/*
Copyright 2014 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 cloudprovider

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/informers"
	clientset "k8s.io/client-go/kubernetes"
	restclient "k8s.io/client-go/rest"
)

// ControllerClientBuilder allows you to get clients and configs for controllers
// Please note a copy also exists in pkg/controller/client_builder.go
// TODO: Make this depend on the separate controller utilities repo (issues/68947)
type ControllerClientBuilder interface {
	Config(name string) (*restclient.Config, error)
	ConfigOrDie(name string) *restclient.Config
	Client(name string) (clientset.Interface, error)
	ClientOrDie(name string) clientset.Interface
}

// Interface is an abstract, pluggable interface for cloud providers.
type Interface interface {
	// Initialize provides the cloud with a kubernetes client builder and may spawn goroutines
	// to perform housekeeping or run custom controllers specific to the cloud provider.
	// Any tasks started here should be cleaned up when the stop channel closes.
	Initialize(clientBuilder ControllerClientBuilder, stop <-chan struct{})
	// LoadBalancer returns a balancer interface. Also returns true if the interface is supported, false otherwise.
	LoadBalancer() (LoadBalancer, bool)
	// Instances returns an instances interface. Also returns true if the interface is supported, false otherwise.
	Instances() (Instances, bool)
	// Zones returns a zones interface. Also returns true if the interface is supported, false otherwise.
	Zones() (Zones, bool)
	// Clusters returns a clusters interface.  Also returns true if the interface is supported, false otherwise.
	Clusters() (Clusters, bool)
	// Routes returns a routes interface along with whether the interface is supported.
	Routes() (Routes, bool)
	// ProviderName returns the cloud provider ID.
	ProviderName() string
	// HasClusterID returns true if a ClusterID is required and set
	HasClusterID() bool
}

type InformerUser interface {
	// SetInformers sets the informer on the cloud object.
	SetInformers(informerFactory informers.SharedInformerFactory)
}

// Clusters is an abstract, pluggable interface for clusters of containers.
type Clusters interface {
	// ListClusters lists the names of the available clusters.
	ListClusters(ctx context.Context) ([]string, error)
	// Master gets back the address (either DNS name or IP address) of the master node for the cluster.
	Master(ctx context.Context, clusterName string) (string, error)
}

// (DEPRECATED) DefaultLoadBalancerName is the default load balancer name that is called from
// LoadBalancer.GetLoadBalancerName. Use this method to maintain backward compatible names for
// LoadBalancers that were created prior to Kubernetes v1.12. In the future, each provider should
// replace this method call in GetLoadBalancerName with a provider-specific implementation that
// is less cryptic than the Service's UUID.
func DefaultLoadBalancerName(service *v1.Service) string {
	//GCE requires that the name of a load balancer starts with a lower case letter.
	ret := "a" + string(service.UID)
	ret = strings.Replace(ret, "-", "", -1)
	//AWS requires that the name of a load balancer is shorter than 32 bytes.
	if len(ret) > 32 {
		ret = ret[:32]
	}
	return ret
}

// GetInstanceProviderID builds a ProviderID for a node in a cloud.
func GetInstanceProviderID(ctx context.Context, cloud Interface, nodeName types.NodeName) (string, error) {
	instances, ok := cloud.Instances()
	if !ok {
		return "", fmt.Errorf("failed to get instances from cloud provider")
	}
	instanceID, err := instances.InstanceID(ctx, nodeName)
	if err != nil {
		return "", fmt.Errorf("failed to get instance ID from cloud provider: %v", err)
	}
	return cloud.ProviderName() + "://" + instanceID, nil
}

