/*
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 openstacktasks

import (
	"fmt"
	"strings"
	"sync"

	"github.com/gophercloud/gophercloud/openstack/compute/v2/extensions/servergroups"
	"github.com/gophercloud/gophercloud/openstack/compute/v2/servers"
	"k8s.io/klog/v2"
	"k8s.io/kops/upup/pkg/fi"
	"k8s.io/kops/upup/pkg/fi/cloudup/openstack"
)

// +kops:fitask
type ServerGroup struct {
	ID          *string
	Name        *string
	ClusterName *string
	IGName      *string
	Policies    []string
	MaxSize     *int32
	Lifecycle   *fi.Lifecycle

	mutex sync.Mutex

	// members caches a list of member instance names.
	// When we create new instances, we can add them to this list also.
	members []string

	// gotMemberList records if we have returned the member list to another task.
	// If we attempt to add a member after doing so, it indicates a missing dependency.
	gotMemberList bool
}

var _ fi.CompareWithID = &ServerGroup{}

func (s *ServerGroup) CompareWithID() *string {
	return s.ID
}

func (s *ServerGroup) Find(context *fi.Context) (*ServerGroup, error) {
	if s == nil || s.Name == nil {
		return nil, nil
	}
	cloud := context.Cloud.(openstack.OpenstackCloud)
	//TODO: move to cloud, add vfs backoff

	page, err := servergroups.List(cloud.ComputeClient(), servergroups.ListOpts{}).AllPages()
	if err != nil {
		return nil, fmt.Errorf("Failed to list server groups: %v", err)
	}
	serverGroups, err := servergroups.ExtractServerGroups(page)
	if err != nil {
		return nil, fmt.Errorf("Failed to extract server groups: %v", err)
	}
	var actual *ServerGroup
	for _, serverGroup := range serverGroups {
		if serverGroup.Name == *s.Name {
			if actual != nil {
				return nil, fmt.Errorf("Found multiple server groups with name %s", fi.StringValue(s.Name))
			}
			actual = &ServerGroup{
				Name:        fi.String(serverGroup.Name),
				ClusterName: s.ClusterName,
				IGName:      s.IGName,
				ID:          fi.String(serverGroup.ID),
				Lifecycle:   s.Lifecycle,
				Policies:    serverGroup.Policies,
				MaxSize:     fi.Int32(int32(len(serverGroup.Members))),
				members:     serverGroup.Members,
			}
		}
	}
	if actual == nil {
		return nil, nil
	}

	// ignore if IG is scaled up, this is handled in instancetasks
	if fi.Int32Value(actual.MaxSize) < fi.Int32Value(s.MaxSize) {
		s.MaxSize = actual.MaxSize
	}

	s.ID = actual.ID
	s.members = actual.members
	return actual, nil
}

func (s *ServerGroup) Run(context *fi.Context) error {
	return fi.DefaultDeltaRunMethod(s, context)
}

func (_ *ServerGroup) CheckChanges(a, e, changes *ServerGroup) error {
	if a == nil {
		if e.Name == nil {
			return fi.RequiredField("Name")
		}
	} else {
		if changes.ID != nil {
			return fi.CannotChangeField("ID")
		}
		if changes.Name != nil {
			return fi.CannotChangeField("Name")
		}
	}
	return nil
}

func (_ *ServerGroup) RenderOpenstack(t *openstack.OpenstackAPITarget, a, e, changes *ServerGroup) error {
	if a == nil {
		klog.V(2).Infof("Creating ServerGroup with Name:%q", fi.StringValue(e.Name))

		opt := servergroups.CreateOpts{
			Name:     fi.StringValue(e.Name),
			Policies: e.Policies,
		}

		g, err := t.Cloud.CreateServerGroup(opt)
		if err != nil {
			return fmt.Errorf("error creating ServerGroup: %v", err)
		}
		e.ID = fi.String(g.ID)
		return nil
	} else if changes.MaxSize != nil && fi.Int32Value(a.MaxSize) > fi.Int32Value(changes.MaxSize) {
		currentLastIndex := fi.Int32Value(a.MaxSize)

		for currentLastIndex > fi.Int32Value(changes.MaxSize) {
			iName := strings.ToLower(fmt.Sprintf("%s-%d.%s", fi.StringValue(a.IGName), currentLastIndex, fi.StringValue(a.ClusterName)))
			instanceName := strings.Replace(iName, ".", "-", -1)
			opts := servers.ListOpts{
				Name: fmt.Sprintf("^%s$", instanceName),
			}
			instances, err := t.Cloud.ListInstances(opts)
			if err != nil {
				return fmt.Errorf("error fetching instance list: %v", err)
			}

			if len(instances) == 1 {
				klog.V(2).Infof("Openstack task ServerGroup scaling down instance %s", instanceName)
				err := t.Cloud.DeleteInstanceWithID(instances[0].ID)
				if err != nil {
					return fmt.Errorf("Could not delete instance %s: %v", instanceName, err)
				}
			} else {
				return fmt.Errorf("found %d instances with name: %s", len(instances), instanceName)
			}
			currentLastIndex -= 1
		}
	}

	klog.V(2).Infof("Openstack task ServerGroup::RenderOpenstack did nothing")
	return nil
}

// AddNewMember is called when we created an instance in this server group.
// It adds it to the internal cached list of members.
// If we have already called GetMembers, this function will panic;
// this can be avoided by use of GetDependencies() (typically by depending on Instance tasks)
func (s *ServerGroup) AddNewMember(memberID string) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	if s.gotMemberList {
		klog.Fatalf("attempt to add member %q after member list already returned", memberID)
	}

	s.members = append(s.members, memberID)
}

// GetMembers returns the ids of servers in this group.
// It also activates the "flag" preventning further calls to AddNewMember,
// guaranteeing that no new members will be added.
func (s *ServerGroup) GetMembers() []string {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	s.gotMemberList = true
	return s.members
}