Adding upstream version 0.0~git20250501.71edba4.

Signed-off-by: Daniel Baumann <daniel@debian.org>
2025-05-18 22:06:39 +02:00 · 2025-05-18 22:06:39 +02:00 · c8085bda34
commit c8085bda34
parent c6ff472a6d
87 changed files with 24009 additions and 0 deletions
--- a/activity.go
+++ b/activity.go
@ -0,0 +1,948 @@
+package activitypub
+
+import (
+	"bytes"
+	"encoding/gob"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+	"time"
+
+	"github.com/valyala/fastjson"
+)
+
+// Activity Types
+const (
+	AcceptType          ActivityVocabularyType = "Accept"
+	AddType             ActivityVocabularyType = "Add"
+	AnnounceType        ActivityVocabularyType = "Announce"
+	ArriveType          ActivityVocabularyType = "Arrive"
+	BlockType           ActivityVocabularyType = "Block"
+	CreateType          ActivityVocabularyType = "Create"
+	DeleteType          ActivityVocabularyType = "Delete"
+	DislikeType         ActivityVocabularyType = "Dislike"
+	FlagType            ActivityVocabularyType = "Flag"
+	FollowType          ActivityVocabularyType = "Follow"
+	IgnoreType          ActivityVocabularyType = "Ignore"
+	InviteType          ActivityVocabularyType = "Invite"
+	JoinType            ActivityVocabularyType = "Join"
+	LeaveType           ActivityVocabularyType = "Leave"
+	LikeType            ActivityVocabularyType = "Like"
+	ListenType          ActivityVocabularyType = "Listen"
+	MoveType            ActivityVocabularyType = "Move"
+	OfferType           ActivityVocabularyType = "Offer"
+	QuestionType        ActivityVocabularyType = "Question"
+	RejectType          ActivityVocabularyType = "Reject"
+	ReadType            ActivityVocabularyType = "Read"
+	RemoveType          ActivityVocabularyType = "Remove"
+	TentativeRejectType ActivityVocabularyType = "TentativeReject"
+	TentativeAcceptType ActivityVocabularyType = "TentativeAccept"
+	TravelType          ActivityVocabularyType = "Travel"
+	UndoType            ActivityVocabularyType = "Undo"
+	UpdateType          ActivityVocabularyType = "Update"
+	ViewType            ActivityVocabularyType = "View"
+)
+
+func (a ActivityVocabularyTypes) Contains(typ ActivityVocabularyType) bool {
+	for _, v := range a {
+		if strings.EqualFold(string(v), string(typ)) {
+			return true
+		}
+	}
+	return false
+}
+
+// ContentManagementActivityTypes use case primarily deals with activities that involve the creation, modification or
+// deletion of content.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-crud
+//
+// This includes, for instance, activities such as "John created a new note", "Sally updated an article", and
+// "Joe deleted the photo".
+var ContentManagementActivityTypes = ActivityVocabularyTypes{
+	CreateType,
+	DeleteType,
+	UpdateType,
+}
+
+// CollectionManagementActivityTypes use case primarily deals with activities involving the management of content within
+// collections.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-collection
+//
+// Examples of collections include things like folders, albums, friend lists, etc.
+// This includes, for instance, activities such as "Sally added a file to Folder A", "John moved the file from Folder A
+// to Folder B", etc.
+var CollectionManagementActivityTypes = ActivityVocabularyTypes{
+	AddType,
+	MoveType,
+	RemoveType,
+}
+
+// ReactionsActivityTypes use case primarily deals with reactions to content.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-reactions
+//
+// This can include activities such as liking or disliking content, ignoring updates, flagging content as being
+// inappropriate, accepting or rejecting objects, etc.
+var ReactionsActivityTypes = ActivityVocabularyTypes{
+	AcceptType,
+	BlockType,
+	DislikeType,
+	FlagType,
+	IgnoreType,
+	LikeType,
+	RejectType,
+	TentativeAcceptType,
+	TentativeRejectType,
+}
+
+// EventRSVPActivityTypes use case primarily deals with invitations to events and RSVP type responses.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-rsvp
+var EventRSVPActivityTypes = ActivityVocabularyTypes{
+	AcceptType,
+	IgnoreType,
+	InviteType,
+	RejectType,
+	TentativeAcceptType,
+	TentativeRejectType,
+}
+
+// GroupManagementActivityTypes use case primarily deals with management of groups.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-group
+//
+// It can include, for instance, activities such as "John added Sally to Group A", "Sally joined Group A",
+// "Joe left Group A", etc.
