[feature] Self-serve email change for users (#2957)

* [feature] Email change

* frontend stuff for changing email

* docs

* tests etc

* differentiate more clearly between local user+account and account

* populate user

6 files changed, 342 insertions, 3 deletions

diff --git a/internal/processing/user/create.go b/internal/processing/user/create.go
new file mode 100644
index 000000000..0d848583e
--- /dev/null
+++ b/internal/processing/user/create.go
@@ -0,0 +1,167 @@
+// 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 user
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
+	"github.com/superseriousbusiness/gotosocial/internal/text"
+	"github.com/superseriousbusiness/oauth2/v4"
+)
+
+// Create processes the given form for creating a new user+account.
+//
+// App should be the app used to create the user+account.
+// If nil, the instance app will be used.
+//
+// Precondition: the form's fields should have already been
+// validated and normalized by the caller.
+func (p *Processor) Create(
+	ctx context.Context,
+	app *gtsmodel.Application,
+	form *apimodel.AccountCreateRequest,
+) (*gtsmodel.User, gtserror.WithCode) {
+	const (
+		usersPerDay = 10
+		regBacklog  = 20
+	)
+
+	// Ensure no more than usersPerDay
+	// have registered in the last 24h.
+	newUsersCount, err := p.state.DB.CountApprovedSignupsSince(ctx, time.Now().Add(-24*time.Hour))
+	if err != nil {
+		err := fmt.Errorf("db error counting new users: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	if newUsersCount >= usersPerDay {
+		err := fmt.Errorf("this instance has hit its limit of new sign-ups for today; you can try again tomorrow")
+		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	// Ensure the new users backlog isn't full.
+	backlogLen, err := p.state.DB.CountUnhandledSignups(ctx)
+	if err != nil {
+		err := fmt.Errorf("db error counting registration backlog length: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	if backlogLen >= regBacklog {
+		err := fmt.Errorf("this instance's sign-up backlog is currently full; you must wait until pending sign-ups are handled by the admin(s)")
+		return nil, gtserror.NewErrorUnprocessableEntity(err, err.Error())
+	}
+
+	emailAvailable, err := p.state.DB.IsEmailAvailable(ctx, form.Email)
+	if err != nil {
+		err := fmt.Errorf("db error checking email availability: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if !emailAvailable {
+		err := fmt.Errorf("email address %s is not available", form.Email)
+		return nil, gtserror.NewErrorConflict(err, err.Error())
+	}
+
+	usernameAvailable, err := p.state.DB.IsUsernameAvailable(ctx, form.Username)
+	if err != nil {
+		err := fmt.Errorf("db error checking username availability: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+	if !usernameAvailable {
+		err := fmt.Errorf("username %s is not available", form.Username)
+		return nil, gtserror.NewErrorConflict(err, err.Error())
+	}
+
+	// Only store reason if one is required.
+	var reason string
+	if config.GetAccountsReasonRequired() {
+		reason = form.Reason
+	}
+
+	// Use instance app if no app provided.
+	if app == nil {
+		app, err = p.state.DB.GetInstanceApplication(ctx)
+		if err != nil {
+			err := fmt.Errorf("db error getting instance app: %w", err)
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+	}
+
+	user, err := p.state.DB.NewSignup(ctx, gtsmodel.NewSignup{
+		Username: form.Username,
+		Email:    form.Email,
+		Password: form.Password,
+		Reason:   text.SanitizeToPlaintext(reason),
+		SignUpIP: form.IP,
+		Locale:   form.Locale,
+		AppID:    app.ID,
+	})
+	if err != nil {
+		err := fmt.Errorf("db error creating new signup: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// There are side effects for creating a new user+account
+	// (confirmation emails etc), perform these async.
+	p.state.Workers.Client.Queue.Push(&messages.FromClientAPI{
+		// Use ap.ObjectProfile here to
+		// distinguish this message (user model)
+		// from ap.ActorPerson (account model).
+		APObjectType:   ap.ObjectProfile,
+		APActivityType: ap.ActivityCreate,
+		GTSModel:       user,
+		Origin:         user.Account,
+	})
+
+	return user, nil
+}
+
+// TokenForNewUser generates an OAuth Bearer token
+// for a new user (with account) created by Create().
+func (p *Processor) TokenForNewUser(
+	ctx context.Context,
+	appToken oauth2.TokenInfo,
+	app *gtsmodel.Application,
+	user *gtsmodel.User,
+) (*apimodel.Token, gtserror.WithCode) {
+	// Generate access token.
+	accessToken, err := p.oauthServer.GenerateUserAccessToken(
+		ctx,
+		appToken,
+		app.ClientSecret,
+		user.ID,
+	)
+	if err != nil {
+		err := fmt.Errorf("error creating new access token for user %s: %w", user.ID, err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return &apimodel.Token{
+		AccessToken: accessToken.GetAccess(),
+		TokenType:   "Bearer",
+		Scope:       accessToken.GetScope(),
+		CreatedAt:   accessToken.GetAccessCreateAt().Unix(),
+	}, nil
+}
diff --git a/internal/processing/user/delete.go b/internal/processing/user/delete.go
new file mode 100644
index 000000000..9783010ef
--- /dev/null
+++ b/internal/processing/user/delete.go
@@ -0,0 +1,48 @@
+// 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 user
+
+import (
+	"context"
+
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
+)
+
+// DeleteSelf is like Account.Delete, but specifically
+// for local user+accounts deleting themselves.
+//
+// Calling DeleteSelf results in a delete message being enqueued in the processor,
+// which causes side effects to occur: delete will be federated out to other instances,
+// and the above Delete function will be called afterwards from the processor, to clear
+// out the account's bits and bobs, and stubbify it.
+func (p *Processor) DeleteSelf(ctx context.Context, account *gtsmodel.Account) gtserror.WithCode {
+	// Process the delete side effects asynchronously.
+	p.state.Workers.Client.Queue.Push(&messages.FromClientAPI{
+		// Use ap.ObjectProfile here to
+		// distinguish this message (user model)
+		// from ap.ActorPerson (account model).
+		APObjectType:   ap.ObjectProfile,
+		APActivityType: ap.ActivityDelete,
+		Origin:         account,
+		Target:         account,
+	})
+	return nil
+}
diff --git a/internal/processing/user/email.go b/internal/processing/user/email.go
index 2b27c6c92..ea9dbb64c 100644
--- a/internal/processing/user/email.go
+++ b/internal/processing/user/email.go
@@ -23,11 +23,92 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/superseriousbusiness/gotosocial/internal/ap"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
+	"github.com/superseriousbusiness/gotosocial/internal/validate"
+	"golang.org/x/crypto/bcrypt"
 )
 
