os/hosts/chocolatebar/virtualisation/create-service.nix

{
  config,
  pkgs,
  lib,
  vm,
  ...
}: let
  psCfg = config.pub-solar;
  xdg = config.home-manager.users."${psCfg.user.name}".xdg;
  varsFile = "${xdg.dataHome}/libvirt/OVMF_VARS_${vm.name}.fd";
  generateXML = import ./guest-xml.nix;
in {
  serviceConfig = {
    Type = "oneshot";
    RemainAfterExit = "yes";
    Restart = "no";
  };

  script = let
    networkXML = pkgs.writeText "network.xml" (import ./network-xml.nix {
      inherit config;
      inherit pkgs;
      inherit lib;
    });
    machineXML = pkgs.writeText "${vm.name}.xml" (vm.generateXML {
      inherit config;
      inherit pkgs;
      inherit lib;
      inherit vm;
      varsFile = varsFile;
    });
  in ''
    echo "Checking if ${vm.name} is already running"
    STATUS=$(${pkgs.libvirt}/bin/virsh list --all | grep "${vm.name}" | ${pkgs.gawk}/bin/awk '{ print $3 " " $4 }' )
    if [[ $STATUS != "shut off" && $STATUS != "" ]]; then
      echo "Domain ${vm.name} is already running or in an inconsistent state:"
      ${pkgs.libvirt}/bin/virsh list --all
      exit 0
    fi

    echo "Creating network XML"
    NET_TMP_FILE="/tmp/network.xml"

    NETUUID="$(${pkgs.libvirt}/bin/virsh net-uuid 'default' || true)"
    (sed "s/UUID/$NETUUID/" '${networkXML}') > "$NET_TMP_FILE"

    echo "Defining and starting network"
    ${pkgs.libvirt}/bin/virsh net-define "$NET_TMP_FILE"
    ${pkgs.libvirt}/bin/virsh net-start 'default' || true

    VARS_FILE=${varsFile}
    if [ ! -f "$VARS_FILE" ]; then
      echo "Copying vars filej"
      cp /run/libvirt/nix-ovmf/OVMF_VARS.fd "$VARS_FILE"
    fi

    echo "Replacing USB device IDs in the XML"
    # Load the template contents into a tmp file
    TMP_FILE="/tmp/${vm.name}.xml"
    cat "${machineXML}" > "$TMP_FILE"

    # Set VM UUID
    UUID="$(${pkgs.libvirt}/bin/virsh domuuid '${vm.name}' || true)"
    sed -i "s/UUID/''${UUID}/" "$TMP_FILE"

    ${
      if vm.handOverUSBDevices
      then ''
        # Hand over mouse
        USB_BUS=3
        USB_DEV=$(${pkgs.usbutils}/bin/lsusb | grep 046d:c52b | grep "Bus 00''${USB_BUS}" | cut -b 18)
        LINE_NUMBER=$(cat $TMP_FILE | grep -n -A 1 0xc52b | tail -n 1 | cut -b 1,2,3)
        sed -i "''${LINE_NUMBER}s/.*/<address bus=\"''${USB_BUS}\" device=\"''${USB_DEV}\" \/>/" "$TMP_FILE"

        # Hand over keyboard
        USB_BUS=$(${pkgs.usbutils}/bin/lsusb | grep 046d:c328 | cut -b 7)
        USB_DEV=$(${pkgs.usbutils}/bin/lsusb | grep 046d:c328 | cut -b 18)
        LINE_NUMBER=$(cat $TMP_FILE | grep -n -A 1 0xc328 | tail -n 1 | cut -b 1,2,3)
        sed -i "''${LINE_NUMBER}s/.*/<address bus=\"''${USB_BUS}\" device=\"''${USB_DEV}\" \/>/" "$TMP_FILE"
      ''
      else ""
    }

    # TODO: Set correct pci address for the GPU too

    # Setup looking glass shm file
    echo "Setting up looking glass shm file"
    ${pkgs.coreutils-full}/bin/truncate -s 0 /dev/shm/looking-glass
    ${pkgs.coreutils-full}/bin/dd if=/dev/zero of=/dev/shm/looking-glass bs=1M count=32

    # Load and start the xml definition
    echo "Loading and starting the VM XML definition"
    ${pkgs.libvirt}/bin/virsh define "$TMP_FILE"
    ${pkgs.libvirt}/bin/virsh start '${vm.name}'
  '';

  preStop = ''
    ${pkgs.libvirt}/bin/virsh shutdown '${vm.name}'
    let "timeout = $(date +%s) + 10"
    while [ "$(${pkgs.libvirt}/bin/virsh list --name | grep --count '^${vm.name}$')" -gt 0 ]; do
      if [ "$(date +%s)" -ge "$timeout" ]; then
        # Meh, we warned it...
        ${pkgs.libvirt}/bin/virsh destroy '${vm.name}'
      else
        # The machine is still running, let's give it some time to shut down
        sleep 0.5
      fi
    done

    ${pkgs.libvirt}/bin/virsh net-destroy 'default' || true
  '';
}