/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.keycloak.protocol.oidc.mappers;

import org.keycloak.models.GroupModel;
import org.keycloak.models.ProtocolMapperModel;
import org.keycloak.models.RoleModel;
import org.keycloak.models.UserModel;
import org.keycloak.models.UserSessionModel;
import org.keycloak.models.utils.RoleUtils;
import org.keycloak.representations.IDToken;

import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Base class for mapping of user role mappings to an ID and Access Token claim.
 *
 * @author <a href="mailto:thomas.darimont@gmail.com">Thomas Darimont</a>
 */
abstract class AbstractUserRoleMappingMapper extends AbstractOIDCProtocolMapper implements OIDCAccessTokenMapper, OIDCIDTokenMapper, UserInfoTokenMapper {

    /**
     * Returns a stream with roles that come from:
     * <ul>
     * <li>Direct assignment of the role to the user</li>
     * <li>Direct assignment of the role to any group of the user or any of its parent group</li>
     * <li>Composite roles are expanded recursively, the composite role itself is also contained in the returned stream</li>
     * </ul>
     * @param user User to enumerate the roles for
     * @return
     */
    public static Stream<RoleModel> getAllUserRolesStream(UserModel user) {
        return Stream.concat(
          user.getRoleMappings().stream(),
          user.getGroups().stream()
            .flatMap(g -> groupAndItsParentsStream(g))
            .flatMap(g -> g.getRoleMappings().stream()))
          .flatMap(RoleUtils::expandCompositeRolesStream);
    }

    /**
     * Returns stream of the given group and its parents (recursively).
     * @param group
     * @return
     */
    private static Stream<GroupModel> groupAndItsParentsStream(GroupModel group) {
        Stream.Builder<GroupModel> sb = Stream.builder();
        while (group != null) {
            sb.add(group);
            group = group.getParent();
        }
        return sb.build();
    }

    /**
     * Retrieves all roles of the current user based on direct roles set to the user, its groups and their parent groups.
     * Then it recursively expands all composite roles, and restricts according to the given predicate {@code restriction}.
     * If the current client sessions is restricted (i.e. no client found in active user session has full scope allowed),
     * the final list of roles is also restricted by the client scope. Finally, the list is mapped to the token into
     * a claim.
     *
     * @param token
     * @param mappingModel
     * @param userSession
     * @param restriction
     * @param prefix
     */
    protected static void setClaim(IDToken token, ProtocolMapperModel mappingModel, UserSessionModel userSession,
      Predicate<RoleModel> restriction, String prefix) {
        String rolePrefix = prefix == null ? "" : prefix;
        UserModel user = userSession.getUser();

        // get a set of all realm roles assigned to the user or its group
        Stream<RoleModel> clientUserRoles = getAllUserRolesStream(user).filter(restriction);

        boolean dontLimitScope = userSession.getClientSessions().stream().anyMatch(cs -> cs.getClient().isFullScopeAllowed());
        if (! dontLimitScope) {
            Set<RoleModel> clientRoles = userSession.getClientSessions().stream()
              .flatMap(cs -> cs.getClient().getScopeMappings().stream())
              .collect(Collectors.toSet());

            clientUserRoles = clientUserRoles.filter(clientRoles::contains);
        }

        Set<String> realmRoleNames = clientUserRoles
          .map(m -> rolePrefix + m.getName())
          .collect(Collectors.toSet());

        OIDCAttributeMapperHelper.mapClaim(token, mappingModel, realmRoleNames);
    }
}