+// EmailChange processes an email address change request for the given user.
+func (p *Processor) EmailChange(
+	ctx context.Context,
+	user *gtsmodel.User,
+	password string,
+	newEmail string,
+) (*apimodel.User, gtserror.WithCode) {
+	// Ensure provided password is correct.
+	if err := bcrypt.CompareHashAndPassword([]byte(user.EncryptedPassword), []byte(password)); err != nil {
+		err := gtserror.Newf("%w", err)
+		return nil, gtserror.NewErrorUnauthorized(err, "password was incorrect")
+	}
+
+	// Ensure new email address is valid.
+	if err := validate.Email(newEmail); err != nil {
+		return nil, gtserror.NewErrorBadRequest(err, err.Error())
+	}
+
+	// Ensure new email address is different
+	// from current email address.
+	if newEmail == user.Email {
+		const help = "new email address cannot be the same as current email address"
+		err := gtserror.New(help)
+		return nil, gtserror.NewErrorBadRequest(err, help)
+	}
+
+	if newEmail == user.UnconfirmedEmail {
+		const help = "you already have an email change request pending for given email address"
+		err := gtserror.New(help)
+		return nil, gtserror.NewErrorBadRequest(err, help)
+	}
+
+	// Ensure this address isn't already used by another account.
+	emailAvailable, err := p.state.DB.IsEmailAvailable(ctx, newEmail)
+	if err != nil {
+		err := gtserror.Newf("db error checking email availability: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	if !emailAvailable {
+		const help = "new email address is already in use on this instance"
+		err := gtserror.New(help)
+		return nil, gtserror.NewErrorConflict(err, help)
+	}
+
+	// Set new email address on user.
+	user.UnconfirmedEmail = newEmail
+	if err := p.state.DB.UpdateUser(
+		ctx, user,
+		"unconfirmed_email",
+	); err != nil {
+		err := gtserror.Newf("db error updating user: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Ensure user populated (we need account).
+	if err := p.state.DB.PopulateUser(ctx, user); err != nil {
+		err := gtserror.Newf("db error populating user: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	// Add email sending job to the queue.
+	p.state.Workers.Client.Queue.Push(&messages.FromClientAPI{
+		// Use ap.ObjectProfile here to
+		// distinguish this message (user model)
+		// from ap.ActorPerson (account model).
+		APObjectType:   ap.ObjectProfile,
+		APActivityType: ap.ActivityUpdate,
+		GTSModel:       user,
+		Origin:         user.Account,
+		Target:         user.Account,
+	})
+
+	return p.converter.UserToAPIUser(ctx, user), nil
+}
+
 // EmailGetUserForConfirmToken retrieves the user (with account) from
 // the database for the given "confirm your email" token string.
 func (p *Processor) EmailGetUserForConfirmToken(ctx context.Context, token string) (*gtsmodel.User, gtserror.WithCode) {
diff --git a/internal/processing/user/get.go b/internal/processing/user/get.go
new file mode 100644
index 000000000..9b19189a8
--- /dev/null
+++ b/internal/processing/user/get.go
@@ -0,0 +1,32 @@
+// 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 user
+
+import (
+	"context"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+// Get returns the API model of the given user.
+// Should only be served if user == the user doing the request.
+func (p *Processor) Get(ctx context.Context, user *gtsmodel.User) (*apimodel.User, gtserror.WithCode) {
+	return p.converter.UserToAPIUser(ctx, user), nil
+}
diff --git a/internal/processing/user/user.go b/internal/processing/user/user.go
index 2fbb9c888..cd8ab9900 100644
--- a/internal/processing/user/user.go
+++ b/internal/processing/user/user.go
@@ -19,18 +19,28 @@ package user
 
