From f133e9ca11a233d4284eff885dbe153cb620b77d Mon Sep 17 00:00:00 2001
From: Anthony Wang <a@exozy.me>
Date: Fri, 21 Oct 2022 21:06:59 +0000
Subject: [PATCH] Implement sending follow activities

I moved around a lot of files to fix import cycles
---
 modules/activitypub/comment.go                |  2 +-
 modules/activitypub/follow.go                 |  8 +--
 modules/activitypub/fork.go                   |  4 +-
 modules/activitypub/iri.go                    | 12 ++---
 modules/activitypub/pull_request.go           |  2 +-
 modules/activitypub/repo.go                   |  5 +-
 modules/activitypub/star.go                   |  4 +-
 routers/api/v1/activitypub/reqsignature.go    |  3 +-
 routers/api/v1/user/follower.go               |  5 +-
 .../web}/authorize_interaction.go             | 16 +++---
 routers/web/user/profile.go                   |  5 +-
 routers/web/web.go                            |  3 +-
 .../user.go => services/user/activitypub.go   | 50 +++++++++++++++++--
 13 files changed, 81 insertions(+), 38 deletions(-)
 rename {modules/activitypub => routers/web}/authorize_interaction.go (78%)
 rename modules/activitypub/user.go => services/user/activitypub.go (55%)

diff --git a/modules/activitypub/comment.go b/modules/activitypub/comment.go
index b5ea350347..7e36bed764 100644
--- a/modules/activitypub/comment.go
+++ b/modules/activitypub/comment.go
@@ -17,7 +17,7 @@ import (
 
 // Create a comment
 func Comment(ctx context.Context, note *ap.Note) error {
-	actorUser, err := personIRIToUser(ctx, note.AttributedTo.GetLink())
+	actorUser, err := PersonIRIToUser(ctx, note.AttributedTo.GetLink())
 	if err != nil {
 		return err
 	}
diff --git a/modules/activitypub/follow.go b/modules/activitypub/follow.go
index 9db9e534cd..a36404810a 100644
--- a/modules/activitypub/follow.go
+++ b/modules/activitypub/follow.go
@@ -17,14 +17,14 @@ import (
 func Follow(ctx context.Context, follow ap.Follow) error {
 	// Actor is the user performing the follow
 	actorIRI := follow.Actor.GetLink()
-	actorUser, err := personIRIToUser(ctx, actorIRI)
+	actorUser, err := PersonIRIToUser(ctx, actorIRI)
 	if err != nil {
 		return err
 	}
 
 	// Object is the user being followed
 	objectIRI := follow.Object.GetLink()
-	objectUser, err := personIRIToUser(ctx, objectIRI)
+	objectUser, err := PersonIRIToUser(ctx, objectIRI)
 	// Must be a local user
 	if err != nil || strings.Contains(objectUser.Name, "@") {
 		return err
@@ -48,14 +48,14 @@ func Unfollow(ctx context.Context, unfollow ap.Undo) error {
 	follow := unfollow.Object.(*ap.Follow)
 	// Actor is the user performing the undo follow
 	actorIRI := follow.Actor.GetLink()
-	actorUser, err := personIRIToUser(ctx, actorIRI)
+	actorUser, err := PersonIRIToUser(ctx, actorIRI)
 	if err != nil {
 		return err
 	}
 
 	// Object is the user being unfollowed
 	objectIRI := follow.Object.GetLink()
-	objectUser, err := personIRIToUser(ctx, objectIRI)
+	objectUser, err := PersonIRIToUser(ctx, objectIRI)
 	// Must be a local user
 	if err != nil || strings.Contains(objectUser.Name, "@") {
 		return err
diff --git a/modules/activitypub/fork.go b/modules/activitypub/fork.go
index 1868c05233..bf41a342a4 100644
--- a/modules/activitypub/fork.go
+++ b/modules/activitypub/fork.go
@@ -52,7 +52,7 @@ func ReceiveFork(ctx context.Context, create ap.Create) error {
 
 	repository := create.Object.(*forgefed.Repository)
 
