[feature] Account alias / move API + db models (#2518)

* [feature] Account alias / move API + db models

* go fmt

* fix little cherry-pick issues

* update error checking, formatting

* add and use new util functions to simplify alias logic

internal/processing/account/move.go

@@ -0,0 +1,153 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package account
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/url"
+	"slices"
+
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"golang.org/x/crypto/bcrypt"
+)
+
+func (p *Processor) MoveSelf(
+	ctx context.Context,
+	authed *oauth.Auth,
+	form *apimodel.AccountMoveRequest,
+) gtserror.WithCode {
+	// Ensure valid MovedToURI.
+	if form.MovedToURI == "" {
+		err := errors.New("no moved_to_uri provided in account Move request")
+		return gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	movedToURI, err := url.Parse(form.MovedToURI)
+	if err != nil {
+		err := fmt.Errorf("invalid moved_to_uri provided in account Move request: %w", err)
+		return gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	if movedToURI.Scheme != "https" && movedToURI.Scheme != "http" {
+		err := errors.New("invalid moved_to_uri provided in account Move request: uri scheme must be http or https")
+		return gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	// Self account Move requires password to ensure it's for real.
+	if form.Password == "" {
+		err := errors.New("no password provided in account Move request")
+		return gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	if err := bcrypt.CompareHashAndPassword(
+		[]byte(authed.User.EncryptedPassword),
+		[]byte(form.Password),
+	); err != nil {
+		err := errors.New("invalid password provided in account Move request")
+		return gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	var (
+		// Current account from which
+		// the move is taking place.
+		account = authed.Account
+
+		// Target account to which
+		// the move is taking place.
+		targetAccount *gtsmodel.Account
+	)
+
+	switch {
+	case account.MovedToURI == "":
+		// No problemo.
+
+	case account.MovedToURI == form.MovedToURI:
+		// Trying to move again to the same
+		// destination, perhaps to reprocess
+		// side effects. This is OK.
+		log.Info(ctx,
+			"reprocessing Move side effects from %s to %s",
+			account.URI, form.MovedToURI,
+		)
+
+	default:
+		// Account already moved, and now
+		// trying to move somewhere else.
+		err := fmt.Errorf(
+			"account %s is already Moved to %s, cannot also Move to %s",
+			account.URI, account.MovedToURI, form.MovedToURI,
+		)
+		return gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	// Ensure we have a valid, up-to-date representation of the target account.
+	targetAccount, _, err = p.federator.GetAccountByURI(ctx, account.Username, movedToURI)
+	if err != nil {
+		err := fmt.Errorf("error dereferencing moved_to_uri account: %w", err)
+		return gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	if !targetAccount.SuspendedAt.IsZero() {
+		err := fmt.Errorf(
+			"target account %s is suspended from this instance; "+
+				"you will not be able to Move to that account",
+			targetAccount.URI,
+		)
+		return gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	// Target account MUST be aliased to this
+	// account for this to be a valid Move.
+	if !slices.Contains(targetAccount.AlsoKnownAsURIs, account.URI) {
+		err := fmt.Errorf(
+			"target account %s is not aliased to this account via alsoKnownAs; "+
+				"if you just changed it, wait five minutes and try the Move again",
+			targetAccount.URI,
+		)
+		return gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	// Target account cannot itself have
+	// already Moved somewhere else.
+	if targetAccount.MovedToURI != "" {
+		err := fmt.Errorf(
+			"target account %s has already Moved somewhere else (%s); "+
+				"you will not be able to Move to that account",
+			targetAccount.URI, targetAccount.MovedToURI,
+		)
+		return gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	// Everything seems OK, so process the Move.
+	p.state.Workers.EnqueueClientAPI(ctx, messages.FromClientAPI{
+		APObjectType:   ap.ActorPerson,
+		APActivityType: ap.ActivityMove,
+		OriginAccount:  account,
+		TargetAccount:  targetAccount,
+	})
+
+	return nil
+}