/*
Copyright (c) 2014-2016 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"
)

type FolderFlag struct {
	common

	*DatacenterFlag

	name   string
	folder *object.Folder
}

var folderFlagKey = flagKey("folder")

func NewFolderFlag(ctx context.Context) (*FolderFlag, context.Context) {
	if v := ctx.Value(folderFlagKey); v != nil {
		return v.(*FolderFlag), ctx
	}

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

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

		env := "GOVC_FOLDER"
		value := os.Getenv(env)
		usage := fmt.Sprintf("Inventory folder [%s]", env)
		f.StringVar(&flag.name, "folder", value, usage)
	})
}

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

func (flag *FolderFlag) Folder() (*object.Folder, error) {
	if flag.folder != nil {
		return flag.folder, nil
	}

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

	if flag.folder, err = finder.FolderOrDefault(context.TODO(), flag.name); err != nil {
		return nil, err
	}

	return flag.folder, nil
}

func (flag *FolderFlag) FolderIfSpecified() (*object.Folder, error) {
	if flag.name == "" {
		return nil, nil
	}
	return flag.Folder()
}

func (flag *FolderFlag) FolderOrDefault(kind string) (*object.Folder, error) {
	if flag.folder != nil {
		return flag.folder, nil
	}

	if flag.name != "" {
		return flag.Folder()
	}

	// RootFolder, no dc required
	if kind == "/" {
		client, err := flag.Client()
		if err != nil {
			return nil, err
		}

		flag.folder = object.NewRootFolder(client)
		return flag.folder, nil
	}

	dc, err := flag.Datacenter()
	if err != nil {
		return nil, err
	}

	folders, err := dc.Folders(context.TODO())
	if err != nil {
		return nil, err
	}

	switch kind {
	case "vm":
		flag.folder = folders.VmFolder
	case "host":
		flag.folder = folders.HostFolder
	case "datastore":
		flag.folder = folders.DatastoreFolder
	case "network":
		flag.folder = folders.NetworkFolder
	default:
		panic(kind)
	}

	return flag.folder, nil
}