// SetList sets the given list object's Items member have the elements given in
// objects.
// Returns an error if list is not a List type (does not have an Items member),
// or if any of the objects are not of the right type.
func SetList(list Object, objects []Object) error {
	itemsPtr, err := GetItemsPtr(list)
	if err != nil {
		return err
	}
	items, err := conversion.EnforcePtr(itemsPtr)
	if err != nil {
		return err
	}
	slice := reflect.MakeSlice(items.Type(), len(objects), len(objects))
	for i := range objects {
		dest := slice.Index(i)
		src, err := conversion.EnforcePtr(objects[i])
		if err != nil {
			return err
		}
		if src.Type().AssignableTo(dest.Type()) {
			dest.Set(src)
		} else if src.Type().ConvertibleTo(dest.Type()) {
			dest.Set(src.Convert(dest.Type()))
		} else {
			return fmt.Errorf("item[%v]: Type mismatch: Expected %v, got %v", dest.Type(), src.Type())
		}
	}
	items.Set(slice)
	return nil
}

func (h *etcdHelper) extractObj(response *etcd.Response, inErr error, objPtr runtime.Object, ignoreNotFound, prevNode bool) (body string, node *etcd.Node, err error) {
	if response != nil {
		if prevNode {
			node = response.PrevNode
		} else {
			node = response.Node
		}
	}
	if inErr != nil || node == nil || len(node.Value) == 0 {
		if ignoreNotFound {
			v, err := conversion.EnforcePtr(objPtr)
			if err != nil {
				return "", nil, err
			}
			v.Set(reflect.Zero(v.Type()))
			return "", nil, nil
		} else if inErr != nil {
			return "", nil, inErr
		}
		return "", nil, fmt.Errorf("unable to locate a value on the response: %#v", response)
	}
	body = node.Value
	err = h.codec.DecodeInto([]byte(body), objPtr)
	if h.versioner != nil {
		_ = h.versioner.UpdateObject(objPtr, node.Expiration, node.ModifiedIndex)
		// being unable to set the version does not prevent the object from being extracted
	}
	return body, node, err
}

// addObjectParams converts a runtime.Object into a set of go-restful Param() definitions on the route.
// The object must be a pointer to a struct; only fields at the top level of the struct that are not
// themselves interfaces or structs are used; only fields with a json tag that is non empty (the standard
// Go JSON behavior for omitting a field) become query parameters. The name of the query parameter is
// the JSON field name. If a description struct tag is set on the field, that description is used on the
// query parameter. In essence, it converts a standard JSON top level object into a query param schema.
func addObjectParams(ws *restful.WebService, route *restful.RouteBuilder, obj interface{}) error {
	sv, err := conversion.EnforcePtr(obj)
	if err != nil {
		return err
	}
	st := sv.Type()
	switch st.Kind() {
	case reflect.Struct:
		for i := 0; i < st.NumField(); i++ {
			name := st.Field(i).Name
			sf, ok := st.FieldByName(name)
			if !ok {
				continue
			}
			switch sf.Type.Kind() {
			case reflect.Interface, reflect.Struct:
			default:
				jsonTag := sf.Tag.Get("json")
				if len(jsonTag) == 0 {
					continue
				}
				jsonName := strings.SplitN(jsonTag, ",", 2)[0]
				if len(jsonName) == 0 {
					continue
				}
				desc := sf.Tag.Get("description")
				route.Param(ws.QueryParameter(jsonName, desc).DataType(typeToJSON(sf.Type.Name())))
			}
		}
	}
	return nil
}

// Implements storage.Interface.
func (h *etcdHelper) Create(key string, obj, out runtime.Object, ttl uint64) error {
	key = h.prefixEtcdKey(key)
	data, err := h.codec.Encode(obj)
	if err != nil {
		return err
	}
	if h.versioner != nil {
		if version, err := h.versioner.ObjectResourceVersion(obj); err == nil && version != 0 {
			return errors.New("resourceVersion may not be set on objects to be created")
		}
	}

	startTime := time.Now()
	response, err := h.client.Create(key, string(data), ttl)
	metrics.RecordEtcdRequestLatency("create", getTypeName(obj), startTime)
	if err != nil {
		return err
	}
	if out != nil {
		if _, err := conversion.EnforcePtr(out); err != nil {
			panic("unable to convert output object to pointer")
		}
		_, _, err = h.extractObj(response, err, out, false, false)
	}
	return err
}

