/*
Copyright 2019 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 alimodel

import (
	"errors"
	"fmt"

	"k8s.io/kops/pkg/apis/kops"
	"k8s.io/kops/pkg/dns"
	"k8s.io/kops/upup/pkg/fi"
	"k8s.io/kops/upup/pkg/fi/cloudup/alitasks"
)

const (
	LoadBalancerListenerStatus    = "running"
	LoadBalancerListenerBandwidth = -1
)

// APILoadBalancerModelBuilder builds a LoadBalancer for accessing the API
type APILoadBalancerModelBuilder struct {
	*ALIModelContext
	Lifecycle *fi.Lifecycle
}

var _ fi.ModelBuilder = &APILoadBalancerModelBuilder{}

func (b *APILoadBalancerModelBuilder) Build(c *fi.ModelBuilderContext) error {
	// Configuration where an ELB fronts the API
	if !b.UseLoadBalancerForAPI() {
		return nil
	}

	lbSpec := b.Cluster.Spec.API.LoadBalancer
	if lbSpec == nil {
		// Skipping API ELB creation; not requested in Spec
		return nil
	}

	switch lbSpec.Type {
	case kops.LoadBalancerTypeInternal:
		// OK
	case kops.LoadBalancerTypePublic:
		// OK
	default:
		return fmt.Errorf("unhandled LoadBalancer type %q", lbSpec.Type)
	}

	// Create LoadBalancer for API ELB
	var loadbalancer *alitasks.LoadBalancer
	{

		loadbalancer = &alitasks.LoadBalancer{
			Name:      s(b.GetNameForLoadBalancer()),
			Lifecycle: b.Lifecycle,
		}

		switch lbSpec.Type {
		case kops.LoadBalancerTypeInternal:
			utilitySubnets := b.GetUtilitySubnets()
			if len(utilitySubnets) == 0 {
				return errors.New("internal loadbalancer requires at least 1 utility subnet")
			}
			loadbalancer.AddressType = s("intranet")
			loadbalancer.VSwitchId = fi.String(utilitySubnets[0].ProviderID)
		case kops.LoadBalancerTypePublic:
			loadbalancer.AddressType = s("internet")
		default:
			return fmt.Errorf("unknown loadbalancer Type: %q", lbSpec.Type)
		}

		c.AddTask(loadbalancer)
	}

	// Create LoadBalancerListener for API ELB
	// TODO: Health check
	var loadbalancerlistener *alitasks.LoadBalancerListener
	{
		loadBalancerListenerStatus := LoadBalancerListenerStatus
		loadBalancerListenerBandwidth := LoadBalancerListenerBandwidth
		loadbalancerlistener = &alitasks.LoadBalancerListener{
			Name:              s("api." + b.ClusterName()),
			Lifecycle:         b.Lifecycle,
			LoadBalancer:      loadbalancer,
			ListenerStatus:    s(loadBalancerListenerStatus),
			ListenerPort:      i(443),
			BackendServerPort: i(443),
			Bandwidth:         i(loadBalancerListenerBandwidth),
		}
		c.AddTask(loadbalancerlistener)
	}

	// Allow traffic into the SLB from KubernetesAPIAccess CIDRs
	var loadBalancerACL *alitasks.LoadBalancerACL
	{

		var cidrs []*string
		for _, cidr := range b.Cluster.Spec.KubernetesAPIAccess {
			if cidr != "0.0.0.0" && cidr != "0.0.0.0/0" {
				cc := cidr
				cidrs = append(cidrs, &cc)
			}
		}

		if len(cidrs) != 0 {
			loadBalancerACL = &alitasks.LoadBalancerACL{
				Name:                 s("api." + b.ClusterName()),
				Lifecycle:            b.Lifecycle,
				LoadBalancer:         loadbalancer,
				LoadBalancerListener: loadbalancerlistener,
				SourceItems:          cidrs,
			}
			c.AddTask(loadBalancerACL)
		}
	}

	// Temporarily do not know the role of the following function
	if dns.IsGossipHostname(b.Cluster.Name) || b.UsePrivateDNS() {
		// Ensure the ELB hostname is included in the TLS certificate,
		// if we're not going to use an alias for it
		loadbalancer.ForAPIServer = true
	}

	return nil

}