amd64.qcow2";
    url = "https://cloud.debian.org/images/cloud/trixie/latest/debian-13-genericcloud-amd64.qcow2";
    hash = "sha256-V9a6DUghJB5j4Vz9Y5aikZ8syhx5Zn2593m8/8xNwIU="; # REPLACE THIS
  };

  # 2. VM DATA DIRECTORY
  vmDataDir = "/home/${builtins.getEnv "USER"}/.local/share/debian-vm";

  # 3. CREATE ALL FILES IN A SCRIPT
  setupScript = pkgs.writeShellScriptBin "setup-vm-files" ''
    set -e
    
    # Create VM directory
    mkdir -p "${vmDataDir}"
    
    # Create persistent disk if it doesn't exist
    if [ ! -f "${vmDataDir}/debian-persistent.qcow2" ]; then
      echo "Creating persistent disk from base image..."
      ${pkgs.qemu}/bin/qemu-img create -f qcow2 \
        -b "${debianImage}" \
        -F qcow2 \
        "${vmDataDir}/debian-persistent.qcow2" \
        20G
    fi
    
    # Create cloud-init configuration
    cat > "${vmDataDir}/user-data" << 'EOF'
    #cloud-config
    password: nixos
    chpasswd: { expire: False }
    ssh_pwauth: True
    runcmd:
      - |
        if [ ! -f /etc/vm-initialized ]; then
          cd /home/debian
          sudo -u debian git clone https://github.com/someone/something
          cd something
          chmod +x install.sh
          sudo -u debian ./install.sh
          touch /etc/vm-initialized
        fi
    EOF
    
    # Create cloud-init ISO
    ${pkgs.cloud-utils}/bin/cloud-localds \
      "${vmDataDir}/cloud-init.iso" \
      "${vmDataDir}/user-data"
    
    echo "VM files created in ${vmDataDir}"
  '';

  # 4. LAUNCH SCRIPT
  runScript = pkgs.writeShellScriptBin "run-debian-vm" ''
    set -e
    
    # Run setup first
    ${setupScript}/bin/setup-vm-files
    
    # Launch QEMU with KVM acceleration
    ${pkgs.qemu_kvm}/bin/qemu-kvm \
      -name "Debian-Persistent-VM" \
      -machine accel=kvm \
      -cpu host \
      -m 2048 \
      -drive file="${vmDataDir}/debian-persistent.qcow2",format=qcow2,if=virtio \
      -drive file="${vmDataDir}/cloud-init.iso",format=raw,if=virtio \
      -netdev user,id=n1,hostfwd=tcp::2222-:22 \
      -device virtio-net-pci,netdev=n1 \
      -display gtk \
      -vga virtio \
      "$@"
  '';

in
{
  system.build.customVM = runScript;
}