/*
Copyright 2018 The Kubernetes Authors.

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 util

import (
	"encoding/json"
	"fmt"
	"os"
	"regexp"

	"github.com/golang/glog"
	"github.com/pkg/errors"

	"k8s.io/api/core/v1"
	apierrs "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	k8s "k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
)

type K8sCMCache struct {
	Client    *k8s.Clientset
	Namespace string
}

const (
	defaultNamespace = "default"

	cmLabel   = "csi-metadata"
	cmDataKey = "content"

	csiMetadataLabelAttr = "com.ceph.ceph-csi/metadata"
)

func GetK8sNamespace() string {
	namespace := os.Getenv("POD_NAMESPACE")
	if namespace == "" {
		return defaultNamespace
	}
	return namespace
}

func NewK8sClient() *k8s.Clientset {
	var cfg *rest.Config
	var err error
	cPath := os.Getenv("KUBERNETES_CONFIG_PATH")
	if cPath != "" {
		cfg, err = clientcmd.BuildConfigFromFlags("", cPath)
		if err != nil {
			glog.Errorf("Failed to get cluster config with error: %v\n", err)
			os.Exit(1)
		}
	} else {
		cfg, err = rest.InClusterConfig()
		if err != nil {
			glog.Errorf("Failed to get cluster config with error: %v\n", err)
			os.Exit(1)
		}
	}
	client, err := k8s.NewForConfig(cfg)
	if err != nil {
		glog.Errorf("Failed to create client with error: %v\n", err)
		os.Exit(1)
	}
	return client
}

func (k8scm *K8sCMCache) getMetadataCM(resourceID string) (*v1.ConfigMap, error) {
	cm, err := k8scm.Client.CoreV1().ConfigMaps(k8scm.Namespace).Get(resourceID, metav1.GetOptions{})
	if err != nil {
		return nil, err
	}
	return cm, nil
}

func (k8scm *K8sCMCache) ForAll(pattern string, destObj interface{}, f ForAllFunc) error {
	listOpts := metav1.ListOptions{LabelSelector: fmt.Sprintf("%s=%s", csiMetadataLabelAttr, cmLabel)}
	cms, err := k8scm.Client.CoreV1().ConfigMaps(k8scm.Namespace).List(listOpts)
	if err != nil {
		return errors.Wrap(err, "k8s-cm-cache: failed to list metadata configmaps")
	}

	for _, cm := range cms.Items {
		data := cm.Data[cmDataKey]
		match, err := regexp.MatchString(pattern, cm.ObjectMeta.Name)
		if err != nil {
			continue
		}
		if !match {
			continue
		}
		if err = json.Unmarshal([]byte(data), destObj); err != nil {
			return errors.Wrap(err, "k8s-cm-cache: unmarshal error")
		}
		if err = f(cm.ObjectMeta.Name); err != nil {
			return err
		}
	}
	return nil
}

func (k8scm *K8sCMCache) Create(identifier string, data interface{}) error {
	cm, err := k8scm.getMetadataCM(identifier)
	if cm != nil && err == nil {
		glog.V(4).Infof("k8s-cm-cache: configmap already exists, skipping configmap creation")
		return nil
	}
	dataJSON, err := json.Marshal(data)
	if err != nil {
		return errors.Wrap(err, "k8s-cm-cache: marshal error")
	}
	cm = &v1.ConfigMap{
		ObjectMeta: metav1.ObjectMeta{
			Name:      identifier,
			Namespace: k8scm.Namespace,
			Labels: map[string]string{
				csiMetadataLabelAttr: cmLabel,
			},
		},
		Data: map[string]string{},
	}
	cm.Data[cmDataKey] = string(dataJSON)

	_, err = k8scm.Client.CoreV1().ConfigMaps(k8scm.Namespace).Create(cm)
	if err != nil {
		if apierrs.IsAlreadyExists(err) {
			glog.V(4).Infof("k8s-cm-cache: configmap already exists")
			return nil
		}
		return errors.Wrapf(err, "k8s-cm-cache: couldn't persist %s metadata as configmap", identifier)
	}

	glog.V(4).Infof("k8s-cm-cache: configmap %s successfully created\n", identifier)
	return nil
}

func (k8scm *K8sCMCache) Get(identifier string, data interface{}) error {
	cm, err := k8scm.getMetadataCM(identifier)
	if err != nil {
		return err
	}
	err = json.Unmarshal([]byte(cm.Data[cmDataKey]), data)
	if err != nil {
		return errors.Wrap(err, "k8s-cm-cache: unmarshal error")
	}
	return nil
}

func (k8scm *K8sCMCache) Delete(identifier string) error {
	err := k8scm.Client.CoreV1().ConfigMaps(k8scm.Namespace).Delete(identifier, nil)
	if err != nil {
		return errors.Wrapf(err, "k8s-cm-cache: couldn't delete metadata configmap %s", identifier)
	}
	glog.V(4).Infof("k8s-cm-cache: successfully deleted metadata configmap %s", identifier)
	return nil
}