// ExtractList returns obj's Items element as an array of runtime.Objects.
// Returns an error if obj is not a List type (does not have an Items member).
func ExtractList(obj Object) ([]Object, error) {
	itemsPtr, err := GetItemsPtr(obj)
	if err != nil {
		return nil, err
	}
	items, err := conversion.EnforcePtr(itemsPtr)
	if err != nil {
		return nil, err
	}
	list := make([]Object, items.Len())
	for i := range list {
		raw := items.Index(i)
		var found bool
		switch raw.Kind() {
		case reflect.Interface, reflect.Ptr:
			list[i], found = raw.Interface().(Object)
		default:
			list[i], found = raw.Addr().Interface().(Object)
		}
		if !found {
			return nil, fmt.Errorf("item[%v]: Expected object, got %#v(%s)", i, raw.Interface(), raw.Kind())
		}
	}
	return list, nil
}

// decodeNodeList walks the tree of each node in the list and decodes into the specified object
func (h *EtcdHelper) decodeNodeList(nodes []*etcd.Node, slicePtr interface{}) error {
	v, err := conversion.EnforcePtr(slicePtr)
	if err != nil || v.Kind() != reflect.Slice {
		// This should not happen at runtime.
		panic("need ptr to slice")
	}
	for _, node := range nodes {
		if node.Dir {
			if err := h.decodeNodeList(node.Nodes, slicePtr); err != nil {
				return err
			}
			continue
		}
		obj := reflect.New(v.Type().Elem())
		if err := h.Codec.DecodeInto([]byte(node.Value), obj.Interface().(runtime.Object)); err != nil {
			return err
		}
		if h.ResourceVersioner != nil {
			_ = h.ResourceVersioner.SetResourceVersion(obj.Interface().(runtime.Object), node.ModifiedIndex)
			// being unable to set the version does not prevent the object from being extracted
		}
		v.Set(reflect.Append(v, obj.Elem()))
	}
	return nil
}

func (h *EtcdHelper) bodyAndExtractObj(key string, objPtr runtime.Object, ignoreNotFound bool) (body string, modifiedIndex uint64, err error) {
	response, err := h.Client.Get(key, false, false)

	if err != nil && !IsEtcdNotFound(err) {
		return "", 0, err
	}
	if err != nil || response.Node == nil || len(response.Node.Value) == 0 {
		if ignoreNotFound {
			v, err := conversion.EnforcePtr(objPtr)
			if err != nil {
				return "", 0, err
			}
			v.Set(reflect.Zero(v.Type()))
			return "", 0, nil
		} else if err != nil {
			return "", 0, err
		}
		return "", 0, fmt.Errorf("key '%v' found no nodes field: %#v", key, response)
	}
	body = response.Node.Value
	err = h.Codec.DecodeInto([]byte(body), objPtr)
	if h.ResourceVersioner != nil {
		_ = h.ResourceVersioner.SetResourceVersion(objPtr, response.Node.ModifiedIndex)
		// being unable to set the version does not prevent the object from being extracted
	}
	return body, response.Node.ModifiedIndex, err
}

// SetObj marshals obj via json, and stores under key. Will do an atomic update if obj's ResourceVersion
// field is set. 'ttl' is time-to-live in seconds, and 0 means forever. If no error is returned and out is
// not nil, out will be set to the read value from etcd.
func (h *EtcdHelper) SetObj(key string, obj, out runtime.Object, ttl uint64) error {
	var response *etcd.Response
	data, err := h.Codec.Encode(obj)
	if err != nil {
		return err
	}

	create := true
	if h.Versioner != nil {
		if version, err := h.Versioner.ObjectResourceVersion(obj); err == nil && version != 0 {
			create = false
			response, err = h.Client.CompareAndSwap(key, string(data), ttl, "", version)
			if err != nil {
				return err
			}
		}
	}
	if create {
		// Create will fail if a key already exists.
		response, err = h.Client.Create(key, string(data), ttl)
	}

