//
// Copyright (c) 2016 Intel Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

package virtcontainers

import (
	"encoding/hex"
	"fmt"
	"os"
	"path/filepath"
	"syscall"
	"time"

	"github.com/sirupsen/logrus"
)

// Process gathers data related to a container process.
type Process struct {
	// Token is the process execution context ID. It must be
	// unique per pod.
	// Token is used to manipulate processes for containers
	// that have not started yet, and later identify them
	// uniquely within a pod.
	Token string

	// Pid is the process ID as seen by the host software
	// stack, e.g. CRI-O, containerd. This is typically the
	// shim PID.
	Pid int

	StartTime time.Time
}

// ContainerStatus describes a container status.
type ContainerStatus struct {
	ID        string
	State     State
	PID       int
	StartTime time.Time
	RootFs    string

	// Annotations allow clients to store arbitrary values,
	// for example to add additional status values required
	// to support particular specifications.
	Annotations map[string]string
}

// ContainerResources describes container resources
type ContainerResources struct {
	// CPUQuota specifies the total amount of time in microseconds
	// The number of microseconds per CPUPeriod that the container is guaranteed CPU access
	CPUQuota int64

	// CPUPeriod specifies the CPU CFS scheduler period of time in microseconds
	CPUPeriod uint64

	// CPUShares specifies container's weight vs. other containers
	CPUShares uint64
}

// ContainerConfig describes one container runtime configuration.
type ContainerConfig struct {
	ID string

	// RootFs is the container workload image on the host.
	RootFs string

	// ReadOnlyRootfs indicates if the rootfs should be mounted readonly
	ReadonlyRootfs bool

	// Cmd specifies the command to run on a container
	Cmd Cmd

	// Annotations allow clients to store arbitrary values,
	// for example to add additional status values required
	// to support particular specifications.
	Annotations map[string]string

	Mounts []Mount

	// Device configuration for devices that must be available within the container.
	DeviceInfos []DeviceInfo

	// Resources container resources
	Resources ContainerResources
}

// valid checks that the container configuration is valid.
func (c *ContainerConfig) valid() bool {
	if c == nil {
		return false
	}

	if c.ID == "" {
		return false
	}

	return true
}

// SystemMountsInfo describes additional information for system mounts that the agent
// needs to handle
type SystemMountsInfo struct {
	// Indicates if /dev has been passed as a bind mount for the host /dev
	BindMountDev bool

	// Size of /dev/shm assigned on the host.
	DevShmSize uint
}

// Container is composed of a set of containers and a runtime environment.
// A Container can be created, deleted, started, stopped, listed, entered, paused and restored.
type Container struct {
	id    string
	podID string

	rootFs string

	config *ContainerConfig

	pod *Pod

	runPath       string
	configPath    string
	containerPath string

	state State

	process Process

	mounts []Mount

	devices []Device

	systemMountsInfo SystemMountsInfo
}

// ID returns the container identifier string.
func (c *Container) ID() string {
	return c.id
}

// Logger returns a logrus logger appropriate for logging Container messages
func (c *Container) Logger() *logrus.Entry {
	return virtLog.WithFields(logrus.Fields{
		"subsystem":    "container",
		"container-id": c.id,
		"pod-id":       c.podID,
	})
}

// Pod returns the pod handler related to this container.
func (c *Container) Pod() VCPod {
	return c.pod
}

// Process returns the container process.
func (c *Container) Process() Process {
	return c.process
}

// GetToken returns the token related to this container's process.
func (c *Container) GetToken() string {
	return c.process.Token
}

// GetPid returns the pid related to this container's process.
func (c *Container) GetPid() int {
	return c.process.Pid
}

