// Copyright (C) 2012 The Android Open Source Project
//
// 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 com.google.gerrit.server.account;

import com.google.gerrit.reviewdb.client.AccountGroup;

import java.util.Collections;
import java.util.Set;

/**
 * Implementations of GroupMembership provide methods to test
 * the presence of a user in a particular group.
 */
public interface GroupMembership {
  GroupMembership EMPTY =
      new ListGroupMembership(Collections.<AccountGroup.UUID>emptySet());

  /**
   * Returns {@code true} when the user this object was created for is a member
   * of the specified group.
   */
  boolean contains(AccountGroup.UUID groupId);

  /**
   * Returns {@code true} when the user this object was created for is a member
   * of any of the specified group.
   */
  boolean containsAnyOf(Iterable<AccountGroup.UUID> groupIds);

  /**
   * Returns a set containing an input member of {@code contains(id)} is true.
   * <p>
   * This is batch form of contains that returns specific group information.
   * Implementors may implement the method as:
   *
   * <pre>
   * Set&lt;AccountGroup.UUID&gt; r = new HashSet&lt;&gt;();
   * for (AccountGroup.UUID id : groupIds)
   *   if (contains(id)) r.add(id);
   * </pre>
   */
  Set<AccountGroup.UUID> intersection(Iterable<AccountGroup.UUID> groupIds);

  /**
   * Returns the set of groups that can be determined by the implementation.
   * This may not return all groups the {@link #contains(AccountGroup.UUID)}
   * would return {@code true} for, but will at least contain all top level
   * groups. This restriction stems from the API of some group systems, which
   * make it expensive to enumerate the members of a group.
   */
  Set<AccountGroup.UUID> getKnownGroups();
}