/*
Copyright 2017 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 gce

import (
	"fmt"

	"k8s.io/klog"

	"github.com/GoogleCloudPlatform/k8s-cloud-provider/pkg/cloud"
	"k8s.io/api/core/v1"
)

// LoadBalancerType defines a specific type for holding load balancer types (eg. Internal)
type LoadBalancerType string

const (
	// ServiceAnnotationLoadBalancerType is annotated on a service with type LoadBalancer
	// dictates what specific kind of GCP LB should be assembled.
	// Currently, only "internal" is supported.
	ServiceAnnotationLoadBalancerType = "cloud.google.com/load-balancer-type"

	// LBTypeInternal is the constant for the official internal type.
	LBTypeInternal LoadBalancerType = "Internal"

	// Deprecating the lowercase spelling of Internal.
	deprecatedTypeInternalLowerCase LoadBalancerType = "internal"

	// ServiceAnnotationILBBackendShare is annotated on a service with "true" when users
	// want to share GCP Backend Services for a set of internal load balancers.
	// ALPHA feature - this may be removed in a future release.
	ServiceAnnotationILBBackendShare = "alpha.cloud.google.com/load-balancer-backend-share"

	// This annotation did not correctly specify "alpha", so both annotations will be checked.
	deprecatedServiceAnnotationILBBackendShare = "cloud.google.com/load-balancer-backend-share"

	// NetworkTierAnnotationKey is annotated on a Service object to indicate which
	// network tier a GCP LB should use. The valid values are "Standard" and
	// "Premium" (default).
	NetworkTierAnnotationKey = "cloud.google.com/network-tier"

	// NetworkTierAnnotationStandard is an annotation to indicate the Service is on the Standard network tier
	NetworkTierAnnotationStandard = cloud.NetworkTierStandard

	// NetworkTierAnnotationPremium is an annotation to indicate the Service is on the Premium network tier
	NetworkTierAnnotationPremium = cloud.NetworkTierPremium

	// NEGAnnotation is an annotation to indicate that the loadbalancer service is using NEGs instead of InstanceGroups
	NEGAnnotation = "cloud.google.com/neg"
)

// GetLoadBalancerAnnotationType returns the type of GCP load balancer which should be assembled.
func GetLoadBalancerAnnotationType(service *v1.Service) (LoadBalancerType, bool) {
	v := LoadBalancerType("")
	if service.Spec.Type != v1.ServiceTypeLoadBalancer {
		return v, false
	}

	l, ok := service.Annotations[ServiceAnnotationLoadBalancerType]
	v = LoadBalancerType(l)
	if !ok {
		return v, false
	}

	switch v {
	case LBTypeInternal, deprecatedTypeInternalLowerCase:
		return LBTypeInternal, true
	default:
		return v, false
	}
}

// GetLoadBalancerAnnotationBackendShare returns whether this service's backend service should be
// shared with other load balancers. Health checks and the healthcheck firewall will be shared regardless.
func GetLoadBalancerAnnotationBackendShare(service *v1.Service) bool {
	if l, exists := service.Annotations[ServiceAnnotationILBBackendShare]; exists && l == "true" {
		return true
	}

	// Check for deprecated annotation key
	if l, exists := service.Annotations[deprecatedServiceAnnotationILBBackendShare]; exists && l == "true" {
		klog.Warningf("Annotation %q is deprecated and replaced with an alpha-specific key: %q", deprecatedServiceAnnotationILBBackendShare, ServiceAnnotationILBBackendShare)
		return true
	}

	return false
}

// GetServiceNetworkTier returns the network tier of GCP load balancer
// which should be assembled, and an error if the specified tier is not
// supported.
func GetServiceNetworkTier(service *v1.Service) (cloud.NetworkTier, error) {
	l, ok := service.Annotations[NetworkTierAnnotationKey]
	if !ok {
		return cloud.NetworkTierDefault, nil
	}

	v := cloud.NetworkTier(l)
	switch v {
	case cloud.NetworkTierStandard:
		fallthrough
	case cloud.NetworkTierPremium:
		return v, nil
	default:
		return cloud.NetworkTierDefault, fmt.Errorf("unsupported network tier: %q", v)
	}
}
