package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/url"
	"os"
	"reflect"
	"strings"
	"time"
	_ "time/tzdata"

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

var (
	c         *govmomi.Client
	ctx       context.Context
	cancel    context.CancelFunc
	sha1ver   string // sha1 revision used to build the program
	buildTime string // when the executable was built
	results   []DrsResults
	location  *time.Location
)

type DrsResults struct {
	ClusterName            string
	DrsScore               int32
	Vcenter                string
	NumVmsDrsBucket0To20   int32
	NumVmsDrsBucket21To40  int32
	NumVmsDrsBucket41To60  int32
	NumVmsDrsBucket61To80  int32
	NumVmsDrsBucket81To100 int32
}

// From https://stackoverflow.com/a/33769379
func Scan(d interface{}) {
	v := reflect.ValueOf(d)
	i := reflect.Indirect(v)
	s := i.Type()
	println(s.NumField()) // will print out 0, if you change Host to have 1 field, it prints out 1
}

func query(t reflect.Type) {
	value := reflect.New(t).Interface()
	Scan(value)
}

func getScsiBusSharingVMs(client *govmomi.Client) error {
	ctx := context.Background()
	m := view.NewManager(client.Client)

	vms, err := m.CreateContainerView(ctx, client.ServiceContent.RootFolder, []string{"VirtualMachine"}, true)
	if err != nil {
		return err
	}
	defer vms.Destroy(ctx)

	var vmList []mo.VirtualMachine

	err = vms.Retrieve(ctx, []string{"VirtualMachine"}, nil, &vmList)
	if err != nil {
		log.Printf("Error retrieving vm list : '%s'\n", err)
		return err
	}

	// Iterate through VMs and check for SCSI bus sharing
	for _, vm := range vmList {
		fmt.Printf("vm: %s\n", vm.Name)

		if len(vm.Config.Hardware.Device) > 0 {
			for _, device := range vm.Config.Hardware.Device {
				//fmt.Printf("device: %v\n", device)
				if scsi, ok := device.(types.BaseVirtualSCSIController); ok {
					fmt.Printf("scsi: %v\n", scsi)
					controller := scsi.GetVirtualSCSIController()
					if controller.SharedBus != "noSharing" {
						fmt.Printf("VM %s is using SCSI bus sharing mode: %v\n", vm.Name, controller.SharedBus)
					}
				}
			}
		}

		/*
			// Retrieve VM's ConfigInfo
			var configInfo types.VirtualMachineConfigInfo
			err = property.DefaultCollector(client.Client).RetrieveOne(ctx, vm.Reference(), []string{"config"}, &configInfo)
			if err != nil {
				log.Fatal(err)
			}
				// Check if SCSI bus sharing is enabled
				if configInfo != nil && configInfo.GetVmConfigInfo() != nil && configInfo.GetVmConfigInfo().GetHardware() != nil {
					hardware := configInfo.GetVmConfigInfo().GetHardware()
					if devices := hardware.GetDevice(); devices != nil {
						for _, device := range devices {
							if scsi, ok := device.(object.VirtualSCSIController); ok {
								if scsi.SharedBus != nil && scsi.SharedBus.Value != "" {
									fmt.Printf("VM %s is using SCSI bus sharing mode: %s\n", vm.Name, scsi.SharedBus.Value)
								}
							}
						}
					}
				}
		*/
	}

	return nil
}

func getNumVmsPerDrsScoreBucket(client *govmomi.Client) error {
	//properties := []string{"drsVmConfig.numVmPerDrsScoreBucket"}
	ctx := context.Background()
	m := view.NewManager(client.Client)

	clusters, err := m.CreateContainerView(ctx, client.ServiceContent.RootFolder, []string{"ClusterComputeResource"}, true)
	if err != nil {
		return err
	}
	defer clusters.Destroy(ctx)

	var clusterList []mo.ClusterComputeResource

	err = clusters.Retrieve(ctx, []string{"ClusterComputeResource"}, nil, &clusterList)
	if err != nil {
		log.Printf("Error retrieving cluster list : '%s'\n", err)
		return err
	}

	for _, cluster := range clusterList {
		log.Printf("Cluster: %s\n", cluster.Name)

		pc := property.DefaultCollector(client.Client)
		clusterProps := mo.ClusterComputeResource{}

		//err := pc.RetrieveOne(ctx, cluster.Reference(), properties, &clusterProps)
		err := pc.RetrieveOne(ctx, cluster.Reference(), nil, &clusterProps)
		if err != nil {
			log.Printf("Error retrieving property : '%s'\n", err)
			return err
		}

