// Copyright (C) 2017 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.pgm.init;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.entities.Account;
import com.google.gerrit.entities.AccountGroup;
import com.google.gerrit.entities.GroupReference;
import com.google.gerrit.entities.InternalGroup;
import com.google.gerrit.exceptions.NoSuchGroupException;
import com.google.gerrit.pgm.init.api.AllUsersNameOnInitProvider;
import com.google.gerrit.pgm.init.api.InitFlags;
import com.google.gerrit.server.GerritPersonIdentProvider;
import com.google.gerrit.server.config.AllUsersName;
import com.google.gerrit.server.config.GerritServerIdProvider;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
import com.google.gerrit.server.git.meta.MetaDataUpdate;
import com.google.gerrit.server.group.db.AuditLogFormatter;
import com.google.gerrit.server.group.db.GroupConfig;
import com.google.gerrit.server.group.db.GroupDelta;
import com.google.gerrit.server.group.db.GroupNameNotes;
import com.google.inject.Inject;
import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import java.time.Instant;
import java.util.stream.Stream;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.internal.storage.file.FileRepository;
import org.eclipse.jgit.lib.PersonIdent;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.lib.RepositoryCache;
import org.eclipse.jgit.util.FS;

/**
 * A database accessor for calls related to groups.
 *
 * <p>All calls which read or write group related details to the NoteDb <strong>during init</strong>
 * are gathered here. For non-init cases, use {@code Groups} or {@code GroupsUpdate} instead.
 *
 * <p>All methods of this class refer to <em>internal</em> groups.
 */
public class GroupsOnInit {

  private final InitFlags flags;
  private final SitePaths site;
  private final AllUsersName allUsers;

  @Inject
  public GroupsOnInit(InitFlags flags, SitePaths site, AllUsersNameOnInitProvider allUsers) {
    this.flags = flags;
    this.site = site;
    this.allUsers = new AllUsersName(allUsers.get());
  }

  /**
   * Returns the {@code AccountGroup} for the specified {@code GroupReference}.
   *
   * @param groupReference the {@code GroupReference} of the group
   * @return the {@code InternalGroup} represented by the {@code GroupReference}
   * @throws IOException if an error occurs while reading from NoteDb
   * @throws ConfigInvalidException if the data in NoteDb is in an incorrect format
   * @throws NoSuchGroupException if a group with such a name doesn't exist
   */
  public InternalGroup getExistingGroup(GroupReference groupReference)
      throws NoSuchGroupException, IOException, ConfigInvalidException {
    File allUsersRepoPath = getPathToAllUsersRepository();
    if (allUsersRepoPath != null) {
      try (Repository allUsersRepo = new FileRepository(allUsersRepoPath)) {
        AccountGroup.UUID groupUuid = groupReference.getUUID();
        GroupConfig groupConfig = GroupConfig.loadForGroup(allUsers, allUsersRepo, groupUuid);
        return groupConfig
            .getLoadedGroup()
            .orElseThrow(() -> new NoSuchGroupException(groupReference.getUUID()));
      }
    }
    throw new NoSuchGroupException(groupReference.getUUID());
  }

  /**
   * Returns {@code GroupReference}s for all internal groups.
   *
   * @return a stream of the {@code GroupReference}s of all internal groups
   * @throws IOException if an error occurs while reading from NoteDb
   * @throws ConfigInvalidException if the data in NoteDb is in an incorrect format
   */
  public Stream<GroupReference> getAllGroupReferences() throws IOException, ConfigInvalidException {
    File allUsersRepoPath = getPathToAllUsersRepository();
    if (allUsersRepoPath != null) {
      try (Repository allUsersRepo = new FileRepository(allUsersRepoPath)) {
        return GroupNameNotes.loadAllGroups(allUsersRepo).stream();
      }
    }
    return Stream.empty();
  }

  /**
   * Adds an account as member to a group. The account is only added as a new member if it isn't
   * already a member of the group.
   *
   * <p><strong>Note</strong>: This method doesn't check whether the account exists! It also doesn't
   * update the account index!
   *
   * @param groupUuid the UUID of the group
   * @param account the account to add
   * @throws NoSuchGroupException if the specified group doesn't exist
   */
  public void addGroupMember(AccountGroup.UUID groupUuid, Account account)
      throws NoSuchGroupException, IOException, ConfigInvalidException {
    File allUsersRepoPath = getPathToAllUsersRepository();
    if (allUsersRepoPath != null) {
      try (Repository repository = new FileRepository(allUsersRepoPath)) {
        addGroupMemberInNoteDb(repository, groupUuid, account);
      }
    }
  }

  private void addGroupMemberInNoteDb(
      Repository repository, AccountGroup.UUID groupUuid, Account account)
      throws IOException, ConfigInvalidException, NoSuchGroupException {
    GroupConfig groupConfig = GroupConfig.loadForGroup(allUsers, repository, groupUuid);
    InternalGroup group =
        groupConfig.getLoadedGroup().orElseThrow(() -> new NoSuchGroupException(groupUuid));

    GroupDelta groupDelta = getMemberAdditionDelta(account);
    AuditLogFormatter auditLogFormatter = getAuditLogFormatter(account);
    groupConfig.setGroupDelta(groupDelta, auditLogFormatter);

    commit(repository, groupConfig, group.getCreatedOn());
  }

  @Nullable
  private File getPathToAllUsersRepository() {
    Path basePath = site.resolve(flags.cfg.getString("gerrit", null, "basePath"));
    checkArgument(basePath != null, "gerrit.basePath must be configured");
    return RepositoryCache.FileKey.resolve(basePath.resolve(allUsers.get()).toFile(), FS.DETECTED);
  }

  private static GroupDelta getMemberAdditionDelta(Account account) {
    return GroupDelta.builder()
        .setMemberModification(members -> Sets.union(members, ImmutableSet.of(account.id())))
        .build();
  }

  private AuditLogFormatter getAuditLogFormatter(Account account)
      throws IOException, ConfigInvalidException {
    String serverId = new GerritServerIdProvider(flags.cfg, site).get();
    return AuditLogFormatter.createBackedBy(ImmutableSet.of(account), ImmutableSet.of(), serverId);
  }

  private void commit(Repository repository, GroupConfig groupConfig, Instant groupCreatedOn)
      throws IOException {
    PersonIdent personIdent =
        new PersonIdent(new GerritPersonIdentProvider(flags.cfg).get(), groupCreatedOn);
    try (MetaDataUpdate metaDataUpdate = createMetaDataUpdate(repository, personIdent)) {
      groupConfig.commit(metaDataUpdate);
    }
  }

  private MetaDataUpdate createMetaDataUpdate(Repository repository, PersonIdent personIdent) {
    MetaDataUpdate metaDataUpdate =
        new MetaDataUpdate(GitReferenceUpdated.DISABLED, allUsers, repository);
    metaDataUpdate.getCommitBuilder().setAuthor(personIdent);
    metaDataUpdate.getCommitBuilder().setCommitter(personIdent);
    return metaDataUpdate;
  }
}