Alterations for Social Linking

SocialLinkModel socialLink = new SocialLinkModel(provider.getId(), socialUser.getId(), socialUser.getUsername());
UserModel user = realm.getUserBySocialLink(socialLink);

// Check if user is already authenticated (this means linking social into existing user account)
String userId = requestData.getClientAttribute("userId");
if (userId != null) {
    UserModel authenticatedUser = realm.getUserById(userId);

    audit.event(EventType.SOCIAL_LINK).user(userId);

    if (user != null) {
        audit.error(Errors.SOCIAL_ID_IN_USE);
        return oauth.forwardToSecurityFailure("This social account is already linked to other user");
    }

    if (!authenticatedUser.isEnabled()) {
        audit.error(Errors.USER_DISABLED);
        return oauth.forwardToSecurityFailure("User is disabled");
    }

    if (!realm.hasRole(authenticatedUser, realm.getApplicationByName(Constants.ACCOUNT_MANAGEMENT_APP).getRole(AccountRoles.MANAGE_ACCOUNT))) {
        audit.error(Errors.NOT_ALLOWED);
        return oauth.forwardToSecurityFailure("Insufficient permissions to link social account");
    }

    if (redirectUri == null) {
        audit.error(Errors.INVALID_REDIRECT_URI);
        return oauth.forwardToSecurityFailure("Unknown redirectUri");
    }

    realm.addSocialLink(authenticatedUser, socialLink);
    logger.debug("Social provider " + provider.getId() + " linked with user " + authenticatedUser.getLoginName());

    audit.success();
    return Response.status(302).location(UriBuilder.fromUri(redirectUri).build()).build();
}

    /* ALTERATIONS BEGIN HERE */

    user = realm.getUserByEmail(socialUser.getEmail());
    // Unauthenticated user and inexistent socialLink. Try to find an existing user by email
    if (user != null) {
        if (!user.isEnabled()) {
            audit.error(Errors.USER_DISABLED);
            return oauth.forwardToSecurityFailure("User is disabled");
        }

        if (!realm.hasRole(user, realm.getApplicationByName(Constants.ACCOUNT_MANAGEMENT_APP).getRole(AccountRoles.MANAGE_ACCOUNT))) {
            audit.error(Errors.NOT_ALLOWED);
            return oauth.forwardToSecurityFailure("Insufficient permissions to link social account");
        }

        realm.addSocialLink(user, socialLink);
        logger.debug("Social provider " + provider.getId() + " linked with unauthenticated user " + user.getLoginName());
    }

    /* ALTERATIONS END HERE */

    if (user == null) {

        if (!realm.isRegistrationAllowed()) {
            audit.error(Errors.REGISTRATION_DISABLED);
            return oauth.forwardToSecurityFailure("Registration not allowed");
        }

        user = realm.addUser(KeycloakModelUtils.generateId());
        user.setEnabled(true);
        user.setFirstName(socialUser.getFirstName());
        user.setLastName(socialUser.getLastName());
        user.setEmail(socialUser.getEmail());

        if (realm.isUpdateProfileOnInitialSocialLogin()) {
            user.addRequiredAction(UserModel.RequiredAction.UPDATE_PROFILE);
        }

        realm.addSocialLink(user, socialLink);

        audit.clone().user(user).event(EventType.REGISTER)
            .detail(Details.REGISTER_METHOD, "social@" + provider.getId())
            .detail(Details.EMAIL, socialUser.getEmail())
            .removeDetail("auth_method")
            .success();
    }

    // Rest of the implementation