+var GroupManagementActivityTypes = ActivityVocabularyTypes{
+	AddType,
+	JoinType,
+	LeaveType,
+	RemoveType,
+}
+
+// ContentExperienceActivityTypes use case primarily deals with describing activities involving listening to, reading,
+// or viewing content.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-experience
+//
+// For instance, "Sally read the article", "Joe listened to the song".
+var ContentExperienceActivityTypes = ActivityVocabularyTypes{
+	ListenType,
+	ReadType,
+	ViewType,
+}
+
+// GeoSocialEventsActivityTypes use case primarily deals with activities involving geo-tagging type activities.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-geo
+//
+// For instance, it can include activities such as "Joe arrived at work", "Sally left work", and
+// "John is travel from home to work".
+var GeoSocialEventsActivityTypes = ActivityVocabularyTypes{
+	ArriveType,
+	LeaveType,
+	TravelType,
+}
+
+// NotificationActivityTypes use case primarily deals with calling attention to particular objects or notifications.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-notification
+var NotificationActivityTypes = ActivityVocabularyTypes{
+	AnnounceType,
+}
+
+// QuestionActivityTypes use case primarily deals with representing inquiries of any type.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-questions
+//
+// See 5.4 Representing Questions for more information.
+// https://www.w3.org/TR/activitystreams-vocabulary/#questions
+var QuestionActivityTypes = ActivityVocabularyTypes{
+	QuestionType,
+}
+
+// RelationshipManagementActivityTypes use case primarily deals with representing activities involving the management of
+// interpersonal and social relationships
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-relationships
+//
+// (e.g. friend requests, management of social network, etc). See 5.2 Representing Relationships Between Entities
+// for more information.
+// https://www.w3.org/TR/activitystreams-vocabulary/#connections
+var RelationshipManagementActivityTypes = ActivityVocabularyTypes{
+	AcceptType,
+	AddType,
+	BlockType,
+	CreateType,
+	DeleteType,
+	FollowType,
+	IgnoreType,
+	InviteType,
+	RejectType,
+}
+
+// NegatingActivityTypes use case primarily deals with the ability to redact previously completed activities.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-undo
+//
+// See 5.5 Inverse Activities and "Undo" for more information.
+// https://www.w3.org/TR/activitystreams-vocabulary/#inverse
+var NegatingActivityTypes = ActivityVocabularyTypes{
+	UndoType,
+}
+
+// OffersActivityTypes use case deals with activities involving offering one object to another.
+//
+// https://www.w3.org/TR/activitystreams-vocabulary/#motivations-offers
+//
+// It can include, for instance, activities such as "Company A is offering a discount on purchase of Product Z to Sally",
+// "Sally is offering to add a File to Folder A", etc.
+var OffersActivityTypes = ActivityVocabularyTypes{
+	OfferType,
+}
+
+var IntransitiveActivityTypes = ActivityVocabularyTypes{
+	ArriveType,
+	TravelType,
+	QuestionType,
+}
+
+var ActivityTypes = ActivityVocabularyTypes{
+	AcceptType,
+	AddType,
+	AnnounceType,
+	BlockType,
+	CreateType,
+	DeleteType,
+	DislikeType,
+	FlagType,
+	FollowType,
+	IgnoreType,
+	InviteType,
+	JoinType,
+	LeaveType,
+	LikeType,
+	ListenType,
+	MoveType,
+	OfferType,
+	RejectType,
+	ReadType,
+	RemoveType,
+	TentativeRejectType,
+	TentativeAcceptType,
+	UndoType,
+	UpdateType,
+	ViewType,
+}
+
+// HasRecipients is an interface implemented by activities to return their audience
+// for further propagation
+//
+// Please take care to the fact that the de-duplication functionality requires a pointer receiver
+// therefore a valid Item interface that wraps around an Object struct, can not be type asserted
+// to HasRecipients.
+type HasRecipients interface {
+	// Recipients is a method that should do a recipients de-duplication step and then return
+	// the remaining recipients.
+	Recipients() ItemCollection
+	// Clean is a method that removes BCC/Bto recipients in preparation for public consumption of
+	// the Object.
