package dsdssandboxes

import (
	"context"

	compute "google.golang.org/api/compute/v1"
)

type setLabelMethod func(string, *compute.InstancesSetLabelsRequest) error
type listVMsmethod func() (*compute.InstanceList, error)
type progressHookMethod func(string)

type ProjectLabeller struct {
	Name         string
	setLabels    setLabelMethod
	listVMs      listVMsmethod
	progressHook progressHookMethod
}

func ProjectLabellerFromConf(conf BillingConf, zone string) (*ProjectLabeller, error) {
	return ProjectLabellerFromName(conf.Metadata.Name, zone)
}

func ProjectLabellerFromName(name string, zone string) (*ProjectLabeller, error) {
	ctx := context.Background()
	service, err := compute.NewService(ctx)
	if err != nil {
		return nil, err
	}

	//Wrap calls to GCP in a closure to allow test injection
	setLabels := func(instance string, labelRequest *compute.InstancesSetLabelsRequest) error {
		_, err := service.Instances.SetLabels(name, zone, instance, labelRequest).Context(ctx).Do()
		return err
	}

	listVMs := func() (*compute.InstanceList, error) {
		instanceList, err := service.Instances.List(name, zone).Context(ctx).Do()
		return instanceList, err
	}

	return &ProjectLabeller{
		Name:         name,
		setLabels:    setLabels,
		listVMs:      listVMs,
		progressHook: nil,
	}, nil
}

// Provide a method that will be called with the name of the VM instance being processed
func (p *ProjectLabeller) SetVMProgressHook(vmHook progressHookMethod) {
	p.progressHook = vmHook
}

// Apply the schedule labels for the provided schedule to all VMs in this project
func (p *ProjectLabeller) AddVMScheduleLabels(schedule Schedule) error {
	instanceList, err := p.listVMs()
	if err != nil {
		return err
	}

	for _, instance := range instanceList.Items {
		if p.progressHook != nil {
			p.progressHook(instance.Name)
		}

		labels := schedule.ToLabelMap()
		err := p.addLabelToVM(instance, labels)
		if err != nil {
			return err
		}
	}

	return nil
}

func (p *ProjectLabeller) addLabelToVM(instance *compute.Instance, labels map[string]string) error {
	fingerprint := instance.LabelFingerprint
	combinedLabels := instance.Labels

	for k, v := range labels {
		combinedLabels[k] = v
	}

	labelRequest := &compute.InstancesSetLabelsRequest{
		Labels:           combinedLabels,
		LabelFingerprint: fingerprint,
	}

	err := p.setLabels(instance.Name, labelRequest)
	if err != nil {
		return err
	}
	return nil
}