-	actor, err := personIRIToUser(ctx, create.Actor.GetLink())
+	actor, err := PersonIRIToUser(ctx, create.Actor.GetLink())
 	if err != nil {
 		return err
 	}
@@ -62,7 +62,7 @@ func ReceiveFork(ctx context.Context, create ap.Create) error {
 
 	// Create the fork
 	repoIRI := repository.GetLink()
-	username, reponame, err := repositoryIRIToName(repoIRI)
+	username, reponame, err := RepositoryIRIToName(repoIRI)
 	if err != nil {
 		return err
 	}
diff --git a/modules/activitypub/iri.go b/modules/activitypub/iri.go
index 235545cd20..b546202c27 100644
--- a/modules/activitypub/iri.go
+++ b/modules/activitypub/iri.go
@@ -17,7 +17,7 @@ import (
 )
 
 // Returns the username corresponding to a Person actor IRI
-func personIRIToName(personIRI ap.IRI) (string, error) {
+func PersonIRIToName(personIRI ap.IRI) (string, error) {
 	personIRISplit := strings.Split(personIRI.String(), "/")
 	if len(personIRISplit) < 3 {
 		return "", errors.New("Not a Person actor IRI")
@@ -35,8 +35,8 @@ func personIRIToName(personIRI ap.IRI) (string, error) {
 }
 
 // Returns the user corresponding to a Person actor IRI
-func personIRIToUser(ctx context.Context, personIRI ap.IRI) (*user_model.User, error) {
-	name, err := personIRIToName(personIRI)
+func PersonIRIToUser(ctx context.Context, personIRI ap.IRI) (*user_model.User, error) {
+	name, err := PersonIRIToName(personIRI)
 	if err != nil {
 		return nil, err
 	}
@@ -50,7 +50,7 @@ func personIRIToUser(ctx context.Context, personIRI ap.IRI) (*user_model.User, e
 }
 
 // Returns the owner and name corresponding to a Repository actor IRI
-func repositoryIRIToName(repoIRI ap.IRI) (string, string, error) {
+func RepositoryIRIToName(repoIRI ap.IRI) (string, string, error) {
 	repoIRISplit := strings.Split(repoIRI.String(), "/")
 	if len(repoIRISplit) < 5 {
 		return "", "", errors.New("Not a Repository actor IRI")
@@ -68,8 +68,8 @@ func repositoryIRIToName(repoIRI ap.IRI) (string, string, error) {
 }
 
 // Returns the repository corresponding to a Repository actor IRI
-func repositoryIRIToRepository(ctx context.Context, repoIRI ap.IRI) (*repo_model.Repository, error) {
-	username, reponame, err := repositoryIRIToName(repoIRI)
+func RepositoryIRIToRepository(ctx context.Context, repoIRI ap.IRI) (*repo_model.Repository, error) {
+	username, reponame, err := RepositoryIRIToName(repoIRI)
 	if err != nil {
 		return nil, err
 	}
diff --git a/modules/activitypub/pull_request.go b/modules/activitypub/pull_request.go
index 3ed766a282..c6e86c482b 100644
--- a/modules/activitypub/pull_request.go
+++ b/modules/activitypub/pull_request.go
@@ -18,7 +18,7 @@ import (
 func PullRequest(ctx context.Context, ticket *forgefed.Ticket) error {
 	// TODO: Clean this up
 