+	Clean()
+}
+
+type Activities interface {
+	Activity
+}
+
+// Activity is a subtype of Object that describes some form of action that may happen,
+// is currently happening, or has already happened.
+// The Activity type itself serves as an abstract base type for all types of activities.
+// It is important to note that the Activity type itself does not carry any specific semantics
+// about the kind of action being taken.
+type Activity struct {
+	// ID provides the globally unique identifier for anActivity Pub Object or Link.
+	ID ID `jsonld:"id,omitempty"`
+	// Type identifies the Activity Pub Object or Link type. Multiple values may be specified.
+	Type ActivityVocabularyType `jsonld:"type,omitempty"`
+	// Name a simple, human-readable, plain-text name for the object.
+	// HTML markup MUST NOT be included. The name MAY be expressed using multiple language-tagged values.
+	Name NaturalLanguageValues `jsonld:"name,omitempty,collapsible"`
+	// Attachment identifies a resource attached or related to an object that potentially requires special handling.
+	// The intent is to provide a model that is at least semantically similar to attachments in email.
+	Attachment Item `jsonld:"attachment,omitempty"`
+	// AttributedTo identifies one or more entities to which this object is attributed. The attributed entities might not be Actors.
+	// For instance, an object might be attributed to the completion of another activity.
+	AttributedTo Item `jsonld:"attributedTo,omitempty"`
+	// Audience identifies one or more entities that represent the total population of entities
+	// for which the object can considered to be relevant.
+	Audience ItemCollection `jsonld:"audience,omitempty"`
+	// Content or textual representation of the Activity Pub Object encoded as a JSON string.
+	// By default, the value of content is HTML.
+	// The mediaType property can be used in the object to indicate a different content type.
+	// (The content MAY be expressed using multiple language-tagged values.)
+	Content NaturalLanguageValues `jsonld:"content,omitempty,collapsible"`
+	// Context identifies the context within which the object exists or an activity was performed.
+	// The notion of "context" used is intentionally vague.
+	// The intended function is to serve as a means of grouping objects and activities that share a
+	// common originating context or purpose. An example could be all activities relating to a common project or event.
+	Context Item `jsonld:"context,omitempty"`
+	// MediaType when used on an Object, identifies the MIME media type of the value of the content property.
+	// If not specified, the content property is assumed to contain text/html content.
+	MediaType MimeType `jsonld:"mediaType,omitempty"`
+	// EndTime the date and time describing the actual or expected ending time of the object.
+	// When used with an Activity object, for instance, the endTime property specifies the moment
+	// the activity concluded or is expected to conclude.
+	EndTime time.Time `jsonld:"endTime,omitempty"`
+	// Generator identifies the entity (e.g. an application) that generated the object.
+	Generator Item `jsonld:"generator,omitempty"`
+	// Icon indicates an entity that describes an icon for this object.
+	// The image should have an aspect ratio of one (horizontal) to one (vertical)
+	// and should be suitable for presentation at a small size.
+	Icon Item `jsonld:"icon,omitempty"`
+	// Image indicates an entity that describes an image for this object.
+	// Unlike the icon property, there are no aspect ratio or display size limitations assumed.
+	Image Item `jsonld:"image,omitempty"`
+	// InReplyTo indicates one or more entities for which this object is considered a response.
+	InReplyTo Item `jsonld:"inReplyTo,omitempty"`
+	// Location indicates one or more physical or logical locations associated with the object.
+	Location Item `jsonld:"location,omitempty"`
+	// Preview identifies an entity that provides a preview of this object.
+	Preview Item `jsonld:"preview,omitempty"`
+	// Published the date and time at which the object was published
+	Published time.Time `jsonld:"published,omitempty"`
+	// Replies identifies a Collection containing objects considered to be responses to this object.
+	Replies Item `jsonld:"replies,omitempty"`
+	// StartTime the date and time describing the actual or expected starting time of the object.
+	// When used with an Activity object, for instance, the startTime property specifies
+	// the moment the activity began or is scheduled to begin.
+	StartTime time.Time `jsonld:"startTime,omitempty"`
+	// Summary a natural language summarization of the object encoded as HTML.
+	// *Multiple language tagged summaries may be provided.)
+	Summary NaturalLanguageValues `jsonld:"summary,omitempty,collapsible"`
+	// Tag one or more "tags" that have been associated with an objects. A tag can be any kind of Activity Pub Object.
+	// The key difference between attachment and tag is that the former implies association by inclusion,
+	// while the latter implies associated by reference.