// SetPid sets and stores the given pid as the pid of container's process.
func (c *Container) SetPid(pid int) error {
	c.process.Pid = pid

	return c.storeProcess()
}

func (c *Container) setStateBlockIndex(index int) error {
	c.state.BlockIndex = index

	err := c.pod.storage.storeContainerResource(c.pod.id, c.id, stateFileType, c.state)
	if err != nil {
		return err
	}

	return nil
}

func (c *Container) setStateFstype(fstype string) error {
	c.state.Fstype = fstype

	err := c.pod.storage.storeContainerResource(c.pod.id, c.id, stateFileType, c.state)
	if err != nil {
		return err
	}

	return nil
}

func (c *Container) setStateHotpluggedDrive(hotplugged bool) error {
	c.state.HotpluggedDrive = hotplugged

	err := c.pod.storage.storeContainerResource(c.pod.id, c.id, stateFileType, c.state)
	if err != nil {
		return err
	}

	return nil
}

// GetAnnotations returns container's annotations
func (c *Container) GetAnnotations() map[string]string {
	return c.config.Annotations
}

func (c *Container) storeProcess() error {
	return c.pod.storage.storeContainerProcess(c.podID, c.id, c.process)
}

func (c *Container) storeMounts() error {
	return c.pod.storage.storeContainerMounts(c.podID, c.id, c.mounts)
}

func (c *Container) fetchMounts() ([]Mount, error) {
	return c.pod.storage.fetchContainerMounts(c.podID, c.id)
}

func (c *Container) storeDevices() error {
	return c.pod.storage.storeContainerDevices(c.podID, c.id, c.devices)
}

func (c *Container) fetchDevices() ([]Device, error) {
	return c.pod.storage.fetchContainerDevices(c.podID, c.id)
}

// storeContainer stores a container config.
func (c *Container) storeContainer() error {
	fs := filesystem{}
	err := fs.storeContainerResource(c.pod.id, c.id, configFileType, *(c.config))
	if err != nil {
		return err
	}

	return nil
}

// setContainerState sets both the in-memory and on-disk state of the
// container.
func (c *Container) setContainerState(state stateString) error {
	if state == "" {
		return errNeedState
	}

	// update in-memory state
	c.state.State = state

	// update on-disk state
	err := c.pod.storage.storeContainerResource(c.pod.id, c.id, stateFileType, c.state)
	if err != nil {
		return err
	}

	return nil
}

func (c *Container) createContainersDirs() error {
	err := os.MkdirAll(c.runPath, dirMode)
	if err != nil {
		return err
	}

	err = os.MkdirAll(c.configPath, dirMode)
	if err != nil {
		c.pod.storage.deleteContainerResources(c.podID, c.id, nil)
		return err
	}

	return nil
}

// mountSharedDirMounts handles bind-mounts by bindmounting to the host shared
// directory which is mounted through 9pfs in the VM.
// It also updates the container mount list with the HostPath info, and store
// container mounts to the storage. This way, we will have the HostPath info
// available when we will need to unmount those mounts.
func (c *Container) mountSharedDirMounts(hostSharedDir, guestSharedDir string) ([]Mount, error) {
	var sharedDirMounts []Mount
	for idx, m := range c.mounts {
		if isSystemMount(m.Destination) || m.Type != "bind" {
			continue
		}

		randBytes, err := generateRandomBytes(8)
		if err != nil {
			return nil, err
		}

		// These mounts are created in the shared dir
		filename := fmt.Sprintf("%s-%s-%s", c.id, hex.EncodeToString(randBytes), filepath.Base(m.Destination))
		mountDest := filepath.Join(hostSharedDir, c.pod.id, filename)

		if err := bindMount(m.Source, mountDest, false); err != nil {
			return nil, err
		}

		// Save HostPath mount value into the mount list of the container.
		c.mounts[idx].HostPath = mountDest

		// Check if mount is readonly, let the agent handle the readonly mount
		// within the VM.
		readonly := false
		for _, flag := range m.Options {
			if flag == "ro" {
				readonly = true
			}
		}

		sharedDirMount := Mount{
			Source:      filepath.Join(guestSharedDir, filename),
			Destination: m.Destination,
			Type:        m.Type,
			Options:     m.Options,
			ReadOnly:    readonly,
		}

		sharedDirMounts = append(sharedDirMounts, sharedDirMount)
	}

	if err := c.storeMounts(); err != nil {
		return nil, err
	}

	return sharedDirMounts, nil
}

func (c *Container) unmountHostMounts() error {
	for _, m := range c.mounts {
		if m.HostPath != "" {
			if err := syscall.Unmount(m.HostPath, 0); err != nil {
				c.Logger().WithFields(logrus.Fields{
					"host-path": m.HostPath,
					"error":     err,
				}).Warn("Could not umount")
				return err
			}
		}
	}

