// waitRemove blocks until either:
// a) the device registered at <device_set_prefix>-<hash> is removed,
// or b) the 10 second timeout expires.
func (devices *DeviceSet) waitRemove(devname string) error {
	log.Debugf("[deviceset %s] waitRemove(%s)", devices.devicePrefix, devname)
	defer log.Debugf("[deviceset %s] waitRemove(%s) END", devices.devicePrefix, devname)
	i := 0
	for ; i < 1000; i += 1 {
		devinfo, err := getInfo(devname)
		if err != nil {
			// If there is an error we assume the device doesn't exist.
			// The error might actually be something else, but we can't differentiate.
			return nil
		}
		if i%100 == 0 {
			log.Debugf("Waiting for removal of %s: exists=%d", devname, devinfo.Exists)
		}
		if devinfo.Exists == 0 {
			break
		}

		devices.Unlock()
		time.Sleep(10 * time.Millisecond)
		devices.Lock()
	}
	if i == 1000 {
		return fmt.Errorf("Timeout while waiting for device %s to be removed", devname)
	}
	return nil
}

func (devices *DeviceSet) AddDevice(hash, baseHash string) error {
	baseInfo, err := devices.lookupDevice(baseHash)
	if err != nil {
		return err
	}

	baseInfo.lock.Lock()
	defer baseInfo.lock.Unlock()

	devices.Lock()
	defer devices.Unlock()

	if info, _ := devices.lookupDevice(hash); info != nil {
		return fmt.Errorf("device %s already exists", hash)
	}

	deviceId := devices.nextDeviceId

	if err := createSnapDevice(devices.getPoolDevName(), &deviceId, baseInfo.Name(), baseInfo.DeviceId); err != nil {
		log.Debugf("Error creating snap device: %s", err)
		return err
	}

	// Ids are 24bit, so wrap around
	devices.nextDeviceId = (deviceId + 1) & 0xffffff

	if _, err := devices.registerDevice(deviceId, hash, baseInfo.Size); err != nil {
		deleteDevice(devices.getPoolDevName(), deviceId)
		log.Debugf("Error registering device: %s", err)
		return err
	}
	return nil
}

func (devices *DeviceSet) deactivatePool() error {
	log.Debugf("[devmapper] deactivatePool()")
	defer log.Debugf("[devmapper] deactivatePool END")
	devname := devices.getPoolDevName()
	devinfo, err := getInfo(devname)
	if err != nil {
		return err
	}
	if devinfo.Exists != 0 {
		return removeDevice(devname)
	}

	return nil
}

func (devices *DeviceSet) setupBaseImage() error {
	oldInfo, _ := devices.lookupDevice("")
	if oldInfo != nil && oldInfo.Initialized {
		return nil
	}

	if oldInfo != nil && !oldInfo.Initialized {
		log.Debugf("Removing uninitialized base image")
		if err := devices.deleteDevice(oldInfo); err != nil {
			return err
		}
	}

	log.Debugf("Initializing base device-manager snapshot")

	id := devices.nextDeviceId

	// Create initial device
	if err := createDevice(devices.getPoolDevName(), &id); err != nil {
		return err
	}

	// Ids are 24bit, so wrap around
	devices.nextDeviceId = (id + 1) & 0xffffff

	log.Debugf("Registering base device (id %v) with FS size %v", id, devices.baseFsSize)
	info, err := devices.registerDevice(id, "", devices.baseFsSize)
	if err != nil {
		_ = deleteDevice(devices.getPoolDevName(), id)
		return err
	}

	log.Debugf("Creating filesystem on base device-manager snapshot")

	if err = devices.activateDeviceIfNeeded(info); err != nil {
		return err
	}

	if err := devices.createFilesystem(info); err != nil {
		return err
	}

	info.Initialized = true
	if err = devices.saveMetadata(info); err != nil {
		info.Initialized = false
		return err
	}

	return nil
}

// CopyWithTar creates a tar archive of filesystem path `src`, and
// unpacks it at filesystem path `dst`.
// The archive is streamed directly with fixed buffering and no
// intermediary disk IO.
//
func CopyWithTar(src, dst string) error {
	srcSt, err := os.Stat(src)
	if err != nil {
		return err
	}
	if !srcSt.IsDir() {
		return CopyFileWithTar(src, dst)
	}
	// Create dst, copy src's content into it
	log.Debugf("Creating dest directory: %s", dst)
	if err := os.MkdirAll(dst, 0755); err != nil && !os.IsExist(err) {
		return err
	}
	log.Debugf("Calling TarUntar(%s, %s)", src, dst)
	return TarUntar(src, dst)
}

func removeDevice(name string) error {
	log.Debugf("[devmapper] removeDevice START")
	defer log.Debugf("[devmapper] removeDevice END")
	task, err := createTask(DeviceRemove, name)
	if task == nil {
		return err
	}
	dmSawBusy = false
	if err = task.Run(); err != nil {
		if dmSawBusy {
			return ErrBusy
		}
		return fmt.Errorf("Error running removeDevice %s", err)
	}
	return nil
}

