/*
Copyright 2015 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 configmap

import (
	"fmt"

	"github.com/golang/glog"
	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/types"
	ioutil "k8s.io/kubernetes/pkg/util/io"
	"k8s.io/kubernetes/pkg/util/mount"
	"k8s.io/kubernetes/pkg/util/strings"
	"k8s.io/kubernetes/pkg/volume"
	volumeutil "k8s.io/kubernetes/pkg/volume/util"
)

// ProbeVolumePlugin is the entry point for plugin detection in a package.
func ProbeVolumePlugins() []volume.VolumePlugin {
	return []volume.VolumePlugin{&configMapPlugin{}}
}

const (
	configMapPluginName = "kubernetes.io/configmap"
)

// configMapPlugin implements the VolumePlugin interface.
type configMapPlugin struct {
	host volume.VolumeHost
}

var _ volume.VolumePlugin = &configMapPlugin{}

func (plugin *configMapPlugin) Init(host volume.VolumeHost) error {
	plugin.host = host
	return nil
}

func (plugin *configMapPlugin) Name() string {
	return configMapPluginName
}

func (plugin *configMapPlugin) CanSupport(spec *volume.Spec) bool {
	return spec.Volume != nil && spec.Volume.ConfigMap != nil
}

func (plugin *configMapPlugin) NewMounter(spec *volume.Spec, pod *api.Pod, opts volume.VolumeOptions) (volume.Mounter, error) {
	return &configMapVolumeMounter{
		configMapVolume: &configMapVolume{spec.Name(), pod.UID, plugin, plugin.host.GetMounter(), plugin.host.GetWriter(), volume.MetricsNil{}},
		source:          *spec.Volume.ConfigMap,
		pod:             *pod,
		opts:            &opts}, nil
}

func (plugin *configMapPlugin) NewUnmounter(volName string, podUID types.UID) (volume.Unmounter, error) {
	return &configMapVolumeUnmounter{&configMapVolume{volName, podUID, plugin, plugin.host.GetMounter(), plugin.host.GetWriter(), volume.MetricsNil{}}}, nil
}

type configMapVolume struct {
	volName string
	podUID  types.UID
	plugin  *configMapPlugin
	mounter mount.Interface
	writer  ioutil.Writer
	volume.MetricsNil
}

var _ volume.Volume = &configMapVolume{}

func (sv *configMapVolume) GetPath() string {
	return sv.plugin.host.GetPodVolumeDir(sv.podUID, strings.EscapeQualifiedNameForDisk(configMapPluginName), sv.volName)
}

// configMapVolumeMounter handles retrieving secrets from the API server
// and placing them into the volume on the host.
type configMapVolumeMounter struct {
	*configMapVolume

	source api.ConfigMapVolumeSource
	pod    api.Pod
	opts   *volume.VolumeOptions
}

var _ volume.Mounter = &configMapVolumeMounter{}

func (sv *configMapVolume) GetAttributes() volume.Attributes {
	return volume.Attributes{
		ReadOnly:        true,
		Managed:         true,
		SupportsSELinux: true,
	}
}

// This is the spec for the volume that this plugin wraps.
var wrappedVolumeSpec = volume.Spec{
	Volume: &api.Volume{VolumeSource: api.VolumeSource{EmptyDir: &api.EmptyDirVolumeSource{Medium: api.StorageMediumMemory}}},
}

func (b *configMapVolumeMounter) SetUp(fsGroup *int64) error {
	return b.SetUpAt(b.GetPath(), fsGroup)
}

func (b *configMapVolumeMounter) SetUpAt(dir string, fsGroup *int64) error {
	glog.V(3).Infof("Setting up volume %v for pod %v at %v", b.volName, b.pod.UID, dir)

	// Wrap EmptyDir, let it do the setup.
	wrapped, err := b.plugin.host.NewWrapperMounter(b.volName, wrappedVolumeSpec, &b.pod, *b.opts)
	if err != nil {
		return err
	}
	if err := wrapped.SetUpAt(dir, fsGroup); err != nil {
		return err
	}

	kubeClient := b.plugin.host.GetKubeClient()
	if kubeClient == nil {
		return fmt.Errorf("Cannot setup configMap volume %v because kube client is not configured", b.volName)
	}

	configMap, err := kubeClient.Core().ConfigMaps(b.pod.Namespace).Get(b.source.Name)
	if err != nil {
		glog.Errorf("Couldn't get configMap %v/%v: %v", b.pod.Namespace, b.source.Name, err)
		return err
	}

	totalBytes := totalBytes(configMap)
	glog.V(3).Infof("Received configMap %v/%v containing (%v) pieces of data, %v total bytes",
		b.pod.Namespace,
		b.source.Name,
		len(configMap.Data),
		totalBytes)

	payload, err := makePayload(b.source.Items, configMap)
	if err != nil {
		return err
	}

	writerContext := fmt.Sprintf("pod %v/%v volume %v", b.pod.Namespace, b.pod.Name, b.volName)
	writer, err := volumeutil.NewAtomicWriter(dir, writerContext)
	if err != nil {
		glog.Errorf("Error creating atomic writer: %v", err)
		return err
	}

	err = writer.Write(payload)
	if err != nil {
		glog.Errorf("Error writing payload to dir: %v", err)
		return err
	}

	err = volume.SetVolumeOwnership(b, fsGroup)
	if err != nil {
		glog.Errorf("Error applying volume ownership settings for group: %v", fsGroup)
		return err
	}

	return nil
}

func makePayload(mappings []api.KeyToPath, configMap *api.ConfigMap) (map[string][]byte, error) {
	payload := make(map[string][]byte, len(configMap.Data))

	if len(mappings) == 0 {
		for name, data := range configMap.Data {
			payload[name] = []byte(data)
		}
	} else {
		for _, ktp := range mappings {
			content, ok := configMap.Data[ktp.Key]
			if !ok {
				glog.Errorf("references non-existent config key")
				return nil, fmt.Errorf("references non-existent config key")
			}

			payload[ktp.Path] = []byte(content)
		}
	}

	return payload, nil
}

func totalBytes(configMap *api.ConfigMap) int {
	totalSize := 0
	for _, value := range configMap.Data {
		totalSize += len(value)
	}

	return totalSize
}

// configMapVolumeUnmounter handles cleaning up configMap volumes.
type configMapVolumeUnmounter struct {
	*configMapVolume
}

var _ volume.Unmounter = &configMapVolumeUnmounter{}

func (c *configMapVolumeUnmounter) TearDown() error {
	return c.TearDownAt(c.GetPath())
}

func (c *configMapVolumeUnmounter) TearDownAt(dir string) error {
	glog.V(3).Infof("Tearing down volume %v for pod %v at %v", c.volName, c.podUID, dir)

	// Wrap EmptyDir, let it do the teardown.
	wrapped, err := c.plugin.host.NewWrapperUnmounter(c.volName, wrappedVolumeSpec, c.podUID)
	if err != nil {
		return err
	}
	return wrapped.TearDownAt(dir)
}