	return nil
}

// newContainer creates a Container structure from a pod and a container configuration.
func newContainer(pod *Pod, contConfig ContainerConfig) (*Container, error) {
	if contConfig.valid() == false {
		return &Container{}, fmt.Errorf("Invalid container configuration")
	}

	c := &Container{
		id:            contConfig.ID,
		podID:         pod.id,
		rootFs:        contConfig.RootFs,
		config:        &contConfig,
		pod:           pod,
		runPath:       filepath.Join(runStoragePath, pod.id, contConfig.ID),
		configPath:    filepath.Join(configStoragePath, pod.id, contConfig.ID),
		containerPath: filepath.Join(pod.id, contConfig.ID),
		state:         State{},
		process:       Process{},
		mounts:        contConfig.Mounts,
	}

	state, err := c.pod.storage.fetchContainerState(c.podID, c.id)
	if err == nil {
		c.state = state
	}

	process, err := c.pod.storage.fetchContainerProcess(c.podID, c.id)
	if err == nil {
		c.process = process
	}

	mounts, err := c.fetchMounts()
	if err == nil {
		c.mounts = mounts
	}

	// Devices will be found in storage after create stage has completed.
	// We fetch devices from storage at all other stages.
	storedDevices, err := c.fetchDevices()
	if err == nil {
		c.devices = storedDevices
	} else {
		// If devices were not found in storage, create Device implementations
		// from the configuration. This should happen at create.

		devices, err := newDevices(contConfig.DeviceInfos)
		if err != nil {
			return &Container{}, err
		}
		c.devices = devices
	}
	return c, nil
}

// createContainer creates and start a container inside a Pod. It has to be
// called only when a new container, not known by the pod, has to be created.
func createContainer(pod *Pod, contConfig ContainerConfig) (*Container, error) {
	if pod == nil {
		return nil, errNeedPod
	}

	c, err := newContainer(pod, contConfig)
	if err != nil {
		return nil, err
	}

	if err := c.createContainersDirs(); err != nil {
		return nil, err
	}

	if !c.pod.config.HypervisorConfig.DisableBlockDeviceUse {
		agentCaps := c.pod.agent.capabilities()
		hypervisorCaps := c.pod.hypervisor.capabilities()

		if agentCaps.isBlockDeviceSupported() && hypervisorCaps.isBlockDeviceHotplugSupported() {
			if err := c.hotplugDrive(); err != nil {
				return nil, err
			}
		}
	}

	// Attach devices
	if err := c.attachDevices(); err != nil {
		return nil, err
	}

	if err := c.addResources(); err != nil {
		return nil, err
	}

	// Deduce additional system mount info that should be handled by the agent
	// inside the VM
	c.getSystemMountInfo()

	if err := c.storeDevices(); err != nil {
		return nil, err
	}

	process, err := pod.agent.createContainer(c.pod, c)
	if err != nil {
		return nil, err
	}
	c.process = *process

	// Store the container process returned by the agent.
	if err := c.storeProcess(); err != nil {
		return nil, err
	}

	if err := c.setContainerState(StateReady); err != nil {
		return nil, err
	}

	return c, nil
}

func (c *Container) delete() error {
	if c.state.State != StateReady &&
		c.state.State != StateStopped {
		return fmt.Errorf("Container not ready or stopped, impossible to delete")
	}

	// Remove the container from pod structure
	if err := c.pod.removeContainer(c.id); err != nil {
		return err
	}

	return c.pod.storage.deleteContainerResources(c.podID, c.id, nil)
}

// checkPodRunning validates the container state.
//
// cmd specifies the operation (or verb) that the retrieval is destined
// for and is only used to make the returned error as descriptive as
// possible.
func (c *Container) checkPodRunning(cmd string) error {
	if cmd == "" {
		return fmt.Errorf("Cmd cannot be empty")
	}

	if c.pod.state.State != StateRunning {
		return fmt.Errorf("Pod not running, impossible to %s the container", cmd)
	}

	return nil
}

func (c *Container) getSystemMountInfo() {
	// check if /dev needs to be bind mounted from host /dev
	c.systemMountsInfo.BindMountDev = false

	for _, m := range c.mounts {
		if m.Source == "/dev" && m.Destination == "/dev" && m.Type == "bind" {
			c.systemMountsInfo.BindMountDev = true
		}
	}

