Refactor: Email verification (#84393)

* Update template names

* Add verifier that we can use to start verify process

* Use userVerifier when verifying email on update

* Add tests
---------

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

pkg/services/user/userimpl/verifier.go

@@ -0,0 +1,82 @@
+package userimpl
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/grafana/grafana/pkg/services/notifications"
+	tempuser "github.com/grafana/grafana/pkg/services/temp_user"
+	"github.com/grafana/grafana/pkg/services/user"
+	"github.com/grafana/grafana/pkg/util"
+)
+
+var _ user.Verifier = (*Verifier)(nil)
+
+func ProvideVerifier(us user.Service, ts tempuser.Service, ns notifications.Service) *Verifier {
+	return &Verifier{us, ts, ns}
+}
+
+type Verifier struct {
+	us user.Service
+	ts tempuser.Service
+	ns notifications.Service
+}
+
+func (s *Verifier) VerifyEmail(ctx context.Context, cmd user.VerifyEmailCommand) error {
+	usr, err := s.us.GetByLogin(ctx, &user.GetUserByLoginQuery{
+		LoginOrEmail: cmd.Email,
+	})
+
+	if err != nil && !errors.Is(err, user.ErrUserNotFound) {
+		return err
+	}
+
+	// if email is already used by another user we stop here
+	if usr != nil && usr.ID != cmd.User.ID {
+		return user.ErrEmailConflict.Errorf("email already used")
+	}
+
+	code, err := util.GetRandomString(20)
+	if err != nil {
+		return fmt.Errorf("failed to generate verification code: %w", err)
+	}
+
+	// invalidate any pending verifications for user
+	if err = s.ts.ExpirePreviousVerifications(
+		ctx, &tempuser.ExpirePreviousVerificationsCommand{InvitedByUserID: cmd.User.ID},
+	); err != nil {
+		return fmt.Errorf("failed to expire previous verifications: %w", err)
+	}
+
+	tmpUsr, err := s.ts.CreateTempUser(ctx, &tempuser.CreateTempUserCommand{
+		OrgID: -1,
+		// used to determine if the user was updating their email or username in the second step of the verification flow
+		Name: string(cmd.Action),
+		// used to fetch the User in the second step of the verification flow
+		InvitedByUserID: cmd.User.ID,
+		Email:           cmd.Email,
+		Code:            code,
+		Status:          tempuser.TmpUserEmailUpdateStarted,
+	})
+
+	if err != nil {
+		return fmt.Errorf("failed to generate temp user for email verification: %w", err)
+	}
+
+	if err := s.ns.SendVerificationEmail(ctx, &notifications.SendVerifyEmailCommand{
+		User:  &cmd.User,
+		Code:  tmpUsr.Code,
+		Email: cmd.Email,
+	}); err != nil {
+		return fmt.Errorf("failed to send verification email: %w", err)
+	}
+
+	if err := s.ts.UpdateTempUserWithEmailSent(ctx, &tempuser.UpdateTempUserWithEmailSentCommand{
+		Code: tmpUsr.Code,
+	}); err != nil {
+		return fmt.Errorf("failed to mark email as sent: %w", err)
+	}
+
+	return nil
+}