fix: harden oidc compat email and email bind tx

backend/internal/service/auth_email_binding.go

@@ -6,7 +6,10 @@ import (
 	"fmt"
 	"net/mail"
 	"strings"
+	"time"
 
+	dbent "github.com/Wei-Shaw/sub2api/ent"
+	"github.com/Wei-Shaw/sub2api/ent/authidentity"
 	infraerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
 )
 
@@ -55,6 +58,13 @@ func (s *AuthService) BindEmailIdentity(
 	}
 
 	firstRealEmailBind := !hasBindableEmailIdentitySubject(currentUser.Email)
+	if firstRealEmailBind && s.entClient != nil {
+		if err := s.bindEmailIdentityWithDefaultsTx(ctx, currentUser, normalizedEmail, hashedPassword); err != nil {
+			return nil, err
+		}
+		return currentUser, nil
+	}
+
 	currentUser.Email = normalizedEmail
 	currentUser.PasswordHash = hashedPassword
 	if err := s.userRepo.Update(ctx, currentUser); err != nil {
@@ -126,3 +136,162 @@ func hasBindableEmailIdentitySubject(email string) bool {
 	normalized := strings.ToLower(strings.TrimSpace(email))
 	return normalized != "" && !isReservedEmail(normalized)
 }
+
+func (s *AuthService) bindEmailIdentityWithDefaultsTx(
+	ctx context.Context,
+	currentUser *User,
+	email string,
+	hashedPassword string,
+) error {
+	if tx := dbent.TxFromContext(ctx); tx != nil {
+		return s.bindEmailIdentityWithDefaults(ctx, tx.Client(), currentUser, email, hashedPassword)
+	}
+
+	tx, err := s.entClient.Tx(ctx)
+	if err != nil {
+		return ErrServiceUnavailable
+	}
+	defer func() { _ = tx.Rollback() }()
+
+	txCtx := dbent.NewTxContext(ctx, tx)
+	if err := s.bindEmailIdentityWithDefaults(txCtx, tx.Client(), currentUser, email, hashedPassword); err != nil {
+		return err
+	}
+	if err := tx.Commit(); err != nil {
+		return ErrServiceUnavailable
+	}
+	return nil
+}
+
+func (s *AuthService) bindEmailIdentityWithDefaults(
+	ctx context.Context,
+	client *dbent.Client,
+	currentUser *User,
+	email string,
+	hashedPassword string,
+) error {
+	if client == nil || currentUser == nil || currentUser.ID <= 0 {
+		return ErrServiceUnavailable
+	}
+
+	oldEmail := currentUser.Email
+	if _, err := client.User.UpdateOneID(currentUser.ID).
+		SetEmail(email).
+		SetPasswordHash(hashedPassword).
+		Save(ctx); err != nil {
+		if dbent.IsConstraintError(err) {
+			return ErrEmailExists
+		}
+		return ErrServiceUnavailable
+	}
+
+	if err := replaceBoundEmailAuthIdentityWithClient(ctx, client, currentUser.ID, oldEmail, email, "auth_service_email_bind"); err != nil {
+		if errors.Is(err, ErrEmailExists) {
+			return ErrEmailExists
+		}
+		return ErrServiceUnavailable
+	}
+
+	if err := s.ApplyProviderDefaultSettingsOnFirstBind(ctx, currentUser.ID, "email"); err != nil {
+		return fmt.Errorf("apply email first bind defaults: %w", err)
+	}
+
+	updatedUser, err := client.User.Get(ctx, currentUser.ID)
+	if err != nil {
+		return ErrServiceUnavailable
+	}
+	currentUser.Email = updatedUser.Email
+	currentUser.PasswordHash = updatedUser.PasswordHash
+	currentUser.Balance = updatedUser.Balance
+	currentUser.Concurrency = updatedUser.Concurrency
+	currentUser.UpdatedAt = updatedUser.UpdatedAt
+	return nil
+}
+
+func replaceBoundEmailAuthIdentityWithClient(
+	ctx context.Context,
+	client *dbent.Client,
+	userID int64,
+	oldEmail string,
+	newEmail string,
+	source string,
+) error {
+	newSubject := normalizeBoundEmailAuthIdentitySubject(newEmail)
+	if err := ensureBoundEmailAuthIdentityWithClient(ctx, client, userID, newSubject, source); err != nil {
+		return err
+	}
+
+	oldSubject := normalizeBoundEmailAuthIdentitySubject(oldEmail)
+	if oldSubject == "" || oldSubject == newSubject {
+		return nil
+	}
+
+	_, err := client.AuthIdentity.Delete().
+		Where(
+			authidentity.UserIDEQ(userID),
+			authidentity.ProviderTypeEQ("email"),
+			authidentity.ProviderKeyEQ("email"),
+			authidentity.ProviderSubjectEQ(oldSubject),
+		).
+		Exec(ctx)
+	return err
+}
+
+func ensureBoundEmailAuthIdentityWithClient(
+	ctx context.Context,
+	client *dbent.Client,
+	userID int64,
+	subject string,
+	source string,
+) error {
+	if client == nil || userID <= 0 || subject == "" {
+		return nil
+	}
+
+	if strings.TrimSpace(source) == "" {
+		source = "auth_service_email_bind"
+	}
+
+	if err := client.AuthIdentity.Create().
+		SetUserID(userID).
+		SetProviderType("email").
+		SetProviderKey("email").
+		SetProviderSubject(subject).
+		SetVerifiedAt(time.Now().UTC()).
+		SetMetadata(map[string]any{"source": strings.TrimSpace(source)}).
+		OnConflictColumns(
+			authidentity.FieldProviderType,
+			authidentity.FieldProviderKey,
+			authidentity.FieldProviderSubject,
+		).
+		DoNothing().
+		Exec(ctx); err != nil {
+		return err
+	}
+
+	identity, err := client.AuthIdentity.Query().
+		Where(
+			authidentity.ProviderTypeEQ("email"),
+			authidentity.ProviderKeyEQ("email"),
+			authidentity.ProviderSubjectEQ(subject),
+		).
+		Only(ctx)
+	if err != nil {
+		if dbent.IsNotFound(err) {
+			return nil
+		}
+		return err
+	}
+	if identity.UserID != userID {
+		return ErrEmailExists
+	}
+	return nil
+}
+
+func normalizeBoundEmailAuthIdentitySubject(email string) string {
+	normalized := strings.ToLower(strings.TrimSpace(email))
+	if normalized == "" || isReservedEmail(normalized) {
+		return ""
+	}
+	return normalized
+}