	// TODO Deduce /dev/shm size. See https://github.com/clearcontainers/runtime/issues/138
}

func (c *Container) start() error {
	if err := c.checkPodRunning("start"); err != nil {
		return err
	}

	if c.state.State != StateReady &&
		c.state.State != StateStopped {
		return fmt.Errorf("Container not ready or stopped, impossible to start")
	}

	if err := c.state.validTransition(c.state.State, StateRunning); err != nil {
		return err
	}

	if err := c.pod.agent.startContainer(*(c.pod), c); err != nil {
		c.Logger().WithError(err).Error("Failed to start container")

		if err := c.stop(); err != nil {
			c.Logger().WithError(err).Warn("Failed to stop container")
		}
		return err
	}

	return c.setContainerState(StateRunning)
}

func (c *Container) stop() error {
	// In case the container status has been updated implicitly because
	// the container process has terminated, it might be possible that
	// someone try to stop the container, and we don't want to issue an
	// error in that case. This should be a no-op.
	//
	// This has to be handled before the transition validation since this
	// is an exception.
	if c.state.State == StateStopped {
		c.Logger().Info("Container already stopped")
		return nil
	}

	if c.pod.state.State != StateReady && c.pod.state.State != StateRunning {
		return fmt.Errorf("Pod not ready or running, impossible to stop the container")
	}

	if err := c.state.validTransition(c.state.State, StateStopped); err != nil {
		return err
	}

	defer func() {
		// If shim is still running something went wrong
		// Make sure we stop the shim process
		if running, _ := isShimRunning(c.process.Pid); running {
			l := c.Logger()
			l.Error("Failed to stop container so stopping dangling shim")
			if err := stopShim(c.process.Pid); err != nil {
				l.WithError(err).Warn("failed to stop shim")
			}
		}

	}()

	// Here we expect that stop() has been called because the container
	// process returned or because it received a signal. In case of a
	// signal, we want to give it some time to end the container process.
	// However, if the signal didn't reach its goal, the caller still
	// expects this container to be stopped, that's why we should not
	// return an error, but instead try to kill it forcefully.
	if err := waitForShim(c.process.Pid); err != nil {
		// Force the container to be killed.
		if err := c.pod.agent.killContainer(*(c.pod), *c, syscall.SIGKILL, true); err != nil {
			return err
		}

		// Wait for the end of container process. We expect this call
		// to succeed. Indeed, we have already given a second chance
		// to the container by trying to kill it with SIGKILL, there
		// is no reason to try to go further if we got an error.
		if err := waitForShim(c.process.Pid); err != nil {
			return err
		}
	}

	if err := c.pod.agent.stopContainer(*(c.pod), *c); err != nil {
		return err
	}

	if err := c.removeResources(); err != nil {
		return err
	}

	if err := c.detachDevices(); err != nil {
		return err
	}

	if err := c.removeDrive(); err != nil {
		return err
	}

	return c.setContainerState(StateStopped)
}

func (c *Container) enter(cmd Cmd) (*Process, error) {
	if err := c.checkPodRunning("enter"); err != nil {
		return nil, err
	}

	if c.state.State != StateRunning {
		return nil, fmt.Errorf("Container not running, impossible to enter")
	}

	process, err := c.pod.agent.exec(c.pod, *c, cmd)
	if err != nil {
		return nil, err
	}

	return process, nil
}

func (c *Container) kill(signal syscall.Signal, all bool) error {
	if c.pod.state.State != StateReady && c.pod.state.State != StateRunning {
		return fmt.Errorf("Pod not ready or running, impossible to signal the container")
	}

	if c.state.State != StateReady && c.state.State != StateRunning {
		return fmt.Errorf("Container not ready or running, impossible to signal the container")
	}

