// © Broadcom. All Rights Reserved.
// The term "Broadcom" refers to Broadcom Inc. and/or its subsidiaries.
// SPDX-License-Identifier: Apache-2.0

package simulator

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"reflect"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"

	"github.com/vmware/govmomi/simulator/internal"
	"github.com/vmware/govmomi/vim25"
	"github.com/vmware/govmomi/vim25/mo"
	"github.com/vmware/govmomi/vim25/soap"
	"github.com/vmware/govmomi/vim25/types"
)

// This is a map from a reference type name to a reference value name prefix.
// It's a convention that VirtualCenter follows. The map is not complete, but
// it should cover the most popular objects.
var refValueMap = map[string]string{
	"DistributedVirtualPortgroup":    "dvportgroup",
	"EnvironmentBrowser":             "envbrowser",
	"HostSystem":                     "host",
	"ResourcePool":                   "resgroup",
	"VirtualApp":                     "resgroup-v",
	"VirtualMachine":                 "vm",
	"VirtualMachineSnapshot":         "snapshot",
	"VmwareDistributedVirtualSwitch": "dvs",
	"DistributedVirtualSwitch":       "dvs",
	"ClusterComputeResource":         "domain-c",
	"ComputeResource":                "domain-s",
	"Folder":                         "group",
	"StoragePod":                     "group-p",
}

// Map returns simulator.Context.Map from the given ctx
func Map(ctx context.Context) *Registry {
	return ctx.(*Context).Map
}

// ServiceFromContext returns the simulator Service from the given ctx
func ServiceFromContext(ctx context.Context) *Service {
	return ctx.(*Context).svc
}

// RegisterObject interface supports callbacks when objects are created, updated and deleted from the Registry
type RegisterObject interface {
	mo.Reference
	PutObject(*Context, mo.Reference)
	UpdateObject(*Context, mo.Reference, []types.PropertyChange)
	RemoveObject(*Context, types.ManagedObjectReference)
}

// Registry manages a map of mo.Reference objects
type Registry struct {
	counter  int64 // Keep first to ensure 64-bit alignment
	m        sync.Mutex
	objects  map[types.ManagedObjectReference]mo.Reference
	handlers map[types.ManagedObjectReference]RegisterObject
	locks    map[types.ManagedObjectReference]*internal.ObjectLock

	Namespace string
	Path      string
	Handler   func(*Context, *Method) (mo.Reference, types.BaseMethodFault)
	Cookie    func(*Context) string

	tagManager tagManager
}

// tagManager is an interface to simplify internal interaction with the vapi tag manager simulator.
type tagManager interface {
	AttachedObjects(string) ([]types.ManagedObjectReference, types.BaseMethodFault)
	AttachedTags(id types.ManagedObjectReference) ([]string, types.BaseMethodFault)
	AttachTag(types.ManagedObjectReference, string) types.BaseMethodFault
	DetachTag(types.ManagedObjectReference, string) types.BaseMethodFault
	GetTagByCategoryAndName(string, string) (string, types.BaseMethodFault)
	GetTagCategoryAndName(string) (string, string, types.BaseMethodFault)
}

// NewRegistry creates a new instances of Registry
func NewRegistry() *Registry {
	r := &Registry{
		objects:  make(map[types.ManagedObjectReference]mo.Reference),
		handlers: make(map[types.ManagedObjectReference]RegisterObject),
		locks:    make(map[types.ManagedObjectReference]*internal.ObjectLock),

		Namespace: vim25.Namespace,
		Path:      vim25.Path,
	}

	return r
}

func (r *Registry) typeFunc(name string) (reflect.Type, bool) {
	if r.Namespace != "" && r.Namespace != vim25.Namespace {
		if kind, ok := defaultMapType(r.Namespace + ":" + name); ok {
			return kind, ok
		}
	}
	return defaultMapType(name)
}

// typeName returns the type of the given object.
func typeName(item mo.Reference) string {
	return reflect.TypeOf(item).Elem().Name()
}