-	actorUser, err := personIRIToUser(ctx, ticket.AttributedTo.GetLink())
+	actorUser, err := PersonIRIToUser(ctx, ticket.AttributedTo.GetLink())
 	if err != nil {
 		log.Warn("Couldn't find ticket actor user", err)
 	}
diff --git a/modules/activitypub/repo.go b/modules/activitypub/repo.go
index cf6f7bf7ce..98b5ab4f7e 100644
--- a/modules/activitypub/repo.go
+++ b/modules/activitypub/repo.go
@@ -16,7 +16,7 @@ import (
 // Create a new federated repo from a Repository object
 func FederatedRepoNew(ctx context.Context, repository *forgefed.Repository) error {
 	ownerIRI := repository.AttributedTo.GetLink()
-	user, err := personIRIToUser(ctx, ownerIRI)
+	user, err := PersonIRIToUser(ctx, ownerIRI)
 	if err != nil {
 		return err
 	}
@@ -25,7 +25,6 @@ func FederatedRepoNew(ctx context.Context, repository *forgefed.Repository) erro
 	if err == nil {
 		return nil
 	}
-	
 
 	repo, err := repo_service.CreateRepository(user, user, repo_module.CreateRepoOptions{
 		Name: repository.Name.String(),
@@ -36,7 +35,7 @@ func FederatedRepoNew(ctx context.Context, repository *forgefed.Repository) erro
 
 	if repository.ForkedFrom != nil {
 		repo.IsFork = true
-		forkedFrom, err := repositoryIRIToRepository(ctx, repository.ForkedFrom.GetLink())
+		forkedFrom, err := RepositoryIRIToRepository(ctx, repository.ForkedFrom.GetLink())
 		if err != nil {
 			return err
 		}
diff --git a/modules/activitypub/star.go b/modules/activitypub/star.go
index 67f16b38b4..3b85ca5a1f 100644
--- a/modules/activitypub/star.go
+++ b/modules/activitypub/star.go
@@ -15,11 +15,11 @@ import (
 
 // Process a Like activity to star a repository
 func ReceiveStar(ctx context.Context, like ap.Like) (err error) {
-	user, err := personIRIToUser(ctx, like.Actor.GetLink())
+	user, err := PersonIRIToUser(ctx, like.Actor.GetLink())
 	if err != nil {
 		return
 	}
-	repo, err := repositoryIRIToRepository(ctx, like.Object.GetLink())
+	repo, err := RepositoryIRIToRepository(ctx, like.Object.GetLink())
 	if err != nil || strings.Contains(repo.Name, "@") || repo.IsPrivate {
 		return
 	}
diff --git a/routers/api/v1/activitypub/reqsignature.go b/routers/api/v1/activitypub/reqsignature.go
index 16731c485a..555e060ade 100644
--- a/routers/api/v1/activitypub/reqsignature.go
+++ b/routers/api/v1/activitypub/reqsignature.go
@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/modules/activitypub"
 	gitea_context "code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/setting"
+	user_service "code.gitea.io/gitea/services/user"
 
 	ap "github.com/go-ap/activitypub"
 	"github.com/go-fed/httpsig"
@@ -84,7 +85,7 @@ func verifyHTTPSignatures(ctx *gitea_context.APIContext) (authenticated bool, er
 		return
 	}
 
-	err = activitypub.FederatedUserNew(ctx, &person)
+	err = user_service.FederatedUserNew(ctx, &person)
 	return authenticated, err
 }
 
diff --git a/routers/api/v1/user/follower.go b/routers/api/v1/user/follower.go
index 22f8f40e1c..f0109d7d6e 100644
--- a/routers/api/v1/user/follower.go
+++ b/routers/api/v1/user/follower.go
@@ -13,6 +13,7 @@ import (
 	"code.gitea.io/gitea/modules/convert"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/routers/api/v1/utils"
+	user_service "code.gitea.io/gitea/services/user"
 )
 
 func responseAPIUsers(ctx *context.APIContext, users []*user_model.User) {
@@ -219,7 +220,7 @@ func Follow(ctx *context.APIContext) {
 	//   "204":
 	//     "$ref": "#/responses/empty"
 
-	if err := user_model.FollowUser(ctx.Doer.ID, ctx.ContextUser.ID); err != nil {
+	if err := user_service.FollowUser(ctx.Doer.ID, ctx.ContextUser.ID); err != nil {
 		ctx.Error(http.StatusInternalServerError, "FollowUser", err)
 		return
 	}
@@ -241,7 +242,7 @@ func Unfollow(ctx *context.APIContext) {
 	//   "204":
 	//     "$ref": "#/responses/empty"
 
