/*
Copyright 2015 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 proxy

import (
	"fmt"
	"net"

	v1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/apimachinery/pkg/util/sets"
	"k8s.io/kubernetes/pkg/proxy/config"
)

// Provider is the interface provided by proxier implementations.
type Provider interface {
	config.EndpointSliceHandler
	config.ServiceHandler
	config.NodeHandler

	// Sync immediately synchronizes the Provider's current state to proxy rules.
	Sync()
	// SyncLoop runs periodic work.
	// This is expected to run as a goroutine or as the main loop of the app.
	// It does not return.
	SyncLoop()
}

// ServicePortName carries a namespace + name + portname.  This is the unique
// identifier for a load-balanced service.
type ServicePortName struct {
	types.NamespacedName
	Port     string
	Protocol v1.Protocol
}

func (spn ServicePortName) String() string {
	return fmt.Sprintf("%s%s", spn.NamespacedName.String(), fmtPortName(spn.Port))
}

func fmtPortName(in string) string {
	if in == "" {
		return ""
	}
	return fmt.Sprintf(":%s", in)
}

// ServicePort is an interface which abstracts information about a service.
type ServicePort interface {
	// String returns service string.  An example format can be: `IP:Port/Protocol`.
	String() string
	// ClusterIP returns service cluster IP in net.IP format.
	ClusterIP() net.IP
	// Port returns service port if present. If return 0 means not present.
	Port() int
	// SessionAffinityType returns service session affinity type
	SessionAffinityType() v1.ServiceAffinity
	// StickyMaxAgeSeconds returns service max connection age
	StickyMaxAgeSeconds() int
	// ExternalIPStrings returns service ExternalIPs as a string array.
	ExternalIPStrings() []string
	// LoadBalancerIPStrings returns service LoadBalancerIPs as a string array.
	LoadBalancerIPStrings() []string
	// Protocol returns service protocol.
	Protocol() v1.Protocol
	// LoadBalancerSourceRanges returns service LoadBalancerSourceRanges if present empty array if not
	LoadBalancerSourceRanges() []string
	// HealthCheckNodePort returns service health check node port if present.  If return 0, it means not present.
	HealthCheckNodePort() int
	// NodePort returns a service Node port if present. If return 0, it means not present.
	NodePort() int
	// ExternalPolicyLocal returns if a service has only node local endpoints for external traffic.
	ExternalPolicyLocal() bool
	// InternalPolicyLocal returns if a service has only node local endpoints for internal traffic.
	InternalPolicyLocal() bool
	// InternalTrafficPolicy returns service InternalTrafficPolicy
	InternalTrafficPolicy() *v1.ServiceInternalTrafficPolicy
	// HintsAnnotation returns the value of the v1.AnnotationTopologyAwareHints annotation.
	HintsAnnotation() string
	// ExternallyAccessible returns true if the service port is reachable via something
	// other than ClusterIP (NodePort/ExternalIP/LoadBalancer)
	ExternallyAccessible() bool
	// UsesClusterEndpoints returns true if the service port ever sends traffic to
	// endpoints based on "Cluster" traffic policy
	UsesClusterEndpoints() bool
	// UsesLocalEndpoints returns true if the service port ever sends traffic to
	// endpoints based on "Local" traffic policy
	UsesLocalEndpoints() bool
}

// Endpoint in an interface which abstracts information about an endpoint.
// TODO: Rename functions to be consistent with ServicePort.
type Endpoint interface {
	// String returns endpoint string.  An example format can be: `IP:Port`.
	// We take the returned value as ServiceEndpoint.Endpoint.
	String() string
	// GetIsLocal returns true if the endpoint is running in same host as kube-proxy, otherwise returns false.
	GetIsLocal() bool
	// IsReady returns true if an endpoint is ready and not terminating.
	// This is only set when watching EndpointSlices. If using Endpoints, this is always
	// true since only ready endpoints are read from Endpoints.
	IsReady() bool
	// IsServing returns true if an endpoint is ready. It does not account
	// for terminating state.
	// This is only set when watching EndpointSlices. If using Endpoints, this is always
	// true since only ready endpoints are read from Endpoints.
	IsServing() bool
	// IsTerminating returns true if an endpoint is terminating. For pods,
	// that is any pod with a deletion timestamp.
	// This is only set when watching EndpointSlices. If using Endpoints, this is always
	// false since terminating endpoints are always excluded from Endpoints.
	IsTerminating() bool
	// GetZoneHints returns the zone hint for the endpoint. This is based on
	// endpoint.hints.forZones[0].name in the EndpointSlice API.
	GetZoneHints() sets.String
	// IP returns IP part of the endpoint.
	IP() string
	// Port returns the Port part of the endpoint.
	Port() (int, error)
	// Equal checks if two endpoints are equal.
	Equal(Endpoint) bool
	// GetNodeName returns the node name for the endpoint
	GetNodeName() string
	// GetZone returns the zone for the endpoint
	GetZone() string
}

// ServiceEndpoint is used to identify a service and one of its endpoint pair.
type ServiceEndpoint struct {
	Endpoint        string
	ServicePortName ServicePortName
}