// valuePrefix returns the value name prefix of a given object
func valuePrefix(typeName string) string {
	v, ok := refValueMap[typeName]
	if ok {
		if strings.Contains(v, "-") {
			return v
		}
	} else {
		v = strings.ToLower(typeName)
	}

	return v + "-"
}

// newReference returns a new MOR, where Type defaults to type of the given item
// and Value defaults to a unique id for the given type.
func (r *Registry) newReference(item mo.Reference) types.ManagedObjectReference {
	ref := item.Reference()

	if ref.Type == "" {
		ref.Type = typeName(item)
	}

	if ref.Value == "" {
		n := atomic.AddInt64(&r.counter, 1)
		ref.Value = fmt.Sprintf("%s%d", valuePrefix(ref.Type), n)
	}

	return ref
}

func (r *Registry) AlignCounter() error {
	maxN := int64(0)
	for ref, _ := range r.objects {
		prefix := valuePrefix(ref.Type)
		suffix := strings.TrimPrefix(ref.Value, prefix)
		n, err := strconv.ParseInt(suffix, 10, 64)
		if err != nil {
			continue
		}
		if n > maxN {
			maxN = n
		}
	}

	r.counter = maxN
	return nil
}

func (r *Registry) setReference(item mo.Reference, ref types.ManagedObjectReference) {
	// mo.Reference() returns a value, not a pointer so use reflect to set the Self field
	reflect.ValueOf(item).Elem().FieldByName("Self").Set(reflect.ValueOf(ref))
}

// AddHandler adds a RegisterObject handler to the Registry.
func (r *Registry) AddHandler(h RegisterObject) {
	r.m.Lock()
	r.handlers[h.Reference()] = h
	r.m.Unlock()
}

// RemoveHandler removes a RegisterObject handler from the Registry.
func (r *Registry) RemoveHandler(h RegisterObject) {
	r.m.Lock()
	delete(r.handlers, h.Reference())
	r.m.Unlock()
}

// NewEntity sets Entity().Self with a new, unique Value.
// Useful for creating object instances from templates.
func (r *Registry) NewEntity(item mo.Entity) mo.Entity {
	e := item.Entity()
	e.Self.Value = ""
	e.Self = r.newReference(item)
	return item
}

// PutEntity sets item.Parent to that of parent.Self before adding item to the Registry.
func (r *Registry) PutEntity(parent mo.Entity, item mo.Entity) mo.Entity {
	e := item.Entity()

	if parent != nil {
		e.Parent = &parent.Entity().Self
	}

	r.Put(item)

	return item
}

// Get returns the object for the given reference.
func (r *Registry) Get(ref types.ManagedObjectReference) mo.Reference {
	r.m.Lock()
	defer r.m.Unlock()

	return r.objects[ref]
}

// Any returns the first instance of entity type specified by kind.
func (r *Registry) Any(kind string) mo.Entity {
	r.m.Lock()
	defer r.m.Unlock()

	for ref, val := range r.objects {
		if ref.Type == kind {
			return val.(mo.Entity)
		}
	}

	return nil
}

// All returns all entities of type specified by kind.
// If kind is empty - all entities will be returned.
func (r *Registry) All(kind string) []mo.Entity {
	r.m.Lock()
	defer r.m.Unlock()

	var entities []mo.Entity
	for ref, val := range r.objects {
		if kind == "" || ref.Type == kind {
			if e, ok := val.(mo.Entity); ok {
				entities = append(entities, e)
			}
		}
	}

	return entities
}

// AllReference returns all mo.Reference objects of type specified by kind.
// If kind is empty - all objects will be returned.
func (r *Registry) AllReference(kind string) []mo.Reference {
	r.m.Lock()
	defer r.m.Unlock()

	var objs []mo.Reference
	for ref, val := range r.objects {
		if kind == "" || ref.Type == kind {
			objs = append(objs, val)
		}
	}

	return objs
}

// applyHandlers calls the given func for each r.handlers
func (r *Registry) applyHandlers(f func(o RegisterObject)) {
	r.m.Lock()
	handlers := make([]RegisterObject, 0, len(r.handlers))
	for _, handler := range r.handlers {
		handlers = append(handlers, handler)
	}
	r.m.Unlock()

	for i := range handlers {
		f(handlers[i])
	}
}

func (r *Registry) reference(item mo.Reference) types.ManagedObjectReference {
	ref := item.Reference()
	if ref.Type == "" || ref.Value == "" {
		ref = r.newReference(item)
		r.setReference(item, ref)
	}
	return ref
}

// Put adds a new object to Registry, generating a ManagedObjectReference if not already set.
func (r *Registry) Put(item mo.Reference) mo.Reference {
	r.m.Lock()

	if me, ok := item.(mo.Entity); ok {
		me.Entity().ConfigStatus = types.ManagedEntityStatusGreen
		me.Entity().OverallStatus = types.ManagedEntityStatusGreen
		me.Entity().EffectiveRole = []int32{-1} // Admin
	}

	r.objects[r.reference(item)] = item

	r.m.Unlock()

	ctx := &Context{
		Map: r,
	}

	r.applyHandlers(func(o RegisterObject) {
		o.PutObject(ctx, item)
	})

	return item
}

// Remove removes an object from the Registry.
func (r *Registry) Remove(ctx *Context, item types.ManagedObjectReference) {
	r.applyHandlers(func(o RegisterObject) {
		o.RemoveObject(ctx, item)
	})

	r.m.Lock()
	delete(r.objects, item)
	delete(r.handlers, item)
	delete(r.locks, item)
	r.m.Unlock()
}

