Transient model for federated unstar (#6740)

This is the first step to https://codeberg.org/forgejo-contrib/federation/src/branch/main/FederationRoadmap.md#federated-unstar-wip

Co-authored-by: Michael Jerger <michael.jerger@meissa-gmbh.de>
Co-authored-by: ansgarz <ansgar.zwick@meissa.de>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/6740
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Mirco <mirco.zachmann@meissa.de>
Co-committed-by: Mirco <mirco.zachmann@meissa.de>

modules/forgefed/activity_undo_like.go

@@ -0,0 +1,80 @@
+// Copyright 2023, 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package forgefed
+
+import (
+	"time"
+
+	"code.gitea.io/gitea/modules/validation"
+
+	ap "github.com/go-ap/activitypub"
+)
+
+// ForgeLike activity data type
+// swagger:model
+type ForgeUndoLike struct {
+	// swagger:ignore
+	ap.Activity
+}
+
+func NewForgeUndoLike(actorIRI, objectIRI string, startTime time.Time) (ForgeUndoLike, error) {
+	result := ForgeUndoLike{}
+	result.Type = ap.UndoType
+	result.Actor = ap.IRI(actorIRI)
+	result.StartTime = startTime
+
+	like := ap.Activity{}
+	like.Type = ap.LikeType
+	like.Actor = ap.IRI(actorIRI)
+	like.Object = ap.IRI(objectIRI)
+	result.Object = &like
+
+	if valid, err := validation.IsValid(result); !valid {
+		return ForgeUndoLike{}, err
+	}
+	return result, nil
+}
+
+func (undo *ForgeUndoLike) UnmarshalJSON(data []byte) error {
+	return undo.Activity.UnmarshalJSON(data)
+}
+
+func (undo ForgeUndoLike) Validate() []string {
+	var result []string
+	result = append(result, validation.ValidateNotEmpty(string(undo.Type), "type")...)
+	result = append(result, validation.ValidateOneOf(string(undo.Type), []any{"Undo"}, "type")...)
+
+	if undo.Actor == nil {
+		result = append(result, "Actor should not be nil.")
+	} else {
+		result = append(result, validation.ValidateNotEmpty(undo.Actor.GetID().String(), "actor")...)
+	}
+
+	result = append(result, validation.ValidateNotEmpty(undo.StartTime.String(), "startTime")...)
+	if undo.StartTime.IsZero() {
+		result = append(result, "StartTime was invalid.")
+	}
+
+	if undo.Object == nil {
+		result = append(result, "object should not be empty.")
+	} else if activity, ok := undo.Object.(*ap.Activity); !ok {
+		result = append(result, "object is not of type Activity")
+	} else {
+		result = append(result, validation.ValidateNotEmpty(string(activity.Type), "type")...)
+		result = append(result, validation.ValidateOneOf(string(activity.Type), []any{"Like"}, "type")...)
+
+		if activity.Actor == nil {
+			result = append(result, "Object.Actor should not be nil.")
+		} else {
+			result = append(result, validation.ValidateNotEmpty(activity.Actor.GetID().String(), "actor")...)
+		}
+
+		if activity.Object == nil {
+			result = append(result, "Object.Object should not be nil.")
+		} else {
+			result = append(result, validation.ValidateNotEmpty(activity.Object.GetID().String(), "object")...)
+		}
+	}
+	return result
+}