	if err != nil {
		return err
	}
	if out != nil {
		if _, err := conversion.EnforcePtr(out); err != nil {
			panic("unable to convert output object to pointer")
		}
		_, _, err = h.extractObj(response, err, out, false, false)
	}

	return err
}

// ListMetaFor returns a pointer to a provided object's ListMeta,
// or an error if the object does not have that pointer.
// TODO: allow runtime.Unknown to extract this object
func ListMetaFor(obj runtime.Object) (*ListMeta, error) {
	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return nil, err
	}
	var meta *ListMeta
	err = runtime.FieldPtr(v, "ListMeta", &meta)
	return meta, err
}

// GetObjectMetaPtr returns a pointer to a provided object's ObjectMeta.
// TODO: allow runtime.Unknown to extract this object
func ObjectMetaFor(obj runtime.Object) (*ObjectMeta, error) {
	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return nil, err
	}
	var objectMeta *ObjectMeta
	if err := runtime.FieldPtr(v, "ObjectMeta", &objectMeta); err != nil {
		return nil, err
	}
	return objectMeta, nil
}

// DeleteObj removes the specified key and returns the value that existed at that spot.
func (h *EtcdHelper) DeleteObj(key string, out runtime.Object) error {
	if _, err := conversion.EnforcePtr(out); err != nil {
		panic("unable to convert output object to pointer")
	}
	response, err := h.Client.Delete(key, false)
	if !IsEtcdNotFound(err) {
		// if the object that existed prior to the delete is returned by etcd, update out.
		if err != nil || response.PrevNode != nil {
			_, _, err = h.extractObj(response, err, out, false, true)
		}
	}
	return err
}

// GetItemsPtr returns a pointer to the list object's Items member.
// If 'list' doesn't have an Items member, it's not really a list type
// and an error will be returned.
// This function will either return a pointer to a slice, or an error, but not both.
func GetItemsPtr(list Object) (interface{}, error) {
	v, err := conversion.EnforcePtr(list)
	if err != nil {
		return nil, err
	}
	items := v.FieldByName("Items")
	if !items.IsValid() {
		return nil, fmt.Errorf("no Items field in %#v", list)
	}
	if items.Kind() != reflect.Slice {
		return nil, fmt.Errorf("Items field is not a slice")
	}
	return items.Addr().Interface(), nil
}

// GuaranteedUpdate calls "tryUpdate()" to update key "key" that is of type "ptrToType". It keeps
// calling tryUpdate() and retrying the update until success if there is etcd index conflict. Note that object
// passed to tryUpdate() may change across invocations of tryUpdate() if other writers are simultaneously
// updating it, so tryUpdate() needs to take into account the current contents of the object when
// deciding how the updated object (that it returns) should look.
//
// Example:
//
// h := &util.EtcdHelper{client, encoding, versioning}
// err := h.GuaranteedUpdate("myKey", &MyType{}, true, func(input runtime.Object) (runtime.Object, uint64, error) {
//	// Before each invocation of the user-defined function, "input" is reset to etcd's current contents for "myKey".
//
//	cur := input.(*MyType) // Guaranteed to succeed.
//
//	// Make a *modification*.
//	cur.Counter++
//
//	// Return the modified object. Return an error to stop iterating. Return a non-zero uint64 to set
//      // the TTL on the object.
//	return cur, 0, nil
// })
//
func (h *EtcdHelper) GuaranteedUpdate(key string, ptrToType runtime.Object, ignoreNotFound bool, tryUpdate EtcdUpdateFunc) error {
	v, err := conversion.EnforcePtr(ptrToType)
	if err != nil {
		// Panic is appropriate, because this is a programming error.
		panic("need ptr to type")
	}
	key = h.PrefixEtcdKey(key)
	for {
		obj := reflect.New(v.Type()).Interface().(runtime.Object)
		origBody, index, err := h.bodyAndExtractObj(key, obj, ignoreNotFound)
		if err != nil {
			return err
		}