func createDevice(poolName string, deviceId *int) error {
	log.Debugf("[devmapper] createDevice(poolName=%v, deviceId=%v)", poolName, *deviceId)

	for {
		task, err := createTask(DeviceTargetMsg, poolName)
		if task == nil {
			return err
		}

		if err := task.SetSector(0); err != nil {
			return fmt.Errorf("Can't set sector %s", err)
		}

		if err := task.SetMessage(fmt.Sprintf("create_thin %d", *deviceId)); err != nil {
			return fmt.Errorf("Can't set message %s", err)
		}

		dmSawExist = false
		if err := task.Run(); err != nil {
			if dmSawExist {
				// Already exists, try next id
				*deviceId++
				continue
			}
			return fmt.Errorf("Error running createDevice %s", err)
		}
		break
	}
	return nil
}

func SetDevDir(dir string) error {
	if res := DmSetDevDir(dir); res != 1 {
		log.Debugf("Error dm_set_dev_dir")
		return ErrSetDevDir
	}
	return nil
}

func UdevWait(cookie uint) error {
	if res := DmUdevWait(cookie); res != 1 {
		log.Debugf("Failed to wait on udev cookie %d", cookie)
		return ErrUdevWait
	}
	return nil
}

func (devices *DeviceSet) registerDevice(id int, hash string, size uint64) (*DevInfo, error) {
	log.Debugf("registerDevice(%v, %v)", id, hash)
	info := &DevInfo{
		Hash:          hash,
		DeviceId:      id,
		Size:          size,
		TransactionId: devices.allocateTransactionId(),
		Initialized:   false,
		devices:       devices,
	}

	devices.devicesLock.Lock()
	devices.Devices[hash] = info
	devices.devicesLock.Unlock()

	if err := devices.saveMetadata(info); err != nil {
		// Try to remove unused device
		devices.devicesLock.Lock()
		delete(devices.Devices, hash)
		devices.devicesLock.Unlock()
		return nil, err
	}

	return info, nil
}

// NewRequest() creates a new *http.Request,
// applies all decorators in the HTTPRequestFactory on the request,
// then applies decorators provided by d on the request.
func (h *HTTPRequestFactory) NewRequest(method, urlStr string, body io.Reader, d ...HTTPRequestDecorator) (*http.Request, error) {
	req, err := http.NewRequest(method, urlStr, body)
	if err != nil {
		return nil, err
	}

	// By default, a nil factory should work.
	if h == nil {
		return req, nil
	}
	for _, dec := range h.decorators {
		req, err = dec.ChangeRequest(req)
		if err != nil {
			return nil, err
		}
	}
	for _, dec := range d {
		req, err = dec.ChangeRequest(req)
		if err != nil {
			return nil, err
		}
	}
	log.Debugf("%v -- HEADERS: %v", req.URL, req.Header)
	return req, err
}

// ensureImage creates a sparse file of <size> bytes at the path
// <root>/devicemapper/<name>.
// If the file already exists, it does nothing.
// Either way it returns the full path.
func (devices *DeviceSet) ensureImage(name string, size int64) (string, error) {
	dirname := devices.loopbackDir()
	filename := path.Join(dirname, name)

	if err := os.MkdirAll(dirname, 0700); err != nil && !os.IsExist(err) {
		return "", err
	}

	if _, err := os.Stat(filename); err != nil {
		if !os.IsNotExist(err) {
			return "", err
		}
		log.Debugf("Creating loopback file %s for device-manage use", filename)
		file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0600)
		if err != nil {
			return "", err
		}
		defer file.Close()

		if err = file.Truncate(size); err != nil {
			return "", err
		}
	}
	return filename, nil
}

func (devices *DeviceSet) log(level int, file string, line int, dmError int, message string) {
	if level >= 7 {
		return // Ignore _LOG_DEBUG
	}

	log.Debugf("libdevmapper(%d): %s:%d (%d) %s", level, file, line, dmError, message)
}

func createBridgeIface(name string) error {
	kv, err := kernel.GetKernelVersion()
	// only set the bridge's mac address if the kernel version is > 3.3
	// before that it was not supported
	setBridgeMacAddr := err == nil && (kv.Kernel >= 3 && kv.Major >= 3)
	log.Debugf("setting bridge mac address = %v", setBridgeMacAddr)
	return netlink.CreateBridge(name, setBridgeMacAddr)
}

func (devices *DeviceSet) activateDeviceIfNeeded(info *DevInfo) error {
	log.Debugf("activateDeviceIfNeeded(%v)", info.Hash)

	if devinfo, _ := getInfo(info.Name()); devinfo != nil && devinfo.Exists != 0 {
		return nil
	}

	return activateDevice(devices.getPoolDevName(), info.Name(), info.DeviceId, info.Size)
}