		// Properties defined at https://vdc-download.vmware.com/vmwb-repository/dcr-public/bf660c0a-f060-46e8-a94d-4b5e6ffc77ad/208bc706-e281-49b6-a0ce-b402ec19ef82/SDK/vsphere-ws/docs/ReferenceGuide/vim.ClusterComputeResource.Summary.html
		ccr := clusterProps.Summary.(*types.ClusterComputeResourceSummary)
		/*
			fmt.Printf("DRS Score: %v\n", ccr.DrsScore)
			fmt.Printf("VMs in DRS Score Bucket 0%% to 20%% : %d\n", ccr.NumVmsPerDrsScoreBucket[0])
			fmt.Printf("VMs in DRS Score Bucket 21%% to 40%% : %d\n", ccr.NumVmsPerDrsScoreBucket[1])
			fmt.Printf("VMs in DRS Score Bucket 41%% to 60%% : %d\n", ccr.NumVmsPerDrsScoreBucket[2])
			fmt.Printf("VMs in DRS Score Bucket 61%% to 80%% : %d\n", ccr.NumVmsPerDrsScoreBucket[3])
			fmt.Printf("VMs in DRS Score Bucket 81%% to 100%% : %d\n", ccr.NumVmsPerDrsScoreBucket[4])
		*/

		// Create a new result
		result := DrsResults{
			Vcenter:                client.URL().Host,
			ClusterName:            cluster.Name,
			DrsScore:               ccr.DrsScore,
			NumVmsDrsBucket0To20:   ccr.NumVmsPerDrsScoreBucket[0],
			NumVmsDrsBucket21To40:  ccr.NumVmsPerDrsScoreBucket[1],
			NumVmsDrsBucket41To60:  ccr.NumVmsPerDrsScoreBucket[2],
			NumVmsDrsBucket61To80:  ccr.NumVmsPerDrsScoreBucket[3],
			NumVmsDrsBucket81To100: ccr.NumVmsPerDrsScoreBucket[4],
		}
		// Append to list of all results
		results = append(results, result)

		/*
			// Print properties (fields)
			objType := reflect.TypeOf(clusterProps)
			for i := 0; i < objType.NumField(); i++ {
				field := objType.Field(i)
				fmt.Printf("Field %d: %s (Type: %s)\n", i, field.Name, field.Type)
			}

			// Print methods
			methods := reflect.TypeOf(clusterProps)
			for i := 0; i < methods.NumMethod(); i++ {
				method := methods.Method(i)
				fmt.Printf("Method %d: %s\n", i, method.Name)
			}
		*/
	}

	return nil
}

func main() {
	// Command line flags
	vURL := flag.String("url", "", "The URL of a vCenter server, eg https://server.domain.example/sdk")
	vUser := flag.String("user", "", "The username to use when connecting to vCenter")
	vPass := flag.String("password", "", "The password to use when connecting to vCenter")
	vTZ := flag.String("tz", "Australia/Sydney", "The timezone to use when converting vCenter UTC times")
	vInsecure := flag.Bool("insecure", true, "Allow insecure connections to vCenter")
	//vmName := flag.String("vmname", "example-vm", "The vm to query metrics")
	//begin := flag.Duration("b", time.Hour, "Begin time") // default BeginTime is 1h ago
	flag.Parse()

	// Print logs to file
	f, err := os.OpenFile("log.txt", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
		log.Fatalf("error opening file: %v", err)
	}
	defer f.Close()
	log.SetOutput(f)

	log.Printf("Starting execution. Built on %s from sha1 %s\n", buildTime, sha1ver)

	// So we can convert vCenter UTC to our local timezone
	log.Printf("Setting timezone to '%s'\n", *vTZ)
	location, err = time.LoadLocation(*vTZ)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error setting timezone to %s : %s\n", *vTZ, err)
		os.Exit(1)
	}

	u, err := url.Parse(*vURL)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error parsing url %s : %s\n", *vURL, err)
		os.Exit(1)
	} else {
		if !strings.HasSuffix(u.Path, "/sdk") {
			u.Path, _ = url.JoinPath(u.Path, "/sdk")
			log.Printf("Updated vCenter URL to '%v'\n", u)
		}
	}

	log.Printf("Connecting to vCenter %s\n", u)
	u.User = url.UserPassword(*vUser, *vPass)

	ctx, cancel = context.WithCancel(context.Background())
	defer cancel()

	// Login to vcenter
	c, err = govmomi.NewClient(ctx, u, *vInsecure)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Logging in error: %s\n", err)
		os.Exit(1)
	}
	defer c.Logout(ctx)

	/*
		err = getNumVmsPerDrsScoreBucket(c)
		if err != nil {
			log.Printf("Error retrieving NumVmsPerDrsScoreBucket: %s\n", err)
			return
		}
	*/

	err = getScsiBusSharingVMs(c)
	if err != nil {
		log.Printf("Error retrieving list of VMs with SCSI Bus Sharing : %s\n", err)
		return
	}

	// Output final results in JSON
	if len(results) > 0 {
		j, _ := json.Marshal(results)
		fmt.Println(string(j))
	} else {
		fmt.Println("{}")
	}
}