	return c.pod.agent.killContainer(*(c.pod), *c, signal, all)
}

func (c *Container) processList(options ProcessListOptions) (ProcessList, error) {
	if err := c.checkPodRunning("ps"); err != nil {
		return nil, err
	}

	if c.state.State != StateRunning {
		return nil, fmt.Errorf("Container not running, impossible to list processes")
	}

	return c.pod.agent.processListContainer(*(c.pod), *c, options)
}

func (c *Container) hotplugDrive() error {
	dev, err := getDeviceForPath(c.rootFs)

	if err == errMountPointNotFound {
		return nil
	}

	if err != nil {
		return err
	}

	c.Logger().WithFields(logrus.Fields{
		"device-major": dev.major,
		"device-minor": dev.minor,
		"mount-point":  dev.mountPoint,
	}).Info("device details")

	isDM, err := checkStorageDriver(dev.major, dev.minor)
	if err != nil {
		return err
	}

	if !isDM {
		return nil
	}

	// If device mapper device, then fetch the full path of the device
	devicePath, fsType, err := getDevicePathAndFsType(dev.mountPoint)
	if err != nil {
		return err
	}

	c.Logger().WithFields(logrus.Fields{
		"device-path": devicePath,
		"fs-type":     fsType,
	}).Info("Block device detected")

	driveIndex, err := c.pod.getAndSetPodBlockIndex()
	if err != nil {
		return err
	}

	// Add drive with id as container id
	devID := makeNameID("drive", c.id)
	drive := Drive{
		File:   devicePath,
		Format: "raw",
		ID:     devID,
		Index:  driveIndex,
	}

	if err := c.pod.hypervisor.hotplugAddDevice(drive, blockDev); err != nil {
		return err
	}
	c.setStateHotpluggedDrive(true)

	if err := c.setStateBlockIndex(driveIndex); err != nil {
		return err
	}

	return c.setStateFstype(fsType)
}

// isDriveUsed checks if a drive has been used for container rootfs
func (c *Container) isDriveUsed() bool {
	if c.state.Fstype == "" {
		return false
	}
	return true
}

func (c *Container) removeDrive() (err error) {
	if c.isDriveUsed() && c.state.HotpluggedDrive {
		c.Logger().Info("unplugging block device")

		devID := makeNameID("drive", c.id)
		drive := Drive{
			ID: devID,
		}

		l := c.Logger().WithField("device-id", devID)
		l.Info("Unplugging block device")

		if err := c.pod.hypervisor.hotplugRemoveDevice(drive, blockDev); err != nil {
			l.WithError(err).Info("Failed to unplug block device")
			return err
		}
	}

	return nil
}

func (c *Container) attachDevices() error {
	for _, device := range c.devices {
		if err := device.attach(c.pod.hypervisor, c); err != nil {
			return err
		}
	}

	return nil
}

func (c *Container) detachDevices() error {
	for _, device := range c.devices {
		if err := device.detach(c.pod.hypervisor); err != nil {
			return err
		}
	}

	return nil
}

func (c *Container) addResources() error {
	//TODO add support for memory, Issue: https://github.com/containers/virtcontainers/issues/578
	if c.config == nil {
		return nil
	}

	vCPUs := ConstraintsToVCPUs(c.config.Resources.CPUQuota, c.config.Resources.CPUPeriod)
	if vCPUs != 0 {
		virtLog.Debugf("hot adding %d vCPUs", vCPUs)
		if err := c.pod.hypervisor.hotplugAddDevice(uint32(vCPUs), cpuDev); err != nil {
			return err
		}
	}

	return nil
}

func (c *Container) removeResources() error {
	//TODO add support for memory, Issue: https://github.com/containers/virtcontainers/issues/578
	if c.config == nil {
		return nil
	}

	vCPUs := ConstraintsToVCPUs(c.config.Resources.CPUQuota, c.config.Resources.CPUPeriod)
	if vCPUs != 0 {
		virtLog.Debugf("hot removing %d vCPUs", vCPUs)
		if err := c.pod.hypervisor.hotplugRemoveDevice(uint32(vCPUs), cpuDev); err != nil {
			return err
		}
	}

	return nil
}