/*
Copyright 2016 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 options

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"github.com/spf13/pflag"

	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/apiserver/pkg/registry/generic"
	genericregistry "k8s.io/apiserver/pkg/registry/generic/registry"
	"k8s.io/apiserver/pkg/server"
	"k8s.io/apiserver/pkg/server/healthz"
	serverstorage "k8s.io/apiserver/pkg/server/storage"
	"k8s.io/apiserver/pkg/storage/etcd3/preflight"
	"k8s.io/apiserver/pkg/storage/storagebackend"
)

type EtcdOptions struct {
	// The value of Paging on StorageConfig will be overriden by the
	// calculated feature gate value.
	StorageConfig                    storagebackend.Config
	EncryptionProviderConfigFilepath string

	EtcdServersOverrides []string

	// To enable protobuf as storage format, it is enough
	// to set it to "application/vnd.kubernetes.protobuf".
	DefaultStorageMediaType string
	DeleteCollectionWorkers int
	EnableGarbageCollection bool

	// Set EnableWatchCache to false to disable all watch caches
	EnableWatchCache bool
	// Set DefaultWatchCacheSize to zero to disable watch caches for those resources that have no explicit cache size set
	DefaultWatchCacheSize int
	// WatchCacheSizes represents override to a given resource
	WatchCacheSizes []string
}

var storageTypes = sets.NewString(
	storagebackend.StorageTypeUnset,
	storagebackend.StorageTypeETCD2,
	storagebackend.StorageTypeETCD3,
)

func NewEtcdOptions(backendConfig *storagebackend.Config) *EtcdOptions {
	return &EtcdOptions{
		StorageConfig:           *backendConfig,
		DefaultStorageMediaType: "application/json",
		DeleteCollectionWorkers: 1,
		EnableGarbageCollection: true,
		EnableWatchCache:        true,
		DefaultWatchCacheSize:   100,
	}
}

func (s *EtcdOptions) Validate() []error {
	if s == nil {
		return nil
	}

	allErrors := []error{}
	if len(s.StorageConfig.ServerList) == 0 {
		allErrors = append(allErrors, fmt.Errorf("--etcd-servers must be specified"))
	}

	if !storageTypes.Has(s.StorageConfig.Type) {
		allErrors = append(allErrors, fmt.Errorf("--storage-backend invalid, must be 'etcd3' or 'etcd2'. If not specified, it will default to 'etcd3'"))
	}

	return allErrors
}

// AddEtcdFlags adds flags related to etcd storage for a specific APIServer to the specified FlagSet
func (s *EtcdOptions) AddFlags(fs *pflag.FlagSet) {
	if s == nil {
		return
	}

	fs.StringSliceVar(&s.EtcdServersOverrides, "etcd-servers-overrides", s.EtcdServersOverrides, ""+
		"Per-resource etcd servers overrides, comma separated. The individual override "+
		"format: group/resource#servers, where servers are http://ip:port, semicolon separated.")

	fs.StringVar(&s.DefaultStorageMediaType, "storage-media-type", s.DefaultStorageMediaType, ""+
		"The media type to use to store objects in storage. "+
		"Some resources or storage backends may only support a specific media type and will ignore this setting.")
	fs.IntVar(&s.DeleteCollectionWorkers, "delete-collection-workers", s.DeleteCollectionWorkers,
		"Number of workers spawned for DeleteCollection call. These are used to speed up namespace cleanup.")

	fs.BoolVar(&s.EnableGarbageCollection, "enable-garbage-collector", s.EnableGarbageCollection, ""+
		"Enables the generic garbage collector. MUST be synced with the corresponding flag "+
		"of the kube-controller-manager.")

	fs.BoolVar(&s.EnableWatchCache, "watch-cache", s.EnableWatchCache,
		"Enable watch caching in the apiserver")

	fs.IntVar(&s.DefaultWatchCacheSize, "default-watch-cache-size", s.DefaultWatchCacheSize,
		"Default watch cache size. If zero, watch cache will be disabled for resources that do not have a default watch size set.")

	fs.StringSliceVar(&s.WatchCacheSizes, "watch-cache-sizes", s.WatchCacheSizes, ""+
		"List of watch cache sizes for every resource (pods, nodes, etc.), comma separated. "+
		"The individual override format: resource#size, where size is a number. It takes effect "+
		"when watch-cache is enabled.")

	fs.StringVar(&s.StorageConfig.Type, "storage-backend", s.StorageConfig.Type,
		"The storage backend for persistence. Options: 'etcd3' (default), 'etcd2'.")

	fs.IntVar(&s.StorageConfig.DeserializationCacheSize, "deserialization-cache-size", s.StorageConfig.DeserializationCacheSize,
		"Number of deserialized json objects to cache in memory.")

	fs.StringSliceVar(&s.StorageConfig.ServerList, "etcd-servers", s.StorageConfig.ServerList,
		"List of etcd servers to connect with (scheme://ip:port), comma separated.")

	fs.StringVar(&s.StorageConfig.Prefix, "etcd-prefix", s.StorageConfig.Prefix,
		"The prefix to prepend to all resource paths in etcd.")

	fs.StringVar(&s.StorageConfig.KeyFile, "etcd-keyfile", s.StorageConfig.KeyFile,
		"SSL key file used to secure etcd communication.")

	fs.StringVar(&s.StorageConfig.CertFile, "etcd-certfile", s.StorageConfig.CertFile,
		"SSL certification file used to secure etcd communication.")

