// PortForward executes socat in the pod's network namespace and copies
// data between stream (representing the user's local connection on their
// computer) and the specified port in the container.
//
// TODO:
//  - match cgroups of container
//  - should we support nsenter + socat on the host? (current impl)
//  - should we support nsenter + socat in a container, running with elevated privs and --pid=host?
func (dm *DockerManager) PortForward(pod *kubecontainer.Pod, port uint16, stream io.ReadWriteCloser) error {
	podInfraContainer := pod.FindContainerByName(PodInfraContainerName)
	if podInfraContainer == nil {
		return fmt.Errorf("cannot find pod infra container in pod %q", kubecontainer.BuildPodFullName(pod.Name, pod.Namespace))
	}
	container, err := dm.client.InspectContainer(string(podInfraContainer.ID))
	if err != nil {
		return err
	}

	if !container.State.Running {
		return fmt.Errorf("container not running (%s)", container)
	}

	containerPid := container.State.Pid
	// TODO what if the host doesn't have it???
	_, lookupErr := exec.LookPath("socat")
	if lookupErr != nil {
		return fmt.Errorf("Unable to do port forwarding: socat not found.")
	}
	args := []string{"-t", fmt.Sprintf("%d", containerPid), "-n", "socat", "-", fmt.Sprintf("TCP4:localhost:%d", port)}
	// TODO use exec.LookPath
	command := exec.Command("nsenter", args...)
	command.Stdin = stream
	command.Stdout = stream
	return command.Run()
}

// isPodRunning returns true if all containers of a manifest are running.
func (kl *Kubelet) isPodRunning(pod *api.Pod, runningPod container.Pod) (bool, error) {
	for _, container := range pod.Spec.Containers {
		c := runningPod.FindContainerByName(container.Name)
		if c == nil {
			glog.Infof("container %q not found", container.Name)
			return false, nil
		}
		inspectResult, err := kl.dockerClient.InspectContainer(string(c.ID))
		if err != nil {
			glog.Infof("failed to inspect container %q: %v", container.Name, err)
			return false, err
		}
		if !inspectResult.State.Running {
			glog.Infof("container %q not running: %#v", container.Name, inspectResult.State)
			return false, nil
		}
	}
	return true, nil
}

// makeRuntimePod constructs the container runtime pod. It will:
// 1, Construct the pod by the information stored in the unit file.
// 2, Construct the pod status from pod info.
func (r *runtime) makeRuntimePod(unitName string, podInfos map[string]*podInfo) (*kubecontainer.Pod, error) {
	f, err := os.Open(path.Join(systemdServiceDir, unitName))
	if err != nil {
		return nil, err
	}
	defer f.Close()

	var pod kubecontainer.Pod
	opts, err := unit.Deserialize(f)
	if err != nil {
		return nil, err
	}

	var rktID string
	for _, opt := range opts {
		if opt.Section != unitKubernetesSection {
			continue
		}
		switch opt.Name {
		case unitPodName:
			err = json.Unmarshal([]byte(opt.Value), &pod)
			if err != nil {
				return nil, err
			}
		case unitRktID:
			rktID = opt.Value
		default:
			return nil, fmt.Errorf("rkt: Unexpected key: %q", opt.Name)
		}
	}

	if len(rktID) == 0 {
		return nil, fmt.Errorf("rkt: cannot find rkt ID of pod %v, unit file is broken", pod)
	}
	info, found := podInfos[rktID]
	if !found {
		return nil, fmt.Errorf("rkt: cannot find info for pod %q, rkt uuid: %q", pod.Name, rktID)
	}
	pod.Status = info.toPodStatus(&pod)
	return &pod, nil
}

func dockerContainersToPod(containers DockerContainers) kubecontainer.Pod {
	var pod kubecontainer.Pod
	for _, c := range containers {
		dockerName, hash, err := ParseDockerName(c.Names[0])
		if err != nil {
			continue
		}
		pod.Containers = append(pod.Containers, &kubecontainer.Container{
			ID:    types.UID(c.ID),
			Name:  dockerName.ContainerName,
			Hash:  hash,
			Image: c.Image,
		})
		// TODO(yifan): Only one evaluation is enough.
		pod.ID = dockerName.PodUID
		name, namespace, _ := kubecontainer.ParsePodFullName(dockerName.PodFullName)
		pod.Name = name
		pod.Namespace = namespace
	}
	return pod
}

// SyncPod syncs the running pod to match the specified desired pod.
func (r *runtime) SyncPod(pod *api.Pod, runningPod kubecontainer.Pod, podStatus api.PodStatus, pullSecrets []api.Secret) error {
	podFullName := kubecontainer.GetPodFullName(pod)
	if len(runningPod.Containers) == 0 {
		glog.V(4).Infof("Pod %q is not running, will start it", podFullName)
		return r.RunPod(pod)
	}

	// Add references to all containers.
	unidentifiedContainers := make(map[types.UID]*kubecontainer.Container)
	for _, c := range runningPod.Containers {
		unidentifiedContainers[c.ID] = c
	}

	restartPod := false
	for _, container := range pod.Spec.Containers {
		expectedHash := kubecontainer.HashContainer(&container)

		c := runningPod.FindContainerByName(container.Name)
		if c == nil {
			if kubecontainer.ShouldContainerBeRestarted(&container, pod, &podStatus, r.readinessManager) {
				glog.V(3).Infof("Container %+v is dead, but RestartPolicy says that we should restart it.", container)
				// TODO(yifan): Containers in one pod are fate-sharing at this moment, see:
				// https://github.com/appc/spec/issues/276.
				restartPod = true
				break
			}
			continue
		}

		// TODO(yifan): Take care of host network change.
		containerChanged := c.Hash != 0 && c.Hash != expectedHash
		if containerChanged {
			glog.Infof("Pod %q container %q hash changed (%d vs %d), it will be killed and re-created.", podFullName, container.Name, c.Hash, expectedHash)
			restartPod = true
			break
		}

		result, err := r.prober.Probe(pod, podStatus, container, string(c.ID), c.Created)
		// TODO(vmarmol): examine this logic.
		if err == nil && result != probe.Success {
			glog.Infof("Pod %q container %q is unhealthy (probe result: %v), it will be killed and re-created.", podFullName, container.Name, result)
			restartPod = true
			break
		}

		if err != nil {
			glog.V(2).Infof("Probe container %q failed: %v", container.Name, err)
		}
		delete(unidentifiedContainers, c.ID)
	}

	// If there is any unidentified containers, restart the pod.
	if len(unidentifiedContainers) > 0 {
		restartPod = true
	}

	if restartPod {
		// TODO(yifan): Handle network plugin.
		if err := r.KillPod(runningPod); err != nil {
			return err
		}
		if err := r.RunPod(pod); err != nil {
			return err
		}
	}
	return nil
}