-	if err := user_model.UnfollowUser(ctx.Doer.ID, ctx.ContextUser.ID); err != nil {
+	if err := user_service.UnfollowUser(ctx.Doer.ID, ctx.ContextUser.ID); err != nil {
 		ctx.Error(http.StatusInternalServerError, "UnfollowUser", err)
 		return
 	}
diff --git a/modules/activitypub/authorize_interaction.go b/routers/web/authorize_interaction.go
similarity index 78%
rename from modules/activitypub/authorize_interaction.go
rename to routers/web/authorize_interaction.go
index c982ce05ad..3679adef8a 100644
--- a/modules/activitypub/authorize_interaction.go
+++ b/routers/web/authorize_interaction.go
@@ -2,14 +2,16 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
-package activitypub
+package web
 
 import (
 	"net/http"
 	"net/url"
 
+	"code.gitea.io/gitea/modules/activitypub"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/forgefed"
+	user_service "code.gitea.io/gitea/services/user"
 
 	ap "github.com/go-ap/activitypub"
 )
@@ -20,7 +22,7 @@ func AuthorizeInteraction(ctx *context.Context) {
 		ctx.ServerError("Could not parse URI", err)
 		return
 	}
-	resp, err := Fetch(uri)
+	resp, err := activitypub.Fetch(uri)
 	if err != nil {
 		ctx.ServerError("Fetch", err)
 		return
@@ -40,12 +42,12 @@ func AuthorizeInteraction(ctx *context.Context) {
 			ctx.ServerError("UnmarshalJSON", err)
 			return
 		}
-		err = FederatedUserNew(ctx, object.(*ap.Person))
+		err = user_service.FederatedUserNew(ctx, object.(*ap.Person))
 		if err != nil {
 			ctx.ServerError("FederatedUserNew", err)
 			return
 		}
-		name, err := personIRIToName(object.GetLink())
+		name, err := activitypub.PersonIRIToName(object.GetLink())
 		if err != nil {
 			ctx.ServerError("personIRIToName", err)
 			return
@@ -53,13 +55,13 @@ func AuthorizeInteraction(ctx *context.Context) {
 		ctx.Redirect(name)
 	case forgefed.RepositoryType:
 		err = forgefed.OnRepository(object, func(r *forgefed.Repository) error {
-			return FederatedRepoNew(ctx, r)
+			return activitypub.FederatedRepoNew(ctx, r)
 		})
 		if err != nil {
 			ctx.ServerError("FederatedRepoNew", err)
 			return
 		}
-		username, reponame, err := repositoryIRIToName(object.GetLink())
+		username, reponame, err := activitypub.RepositoryIRIToName(object.GetLink())
 		if err != nil {
 			ctx.ServerError("repositoryIRIToName", err)
 			return
@@ -67,7 +69,7 @@ func AuthorizeInteraction(ctx *context.Context) {
 		ctx.Redirect(username + "/" + reponame)
 	case forgefed.TicketType:
 		err = forgefed.OnTicket(object, func(t *forgefed.Ticket) error {
-			return ReceiveIssue(ctx, t)
+			return activitypub.ReceiveIssue(ctx, t)
 		})
 		if err != nil {
 			ctx.ServerError("ReceiveIssue", err)
diff --git a/routers/web/user/profile.go b/routers/web/user/profile.go
index 6e16b377db..bc56407e55 100644
--- a/routers/web/user/profile.go
+++ b/routers/web/user/profile.go
@@ -23,6 +23,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/routers/web/feed"
 	"code.gitea.io/gitea/routers/web/org"
+	user_service "code.gitea.io/gitea/services/user"
 )
 