		ret, ttl, err := tryUpdate(obj)
		if err != nil {
			return err
		}

		data, err := h.Codec.Encode(ret)
		if err != nil {
			return err
		}

		// First time this key has been used, try creating new value.
		if index == 0 {
			startTime := time.Now()
			response, err := h.Client.Create(key, string(data), ttl)
			recordEtcdRequestLatency("create", getTypeName(ptrToType), startTime)
			if IsEtcdNodeExist(err) {
				continue
			}
			_, _, err = h.extractObj(response, err, ptrToType, false, false)
			return err
		}

		if string(data) == origBody {
			return nil
		}

		startTime := time.Now()
		response, err := h.Client.CompareAndSwap(key, string(data), ttl, origBody, index)
		recordEtcdRequestLatency("compareAndSwap", getTypeName(ptrToType), startTime)
		if IsEtcdTestFailed(err) {
			continue
		}
		_, _, err = h.extractObj(response, err, ptrToType, false, false)
		return err
	}
}

// Implements storage.Interface.
func (h *etcdHelper) Delete(key string, out runtime.Object) error {
	key = h.prefixEtcdKey(key)
	if _, err := conversion.EnforcePtr(out); err != nil {
		panic("unable to convert output object to pointer")
	}

	startTime := time.Now()
	response, err := h.client.Delete(key, false)
	metrics.RecordEtcdRequestLatency("delete", getTypeName(out), startTime)
	if !IsEtcdNotFound(err) {
		// if the object that existed prior to the delete is returned by etcd, update out.
		if err != nil || response.PrevNode != nil {
			_, _, err = h.extractObj(response, err, out, false, true)
		}
	}
	return err
}

// WithType extracts a list of runtime objects with the specified type
func (g *Generated) WithType(slicePtr interface{}) bool {
	found := false
	v, err := conversion.EnforcePtr(slicePtr)
	if err != nil || v.Kind() != reflect.Slice {
		// This should not happen at runtime.
		panic("need ptr to slice")
	}
	t := v.Type().Elem()
	for i := range g.Items {
		obj := reflect.ValueOf(g.Items[i]).Elem()
		if !obj.Type().ConvertibleTo(t) {
			continue
		}
		found = true
		v.Set(reflect.Append(v, obj.Convert(t)))
	}
	return found
}

// AtomicUpdate generalizes the pattern that allows for making atomic updates to etcd objects.
// Note, tryUpdate may be called more than once.
//
// Example:
//
// h := &util.EtcdHelper{client, encoding, versioning}
// err := h.AtomicUpdate("myKey", &MyType{}, func(input runtime.Object) (runtime.Object, error) {
//	// Before this function is called, currentObj has been reset to etcd's current
//	// contents for "myKey".
//
//	cur := input.(*MyType) // Guaranteed to work.
//
//	// Make a *modification*.
//	cur.Counter++
//
//	// Return the modified object. Return an error to stop iterating.
//	return cur, nil
// })
//
func (h *EtcdHelper) AtomicUpdate(key string, ptrToType runtime.Object, tryUpdate EtcdUpdateFunc) error {
	v, err := conversion.EnforcePtr(ptrToType)
	if err != nil {
		// Panic is appropriate, because this is a programming error.
		panic("need ptr to type")
	}
	for {
		obj := reflect.New(v.Type()).Interface().(runtime.Object)
		origBody, index, err := h.bodyAndExtractObj(key, obj, true)
		if err != nil {
			return err
		}

		ret, err := tryUpdate(obj)
		if err != nil {
			return err
		}

		data, err := h.Codec.Encode(ret)
		if err != nil {
			return err
		}

		glog.V(3).Infof("Atomic update(%s): %+v", key, ret)
		// First time this key has been used, try creating new value.
		if index == 0 {
			_, err = h.Client.Create(key, string(data), 0)
			if IsEtcdNodeExist(err) {
				continue
			}
			return err
		}

		if string(data) == origBody {
			return nil
		}

		_, err = h.Client.CompareAndSwap(key, string(data), 0, origBody, index)
		if IsEtcdTestFailed(err) {
			continue
		}
		return err
	}
}

