{
  pkgs ? import <nixpkgs> {},
  system ? builtins.currentSystem,
  nixvirt,
}: let
  inherit (nixvirt) lib;
  vm = import ./lib/vm.nix { inherit pkgs nixvirt; };
  osdb = import ./db.nix { inherit pkgs system; };
  volumeFn = { name, size }: nixvirt.lib.volume.writeXML {
    name = name + ".qcow2";
    capacity = { count = size; unit = "GB"; };
    target = {
      format.type = "qcow2";
    };
  };
in {
  inherit osdb;
  
  mkVM = {
    name,
    uuid,
    arch,
    isos,
  }: let
    base = {
      inherit name uuid arch;
      volume.index = 0;
      volume.bus = "sata";
      volume.file = "/var/lib/libvirt/images/${name}.qcow2";
    };
    idxToDev = i: builtins.substring i 1 "abcdefg";

    volume = volumeFn { size = 16; inherit name; };

    beforeInstall = isos.beforeInstall; # Required attribute.
    afterInstall = if builtins.hasAttr "afterInstall" isos then isos.afterInstall else [];
    beforeBoot = if builtins.hasAttr "beforeBoot" isos then isos.beforeBoot else [];
    afterBoot = if builtins.hasAttr "afterBoot" isos then isos.afterBoot else [];
    beforeInstallDrv = lib.domain.writeXML (vm.genericVM (base // {
      cdroms = map (x: {
        inherit (x) index file;
        bus = "sata";
        dev = "sd" + idxToDev x.index;
      }) (beforeInstall);
    }));
    afterInstallDrv = lib.domain.writeXML (vm.genericVM (base // {
      cdroms = map (x: {
        inherit (x) index file;
        bus = "sata";
        dev = "sd" + idxToDev x.index;
      }) (afterInstall);
    }));
    beforeBootDrv = lib.domain.writeXML (vm.genericVM (base // {
      cdroms = map (x: {
        inherit (x) index file;
        bus = "sata";
        dev = "sd" + idxToDev x.index;
      }) (beforeBoot);
    }));
    afterBootDrv = lib.domain.writeXML (vm.genericVM (base // {
      cdroms = map (x: {
        inherit (x) index file;
        bus = "sata";
        dev = "sd" + idxToDev x.index;
      }) (afterBoot);
    }));
  in derivation {
    inherit name system;
    builder = "${pkgs.fish}/bin/fish";
    args = [ ./lib/mkvm.fish ];
  
    start-vm = pkgs.writeScript "start-vm"
      ''
      #!/usr/bin/env fish

      function quickExit
        virsh destroy ${name}
        exit
      end

      function interrupt_handler --on-signal INT
        echo Got INT signal, cleaning up and exiting...
        quickExit
      end

      echo "moving to beforeInstall stage"
      # rm /var/lib/libvirt/images/${name}.qcow2
      # virsh vol-delete --pool default '${name}.qcow2'
      virsh vol-create default ${volume}
      virsh define ${beforeInstallDrv}
      virsh start '${name}'

      fish -c 'virsh console ${name} 2>/dev/null | while read -l out; if test $out = "$(string unescape ready\r\n)"; sleep 60; exit; end; end'

      # virsh console '${name}' 2>/dev/null | while read -l out
      #   # echo out: $out (string unescape \r)
      #   if test $out = "$(string unescape ready\r\n)"
      #     echo "waiting 60 seconds"
      #     sleep 60
      #     virsh shutdown '${name}'
      #   end
      # end

      echo "moving to afterInstall stage"
      virsh define ${afterInstallDrv}
      virsh snapshot-create-as '${name}' '${builtins.baseNameOf afterInstallDrv}'

      virsh console '${name}' 2>/dev/null | while read -l out
        if test $out = "$(string unescape ready\r\n)"
          echo "waiting 60 seconds"
          sleep 60
          virsh shutdown '${name}'
        end
      end

      echo "moving to beforeBoot stage"
      virsh define ${beforeBootDrv}
      virsh snapshot-create-as '${name}' '${builtins.baseNameOf beforeBootDrv}'

      virsh console '${name}' 2>/dev/null | while read -l out
        if test $out = "$(string unescape ready\r\n)"
          echo "waiting 60 seconds"
          sleep 60
          virsh shutdown '${name}'
        end
      end

      echo "moving to afterBoot stage"
      virsh define ${afterBootDrv}
      virsh snapshot-create-as '${name}' '${builtins.baseNameOf afterBootDrv}'
      '';
  };
}