 // Profile render user's profile page
@@ -302,9 +303,9 @@ func Action(ctx *context.Context) {
 	var err error
 	switch ctx.FormString("action") {
 	case "follow":
-		err = user_model.FollowUser(ctx.Doer.ID, ctx.ContextUser.ID)
+		err = user_service.FollowUser(ctx.Doer.ID, ctx.ContextUser.ID)
 	case "unfollow":
-		err = user_model.UnfollowUser(ctx.Doer.ID, ctx.ContextUser.ID)
+		err = user_service.UnfollowUser(ctx.Doer.ID, ctx.ContextUser.ID)
 	}
 
 	if err != nil {
diff --git a/routers/web/web.go b/routers/web/web.go
index c741b4b602..1b0d0ec1a4 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -12,7 +12,6 @@ import (
 
 	"code.gitea.io/gitea/models/perm"
 	"code.gitea.io/gitea/models/unit"
-	"code.gitea.io/gitea/modules/activitypub"
 	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/git"
@@ -1317,7 +1316,7 @@ func RegisterRoutes(m *web.Route) {
 	}, reqSignIn)
 
 	if setting.Federation.Enabled {
-		m.Get("/authorize_interaction", activitypub.AuthorizeInteraction)
+		m.Get("/authorize_interaction", AuthorizeInteraction)
 	}
 
 	if setting.API.EnableSwagger {
diff --git a/modules/activitypub/user.go b/services/user/activitypub.go
similarity index 55%
rename from modules/activitypub/user.go
rename to services/user/activitypub.go
index 89732044ca..e1c95b5675 100644
--- a/modules/activitypub/user.go
+++ b/services/user/activitypub.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
-package activitypub
+package user
 
 import (
 	"context"
@@ -11,15 +11,55 @@ import (
 
 	"code.gitea.io/gitea/models/auth"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/activitypub"
 	"code.gitea.io/gitea/modules/setting"
-	user_service "code.gitea.io/gitea/services/user"
 
 	ap "github.com/go-ap/activitypub"
 )
 
+// FollowUser marks someone be another's follower.
+func FollowUser(userID, followID int64) (err error) {
+	if userID == followID || user_model.IsFollowing(userID, followID) {
+		return nil
+	}
+	
+	followUser, err := user_model.GetUserByID(followID)
+	if err != nil {
+		return err
+	}
+	if followUser.LoginType == auth.Federated {
+		// Following remote user
+		actorUser, err := user_model.GetUserByID(userID)
+		if err != nil {
+			return err
+		}
+
+		object := ap.PersonNew(ap.IRI(followUser.LoginName))
+		follow := ap.FollowNew("", object)
+		follow.Type = ap.FollowType
+		follow.Actor = ap.PersonNew(ap.IRI(setting.AppURL+"api/v1/activitypub/user/"+actorUser.Name))
+		follow.To = ap.ItemCollection{ap.Item(ap.IRI(followUser.LoginName+"/inbox"))}
+		err = activitypub.Send(actorUser, follow)
+		if err != nil {
+			return err
+		}
+	}
+
+	return user_model.FollowUser(userID, followID)
+}
+
+// UnfollowUser unmarks someone as another's follower.
+func UnfollowUser(userID, followID int64) (err error) {
+	if userID == followID || !user_model.IsFollowing(userID, followID) {
+		return nil
+	}
+	
+	return user_model.UnfollowUser(userID, followID)
+}
+
 // Create a new federated user from a Person object
 func FederatedUserNew(ctx context.Context, person *ap.Person) error {
-	name, err := personIRIToName(person.GetLink())
+	name, err := activitypub.PersonIRIToName(person.GetLink())
 	if err != nil {
 		return err
 	}
@@ -63,12 +103,12 @@ func FederatedUserNew(ctx context.Context, person *ap.Person) error {
 			return err
 		}
 
-		body, err := Fetch(iconURL)
+		body, err := activitypub.Fetch(iconURL)
 		if err != nil {
 			return err
 		}
 
-		err = user_service.UploadAvatar(user, body)
+		err = UploadAvatar(user, body)
 		if err != nil {
 			return err
 		}