/*
Copyright (c) 2017 VMware, Inc. All Rights Reserved.

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 flags

import (
	"context"
	"flag"
	"fmt"
	"os"

	"github.com/vmware/govmomi/object"
	"github.com/vmware/govmomi/property"
	"github.com/vmware/govmomi/view"
	"github.com/vmware/govmomi/vim25/mo"
	"github.com/vmware/govmomi/vim25/types"
)

type ClusterFlag struct {
	common

	*DatacenterFlag

	Name string

	cluster *object.ClusterComputeResource
	pc      *property.Collector
}

var clusterFlagKey = flagKey("cluster")

func NewClusterFlag(ctx context.Context) (*ClusterFlag, context.Context) {
	if v := ctx.Value(clusterFlagKey); v != nil {
		return v.(*ClusterFlag), ctx
	}

	v := &ClusterFlag{}
	v.DatacenterFlag, ctx = NewDatacenterFlag(ctx)
	ctx = context.WithValue(ctx, clusterFlagKey, v)
	return v, ctx
}

func (f *ClusterFlag) Register(ctx context.Context, fs *flag.FlagSet) {
	f.RegisterOnce(func() {
		f.DatacenterFlag.Register(ctx, fs)

		env := "GOVC_CLUSTER"
		value := os.Getenv(env)
		usage := fmt.Sprintf("Cluster [%s]", env)
		fs.StringVar(&f.Name, "cluster", value, usage)
	})
}

// RegisterPlacement registers the -cluster flag without using GOVC_CLUSTER env as the default value,
// usage is specific to VM placement.
func (f *ClusterFlag) RegisterPlacement(ctx context.Context, fs *flag.FlagSet) {
	f.RegisterOnce(func() {
		f.DatacenterFlag.Register(ctx, fs)

		fs.StringVar(&f.Name, "cluster", "", "Use cluster for VM placement via DRS")
	})
}

func (f *ClusterFlag) Process(ctx context.Context) error {
	return f.ProcessOnce(func() error {
		if err := f.DatacenterFlag.Process(ctx); err != nil {
			return err
		}
		return nil
	})
}

func (f *ClusterFlag) Cluster() (*object.ClusterComputeResource, error) {
	if f.cluster != nil {
		return f.cluster, nil
	}

	finder, err := f.Finder()
	if err != nil {
		return nil, err
	}

	if f.cluster, err = finder.ClusterComputeResourceOrDefault(context.TODO(), f.Name); err != nil {
		return nil, err
	}

	f.pc = property.DefaultCollector(f.cluster.Client())

	return f.cluster, nil
}

func (f *ClusterFlag) ClusterIfSpecified() (*object.ClusterComputeResource, error) {
	if f.Name == "" {
		return nil, nil
	}
	return f.Cluster()
}

func (f *ClusterFlag) Reconfigure(ctx context.Context, spec types.BaseComputeResourceConfigSpec) error {
	cluster, err := f.Cluster()
	if err != nil {
		return err
	}

	task, err := cluster.Reconfigure(ctx, spec, true)
	if err != nil {
		return err
	}

	logger := f.ProgressLogger(fmt.Sprintf("Reconfigure %s...", cluster.InventoryPath))
	defer logger.Wait()

	_, err = task.WaitForResult(ctx, logger)
	return err
}

func (f *ClusterFlag) objectMap(ctx context.Context, kind string, names []string) (map[string]types.ManagedObjectReference, error) {
	cluster, err := f.Cluster()
	if err != nil {
		return nil, err
	}

	objects := make(map[string]types.ManagedObjectReference, len(names))
	for _, name := range names {
		objects[name] = types.ManagedObjectReference{}
	}

	m := view.NewManager(cluster.Client())
	v, err := m.CreateContainerView(ctx, cluster.Reference(), []string{kind}, true)
	if err != nil {
		return nil, err
	}

	defer func() {
		_ = v.Destroy(ctx)
	}()

	var entities []mo.ManagedEntity

	err = v.Retrieve(ctx, []string{"ManagedEntity"}, []string{"name"}, &entities)
	if err != nil {
		return nil, err
	}

	for _, e := range entities {
		if _, ok := objects[e.Name]; ok {
			objects[e.Name] = e.Self
		}
	}

	for name, ref := range objects {
		if ref.Value == "" {
			return nil, fmt.Errorf("%s %q not found", kind, name)
		}
	}

	return objects, nil
}

func (f *ClusterFlag) ObjectList(ctx context.Context, kind string, names []string) ([]types.ManagedObjectReference, error) {
	objs, err := f.objectMap(ctx, kind, names)
	if err != nil {
		return nil, err
	}

	var refs []types.ManagedObjectReference

	for _, name := range names { // preserve order
		refs = append(refs, objs[name])
	}

	return refs, nil
}

func (f *ClusterFlag) Names(ctx context.Context, refs []types.ManagedObjectReference) (map[types.ManagedObjectReference]string, error) {
	names := make(map[types.ManagedObjectReference]string, len(refs))

	if len(refs) != 0 {
		var objs []mo.ManagedEntity
		err := f.pc.Retrieve(ctx, refs, []string{"name"}, &objs)
		if err != nil {
			return nil, err
		}

		for _, obj := range objs {
			names[obj.Self] = obj.Name
		}
	}

	return names, nil
}