asvocab_interfaces.go

package astreams

import (
	"encoding/json"
	"io"
	"reflect"
)

type JsonPayload struct {
	Type string `json:"type"`
}

// ActivityStreamer is a generic type constraint representing all valid Activity Streams 2.0 types
type ActivityStreamer interface {
	Object | Link | Actor | Activity | IntransitiveActivity | Collection | CollectionPage |
		OrderedCollection | OrderedCollectionPage | Location | Icon | Image | Place | Profile |
		Tombstone | Relationship | Question
}

// DecodePayloadObjectType can be used to check the specific type of unknown JSON payload
/*
	payloadMeta, err := DecodePayloadObjectType(payload)
	if err != nil {
		//
	}

	switch payloadMeta.Type {
	case "Note":
		var note Note
		err = json.Unmarshal([]byte(tc), &note)
		if err != nil {
			//
		}
	case "Offer":
		var offer Offer
		err = json.Unmarshal([]byte(tc), &offer)
		if err != nil {
			//
		}
	case "Person":
		var person Person
		err = json.Unmarshal([]byte(tc), &person)
		if err != nil {
			//
		}

		if person.Name == "" {
			//
		}
	default:
		var obj ObjectOrLinkOrString
		err = json.Unmarshal([]byte(tc), &obj)
		if err != nil {
			//
		}
	}
*/
func DecodePayloadObjectType(payload io.Reader) (JsonPayload, error) {
	var payloadType JsonPayload
	err := json.NewDecoder(payload).Decode(&payloadType)
	if err != nil {
		return payloadType, err
	}

	return payloadType, nil
}

// ObjectLinker can be either a (sub)type of 'Object' or a (sub)type of 'Link'
type ObjectLinker interface {
	IsObject() bool
	IsLink() bool
	GetObject() *Object
	GetLink() *Link
}

// ConcreteType returns both, the type name obtained using reflection,
// and the Type property of the Object / Link JSON payload.
// The object's own Type property is going to be more specific, so use that where useful.
func ConcreteType(t ObjectLinker) (reflectType, astreamsType string) {
	if t.IsLink() {
		return reflect.TypeOf(t).Name(), t.GetLink().Type
	}
	return reflect.TypeOf(t).Name(), t.GetObject().Type
}

// Implements 'ObjectLinker' interface for 'Object'
func (o Object) IsObject() bool {
	return true
}

func (o Object) IsLink() bool {
	return false
}

func (o Object) GetObject() *Object {
	return &o
}

func (o Object) GetLink() *Link {
	return nil
}

// Implements 'ObjectLinker' interface for 'Link'
func (l Link) IsObject() bool {
	return false
}

func (l Link) IsLink() bool {
	return true
}

func (l Link) GetObject() *Object {
	return nil
}

func (l Link) GetLink() *Link {
	return &l
}