 import (
 	"github.com/superseriousbusiness/gotosocial/internal/email"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
 )
 
 type Processor struct {
 	state       *state.State
+	converter   *typeutils.Converter
+	oauthServer oauth.Server
 	emailSender email.Sender
 }
 
-// New returns a new user processor
-func New(state *state.State, emailSender email.Sender) Processor {
+// New returns a new user processor.
+func New(
+	state *state.State,
+	converter *typeutils.Converter,
+	oauthServer oauth.Server,
+	emailSender email.Sender,
+) Processor {
 	return Processor{
 		state:       state,
+		converter:   converter,
 		emailSender: emailSender,
 	}
 }
diff --git a/internal/processing/user/user_test.go b/internal/processing/user/user_test.go
index 61e8f8b05..e473c5bb0 100644
--- a/internal/processing/user/user_test.go
+++ b/internal/processing/user/user_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/processing/user"
 	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
 	"github.com/superseriousbusiness/gotosocial/testrig"
 )
 
@@ -53,7 +54,7 @@ func (suite *UserStandardTestSuite) SetupTest() {
 	suite.emailSender = testrig.NewEmailSender("../../../web/template/", suite.sentEmails)
 	suite.testUsers = testrig.NewTestUsers()
 
-	suite.user = user.New(&suite.state, suite.emailSender)
+	suite.user = user.New(&suite.state, typeutils.NewConverter(&suite.state), testrig.NewTestOauthServer(suite.db), suite.emailSender)
 
 	testrig.StandardDBSetup(suite.db, nil)
 }