// LoadBalancer is an abstract, pluggable interface for load balancers.
//
// Cloud provider may chose to implement the logic for
// constructing/destroying specific kinds of load balancers in a
// controller separate from the ServiceController.  If this is the case,
// then {Ensure,Update}LoadBalancer must return the ImplementedElsewhere error.
// For the given LB service, the GetLoadBalancer must return "exists=True" if
// there exists a LoadBalancer instance created by ServiceController.
// In all other cases, GetLoadBalancer must return a NotFound error.
// EnsureLoadBalancerDeleted must not return ImplementedElsewhere to ensure
// proper teardown of resources that were allocated by the ServiceController.
// This can happen if a user changes the type of LB via an update to the resource
// or when migrating from ServiceController to alternate implementation.
// The finalizer on the service will be added and removed by ServiceController
// irrespective of the ImplementedElsewhere error. Additional finalizers for
// LB services must be managed in the alternate implementation.
type LoadBalancer interface {
	// TODO: Break this up into different interfaces (LB, etc) when we have more than one type of service
	// GetLoadBalancer returns whether the specified load balancer exists, and
	// if so, what its status is.
	// Implementations must treat the *v1.Service parameter as read-only and not modify it.
	// Parameter 'clusterName' is the name of the cluster as presented to kube-controller-manager
	GetLoadBalancer(ctx context.Context, clusterName string, service *v1.Service) (status *v1.LoadBalancerStatus, exists bool, err error)
	// GetLoadBalancerName returns the name of the load balancer. Implementations must treat the
	// *v1.Service parameter as read-only and not modify it.
	GetLoadBalancerName(ctx context.Context, clusterName string, service *v1.Service) string
	// EnsureLoadBalancer creates a new load balancer 'name', or updates the existing one. Returns the status of the balancer
	// Implementations must treat the *v1.Service and *v1.Node
	// parameters as read-only and not modify them.
	// Parameter 'clusterName' is the name of the cluster as presented to kube-controller-manager
	EnsureLoadBalancer(ctx context.Context, clusterName string, service *v1.Service, nodes []*v1.Node) (*v1.LoadBalancerStatus, error)
	// UpdateLoadBalancer updates hosts under the specified load balancer.
	// Implementations must treat the *v1.Service and *v1.Node
	// parameters as read-only and not modify them.
	// Parameter 'clusterName' is the name of the cluster as presented to kube-controller-manager
	UpdateLoadBalancer(ctx context.Context, clusterName string, service *v1.Service, nodes []*v1.Node) error
	// EnsureLoadBalancerDeleted deletes the specified load balancer if it
	// exists, returning nil if the load balancer specified either didn't exist or
	// was successfully deleted.
	// This construction is useful because many cloud providers' load balancers
	// have multiple underlying components, meaning a Get could say that the LB
	// doesn't exist even if some part of it is still laying around.
	// Implementations must treat the *v1.Service parameter as read-only and not modify it.
	// Parameter 'clusterName' is the name of the cluster as presented to kube-controller-manager
	EnsureLoadBalancerDeleted(ctx context.Context, clusterName string, service *v1.Service) error
}

// Instances is an abstract, pluggable interface for sets of instances.
type Instances interface {
	// NodeAddresses returns the addresses of the specified instance.
	// TODO(roberthbailey): This currently is only used in such a way that it
	// returns the address of the calling instance. We should do a rename to
	// make this clearer.
	NodeAddresses(ctx context.Context, name types.NodeName) ([]v1.NodeAddress, error)
	// NodeAddressesByProviderID returns the addresses of the specified instance.
	// The instance is specified using the providerID of the node. The
	// ProviderID is a unique identifier of the node. This will not be called
	// from the node whose nodeaddresses are being queried. i.e. local metadata
	// services cannot be used in this method to obtain nodeaddresses
	NodeAddressesByProviderID(ctx context.Context, providerID string) ([]v1.NodeAddress, error)
	// InstanceID returns the cloud provider ID of the node with the specified NodeName.
	// Note that if the instance does not exist, we must return ("", cloudprovider.InstanceNotFound)
	// cloudprovider.InstanceNotFound should NOT be returned for instances that exist but are stopped/sleeping
	InstanceID(ctx context.Context, nodeName types.NodeName) (string, error)
	// InstanceType returns the type of the specified instance.
	InstanceType(ctx context.Context, name types.NodeName) (string, error)
	// InstanceTypeByProviderID returns the type of the specified instance.
	InstanceTypeByProviderID(ctx context.Context, providerID string) (string, error)
	// AddSSHKeyToAllInstances adds an SSH public key as a legal identity for all instances
	// expected format for the key is standard ssh-keygen format: <protocol> <blob>
	AddSSHKeyToAllInstances(ctx context.Context, user string, keyData []byte) error
	// CurrentNodeName returns the name of the node we are currently running on
	// On most clouds (e.g. GCE) this is the hostname, so we provide the hostname
	CurrentNodeName(ctx context.Context, hostname string) (types.NodeName, error)
	// InstanceExistsByProviderID returns true if the instance for the given provider exists.
	// If false is returned with no error, the instance will be immediately deleted by the cloud controller manager.
	// This method should still return true for instances that exist but are stopped/sleeping.
	InstanceExistsByProviderID(ctx context.Context, providerID string) (bool, error)
	// InstanceShutdownByProviderID returns true if the instance is shutdown in cloudprovider
	InstanceShutdownByProviderID(ctx context.Context, providerID string) (bool, error)
}

