# prog/vm/metal/nexus.rb

label def stopped
  when_stop_set? do
    # Stop the VM
    host.sshable.cmd("sudo systemctl stop :vm_name", vm_name:)

    # Release CPU and memory back to host
    vm_host.update(
      used_cores: Sequel[:used_cores] - vm.cores,
      used_hugepages_1g: Sequel[:used_hugepages_1g] - vm.memory_gib
    )

    # For sliced VMs
    if vm.vm_host_slice
      vm.vm_host_slice.update(
        used_cpu_percent: Sequel[:used_cpu_percent] - vm.cpu_percent_limit,
        used_memory_gib: Sequel[:used_memory_gib] - vm.memory_gib
      )
    end

    # Finalize billing records
    active_billing_records.each(&:finalize)

    vm.update(display_state: "stopped")
  end

  decr_stop

  # Check for resume signal
  when_resume_set? do
    hop_resuming
  end

  nap 60
end

label def resuming
  # Check if original host has capacity
  if host_has_capacity?
    reallocate_on_current_host
  else
    # Option 1: Wait for capacity
    # Option 2: Migrate to different host with capacity
    hop_find_new_host
  end

  # Reallocate resources
  vm_host.update(
    used_cores: Sequel[:used_cores] + vm.cores,
    used_hugepages_1g: Sequel[:used_hugepages_1g] + vm.memory_gib
  )

  # Restart systemd service
  host.sshable.cmd("sudo systemctl start :vm_name", vm_name:)

  # Create new billing records
  create_billing_records

  vm.update(display_state: "starting")

  hop_wait_sshable
end

def host_has_capacity?
  vm_host.used_cores + vm.cores <= vm_host.total_cores &&
    vm_host.used_hugepages_1g + vm.memory_gib <= vm_host.total_hugepages_1g
end

# model/vm.rb
semaphore :resume  # Add to existing semaphores

# routes/project/location/vm.rb

# Stop VM - releases CPU/memory, stops billing
post "/:vm_name/stop" do
  authorize("Vm:stop", @location.id)

  vm = @project.vms_dataset.where(location: @location.name, name: params[:vm_name]).first
  raise ResourceNotFound, "VM not found" unless vm
  raise InvalidRequest, "VM is not running" unless vm.display_state == "running"

  vm.incr_stop

  serialize(vm, :detailed)
end

# Resume VM - reallocates resources, resumes billing
post "/:vm_name/resume" do
  authorize("Vm:resume", @location.id)

  vm = @project.vms_dataset.where(location: @location.name, name: params[:vm_name]).first
  raise ResourceNotFound, "VM not found" unless vm
  raise InvalidRequest, "VM is not stopped" unless vm.display_state == "stopped"

  vm.incr_resume

  serialize(vm, :detailed)
end

# serializers/vm.rb
def self.serialize_detailed(vm)
  {
    # ... existing fields ...
    can_stop: vm.display_state == "running",
    can_resume: vm.display_state == "stopped",
  }
end