feat(platform): align account user membership

internal/repository/account_repo.go

@@ -100,6 +100,46 @@ func (r *AccountRepo) AddUserToAccount(ctx context.Context, accountID, userID ui
 	return r.db.WithContext(ctx).Create(&au).Error
 }
 
+// UpsertAccountUser creates or updates an AccountUser membership.
+// Reference: Chatwoot Platform::Api::V1::AccountUsersController#create uses
+// account.account_users.find_or_initialize_by(user_id: ...).update!(params).
+func (r *AccountRepo) UpsertAccountUser(ctx context.Context, accountID, userID uint, role *string) (*model.AccountUser, error) {
+	var au model.AccountUser
+	err := r.db.WithContext(ctx).
+		Where("account_id = ? AND user_id = ?", accountID, userID).
+		First(&au).Error
+	if err != nil && err != gorm.ErrRecordNotFound {
+		return nil, err
+	}
+
+	if err == gorm.ErrRecordNotFound {
+		au = model.AccountUser{
+			AccountID:    accountID,
+			UserID:       userID,
+			Role:         "agent",
+			Availability: "offline",
+			AutoOffline:  true,
+		}
+	}
+	if role != nil && *role != "" {
+		au.Role = *role
+	}
+
+	if err == gorm.ErrRecordNotFound {
+		if err := r.db.WithContext(ctx).Create(&au).Error; err != nil {
+			return nil, err
+		}
+		return &au, nil
+	}
+
+	if role != nil {
+		if err := r.db.WithContext(ctx).Model(&au).Update("role", au.Role).Error; err != nil {
+			return nil, err
+		}
+	}
+	return &au, nil
+}
+
 // RemoveUserFromAccount deletes an AccountUser association.
 func (r *AccountRepo) RemoveUserFromAccount(ctx context.Context, accountID, userID uint) error {
 	return r.db.WithContext(ctx).Exec(
@@ -171,4 +211,4 @@ func (r *AccountRepo) FindAccountUserByUserAndAccount(ctx context.Context, accou
 		return nil, err
 	}
 	return &au, nil
-}
+}