+	Tag ItemCollection `jsonld:"tag,omitempty"`
+	// Updated the date and time at which the object was updated
+	Updated time.Time `jsonld:"updated,omitempty"`
+	// URL identifies one or more links to representations of the object
+	URL Item `jsonld:"url,omitempty"`
+	// To identifies an entity considered to be part of the public primary audience of an Activity Pub Object
+	To ItemCollection `jsonld:"to,omitempty"`
+	// Bto identifies anActivity Pub Object that is part of the private primary audience of this Activity Pub Object.
+	Bto ItemCollection `jsonld:"bto,omitempty"`
+	// CC identifies anActivity Pub Object that is part of the public secondary audience of this Activity Pub Object.
+	CC ItemCollection `jsonld:"cc,omitempty"`
+	// BCC identifies one or more Objects that are part of the private secondary audience of this Activity Pub Object.
+	BCC ItemCollection `jsonld:"bcc,omitempty"`
+	// Duration when the object describes a time-bound resource, such as an audio or video, a meeting, etc,
+	// the duration property indicates the object's approximate duration.
+	// The value must be expressed as an xsd:duration as defined by [ xmlschema11-2],
+	// section 3.3.6 (e.g. a period of 5 seconds is represented as "PT5S").
+	Duration time.Duration `jsonld:"duration,omitempty"`
+	// This is a list of all Like activities with this object as the object property, added as a side effect.
+	// The likes collection MUST be either an OrderedCollection or a Collection and MAY be filtered on privileges
+	// of an authenticated user or as appropriate when no authentication is given.
+	Likes Item `jsonld:"likes,omitempty"`
+	// This is a list of all Announce activities with this object as the object property, added as a side effect.
+	// The shares collection MUST be either an OrderedCollection or a Collection and MAY be filtered on privileges
+	// of an authenticated user or as appropriate when no authentication is given.
+	Shares Item `jsonld:"shares,omitempty"`
+	// Source property is intended to convey some sort of source from which the content markup was derived,
+	// as a form of provenance, or to support future editing by clients.
+	// In general, clients do the conversion from source to content, not the other way around.
+	Source Source `jsonld:"source,omitempty"`
+	// CanReceiveActivities describes one or more entities that either performed or are expected to perform the activity.
+	// Any single activity can have multiple actors. The actor may be specified using an indirect Link.
+	Actor Item `jsonld:"actor,omitempty"`
+	// Target describes the indirect object, or target, of the activity.
+	// The precise meaning of the target is largely dependent on the type of action being described
+	// but will often be the object of the English preposition "to".
+	// For instance, in the activity "John added a movie to his wishlist",
+	// the target of the activity is John's wishlist. An activity can have more than one target.
+	Target Item `jsonld:"target,omitempty"`
+	// Result describes the result of the activity. For instance, if a particular action results in the creation
+	// of a new resource, the result property can be used to describe that new resource.
+	Result Item `jsonld:"result,omitempty"`
+	// Origin describes an indirect object of the activity from which the activity is directed.
+	// The precise meaning of the origin is the object of the English preposition "from".
+	// For instance, in the activity "John moved an item to List B from List A", the origin of the activity is "List A".
+	Origin Item `jsonld:"origin,omitempty"`
+	// Instrument identifies one or more objects used (or to be used) in the completion of an Activity.
+	Instrument Item `jsonld:"instrument,omitempty"`
+	// Object When used within an Activity, describes the direct object of the activity.
+	// For instance, in the activity "John added a movie to his wishlist",
+	// the object of the activity is the movie added.
+	// When used within a Relationship describes the entity to which the subject is related.
+	Object Item `jsonld:"object,omitempty"`
+}
+
+// GetType returns the ActivityVocabulary type of the current Activity
+func (a Activity) GetType() ActivityVocabularyType {
+	return a.Type
+}
+
+// IsLink returns false for Activity objects
+func (a Activity) IsLink() bool {
+	return false
+}
+
+// GetID returns the ID corresponding to the Activity object
+func (a Activity) GetID() ID {
+	return a.ID
+}
+
+// GetLink returns the IRI corresponding to the Activity object
+func (a Activity) GetLink() IRI {
+	return IRI(a.ID)
+}
+
+// IsObject returns true for Activity objects
+func (a Activity) IsObject() bool {
+	return true
+}
+
+// IsCollection returns false for Activity objects
+func (a Activity) IsCollection() bool {
+	return false
+}
+
+func removeFromCollection(col ItemCollection, items ...Item) ItemCollection {
+	result := make(ItemCollection, 0)
+	if len(items) == 0 {
+		return col
+	}
+	for _, ob := range col {
+		found := false
+		for _, it := range items {
+			if ob.GetID().Equals(it.GetID(), false) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			result = append(result, ob)
+		}
+	}
+	return result
+}
+
+func removeFromAudience(a *Activity, items ...Item) error {
+	if a.To != nil {
+		a.To = removeFromCollection(a.To, items...)