// Update dispatches object property changes to RegisterObject handlers,
// such as any PropertyCollector instances with in-progress WaitForUpdates calls.
// The changes are also applied to the given object via mo.ApplyPropertyChange,
// so there is no need to set object fields directly.
func (r *Registry) Update(ctx *Context, obj mo.Reference, changes []types.PropertyChange) {
	for i := range changes {
		if changes[i].Op == "" {
			changes[i].Op = types.PropertyChangeOpAssign
		}
		if changes[i].Val != nil {
			rval := reflect.ValueOf(changes[i].Val)
			changes[i].Val = wrapValue(rval, rval.Type())
		}
	}

	val := getManagedObject(obj).Addr().Interface().(mo.Reference)

	mo.ApplyPropertyChange(val, changes)

	r.applyHandlers(func(o RegisterObject) {
		o.UpdateObject(ctx, val, changes)
	})
}

func (r *Registry) AtomicUpdate(ctx *Context, obj mo.Reference, changes []types.PropertyChange) {
	r.WithLock(ctx, obj, func() {
		ctx.Update(obj, changes)
	})
}

// getEntityParent traverses up the inventory and returns the first object of type kind.
// If no object of type kind is found, the method will panic when it reaches the
// inventory root Folder where the Parent field is nil.
func (r *Registry) getEntityParent(item mo.Entity, kind string) mo.Entity {
	var ok bool
	for {
		parent := item.Entity().Parent

		item, ok = r.Get(*parent).(mo.Entity)
		if !ok {
			return nil
		}
		if item.Reference().Type == kind {
			return item
		}
	}
}

// getEntityDatacenter returns the Datacenter containing the given item
func (r *Registry) getEntityDatacenter(item mo.Entity) *Datacenter {
	dc, ok := r.getEntityParent(item, "Datacenter").(*Datacenter)
	if ok {
		return dc
	}
	return nil
}

func (r *Registry) getEntityFolder(item mo.Entity, kind string) *mo.Folder {
	dc := r.getEntityDatacenter(item)

	var ref types.ManagedObjectReference

	switch kind {
	case "datastore":
		ref = dc.DatastoreFolder
	}

	folder, _ := asFolderMO(r.Get(ref))

	// If Model was created with Folder option, use that Folder; else use top-level folder
	for _, child := range folder.ChildEntity {
		if child.Type == "Folder" {
			folder, _ = asFolderMO(r.Get(child))
			break
		}
	}

	return folder
}

// getEntityComputeResource returns the ComputeResource parent for the given item.
// A ResourcePool for example may have N Parents of type ResourcePool, but the top
// most Parent pool is always a ComputeResource child.
func (r *Registry) getEntityComputeResource(item mo.Entity) mo.Entity {
	for {
		parent := item.Entity().Parent

		item = r.Get(*parent).(mo.Entity)

		switch item.Reference().Type {
		case "ComputeResource":
			return item
		case "ClusterComputeResource":
			return item
		}
	}
}

func entityName(e mo.Entity) string {
	name := e.Entity().Name
	if name != "" {
		return name
	}

	obj := getManagedObject(e).Addr().Interface()

	// The types below have their own 'Name' field, so ManagedEntity.Name (me.Name) is empty.
	// See also mo.Ancestors
	switch x := obj.(type) {
	case *mo.Network:
		return x.Name
	case *mo.DistributedVirtualSwitch:
		return x.Name
	case *mo.DistributedVirtualPortgroup:
		return x.Name
	case *mo.OpaqueNetwork:
		return x.Name
	}

	log.Panicf("%T object %s does not have a Name", obj, e.Reference())
	return name
}