	fs.StringVar(&s.StorageConfig.CAFile, "etcd-cafile", s.StorageConfig.CAFile,
		"SSL Certificate Authority file used to secure etcd communication.")

	fs.BoolVar(&s.StorageConfig.Quorum, "etcd-quorum-read", s.StorageConfig.Quorum,
		"If true, enable quorum read.")

	fs.StringVar(&s.EncryptionProviderConfigFilepath, "experimental-encryption-provider-config", s.EncryptionProviderConfigFilepath,
		"The file containing configuration for encryption providers to be used for storing secrets in etcd")
}

func (s *EtcdOptions) ApplyTo(c *server.Config) error {
	if s == nil {
		return nil
	}

	s.addEtcdHealthEndpoint(c)
	c.RESTOptionsGetter = &SimpleRestOptionsFactory{Options: *s}
	return nil
}

func (s *EtcdOptions) ApplyWithStorageFactoryTo(factory serverstorage.StorageFactory, c *server.Config) error {
	s.addEtcdHealthEndpoint(c)
	c.RESTOptionsGetter = &storageFactoryRestOptionsFactory{Options: *s, StorageFactory: factory}
	return nil
}

func (s *EtcdOptions) addEtcdHealthEndpoint(c *server.Config) {
	c.HealthzChecks = append(c.HealthzChecks, healthz.NamedCheck("etcd", func(r *http.Request) error {
		done, err := preflight.EtcdConnection{ServerList: s.StorageConfig.ServerList}.CheckEtcdServers()
		if !done {
			return fmt.Errorf("etcd failed")
		}
		if err != nil {
			return err
		}
		return nil
	}))
}

type SimpleRestOptionsFactory struct {
	Options EtcdOptions
}

func (f *SimpleRestOptionsFactory) GetRESTOptions(resource schema.GroupResource) (generic.RESTOptions, error) {
	ret := generic.RESTOptions{
		StorageConfig:           &f.Options.StorageConfig,
		Decorator:               generic.UndecoratedStorage,
		EnableGarbageCollection: f.Options.EnableGarbageCollection,
		DeleteCollectionWorkers: f.Options.DeleteCollectionWorkers,
		ResourcePrefix:          resource.Group + "/" + resource.Resource,
	}
	if f.Options.EnableWatchCache {
		sizes, err := ParseWatchCacheSizes(f.Options.WatchCacheSizes)
		if err != nil {
			return generic.RESTOptions{}, err
		}
		cacheSize, ok := sizes[resource]
		if !ok {
			cacheSize = f.Options.DefaultWatchCacheSize
		}
		ret.Decorator = genericregistry.StorageWithCacher(cacheSize)
	}
	return ret, nil
}

type storageFactoryRestOptionsFactory struct {
	Options        EtcdOptions
	StorageFactory serverstorage.StorageFactory
}

func (f *storageFactoryRestOptionsFactory) GetRESTOptions(resource schema.GroupResource) (generic.RESTOptions, error) {
	storageConfig, err := f.StorageFactory.NewConfig(resource)
	if err != nil {
		return generic.RESTOptions{}, fmt.Errorf("unable to find storage destination for %v, due to %v", resource, err.Error())
	}

	ret := generic.RESTOptions{
		StorageConfig:           storageConfig,
		Decorator:               generic.UndecoratedStorage,
		DeleteCollectionWorkers: f.Options.DeleteCollectionWorkers,
		EnableGarbageCollection: f.Options.EnableGarbageCollection,
		ResourcePrefix:          f.StorageFactory.ResourcePrefix(resource),
	}
	if f.Options.EnableWatchCache {
		sizes, err := ParseWatchCacheSizes(f.Options.WatchCacheSizes)
		if err != nil {
			return generic.RESTOptions{}, err
		}
		cacheSize, ok := sizes[resource]
		if !ok {
			cacheSize = f.Options.DefaultWatchCacheSize
		}
		ret.Decorator = genericregistry.StorageWithCacher(cacheSize)
	}

	return ret, nil
}

// ParseWatchCacheSizes turns a list of cache size values into a map of group resources
// to requested sizes.
func ParseWatchCacheSizes(cacheSizes []string) (map[schema.GroupResource]int, error) {
	watchCacheSizes := make(map[schema.GroupResource]int)
	for _, c := range cacheSizes {
		tokens := strings.Split(c, "#")
		if len(tokens) != 2 {
			return nil, fmt.Errorf("invalid value of watch cache size: %s", c)
		}

		size, err := strconv.Atoi(tokens[1])
		if err != nil {
			return nil, fmt.Errorf("invalid size of watch cache size: %s", c)
		}
		if size < 0 {
			return nil, fmt.Errorf("watch cache size cannot be negative: %s", c)
		}

		watchCacheSizes[schema.ParseGroupResource(tokens[0])] = size
	}
	return watchCacheSizes, nil
}

// WriteWatchCacheSizes turns a map of cache size values into a list of string specifications.
func WriteWatchCacheSizes(watchCacheSizes map[schema.GroupResource]int) ([]string, error) {
	var cacheSizes []string

	for resource, size := range watchCacheSizes {
		if size < 0 {
			return nil, fmt.Errorf("watch cache size cannot be negative for resource %s", resource)
		}
		cacheSizes = append(cacheSizes, fmt.Sprintf("%s#%d", resource.String(), size))
	}
	return cacheSizes, nil
}