+	}
+	if a.Bto != nil {
+		a.Bto = removeFromCollection(a.Bto, items...)
+	}
+	if a.CC != nil {
+		a.CC = removeFromCollection(a.CC, items...)
+	}
+	if a.BCC != nil {
+		a.BCC = removeFromCollection(a.BCC, items...)
+	}
+	if a.Audience != nil {
+		a.Audience = removeFromCollection(a.Audience, items...)
+	}
+	return nil
+}
+
+// Recipients performs recipient de-duplication on the Activity's To, Bto, CC and BCC properties
+func (a *Activity) Recipients() ItemCollection {
+	var alwaysRemove ItemCollection
+	if a.GetType() == BlockType && a.Object != nil {
+		alwaysRemove = append(alwaysRemove, a.Object)
+	}
+	if len(alwaysRemove) > 0 {
+		_ = removeFromAudience(a, alwaysRemove...)
+	}
+	aud := a.Audience
+	return ItemCollectionDeduplication(&a.To, &a.CC, &a.Bto, &a.BCC, &aud)
+}
+
+// CleanRecipients checks if the "it" Item has recipients and cleans them if it does
+func CleanRecipients(it Item) Item {
+	if IsNil(it) {
+		return nil
+	}
+	if s, ok := it.(HasRecipients); ok {
+		s.Clean()
+	}
+	return it
+}
+
+// Clean removes Bto and BCC properties
+func (a *Activity) Clean() {
+	_ = OnObject(a, func(o *Object) error {
+		o.Clean()
+		return nil
+	})
+	CleanRecipients(a.Object)
+	CleanRecipients(a.Actor)
+	CleanRecipients(a.Target)
+}
+
+type (
+	// Accept indicates that the actor accepts the object. The target property can be used in certain circumstances to indicate
+	// the context into which the object has been accepted.
+	Accept = Activity
+
+	// Add indicates that the actor has added the object to the target. If the target property is not explicitly specified,
+	// the target would need to be determined implicitly by context.
+	// The origin can be used to identify the context from which the object originated.
+	Add = Activity
+
+	// Announce indicates that the actor is calling the target's attention the object.
+	// The origin typically has no defined meaning.
+	Announce = Activity
+
+	// Block indicates that the actor is blocking the object. Blocking is a stronger form of Ignore.
+	// The typical use is to support social systems that allow one user to block activities or content of other users.
+	// The target and origin typically have no defined meaning.
+	Block = Ignore
+
+	// Create indicates that the actor has created the object.
+	Create = Activity
+
+	// Delete indicates that the actor has deleted the object.
+	// If specified, the origin indicates the context from which the object was deleted.
+	Delete = Activity
+
+	// Dislike indicates that the actor dislikes the object.
+	Dislike = Activity
+
+	// Flag indicates that the actor is "flagging" the object.
+	// Flagging is defined in the sense common to many social platforms as reporting content as being
+	// inappropriate for any number of reasons.
+	Flag = Activity
+
+	// Follow indicates that the actor is "following" the object. Following is defined in the sense typically used within
+	// Social systems in which the actor is interested in any activity performed by or on the object.
+	// The target and origin typically have no defined meaning.
+	Follow = Activity
+
+	// Ignore indicates that the actor is ignoring the object. The target and origin typically have no defined meaning.
+	Ignore = Activity
+
+	// Invite is a specialization of Offer in which the actor is extending an invitation for the object to the target.
+	Invite = Offer
+
+	// Join indicates that the actor has joined the object. The target and origin typically have no defined meaning.
+	Join = Activity
+
+	// Leave indicates that the actor has left the object. The target and origin typically have no meaning.
+	Leave = Activity
+
+	// Like indicates that the actor likes, recommends or endorses the object.
