//go:build !providerless
// +build !providerless

/*
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 (
	"context"
	"flag"
	"fmt"
	"sort"
	"strings"

	v1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	corev1apply "k8s.io/client-go/applyconfigurations/core/v1"
	metav1apply "k8s.io/client-go/applyconfigurations/meta/v1"
	"k8s.io/klog/v2"

	"github.com/GoogleCloudPlatform/k8s-cloud-provider/pkg/cloud"
	cloudprovider "k8s.io/cloud-provider"
	netutils "k8s.io/utils/net"
)

type cidrs struct {
	ipn   netutils.IPNetSet
	isSet bool
}

var (
	l4LbSrcRngsFlag cidrs
	l7lbSrcRngsFlag cidrs
)

func init() {
	var err error
	// L3/4 health checkers have client addresses within these known CIDRs.
	l4LbSrcRngsFlag.ipn, err = netutils.ParseIPNets([]string{"130.211.0.0/22", "35.191.0.0/16", "209.85.152.0/22", "209.85.204.0/22"}...)
	if err != nil {
		panic("Incorrect default GCE L3/4 source ranges")
	}
	// L7 health checkers have client addresses within these known CIDRs.
	l7lbSrcRngsFlag.ipn, err = netutils.ParseIPNets([]string{"130.211.0.0/22", "35.191.0.0/16"}...)
	if err != nil {
		panic("Incorrect default GCE L7 source ranges")
	}

	flag.Var(&l4LbSrcRngsFlag, "cloud-provider-gce-lb-src-cidrs", "CIDRs opened in GCE firewall for L4 LB traffic proxy & health checks")
	flag.Var(&l7lbSrcRngsFlag, "cloud-provider-gce-l7lb-src-cidrs", "CIDRs opened in GCE firewall for L7 LB traffic proxy & health checks")
}

// String is the method to format the flag's value, part of the flag.Value interface.
func (c *cidrs) String() string {
	s := c.ipn.StringSlice()
	sort.Strings(s)
	return strings.Join(s, ",")
}

// Set supports a value of CSV or the flag repeated multiple times
func (c *cidrs) Set(value string) error {
	// On first Set(), clear the original defaults
	if !c.isSet {
		c.isSet = true
		c.ipn = make(netutils.IPNetSet)
	} else {
		return fmt.Errorf("GCE LB CIDRs have already been set")
	}

	for _, cidr := range strings.Split(value, ",") {
		_, ipnet, err := netutils.ParseCIDRSloppy(cidr)
		if err != nil {
			return err
		}

		c.ipn.Insert(ipnet)
	}
	return nil
}

// L4LoadBalancerSrcRanges contains the ranges of ips used by the L3/L4 GCE load balancers
// for proxying client requests and performing health checks.
func L4LoadBalancerSrcRanges() []string {
	return l4LbSrcRngsFlag.ipn.StringSlice()
}

// L7LoadBalancerSrcRanges contains the ranges of ips used by the GCE load balancers L7
// for proxying client requests and performing health checks.
func L7LoadBalancerSrcRanges() []string {
	return l7lbSrcRngsFlag.ipn.StringSlice()
}

// GetLoadBalancer is an implementation of LoadBalancer.GetLoadBalancer
func (g *Cloud) GetLoadBalancer(ctx context.Context, clusterName string, svc *v1.Service) (*v1.LoadBalancerStatus, bool, error) {
	loadBalancerName := g.GetLoadBalancerName(ctx, clusterName, svc)
	fwd, err := g.GetRegionForwardingRule(loadBalancerName, g.region)
	if err == nil {
		status := &v1.LoadBalancerStatus{}
		status.Ingress = []v1.LoadBalancerIngress{{IP: fwd.IPAddress}}

		return status, true, nil
	}
	// Checking for finalizer is more accurate because controller restart could happen in the middle of resource
	// deletion. So even though forwarding rule was deleted, cleanup might not have been complete.
	if hasFinalizer(svc, ILBFinalizerV1) {
		return &v1.LoadBalancerStatus{}, true, nil
	}
	return nil, false, ignoreNotFound(err)
}

// GetLoadBalancerName is an implementation of LoadBalancer.GetLoadBalancerName.
func (g *Cloud) GetLoadBalancerName(ctx context.Context, clusterName string, svc *v1.Service) string {
	// TODO: replace DefaultLoadBalancerName to generate more meaningful loadbalancer names.
	return cloudprovider.DefaultLoadBalancerName(svc)
}

