# 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=";
  };

  # 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 (with 20GB initial size)
    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
# User configuration
users:
  - name: debian
    sudo: ALL=(ALL) NOPASSWD:ALL
    groups: sudo, users, adm
    shell: /bin/bash
    lock_passwd: false
    passwd: nixos
    system: false
    create_groups: true

# Enable password authentication
ssh_pwauth: true
chpasswd:
  expire: false
  list: |
    debian:nixos
    root:nixos

# Update system
package_update: true
package_upgrade: true

# Install packages
packages:
  - git
  - curl
  - wget

# Run commands - FIXED: Moved all setup to runcmd instead of write_files
runcmd:
  # Configure sudo
  - [sed, -i, '/^%sudo/s/ALL$/NOPASSWD:ALL/', /etc/sudoers]

  # Create log directory
  - [mkdir, -p, /var/log]

  # Update and install packages
  - [apt-get, update]
  - [apt-get, install, -y, git, curl, wget]

  # Set up user environment
  - [chown, -R, debian:debian, /home/debian]
  - [chmod, 700, /home/debian]

  # Execute setup as debian user - FIXED: All commands in one script
  - |
    su - debian -c '
      set -e
      echo "Starting first-boot setup as debian user..."

      # Clone repository
      cd /home/debian
      echo "Cloning GRCon23Tutorial repository..."
      git clone https://github.com/ARDC-TOBB-ETU/GRCon23Tutorial --depth=1

      # Run installation
      cd GRCon23Tutorial
      echo "Running installation script..."
      chmod +x install.sh
      ./install.sh

      # Source conda and start Jupyter Lab
      echo "Setting up conda environment and starting Jupyter Lab..."
      source "/home/debian/conda/etc/profile.d/conda.sh"
      conda activate GRCon23
      jupyter-lab --ip=0.0.0.0 --port=8888 --no-browser &
      JUPYTER_PID=$!
      echo $JUPYTER_PID > /tmp/jupyter.pid
      echo "Jupyter Lab started with PID: $JUPYTER_PID"

      echo "First-boot setup completed!"
      echo "Jupyter Lab running on port 8888"
    '

  # Create marker file
  - [touch, /etc/vm-initialized]
  - [echo, "VM setup completed at $(date)", ">>", /var/log/vm-init.log]
  - [echo, "Jupyter Lab should be running on port 8888", ">>", /var/log/vm-init.log]

# Final message
final_message: |
  VM initialization complete!

  Setup completed:
  1. Git cloned GRCon23Tutorial repository
  2. Ran ./install.sh
  3. Started Jupyter Lab on port 8888

  Access:
    SSH: ssh debian@localhost -p 2222
    Password: nixos
    Jupyter Lab: http://localhost:8888 (forwarded from VM port 8888)

  Check status in VM:
    sudo journalctl -u cloud-init
    cat /var/log/vm-init.log
EOF

    # Create cloud-init ISO
    ${pkgs.cloud-utils}/bin/cloud-localds \
      "${vmDataDir}/cloud-init.iso" \
      "${vmDataDir}/user-data"

    echo "VM files created in ${vmDataDir}"
    echo "First boot will:"
    echo "1. Clone GRCon23Tutorial repository"
    echo "2. Run ./install.sh"
    echo "3. Start Jupyter Lab on port 8888"
    echo ""
    echo "Access Jupyter at: http://localhost:8888"
  '';

  # 4. LAUNCH SCRIPT WITH PORT FORWARDING
  runScript = pkgs.writeShellScriptBin "run-debian-vm" ''
    set -e

    # Run setup first
    ${setupScript}/bin/setup-vm-files

    # Check if VM is already running
    if pgrep -f "debian-persistent.qcow2" > /dev/null; then
      echo "VM appears to be already running. Stopping it first..."
      pkill -f "debian-persistent.qcow2"
      sleep 2
    fi

    echo "Starting Debian VM..."
    echo ""
    echo "First boot will:"
    echo "1. Clone GRCon23Tutorial repository"
    echo "2. Run ./install.sh"
    echo "3. Start Jupyter Lab on port 8888"
    echo ""
    echo "Access after boot:"
    echo "  SSH: ssh debian@localhost -p 2222"
    echo "  Jupyter: http://localhost:8888"
    echo "  Password for 'debian' user: nixos"
    echo ""
    echo "Press Ctrl+Alt+G to release mouse from VM window"

    # Launch QEMU with port 8888 forwarded
    ${pkgs.qemu_kvm}/bin/qemu-kvm \
      -name "Debian-GRCon-VM" \
      -machine accel=kvm \
      -cpu host \
      -smp 2 \
      -m 2048 \
      -drive file="${vmDataDir}/debian-persistent.qcow2",format=qcow2,if=virtio \
      -drive file="${vmDataDir}/cloud-init.iso",format=raw,if=virtio \
      -netdev user,id=n1,hostfwd=tcp::2222-:22,hostfwd=tcp::8888-:8888 \
      -device virtio-net-pci,netdev=n1 \
      -display gtk \
      -vga virtio \
      "$@"
  '';

in
{
  system.build.customVM = runScript;
}