// Accessor takes an arbitary object pointer and returns meta.Interface.
// obj must be a pointer to an API type. An error is returned if the minimum
// required fields are missing. Fields that are not required return the default
// value and are a no-op if set.
// TODO: add a fast path for *TypeMeta and *ObjectMeta for internal objects
func Accessor(obj interface{}) (Interface, error) {
	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return nil, err
	}
	t := v.Type()
	if v.Kind() != reflect.Struct {
		return nil, fmt.Errorf("expected struct, but got %v: %v (%#v)", v.Kind(), t, v.Interface())
	}

	typeMeta := v.FieldByName("TypeMeta")
	if !typeMeta.IsValid() {
		return nil, fmt.Errorf("struct %v lacks embedded TypeMeta type", t)
	}

	a := &genericAccessor{}
	if err := extractFromTypeMeta(typeMeta, a); err != nil {
		return nil, fmt.Errorf("unable to find type fields on %#v: %v", typeMeta, err)
	}

	objectMeta := v.FieldByName("ObjectMeta")
	if objectMeta.IsValid() {
		// look for the ObjectMeta fields
		if err := extractFromObjectMeta(objectMeta, a); err != nil {
			return nil, fmt.Errorf("unable to find object fields on %#v: %v", objectMeta, err)
		}
	} else {
		listMeta := v.FieldByName("ListMeta")
		if listMeta.IsValid() {
			// look for the ListMeta fields
			if err := extractFromListMeta(listMeta, a); err != nil {
				return nil, fmt.Errorf("unable to find list fields on %#v: %v", listMeta, err)
			}
		} else {
			// look for the older TypeMeta with all metadata
			if err := extractFromObjectMeta(typeMeta, a); err != nil {
				return nil, fmt.Errorf("unable to find object fields on %#v: %v", typeMeta, err)
			}
		}
	}

	return a, nil
}

// ExtractList returns obj's Items element as an array of runtime.Objects.
// Returns an error if obj is not a List type (does not have an Items member).
func ExtractList(obj Object) ([]Object, error) {
	itemsPtr, err := GetItemsPtr(obj)
	if err != nil {
		return nil, err
	}
	items, err := conversion.EnforcePtr(itemsPtr)
	if err != nil {
		return nil, err
	}
	list := make([]Object, items.Len())
	for i := range list {
		raw := items.Index(i)
		item, ok := raw.Addr().Interface().(Object)
		if !ok {
			return nil, fmt.Errorf("item[%v]: Expected object, got %#v", i, raw.Interface())
		}
		list[i] = item
	}
	return list, nil
}

// fieldPtr puts the address of fieldName, which must be a member of v,
// into dest, which must be an address of a variable to which this field's
// address can be assigned.
func fieldPtr(v reflect.Value, fieldName string, dest interface{}) error {
	field := v.FieldByName(fieldName)
	if !field.IsValid() {
		return fmt.Errorf("Couldn't find %v field in %#v", fieldName, v.Interface())
	}
	v, err := conversion.EnforcePtr(dest)
	if err != nil {
		return err
	}
	field = field.Addr()
	if field.Type().AssignableTo(v.Type()) {
		v.Set(field)
		return nil
	}
	if field.Type().ConvertibleTo(v.Type()) {
		v.Set(field.Convert(v.Type()))
		return nil
	}
	return fmt.Errorf("Couldn't assign/convert %v to %v", field.Type(), v.Type())
}

// TypeAccessor returns an interface that allows retrieving and modifying the APIVersion
// and Kind of an in-memory internal object.
// TODO: this interface is used to test code that does not have ObjectMeta or ListMeta
// in round tripping (objects which can use apiVersion/kind, but do not fit the Kube
// api conventions).
func TypeAccessor(obj interface{}) (TypeInterface, error) {
	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return nil, err
	}
	t := v.Type()
	if v.Kind() != reflect.Struct {
		return nil, fmt.Errorf("expected struct, but got %v: %v (%#v)", v.Kind(), t, v.Interface())
	}

	typeMeta := v.FieldByName("TypeMeta")
	if !typeMeta.IsValid() {
		return nil, fmt.Errorf("struct %v lacks embedded TypeMeta type", t)
	}
	a := &genericAccessor{}
	if err := extractFromTypeMeta(typeMeta, a); err != nil {
		return nil, fmt.Errorf("unable to find type fields on %#v: %v", typeMeta, err)
	}
	return a, nil
}