+	// The target and origin typically have no defined meaning.
+	Like = Activity
+
+	// Listen inherits all properties from Activity.
+	Listen = Activity
+
+	// Move indicates that the actor has moved object from origin to target.
+	// If the origin or target are not specified, either can be determined by context.
+	Move = Activity
+
+	// Offer indicates that the actor is offering the object.
+	// If specified, the target indicates the entity to which the object is being offered.
+	Offer = Activity
+
+	// Reject indicates that the actor is rejecting the object. The target and origin typically have no defined meaning.
+	Reject = Activity
+
+	// Read indicates that the actor has read the object.
+	Read = Activity
+
+	// Remove indicates that the actor is removing the object. If specified,
+	// the origin indicates the context from which the object is being removed.
+	Remove = Activity
+
+	// TentativeReject is a specialization of Reject in which the rejection is considered tentative.
+	TentativeReject = Reject
+
+	// TentativeAccept is a specialization of Accept indicating that the acceptance is tentative.
+	TentativeAccept = Accept
+
+	// Undo indicates that the actor is undoing the object. In most cases, the object will be an Activity describing
+	// some previously performed action (for instance, a person may have previously "liked" an article but,
+	// for whatever reason, might choose to undo that like at some later point in time).
+	// The target and origin typically have no defined meaning.
+	Undo = Activity
+
+	// Update indicates that the actor has updated the object. Note, however, that this vocabulary does not define a mechanism
+	// for describing the actual set of modifications made to object.
+	// The target and origin typically have no defined meaning.
+	Update = Activity
+
+	// View indicates that the actor has viewed the object.
+	View = Activity
+)
+
+// AcceptNew initializes an Accept activity
+func AcceptNew(id ID, ob Item) *Accept {
+	a := ActivityNew(id, AcceptType, ob)
+	o := Accept(*a)
+	return &o
+}
+
+// AddNew initializes an Add activity
+func AddNew(id ID, ob, trgt Item) *Add {
+	a := ActivityNew(id, AddType, ob)
+	o := Add(*a)
+	o.Target = trgt
+	return &o
+}
+
+// AnnounceNew initializes an Announce activity
+func AnnounceNew(id ID, ob Item) *Announce {
+	a := ActivityNew(id, AnnounceType, ob)
+	o := Announce(*a)
+	return &o
+}
+
+// BlockNew initializes a Block activity
+func BlockNew(id ID, ob Item) *Block {
+	a := ActivityNew(id, BlockType, ob)
+	o := Block(*a)
+	return &o
+}
+
+// CreateNew initializes a Create activity
+func CreateNew(id ID, ob Item) *Create {
+	a := ActivityNew(id, CreateType, ob)
+	o := Create(*a)
+	return &o
+}
+
+// DeleteNew initializes a Delete activity
+func DeleteNew(id ID, ob Item) *Delete {
+	a := ActivityNew(id, DeleteType, ob)
+	o := Delete(*a)
+	return &o
+}
+
+// DislikeNew initializes a Dislike activity
+func DislikeNew(id ID, ob Item) *Dislike {
+	a := ActivityNew(id, DislikeType, ob)
+	o := Dislike(*a)
+	return &o
+}
+
+// FlagNew initializes a Flag activity
+func FlagNew(id ID, ob Item) *Flag {
+	a := ActivityNew(id, FlagType, ob)
+	o := Flag(*a)
+	return &o
+}
+
+// FollowNew initializes a Follow activity
+func FollowNew(id ID, ob Item) *Follow {
+	a := ActivityNew(id, FollowType, ob)
+	o := Follow(*a)
+	return &o
+}
+
+// IgnoreNew initializes an Ignore activity
+func IgnoreNew(id ID, ob Item) *Ignore {
+	a := ActivityNew(id, IgnoreType, ob)
+	o := Ignore(*a)
+	return &o
+}
+
+// InviteNew initializes an Invite activity
+func InviteNew(id ID, ob Item) *Invite {
+	a := ActivityNew(id, InviteType, ob)
+	o := Invite(*a)
+	return &o
+}
+
+// JoinNew initializes a Join activity
+func JoinNew(id ID, ob Item) *Join {
+	a := ActivityNew(id, JoinType, ob)
+	o := Join(*a)
+	return &o
+}
+
+// LeaveNew initializes a Leave activity
+func LeaveNew(id ID, ob Item) *Leave {
+	a := ActivityNew(id, LeaveType, ob)
