[feature] Option to hide followers/following (#2788)

internal/processing/account/relationships.go

@@ -31,11 +31,25 @@ import (
 // FollowersGet fetches a list of the target account's followers.
 func (p *Processor) FollowersGet(ctx context.Context, requestingAccount *gtsmodel.Account, targetAccountID string, page *paging.Page) (*apimodel.PageableResponse, gtserror.WithCode) {
 	// Fetch target account to check it exists, and visibility of requester->target.
-	_, errWithCode := p.c.GetVisibleTargetAccount(ctx, requestingAccount, targetAccountID)
+	targetAccount, errWithCode := p.c.GetVisibleTargetAccount(ctx, requestingAccount, targetAccountID)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
+	if targetAccount.IsInstance() {
+		// Instance accounts can't follow/be followed.
+		return paging.EmptyResponse(), nil
+	}
+
+	// If account isn't requesting its own followers list,
+	// but instead the list for a local account that has
+	// hide_followers set, just return an empty array.
+	if targetAccountID != requestingAccount.ID &&
+		targetAccount.IsLocal() &&
+		*targetAccount.Settings.HideCollections {
+		return paging.EmptyResponse(), nil
+	}
+
 	follows, err := p.state.DB.GetAccountFollowers(ctx, targetAccountID, page)
 	if err != nil && !errors.Is(err, db.ErrNoEntries) {
 		err = gtserror.Newf("db error getting followers: %w", err)
@@ -76,11 +90,25 @@ func (p *Processor) FollowersGet(ctx context.Context, requestingAccount *gtsmode
 // FollowingGet fetches a list of the accounts that target account is following.
 func (p *Processor) FollowingGet(ctx context.Context, requestingAccount *gtsmodel.Account, targetAccountID string, page *paging.Page) (*apimodel.PageableResponse, gtserror.WithCode) {
 	// Fetch target account to check it exists, and visibility of requester->target.
-	_, errWithCode := p.c.GetVisibleTargetAccount(ctx, requestingAccount, targetAccountID)
+	targetAccount, errWithCode := p.c.GetVisibleTargetAccount(ctx, requestingAccount, targetAccountID)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
+	if targetAccount.IsInstance() {
+		// Instance accounts can't follow/be followed.
+		return paging.EmptyResponse(), nil
+	}
+
+	// If account isn't requesting its own following list,
+	// but instead the list for a local account that has
+	// hide_followers set, just return an empty array.
+	if targetAccountID != requestingAccount.ID &&
+		targetAccount.IsLocal() &&
+		*targetAccount.Settings.HideCollections {
+		return paging.EmptyResponse(), nil
+	}
+
 	// Fetch known accounts that follow given target account ID.
 	follows, err := p.state.DB.GetAccountFollows(ctx, targetAccountID, page)
 	if err != nil && !errors.Is(err, db.ErrNoEntries) {

internal/processing/account/update.go

@@ -284,6 +284,10 @@ func (p *Processor) Update(ctx context.Context, account *gtsmodel.Account, form
 		account.Settings.EnableRSS = form.EnableRSS
 	}
 
+	if form.HideCollections != nil {
+		account.Settings.HideCollections = form.HideCollections
+	}
+
 	if err := p.state.DB.UpdateAccount(ctx, account); err != nil {
 		return nil, gtserror.NewErrorInternalError(fmt.Errorf("could not update account %s: %s", account.ID, err))
 	}

internal/processing/fedi/collections.go

@@ -140,15 +140,25 @@ func (p *Processor) FollowersGet(ctx context.Context, requestedUser string, page
 	params.ID = collectionID
 	params.Total = total
 
-	if page == nil {
+	switch {
+
+	case receiver.IsInstance() ||
+		*receiver.Settings.HideCollections:
+		// Instance account (can't follow/be followed),
+		// or an account that hides followers/following.
+		// Respect this by just returning totalItems.
+		obj = ap.NewASOrderedCollection(params)
+
+	case page == nil:
 		// i.e. paging disabled, return collection
 		// that links to first page (i.e. path below).
+		params.First = new(paging.Page)
 		params.Query = make(url.Values, 1)
 		params.Query.Set("limit", "40") // enables paging
 		obj = ap.NewASOrderedCollection(params)
-	} else {
-		// i.e. paging enabled
 
+	default:
+		// i.e. paging enabled
 		// Get the request page of full follower objects with attached accounts.
 		followers, err := p.state.DB.GetAccountFollowers(ctx, receiver.ID, page)
 		if err != nil {
@@ -239,15 +249,24 @@ func (p *Processor) FollowingGet(ctx context.Context, requestedUser string, page
 	params.ID = collectionID
 	params.Total = total
 
-	if page == nil {
+	switch {
+	case receiver.IsInstance() ||
+		*receiver.Settings.HideCollections:
+		// Instance account (can't follow/be followed),
+		// or an account that hides followers/following.
+		// Respect this by just returning totalItems.
+		obj = ap.NewASOrderedCollection(params)
+
+	case page == nil:
 		// i.e. paging disabled, return collection
 		// that links to first page (i.e. path below).
+		params.First = new(paging.Page)
 		params.Query = make(url.Values, 1)
 		params.Query.Set("limit", "40") // enables paging
 		obj = ap.NewASOrderedCollection(params)
-	} else {
-		// i.e. paging enabled
 
+	default:
+		// i.e. paging enabled
 		// Get the request page of full follower objects with attached accounts.
 		follows, err := p.state.DB.GetAccountFollows(ctx, receiver.ID, page)
 		if err != nil {

internal/processing/fedi/status.go

@@ -156,6 +156,7 @@ func (p *Processor) StatusRepliesGet(
 	if page == nil {
 		// i.e. paging disabled, return collection
 		// that links to first page (i.e. path below).
+		params.First = new(paging.Page)
 		params.Query = make(url.Values, 1)
 		params.Query.Set("limit", "20") // enables paging
 		obj = ap.NewASOrderedCollection(params)