// Copyright (C) 2016 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.index.account;

import static com.google.gerrit.server.git.QueueProvider.QueueType.BATCH;

import com.google.common.base.Stopwatch;
import com.google.common.flogger.FluentLogger;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.gerrit.entities.Account;
import com.google.gerrit.index.SiteIndexer;
import com.google.gerrit.server.account.AccountCache;
import com.google.gerrit.server.account.AccountState;
import com.google.gerrit.server.account.Accounts;
import com.google.gerrit.server.index.IndexExecutor;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import org.eclipse.jgit.lib.ProgressMonitor;
import org.eclipse.jgit.lib.TextProgressMonitor;

/**
 * Implementation that can index all accounts on a host. Used by Gerrit's initialization and upgrade
 * programs as well as by REST API endpoints that offer this functionality.
 */
@Singleton
public class AllAccountsIndexer extends SiteIndexer<Account.Id, AccountState, AccountIndex> {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final ListeningExecutorService executor;
  private final Accounts accounts;
  private final AccountCache accountCache;

  @Inject
  AllAccountsIndexer(
      @IndexExecutor(BATCH) ListeningExecutorService executor,
      Accounts accounts,
      AccountCache accountCache) {
    this.executor = executor;
    this.accounts = accounts;
    this.accountCache = accountCache;
  }

  @Override
  public SiteIndexer.Result indexAll(AccountIndex index) {
    ProgressMonitor progress = new TextProgressMonitor(newPrintWriter(progressOut));
    progress.start(2);
    Stopwatch sw = Stopwatch.createStarted();
    List<Account.Id> ids;
    try {
      ids = collectAccounts(progress);
    } catch (IOException e) {
      logger.atSevere().withCause(e).log("Error collecting accounts");
      return SiteIndexer.Result.create(sw, false, 0, 0);
    }
    return reindexAccounts(index, ids, progress);
  }

  private SiteIndexer.Result reindexAccounts(
      AccountIndex index, List<Account.Id> ids, ProgressMonitor progress) {
    progress.beginTask("Reindexing accounts", ids.size());
    List<ListenableFuture<?>> futures = new ArrayList<>(ids.size());
    AtomicBoolean ok = new AtomicBoolean(true);
    AtomicInteger done = new AtomicInteger();
    AtomicInteger failed = new AtomicInteger();
    Stopwatch sw = Stopwatch.createStarted();
    for (Account.Id id : ids) {
      String desc = "account " + id;
      ListenableFuture<?> future =
          executor.submit(
              () -> {
                try {
                  Optional<AccountState> a = accountCache.get(id);
                  if (a.isPresent()) {
                    index.replace(a.get());
                  } else {
                    index.delete(id);
                  }
                  verboseWriter.println("Reindexed " + desc);
                  done.incrementAndGet();
                } catch (Exception e) {
                  failed.incrementAndGet();
                  throw e;
                }
                return null;
              });
      addErrorListener(future, desc, progress, ok);
      futures.add(future);
    }

    try {
      Futures.successfulAsList(futures).get();
    } catch (ExecutionException | InterruptedException e) {
      logger.atSevere().withCause(e).log("Error waiting on account futures");
      return SiteIndexer.Result.create(sw, false, 0, 0);
    }

    progress.endTask();
    return SiteIndexer.Result.create(sw, ok.get(), done.get(), failed.get());
  }

  private List<Account.Id> collectAccounts(ProgressMonitor progress) throws IOException {
    progress.beginTask("Collecting accounts", ProgressMonitor.UNKNOWN);
    List<Account.Id> ids = new ArrayList<>();
    for (Account.Id accountId : accounts.allIds()) {
      ids.add(accountId);
      progress.update(1);
    }
    progress.endTask();
    return ids;
  }
}