+	o := Leave(*a)
+	return &o
+}
+
+// LikeNew initializes a Like activity
+func LikeNew(id ID, ob Item) *Like {
+	a := ActivityNew(id, LikeType, ob)
+	o := Like(*a)
+	return &o
+}
+
+// ListenNew initializes a Listen activity
+func ListenNew(id ID, ob Item) *Listen {
+	a := ActivityNew(id, ListenType, ob)
+	o := Listen(*a)
+	return &o
+}
+
+// MoveNew initializes a Move activity
+func MoveNew(id ID, ob Item) *Move {
+	a := ActivityNew(id, MoveType, ob)
+	o := Move(*a)
+	return &o
+}
+
+// OfferNew initializes an Offer activity
+func OfferNew(id ID, ob Item) *Offer {
+	a := ActivityNew(id, OfferType, ob)
+	o := Offer(*a)
+	return &o
+}
+
+// RejectNew initializes a Reject activity
+func RejectNew(id ID, ob Item) *Reject {
+	a := ActivityNew(id, RejectType, ob)
+	o := Reject(*a)
+	return &o
+}
+
+// ReadNew initializes a Read activity
+func ReadNew(id ID, ob Item) *Read {
+	a := ActivityNew(id, ReadType, ob)
+	o := Read(*a)
+	return &o
+}
+
+// RemoveNew initializes a Remove activity
+func RemoveNew(id ID, ob, trgt Item) *Remove {
+	a := ActivityNew(id, RemoveType, ob)
+	o := Remove(*a)
+	o.Target = trgt
+	return &o
+}
+
+// TentativeRejectNew initializes a TentativeReject activity
+func TentativeRejectNew(id ID, ob Item) *TentativeReject {
+	a := ActivityNew(id, TentativeRejectType, ob)
+	o := TentativeReject(*a)
+	return &o
+}
+
+// TentativeAcceptNew initializes a TentativeAccept activity
+func TentativeAcceptNew(id ID, ob Item) *TentativeAccept {
+	a := ActivityNew(id, TentativeAcceptType, ob)
+	o := TentativeAccept(*a)
+	return &o
+}
+
+// UndoNew initializes an Undo activity
+func UndoNew(id ID, ob Item) *Undo {
+	a := ActivityNew(id, UndoType, ob)
+	o := Undo(*a)
+	return &o
+}
+
+// UpdateNew initializes an Update activity
+func UpdateNew(id ID, ob Item) *Update {
+	a := ActivityNew(id, UpdateType, ob)
+	u := Update(*a)
+	return &u
+}
+
+// ViewNew initializes a View activity
+func ViewNew(id ID, ob Item) *View {
+	a := ActivityNew(id, ViewType, ob)
+	o := View(*a)
+	return &o
+}
+
+// ActivityNew initializes a basic activity
+func ActivityNew(id ID, typ ActivityVocabularyType, ob Item) *Activity {
+	if !ActivityTypes.Contains(typ) {
+		typ = ActivityType
+	}
+	a := Activity{ID: id, Type: typ}
+	a.Name = NaturalLanguageValuesNew()
+	a.Content = NaturalLanguageValuesNew()
+
+	a.Object = ob
+
+	return &a
+}
+
+// UnmarshalJSON decodes an incoming JSON document into the receiver object.
+func (a *Activity) UnmarshalJSON(data []byte) error {
+	p := fastjson.Parser{}
+	val, err := p.ParseBytes(data)
+	if err != nil {
+		return err
+	}
+	return JSONLoadActivity(val, a)
+}
+
+func fmtActivityProps(w io.Writer) func(*Activity) error {
+	return func(a *Activity) error {
+		if !IsNil(a.Object) {
+			_, _ = fmt.Fprintf(w, " object: %s", a.Object)
+		}
+		return OnIntransitiveActivity(a, fmtIntransitiveActivityProps(w))
+	}
+}
+
+func (a Activity) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 's':
+		if a.Type != "" && a.ID != "" {
+			_, _ = fmt.Fprintf(s, "%T[%s]( %s )", a, a.Type, a.ID)
+		} else if a.ID != "" {
+			_, _ = fmt.Fprintf(s, "%T( %s )", a, a.ID)
+		} else {
+			_, _ = fmt.Fprintf(s, "%T[%p]", a, &a)
+		}
+	case 'v':
+		_, _ = fmt.Fprintf(s, "%T[%s] {", a, a.Type)
+		fmtActivityProps(s)(&a)
+		_, _ = io.WriteString(s, " }")
+	}
+}
+
+// ToActivity
+func ToActivity(it Item) (*Activity, error) {
+	switch i := it.(type) {
+	case *Activity:
+		return i, nil
+	case Activity:
+		return &i, nil
+	default:
+		// NOTE(marius): this is an ugly way of dealing with the interface conversion error: types from different scopes
+		typ := reflect.TypeOf(new(Activity))
+		if reflect.TypeOf(it).ConvertibleTo(typ) {
+			if i, ok := reflect.ValueOf(it).Convert(typ).Interface().(*Activity); ok {
+				return i, nil
+			}
+		}
+	}
+	return nil, ErrorInvalidType[Activity](it)
+}
+
+// MarshalJSON encodes the receiver object to a JSON document.