// FindByName returns the first mo.Entity of the given refs whose Name field is equal to the given name.
// If there is no match, nil is returned.
// This method is useful for cases where objects are required to have a unique name, such as Datastore with
// a HostStorageSystem or HostSystem within a ClusterComputeResource.
func (r *Registry) FindByName(name string, refs []types.ManagedObjectReference) mo.Entity {
	for _, ref := range refs {
		if e, ok := r.Get(ref).(mo.Entity); ok {
			if name == entityName(e) {
				return e
			}
		}
	}

	return nil
}

// FindReference returns the 1st match found in refs, or nil if not found.
func FindReference(refs []types.ManagedObjectReference, match ...types.ManagedObjectReference) *types.ManagedObjectReference {
	for _, ref := range refs {
		for _, m := range match {
			if ref == m {
				return &ref
			}
		}
	}

	return nil
}

// AppendReference appends the given refs to field.
func (r *Registry) AppendReference(ctx *Context, obj mo.Reference, field *[]types.ManagedObjectReference, ref ...types.ManagedObjectReference) {
	r.WithLock(ctx, obj, func() {
		*field = append(*field, ref...)
	})
}

// AddReference appends ref to field if not already in the given field.
func (r *Registry) AddReference(ctx *Context, obj mo.Reference, field *[]types.ManagedObjectReference, ref types.ManagedObjectReference) {
	r.WithLock(ctx, obj, func() {
		if FindReference(*field, ref) == nil {
			*field = append(*field, ref)
		}
	})
}

// RemoveReference removes ref from the given field.
func RemoveReference(field *[]types.ManagedObjectReference, ref types.ManagedObjectReference) {
	for i, r := range *field {
		if r == ref {
			*field = append((*field)[:i], (*field)[i+1:]...)
			break
		}
	}
}

// RemoveReference removes ref from the given field.
func (r *Registry) RemoveReference(ctx *Context, obj mo.Reference, field *[]types.ManagedObjectReference, ref types.ManagedObjectReference) {
	r.WithLock(ctx, obj, func() {
		RemoveReference(field, ref)
	})
}

func (r *Registry) removeString(ctx *Context, obj mo.Reference, field *[]string, val string) {
	r.WithLock(ctx, obj, func() {
		for i, name := range *field {
			if name == val {
				*field = append((*field)[:i], (*field)[i+1:]...)
				break
			}
		}
	})
}

func (r *Registry) content() types.ServiceContent {
	return r.Get(vim25.ServiceInstance).(interface {
		ServiceContent() types.ServiceContent
	}).ServiceContent()
}

// IsESX returns true if this Registry maps an ESX model
func (r *Registry) IsESX() bool {
	return r.content().About.ApiType == "HostAgent"
}

// IsVPX returns true if this Registry maps a VPX model
func (r *Registry) IsVPX() bool {
	return !r.IsESX()
}

// SearchIndex returns the SearchIndex singleton
func (r *Registry) SearchIndex() *SearchIndex {
	return r.Get(r.content().SearchIndex.Reference()).(*SearchIndex)
}

// AlarmManager returns the AlarmManager singleton
func (r *Registry) AlarmManager() *AlarmManager {
	ref := r.content().AlarmManager
	if ref == nil {
		return nil // ESX
	}
	return r.Get(*ref).(*AlarmManager)
}

// EventManager returns the EventManager singleton
func (r *Registry) EventManager() *EventManager {
	return r.Get(r.content().EventManager.Reference()).(*EventManager)
}

// FileManager returns the FileManager singleton
func (r *Registry) FileManager() *FileManager {
	return r.Get(r.content().FileManager.Reference()).(*FileManager)
}

// CryptoManager returns the CryptoManagerKmip singleton
func (r *Registry) CryptoManager() *CryptoManagerKmip {
	return r.Get(r.content().CryptoManager.Reference()).(*CryptoManagerKmip)
}

type VirtualDiskManagerInterface interface {
	mo.Reference
	MO() mo.VirtualDiskManager
	CreateVirtualDiskTask(*Context, *types.CreateVirtualDisk_Task) soap.HasFault
	DeleteVirtualDiskTask(*Context, *types.DeleteVirtualDisk_Task) soap.HasFault
	MoveVirtualDiskTask(*Context, *types.MoveVirtualDisk_Task) soap.HasFault
	CopyVirtualDiskTask(*Context, *types.CopyVirtualDisk_Task) soap.HasFault
	QueryVirtualDiskUuid(*Context, *types.QueryVirtualDiskUuid) soap.HasFault
	SetVirtualDiskUuid(*Context, *types.SetVirtualDiskUuid) soap.HasFault
}

// VirtualDiskManager returns the VirtualDiskManager singleton
func (r *Registry) VirtualDiskManager() VirtualDiskManagerInterface {
	return r.Get(r.content().VirtualDiskManager.Reference()).(VirtualDiskManagerInterface)
}

// ViewManager returns the ViewManager singleton
func (r *Registry) ViewManager() *ViewManager {
	return r.Get(r.content().ViewManager.Reference()).(*ViewManager)
}

