/*
Copyright 2014 The Kubernetes Authors All rights reserved.

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 host_path

import (
	"fmt"

	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/types"
	"k8s.io/kubernetes/pkg/util/mount"
	"k8s.io/kubernetes/pkg/volume"
)

// This is the primary entrypoint for volume plugins.
// The volumeConfig arg provides the ability to configure volume behavior.  It is implemented as a pointer to allow nils.
// The hostPathPlugin is used to store the volumeConfig and give it, when needed, to the func that creates HostPath Recyclers.
// Tests that exercise recycling should not use this func but instead use ProbeRecyclablePlugins() to override default behavior.
func ProbeVolumePlugins(volumeConfig volume.VolumeConfig) []volume.VolumePlugin {
	return []volume.VolumePlugin{
		&hostPathPlugin{
			host:            nil,
			newRecyclerFunc: newRecycler,
			config:          volumeConfig,
		},
	}
}

func ProbeRecyclableVolumePlugins(recyclerFunc func(spec *volume.Spec, host volume.VolumeHost, volumeConfig volume.VolumeConfig) (volume.Recycler, error), volumeConfig volume.VolumeConfig) []volume.VolumePlugin {
	return []volume.VolumePlugin{
		&hostPathPlugin{
			host:            nil,
			newRecyclerFunc: recyclerFunc,
			config:          volumeConfig,
		},
	}
}

type hostPathPlugin struct {
	host volume.VolumeHost
	// decouple creating recyclers by deferring to a function.  Allows for easier testing.
	newRecyclerFunc func(spec *volume.Spec, host volume.VolumeHost, volumeConfig volume.VolumeConfig) (volume.Recycler, error)
	config          volume.VolumeConfig
}

var _ volume.VolumePlugin = &hostPathPlugin{}
var _ volume.PersistentVolumePlugin = &hostPathPlugin{}
var _ volume.RecyclableVolumePlugin = &hostPathPlugin{}

const (
	hostPathPluginName = "kubernetes.io/host-path"
)

func (plugin *hostPathPlugin) Init(host volume.VolumeHost) {
	plugin.host = host
}

func (plugin *hostPathPlugin) Name() string {
	return hostPathPluginName
}

func (plugin *hostPathPlugin) CanSupport(spec *volume.Spec) bool {
	return (spec.PersistentVolume != nil && spec.PersistentVolume.Spec.HostPath != nil) ||
		(spec.Volume != nil && spec.Volume.HostPath != nil)
}

func (plugin *hostPathPlugin) GetAccessModes() []api.PersistentVolumeAccessMode {
	return []api.PersistentVolumeAccessMode{
		api.ReadWriteOnce,
	}
}

func (plugin *hostPathPlugin) NewBuilder(spec *volume.Spec, pod *api.Pod, _ volume.VolumeOptions, _ mount.Interface) (volume.Builder, error) {
	if spec.Volume != nil && spec.Volume.HostPath != nil {
		return &hostPathBuilder{
			hostPath: &hostPath{path: spec.Volume.HostPath.Path},
			readOnly: false,
		}, nil
	} else {
		return &hostPathBuilder{
			hostPath: &hostPath{path: spec.PersistentVolume.Spec.HostPath.Path},
			readOnly: spec.ReadOnly,
		}, nil
	}
}

func (plugin *hostPathPlugin) NewCleaner(volName string, podUID types.UID, _ mount.Interface) (volume.Cleaner, error) {
	return &hostPathCleaner{&hostPath{""}}, nil
}

func (plugin *hostPathPlugin) NewRecycler(spec *volume.Spec) (volume.Recycler, error) {
	return plugin.newRecyclerFunc(spec, plugin.host, plugin.config)
}

func newRecycler(spec *volume.Spec, host volume.VolumeHost, config volume.VolumeConfig) (volume.Recycler, error) {
	if spec.PersistentVolume == nil || spec.PersistentVolume.Spec.HostPath == nil {
		return nil, fmt.Errorf("spec.PersistentVolumeSource.HostPath is nil")
	}
	return &hostPathRecycler{
		name:    spec.Name(),
		path:    spec.PersistentVolume.Spec.HostPath.Path,
		host:    host,
		config:  config,
		timeout: volume.CalculateTimeoutForVolume(config.RecyclerMinimumTimeout, config.RecyclerTimeoutIncrement, spec.PersistentVolume),
	}, nil
}

// HostPath volumes represent a bare host file or directory mount.
// The direct at the specified path will be directly exposed to the container.
type hostPath struct {
	path string
}

func (hp *hostPath) GetPath() string {
	return hp.path
}

type hostPathBuilder struct {
	*hostPath
	readOnly bool
}

var _ volume.Builder = &hostPathBuilder{}

// SetUp does nothing.
func (b *hostPathBuilder) SetUp() error {
	return nil
}

// SetUpAt does not make sense for host paths - probably programmer error.
func (b *hostPathBuilder) SetUpAt(dir string) error {
	return fmt.Errorf("SetUpAt() does not make sense for host paths")
}

func (b *hostPathBuilder) IsReadOnly() bool {
	return b.readOnly
}

func (b *hostPathBuilder) GetPath() string {
	return b.path
}

type hostPathCleaner struct {
	*hostPath
}

var _ volume.Cleaner = &hostPathCleaner{}

// TearDown does nothing.
func (c *hostPathCleaner) TearDown() error {
	return nil
}

// TearDownAt does not make sense for host paths - probably programmer error.
func (c *hostPathCleaner) TearDownAt(dir string) error {
	return fmt.Errorf("TearDownAt() does not make sense for host paths")
}

// hostPathRecycler scrubs a hostPath volume by running "rm -rf" on the volume in a pod
// This recycler only works on a single host cluster and is for testing purposes only.
type hostPathRecycler struct {
	name    string
	path    string
	host    volume.VolumeHost
	config  volume.VolumeConfig
	timeout int64
}

func (r *hostPathRecycler) GetPath() string {
	return r.path
}

// Recycle recycles/scrubs clean a HostPath volume.
// Recycle blocks until the pod has completed or any error occurs.
// HostPath recycling only works in single node clusters and is meant for testing purposes only.
func (r *hostPathRecycler) Recycle() error {
	pod := r.config.RecyclerPodTemplate
	// overrides
	pod.Spec.ActiveDeadlineSeconds = &r.timeout
	pod.GenerateName = "pv-recycler-hostpath-"
	pod.Spec.Volumes[0].VolumeSource = api.VolumeSource{
		HostPath: &api.HostPathVolumeSource{
			Path: r.path,
		},
	}
	return volume.RecycleVolumeByWatchingPodUntilCompletion(pod, r.host.GetKubeClient())
}