// New takes a driver and returns a new manager.
func New(driver storage.StorageDriver, sysfs sysfs.SysFs) (Manager, error) {
	if driver == nil {
		return nil, fmt.Errorf("nil storage driver!")
	}

	// Detect the container we are running on.
	selfContainer, err := cgroups.GetThisCgroupDir("cpu")
	if err != nil {
		return nil, err
	}
	glog.Infof("cAdvisor running in container: %q", selfContainer)

	newManager := &manager{
		containers:        make(map[namespacedContainerName]*containerData),
		quitChannels:      make([]chan error, 0, 2),
		storageDriver:     driver,
		cadvisorContainer: selfContainer,
	}

	machineInfo, err := getMachineInfo(sysfs)
	if err != nil {
		return nil, err
	}
	newManager.machineInfo = *machineInfo
	glog.Infof("Machine: %+v", newManager.machineInfo)

	versionInfo, err := getVersionInfo()
	if err != nil {
		return nil, err
	}
	newManager.versionInfo = *versionInfo
	glog.Infof("Version: %+v", newManager.versionInfo)

	return newManager, nil
}

// New takes a memory storage and returns a new manager.
func New(memoryCache *memory.InMemoryCache, sysfs sysfs.SysFs, maxHousekeepingInterval time.Duration, allowDynamicHousekeeping bool) (Manager, error) {
	if memoryCache == nil {
		return nil, fmt.Errorf("manager requires memory storage")
	}

	// Detect the container we are running on.
	selfContainer, err := cgroups.GetThisCgroupDir("cpu")
	if err != nil {
		return nil, err
	}
	glog.Infof("cAdvisor running in container: %q", selfContainer)

	dockerInfo, err := docker.DockerInfo()
	if err != nil {
		glog.Warningf("Unable to connect to Docker: %v", err)
	}
	context := fs.Context{DockerRoot: docker.RootDir(), DockerInfo: dockerInfo}
	fsInfo, err := fs.NewFsInfo(context)
	if err != nil {
		return nil, err
	}

	// If cAdvisor was started with host's rootfs mounted, assume that its running
	// in its own namespaces.
	inHostNamespace := false
	if _, err := os.Stat("/rootfs/proc"); os.IsNotExist(err) {
		inHostNamespace = true
	}
	newManager := &manager{
		containers:               make(map[namespacedContainerName]*containerData),
		quitChannels:             make([]chan error, 0, 2),
		memoryCache:              memoryCache,
		fsInfo:                   fsInfo,
		cadvisorContainer:        selfContainer,
		inHostNamespace:          inHostNamespace,
		startupTime:              time.Now(),
		maxHousekeepingInterval:  maxHousekeepingInterval,
		allowDynamicHousekeeping: allowDynamicHousekeeping,
	}

	machineInfo, err := getMachineInfo(sysfs, fsInfo)
	if err != nil {
		return nil, err
	}
	newManager.machineInfo = *machineInfo
	glog.Infof("Machine: %+v", newManager.machineInfo)

	versionInfo, err := getVersionInfo()
	if err != nil {
		return nil, err
	}
	glog.Infof("Version: %+v", *versionInfo)

	newManager.eventHandler = events.NewEventManager(parseEventsStoragePolicy())
	return newManager, nil
}

// New takes a memory storage and returns a new manager.
func New(memoryStorage *memory.InMemoryStorage, sysfs sysfs.SysFs) (Manager, error) {
	if memoryStorage == nil {
		return nil, fmt.Errorf("manager requires memory storage")
	}

	// Detect the container we are running on.
	selfContainer, err := cgroups.GetThisCgroupDir("cpu")
	if err != nil {
		return nil, err
	}
	glog.Infof("cAdvisor running in container: %q", selfContainer)

	context := fs.Context{DockerRoot: docker.RootDir()}
	fsInfo, err := fs.NewFsInfo(context)
	if err != nil {
		return nil, err
	}
	newManager := &manager{
		containers:        make(map[namespacedContainerName]*containerData),
		quitChannels:      make([]chan error, 0, 2),
		memoryStorage:     memoryStorage,
		fsInfo:            fsInfo,
		cadvisorContainer: selfContainer,
		startupTime:       time.Now(),
	}

	machineInfo, err := getMachineInfo(sysfs, fsInfo)
	if err != nil {
		return nil, err
	}
	newManager.machineInfo = *machineInfo
	glog.Infof("Machine: %+v", newManager.machineInfo)

	versionInfo, err := getVersionInfo()
	if err != nil {
		return nil, err
	}
	newManager.versionInfo = *versionInfo
	glog.Infof("Version: %+v", newManager.versionInfo)

	newManager.eventHandler = events.NewEventManager()

	// Register Docker container factory.
	err = docker.Register(newManager, fsInfo)
	if err != nil {
		glog.Errorf("Docker container factory registration failed: %v.", err)
	}

	// Register the raw driver.
	err = raw.Register(newManager, fsInfo)
	if err != nil {
		glog.Errorf("Registration of the raw container factory failed: %v", err)
	}

	return newManager, nil
}

func findCgroupRootAndDir(subsystem string) (string, string, error) {
	cgroupRoot, err := cgroups.FindCgroupMountpoint(subsystem)
	if err != nil {
		return "", "", err
	}

	cgroupDir, err := cgroups.GetThisCgroupDir(subsystem)
	if err != nil {
		return "", "", err
	}
	return cgroupRoot, cgroupDir, nil
}

func (d *driver) GetPidsForContainer(id string) ([]int, error) {
	pids := []int{}

	// cpu is chosen because it is the only non optional subsystem in cgroups
	subsystem := "cpu"
	cgroupRoot, err := cgroups.FindCgroupMountpoint(subsystem)
	if err != nil {
		return pids, err
	}

	cgroupDir, err := cgroups.GetThisCgroupDir(subsystem)
	if err != nil {
		return pids, err
	}

	filename := filepath.Join(cgroupRoot, cgroupDir, id, "tasks")
	if _, err := os.Stat(filename); os.IsNotExist(err) {
		// With more recent lxc versions use, cgroup will be in lxc/
		filename = filepath.Join(cgroupRoot, cgroupDir, "lxc", id, "tasks")
	}

	output, err := ioutil.ReadFile(filename)
	if err != nil {
		return pids, err
	}
	for _, p := range strings.Split(string(output), "\n") {
		if len(p) == 0 {
			continue
		}
		pid, err := strconv.Atoi(p)
		if err != nil {
			return pids, fmt.Errorf("Invalid pid '%s': %s", p, err)
		}
		pids = append(pids, pid)
	}
	return pids, nil
}

func detectDockerContainer() (string, error) {
	return cgroups.GetThisCgroupDir("cpu")
}