// EnsureLoadBalancer is an implementation of LoadBalancer.EnsureLoadBalancer.
func (g *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, svc *v1.Service, nodes []*v1.Node) (*v1.LoadBalancerStatus, error) {
	loadBalancerName := g.GetLoadBalancerName(ctx, clusterName, svc)
	desiredScheme := getSvcScheme(svc)
	clusterID, err := g.ClusterID.GetID()
	if err != nil {
		return nil, err
	}

	// Services with multiples protocols are not supported by this controller, warn the users and sets
	// the corresponding Service Status Condition.
	// https://github.com/kubernetes/enhancements/tree/master/keps/sig-network/1435-mixed-protocol-lb
	if err := checkMixedProtocol(svc.Spec.Ports); err != nil {
		if hasLoadBalancerPortsError(svc) {
			return nil, err
		}
		klog.Warningf("Ignoring service %s/%s using different ports protocols", svc.Namespace, svc.Name)
		g.eventRecorder.Event(svc, v1.EventTypeWarning, v1.LoadBalancerPortsErrorReason, "LoadBalancers with multiple protocols are not supported.")
		svcApplyStatus := corev1apply.ServiceStatus().WithConditions(
			metav1apply.Condition().
				WithType(v1.LoadBalancerPortsError).
				WithStatus(metav1.ConditionTrue).
				WithReason(v1.LoadBalancerPortsErrorReason).
				WithMessage("LoadBalancer with multiple protocols are not supported"))
		svcApply := corev1apply.Service(svc.Name, svc.Namespace).WithStatus(svcApplyStatus)
		if _, errApply := g.client.CoreV1().Services(svc.Namespace).ApplyStatus(ctx, svcApply, metav1.ApplyOptions{FieldManager: "gce-legacy-cloud-controller", Force: true}); errApply != nil {
			return nil, errApply
		}
		return nil, err
	}

	klog.V(4).Infof("EnsureLoadBalancer(%v, %v, %v, %v, %v): ensure %v loadbalancer", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, desiredScheme)

	existingFwdRule, err := g.GetRegionForwardingRule(loadBalancerName, g.region)
	if err != nil && !isNotFound(err) {
		return nil, err
	}

	if existingFwdRule != nil {
		existingScheme := cloud.LbScheme(strings.ToUpper(existingFwdRule.LoadBalancingScheme))

		// If the loadbalancer type changes between INTERNAL and EXTERNAL, the old load balancer should be deleted.
		if existingScheme != desiredScheme {
			klog.V(4).Infof("EnsureLoadBalancer(%v, %v, %v, %v, %v): deleting existing %v loadbalancer", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, existingScheme)
			switch existingScheme {
			case cloud.SchemeInternal:
				err = g.ensureInternalLoadBalancerDeleted(clusterName, clusterID, svc)
			default:
				err = g.ensureExternalLoadBalancerDeleted(clusterName, clusterID, svc)
			}
			klog.V(4).Infof("EnsureLoadBalancer(%v, %v, %v, %v, %v): done deleting existing %v loadbalancer. err: %v", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, existingScheme, err)
			if err != nil {
				return nil, err
			}

			// Assume the ensureDeleted function successfully deleted the forwarding rule.
			existingFwdRule = nil
		}
	}

	var status *v1.LoadBalancerStatus
	switch desiredScheme {
	case cloud.SchemeInternal:
		status, err = g.ensureInternalLoadBalancer(clusterName, clusterID, svc, existingFwdRule, nodes)
	default:
		status, err = g.ensureExternalLoadBalancer(clusterName, clusterID, svc, existingFwdRule, nodes)
	}
	if err != nil {
		klog.Errorf("Failed to EnsureLoadBalancer(%s, %s, %s, %s, %s), err: %v", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, err)
		return status, err
	}
	klog.V(4).Infof("EnsureLoadBalancer(%s, %s, %s, %s, %s): done ensuring loadbalancer.", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region)
	return status, err
}

// UpdateLoadBalancer is an implementation of LoadBalancer.UpdateLoadBalancer.
func (g *Cloud) UpdateLoadBalancer(ctx context.Context, clusterName string, svc *v1.Service, nodes []*v1.Node) error {
	loadBalancerName := g.GetLoadBalancerName(ctx, clusterName, svc)
	scheme := getSvcScheme(svc)
	clusterID, err := g.ClusterID.GetID()
	if err != nil {
		return err
	}