+func (a Activity) MarshalJSON() ([]byte, error) {
+	b := make([]byte, 0)
+	JSONWrite(&b, '{')
+
+	if !JSONWriteActivityValue(&b, a) {
+		return nil, nil
+	}
+	JSONWrite(&b, '}')
+	return b, nil
+}
+
+// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
+func (a *Activity) UnmarshalBinary(data []byte) error {
+	return a.GobDecode(data)
+}
+
+// MarshalBinary implements the encoding.BinaryMarshaler interface.
+func (a Activity) MarshalBinary() ([]byte, error) {
+	return a.GobEncode()
+}
+
+func mapIntransitiveActivityProperties(mm map[string][]byte, a *IntransitiveActivity) (hasData bool, err error) {
+	err = OnObject(a, func(o *Object) error {
+		hasData, err = mapObjectProperties(mm, o)
+		return err
+	})
+	if a.Actor != nil {
+		if mm["actor"], err = gobEncodeItem(a.Actor); err != nil {
+			return hasData, err
+		}
+		hasData = true
+	}
+	if a.Target != nil {
+		if mm["target"], err = gobEncodeItem(a.Target); err != nil {
+			return hasData, err
+		}
+		hasData = true
+	}
+	if a.Result != nil {
+		if mm["result"], err = gobEncodeItem(a.Result); err != nil {
+			return hasData, err
+		}
+		hasData = true
+	}
+	if a.Instrument != nil {
+		if mm["instrument"], err = gobEncodeItem(a.Instrument); err != nil {
+			return hasData, err
+		}
+		hasData = true
+	}
+	return hasData, err
+}
+
+func mapActivityProperties(mm map[string][]byte, a *Activity) (hasData bool, err error) {
+	err = OnIntransitiveActivity(a, func(a *IntransitiveActivity) error {
+		hasData, err = mapIntransitiveActivityProperties(mm, a)
+		return err
+	})
+	if a.Object != nil {
+		if mm["object"], err = gobEncodeItem(a.Object); err != nil {
+			return hasData, err
+		}
+		hasData = true
+	}
+	return hasData, err
+}
+
+// GobEncode
+func (a Activity) GobEncode() ([]byte, error) {
+	mm := make(map[string][]byte)
+	hasData, err := mapActivityProperties(mm, &a)
+	if err != nil {
+		return nil, err
+	}
+	if !hasData {
+		return []byte{}, nil
+	}
+	bb := bytes.Buffer{}
+	g := gob.NewEncoder(&bb)
+	if err := g.Encode(mm); err != nil {
+		return nil, err
+	}
+	return bb.Bytes(), nil
+}
+
+// GobDecode
+func (a *Activity) GobDecode(data []byte) error {
+	if len(data) == 0 {
+		return nil
+	}
+	mm, err := gobDecodeObjectAsMap(data)
+	if err != nil {
+		return err
+	}
+	return unmapActivityProperties(mm, a)
+}
+
+// Equals verifies if our receiver Object is equals with the "with" Object
+func (a Activity) Equals(with Item) bool {
+	result := true
+	err := OnActivity(with, func(w *Activity) error {
+		_ = OnIntransitiveActivity(a, func(oi *IntransitiveActivity) error {
+			result = oi.Equals(w)
+			return nil
+		})
+		if w.Object != nil {
+			if !ItemsEqual(a.Object, w.Object) {
+				result = false
+				return nil
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		result = false
+	}
+	return result
+}