// TarUntar is a convenience function which calls Tar and Untar, with
// the output of one piped into the other. If either Tar or Untar fails,
// TarUntar aborts and returns the error.
func TarUntar(src string, dst string) error {
	log.Debugf("TarUntar(%s %s)", src, dst)
	archive, err := TarWithOptions(src, &TarOptions{Compression: Uncompressed})
	if err != nil {
		return err
	}
	defer archive.Close()
	return Untar(archive, dst, nil)
}

func ExportChanges(dir string, changes []Change) (Archive, error) {
	reader, writer := io.Pipe()
	tw := tar.NewWriter(writer)

	go func() {
		twBuf := bufio.NewWriterSize(nil, twBufSize)
		// In general we log errors here but ignore them because
		// during e.g. a diff operation the container can continue
		// mutating the filesystem and we can see transient errors
		// from this
		for _, change := range changes {
			if change.Kind == ChangeDelete {
				whiteOutDir := filepath.Dir(change.Path)
				whiteOutBase := filepath.Base(change.Path)
				whiteOut := filepath.Join(whiteOutDir, ".wh."+whiteOutBase)
				timestamp := time.Now()
				hdr := &tar.Header{
					Name:       whiteOut[1:],
					Size:       0,
					ModTime:    timestamp,
					AccessTime: timestamp,
					ChangeTime: timestamp,
				}
				if err := tw.WriteHeader(hdr); err != nil {
					log.Debugf("Can't write whiteout header: %s", err)
				}
			} else {
				path := filepath.Join(dir, change.Path)
				if err := addTarFile(path, change.Path[1:], tw, twBuf); err != nil {
					log.Debugf("Can't add file %s to tar: %s", path, err)
				}
			}
		}

		// Make sure to check the error on Close.
		if err := tw.Close(); err != nil {
			log.Debugf("Can't close layer: %s", err)
		}
		writer.Close()
	}()
	return reader, nil
}

func (devices *DeviceSet) deleteDevice(info *DevInfo) error {
	if devices.doBlkDiscard {
		// This is a workaround for the kernel not discarding block so
		// on the thin pool when we remove a thinp device, so we do it
		// manually
		if err := devices.activateDeviceIfNeeded(info); err == nil {
			if err := BlockDeviceDiscard(info.DevName()); err != nil {
				log.Debugf("Error discarding block on device: %s (ignoring)", err)
			}
		}
	}

	devinfo, _ := getInfo(info.Name())
	if devinfo != nil && devinfo.Exists != 0 {
		if err := devices.removeDeviceAndWait(info.Name()); err != nil {
			log.Debugf("Error removing device: %s", err)
			return err
		}
	}

	if err := deleteDevice(devices.getPoolDevName(), info.DeviceId); err != nil {
		log.Debugf("Error deleting device: %s", err)
		return err
	}

	devices.allocateTransactionId()
	devices.devicesLock.Lock()
	delete(devices.Devices, info.Hash)
	devices.devicesLock.Unlock()

	if err := devices.removeMetadata(info); err != nil {
		devices.devicesLock.Lock()
		devices.Devices[info.Hash] = info
		devices.devicesLock.Unlock()
		log.Debugf("Error removing meta data: %s", err)
		return err
	}

	return nil
}

func (devices *DeviceSet) deactivateDevice(info *DevInfo) error {
	log.Debugf("[devmapper] deactivateDevice(%s)", info.Hash)
	defer log.Debugf("[devmapper] deactivateDevice END")

	// Wait for the unmount to be effective,
	// by watching the value of Info.OpenCount for the device
	if err := devices.waitClose(info); err != nil {
		log.Errorf("Warning: error waiting for device %s to close: %s", info.Hash, err)
	}

	devinfo, err := getInfo(info.Name())
	if err != nil {
		return err
	}
	if devinfo.Exists != 0 {
		if err := devices.removeDeviceAndWait(info.Name()); err != nil {
			return err
		}
	}

	return nil
}

func (devices *DeviceSet) UnmountDevice(hash string) error {
	log.Debugf("[devmapper] UnmountDevice(hash=%s)", hash)
	defer log.Debugf("[devmapper] UnmountDevice END")

	info, err := devices.lookupDevice(hash)
	if err != nil {
		return err
	}

	info.lock.Lock()
	defer info.lock.Unlock()

	devices.Lock()
	defer devices.Unlock()

	if info.mountCount == 0 {
		return fmt.Errorf("UnmountDevice: device not-mounted id %s\n", hash)
	}

	info.mountCount--
	if info.mountCount > 0 {
		return nil
	}

	log.Debugf("[devmapper] Unmount(%s)", info.mountPath)
	if err := syscall.Unmount(info.mountPath, 0); err != nil {
		return err
	}
	log.Debugf("[devmapper] Unmount done")

	if err := devices.deactivateDevice(info); err != nil {
		return err
	}

	info.mountPath = ""

	return nil
}