	// Services with multiples protocols are not supported by this controller, warn the users and sets
	// the corresponding Service Status Condition, but keep processing the Update to not break upgrades.
	// https://github.com/kubernetes/enhancements/tree/master/keps/sig-network/1435-mixed-protocol-lb
	if err := checkMixedProtocol(svc.Spec.Ports); err != nil && !hasLoadBalancerPortsError(svc) {
		klog.Warningf("Ignoring update for service %s/%s using different ports protocols", svc.Namespace, svc.Name)
		g.eventRecorder.Event(svc, v1.EventTypeWarning, v1.LoadBalancerPortsErrorReason, "LoadBalancer with multiple protocols are not supported.")
		svcApplyStatus := corev1apply.ServiceStatus().WithConditions(
			metav1apply.Condition().
				WithType(v1.LoadBalancerPortsError).
				WithStatus(metav1.ConditionTrue).
				WithReason(v1.LoadBalancerPortsErrorReason).
				WithMessage("LoadBalancer with multiple protocols are not supported"))
		svcApply := corev1apply.Service(svc.Name, svc.Namespace).WithStatus(svcApplyStatus)
		if _, errApply := g.client.CoreV1().Services(svc.Namespace).ApplyStatus(ctx, svcApply, metav1.ApplyOptions{FieldManager: "gce-legacy-cloud-controller", Force: true}); errApply != nil {
			// the error is retried by the controller loop
			return errApply
		}
	}

	klog.V(4).Infof("UpdateLoadBalancer(%v, %v, %v, %v, %v): updating with %d nodes", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, len(nodes))

	switch scheme {
	case cloud.SchemeInternal:
		err = g.updateInternalLoadBalancer(clusterName, clusterID, svc, nodes)
	default:
		err = g.updateExternalLoadBalancer(clusterName, svc, nodes)
	}
	klog.V(4).Infof("UpdateLoadBalancer(%v, %v, %v, %v, %v): done updating. err: %v", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, err)
	return err
}

// EnsureLoadBalancerDeleted is an implementation of LoadBalancer.EnsureLoadBalancerDeleted.
func (g *Cloud) EnsureLoadBalancerDeleted(ctx context.Context, clusterName string, svc *v1.Service) error {
	loadBalancerName := g.GetLoadBalancerName(ctx, clusterName, svc)
	scheme := getSvcScheme(svc)
	clusterID, err := g.ClusterID.GetID()
	if err != nil {
		return err
	}

	klog.V(4).Infof("EnsureLoadBalancerDeleted(%v, %v, %v, %v, %v): deleting loadbalancer", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region)

	switch scheme {
	case cloud.SchemeInternal:
		err = g.ensureInternalLoadBalancerDeleted(clusterName, clusterID, svc)
	default:
		err = g.ensureExternalLoadBalancerDeleted(clusterName, clusterID, svc)
	}
	klog.V(4).Infof("EnsureLoadBalancerDeleted(%v, %v, %v, %v, %v): done deleting loadbalancer. err: %v", clusterName, svc.Namespace, svc.Name, loadBalancerName, g.region, err)
	return err
}

func getSvcScheme(svc *v1.Service) cloud.LbScheme {
	if t := GetLoadBalancerAnnotationType(svc); t == LBTypeInternal {
		return cloud.SchemeInternal
	}
	return cloud.SchemeExternal
}

// checkMixedProtocol checks if the Service Ports uses different protocols,
// per examples, TCP and UDP.
func checkMixedProtocol(ports []v1.ServicePort) error {
	if len(ports) == 0 {
		return nil
	}

	firstProtocol := ports[0].Protocol
	for _, port := range ports[1:] {
		if port.Protocol != firstProtocol {
			return fmt.Errorf("mixed protocol is not supported for LoadBalancer")
		}
	}
	return nil
}

// hasLoadBalancerPortsError checks if the Service has the LoadBalancerPortsError set to True
func hasLoadBalancerPortsError(service *v1.Service) bool {
	if service == nil {
		return false
	}

	for _, cond := range service.Status.Conditions {
		if cond.Type == v1.LoadBalancerPortsError {
			return cond.Status == metav1.ConditionTrue
		}
	}
	return false
}