// UserDirectory returns the UserDirectory singleton
func (r *Registry) UserDirectory() *UserDirectory {
	return r.Get(r.content().UserDirectory.Reference()).(*UserDirectory)
}

// SessionManager returns the SessionManager singleton
func (r *Registry) SessionManager() *SessionManager {
	return r.Get(r.content().SessionManager.Reference()).(*SessionManager)
}

// OptionManager returns the OptionManager singleton
func (r *Registry) OptionManager() *OptionManager {
	return r.Get(r.content().Setting.Reference()).(*OptionManager)
}

// CustomFieldsManager returns CustomFieldsManager singleton
func (r *Registry) CustomFieldsManager() *CustomFieldsManager {
	return r.Get(r.content().CustomFieldsManager.Reference()).(*CustomFieldsManager)
}

// TenantManager returns TenantManager singleton
func (r *Registry) TenantManager() *TenantManager {
	return r.Get(r.content().TenantManager.Reference()).(*TenantManager)
}

// VmCompatibilityChecker returns VmCompatibilityChecker singleton
func (r *Registry) VmCompatibilityChecker() *VmCompatibilityChecker {
	return r.Get(r.content().VmCompatibilityChecker.Reference()).(*VmCompatibilityChecker)
}

// VmProvisioningChecker returns VmProvisioningChecker singleton
func (r *Registry) VmProvisioningChecker() *VmProvisioningChecker {
	return r.Get(r.content().VmProvisioningChecker.Reference()).(*VmProvisioningChecker)
}

// ExtensionManager returns the ExtensionManager singleton
func (r *Registry) ExtensionManager() *ExtensionManager {
	return r.Get(r.content().ExtensionManager.Reference()).(*ExtensionManager)
}

// VStorageObjectManager returns the VStorageObjectManager singleton
func (r *Registry) VStorageObjectManager() *VcenterVStorageObjectManager {
	return r.Get(r.content().VStorageObjectManager.Reference()).(*VcenterVStorageObjectManager)
}

func (r *Registry) MarshalJSON() ([]byte, error) {
	r.m.Lock()
	defer r.m.Unlock()

	vars := struct {
		Objects int `json:"objects"`
		Locks   int `json:"locks"`
	}{
		len(r.objects),
		len(r.locks),
	}

	return json.Marshal(vars)
}

func (r *Registry) locker(obj mo.Reference) *internal.ObjectLock {
	var ref types.ManagedObjectReference

	switch x := obj.(type) {
	case types.ManagedObjectReference:
		ref = x
		obj = r.Get(ref) // to check for sync.Locker
	case *types.ManagedObjectReference:
		ref = *x
		obj = r.Get(ref) // to check for sync.Locker
	default:
		// Use of obj.Reference() may cause a read race, prefer the mo 'Self' field to avoid this
		self := reflect.ValueOf(obj).Elem().FieldByName("Self")
		if self.IsValid() {
			ref = self.Interface().(types.ManagedObjectReference)
		} else {
			ref = obj.Reference()
		}
	}

	if mu, ok := obj.(sync.Locker); ok {
		// Objects that opt out of default locking are responsible for
		// implementing their own lock sharing, if needed. Returning
		// nil as heldBy means that WithLock will call Lock/Unlock
		// every time.
		return internal.NewObjectLock(mu)
	}

	r.m.Lock()
	mu, ok := r.locks[ref]
	if !ok {
		mu = internal.NewObjectLock(new(sync.Mutex))
		r.locks[ref] = mu
	}
	r.m.Unlock()

	return mu
}

var enableLocker = os.Getenv("VCSIM_LOCKER") != "false"

// WithLock holds a lock for the given object while then given function is run.
func (r *Registry) WithLock(onBehalfOf *Context, obj mo.Reference, f func()) {
	unlock := r.AcquireLock(onBehalfOf, obj)
	f()
	unlock()
}

// AcquireLock acquires the lock for onBehalfOf then returns. The lock MUST be
// released by calling the returned function. WithLock should be preferred
// wherever possible.
func (r *Registry) AcquireLock(onBehalfOf *Context, obj mo.Reference) func() {
	if onBehalfOf == nil {
		panic(fmt.Sprintf("Attempt to lock %v with nil onBehalfOf", obj))
	}

	if !enableLocker {
		return func() {}
	}

	l := r.locker(obj)
	l.Acquire(onBehalfOf)
	return func() {
		l.Release(onBehalfOf)
	}
}

// nopLocker can be embedded to opt-out of auto-locking (see Registry.WithLock)
type nopLocker struct{}

func (*nopLocker) Lock()   {}
func (*nopLocker) Unlock() {}