// Route is a representation of an advanced routing rule.
type Route struct {
	// Name is the name of the routing rule in the cloud-provider.
	// It will be ignored in a Create (although nameHint may influence it)
	Name string
	// TargetNode is the NodeName of the target instance.
	TargetNode types.NodeName
	// DestinationCIDR is the CIDR format IP range that this routing rule
	// applies to.
	DestinationCIDR string
	// Blackhole is set to true if this is a blackhole route
	// The node controller will delete the route if it is in the managed range.
	Blackhole bool
}

// Routes is an abstract, pluggable interface for advanced routing rules.
type Routes interface {
	// ListRoutes lists all managed routes that belong to the specified clusterName
	ListRoutes(ctx context.Context, clusterName string) ([]*Route, error)
	// CreateRoute creates the described managed route
	// route.Name will be ignored, although the cloud-provider may use nameHint
	// to create a more user-meaningful name.
	CreateRoute(ctx context.Context, clusterName string, nameHint string, route *Route) error
	// DeleteRoute deletes the specified managed route
	// Route should be as returned by ListRoutes
	DeleteRoute(ctx context.Context, clusterName string, route *Route) error
}

var (
	DiskNotFound         = errors.New("disk is not found")
	ImplementedElsewhere = errors.New("implemented by alternate to cloud provider")
	InstanceNotFound     = errors.New("instance not found")
	NotImplemented       = errors.New("unimplemented")
)

// Zone represents the location of a particular machine.
type Zone struct {
	FailureDomain string
	Region        string
}

// Zones is an abstract, pluggable interface for zone enumeration.
type Zones interface {
	// GetZone returns the Zone containing the current failure zone and locality region that the program is running in
	// In most cases, this method is called from the kubelet querying a local metadata service to acquire its zone.
	// For the case of external cloud providers, use GetZoneByProviderID or GetZoneByNodeName since GetZone
	// can no longer be called from the kubelets.
	GetZone(ctx context.Context) (Zone, error)

	// GetZoneByProviderID returns the Zone containing the current zone and locality region of the node specified by providerID
	// This method is particularly used in the context of external cloud providers where node initialization must be done
	// outside the kubelets.
	GetZoneByProviderID(ctx context.Context, providerID string) (Zone, error)

	// GetZoneByNodeName returns the Zone containing the current zone and locality region of the node specified by node name
	// This method is particularly used in the context of external cloud providers where node initialization must be done
	// outside the kubelets.
	GetZoneByNodeName(ctx context.Context, nodeName types.NodeName) (Zone, error)
}

// PVLabeler is an abstract, pluggable interface for fetching labels for volumes
type PVLabeler interface {
	GetLabelsForVolume(ctx context.Context, pv *v1.PersistentVolume) (map[string]string, error)
}
