// Copyright (C) 2010 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.query.change;

import static com.google.common.base.Preconditions.checkState;
import static com.google.gerrit.server.query.change.ChangeQueryBuilder.FIELD_LIMIT;
import static java.util.concurrent.TimeUnit.MINUTES;

import com.google.common.collect.ImmutableListMultimap;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.extensions.common.PluginDefinedInfo;
import com.google.gerrit.extensions.registration.DynamicMap;
import com.google.gerrit.index.IndexConfig;
import com.google.gerrit.index.QueryOptions;
import com.google.gerrit.index.query.IndexPredicate;
import com.google.gerrit.index.query.Predicate;
import com.google.gerrit.index.query.QueryProcessor;
import com.google.gerrit.metrics.MetricMaker;
import com.google.gerrit.server.AnonymousUser;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.DynamicOptions;
import com.google.gerrit.server.DynamicOptions.DynamicBean;
import com.google.gerrit.server.account.AccountLimits;
import com.google.gerrit.server.index.change.ChangeIndexCollection;
import com.google.gerrit.server.index.change.ChangeIndexRewriter;
import com.google.gerrit.server.index.change.ChangeSchemaDefinitions;
import com.google.gerrit.server.index.change.IndexedChangeQuery;
import com.google.gerrit.server.notedb.ChangeNotes;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.project.ProjectCache;
import com.google.inject.Inject;
import com.google.inject.Provider;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Query processor for the change index.
 *
 * <p>Instances are one-time-use. Other singleton classes should inject a Provider rather than
 * holding on to a single instance.
 */
public class ChangeQueryProcessor extends QueryProcessor<ChangeData>
    implements DynamicOptions.BeanReceiver, PluginDefinedAttributesFactory {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  /**
   * Register a ChangeAttributeFactory in a config Module like this:
   *
   * <p>bind(ChangeAttributeFactory.class) .annotatedWith(Exports.named("export-name"))
   * .to(YourClass.class);
   */
  public interface ChangeAttributeFactory {
    PluginDefinedInfo create(ChangeData a, ChangeQueryProcessor qp, String plugin);
  }

  private final Provider<CurrentUser> userProvider;
  private final ChangeNotes.Factory notesFactory;
  private final ImmutableListMultimap<String, ChangeAttributeFactory> attributeFactoriesByPlugin;
  private final PermissionBackend permissionBackend;
  private final ProjectCache projectCache;
  private final Provider<AnonymousUser> anonymousUserProvider;
  private final Map<String, DynamicBean> dynamicBeans = new HashMap<>();

  static {
    // It is assumed that basic rewrites do not touch visibleto predicates.
    checkState(
        !ChangeIsVisibleToPredicate.class.isAssignableFrom(IndexPredicate.class),
        "ChangeQueryProcessor assumes visibleto is not used by the index rewriter.");
  }

  @Inject
  ChangeQueryProcessor(
      Provider<CurrentUser> userProvider,
      AccountLimits.Factory limitsFactory,
      MetricMaker metricMaker,
      IndexConfig indexConfig,
      ChangeIndexCollection indexes,
      ChangeIndexRewriter rewriter,
      ChangeNotes.Factory notesFactory,
      DynamicMap<ChangeAttributeFactory> attributeFactories,
      PermissionBackend permissionBackend,
      ProjectCache projectCache,
      Provider<AnonymousUser> anonymousUserProvider) {
    super(
        metricMaker,
        ChangeSchemaDefinitions.INSTANCE,
        indexConfig,
        indexes,
        rewriter,
        FIELD_LIMIT,
        () -> limitsFactory.create(userProvider.get()).getQueryLimit());
    this.userProvider = userProvider;
    this.notesFactory = notesFactory;
    this.permissionBackend = permissionBackend;
    this.projectCache = projectCache;
    this.anonymousUserProvider = anonymousUserProvider;

    ImmutableListMultimap.Builder<String, ChangeAttributeFactory> factoriesBuilder =
        ImmutableListMultimap.builder();
    // Eagerly call Extension#get() rather than storing Extensions, since that method invokes the
    // Provider on every call, which could be expensive if we invoke it once for every change.
    attributeFactories.forEach(e -> factoriesBuilder.put(e.getPluginName(), e.get()));
    attributeFactoriesByPlugin = factoriesBuilder.build();
  }

  @Override
  public ChangeQueryProcessor enforceVisibility(boolean enforce) {
    super.enforceVisibility(enforce);
    return this;
  }

  @Override
  protected QueryOptions createOptions(
      IndexConfig indexConfig, int start, int limit, Set<String> requestedFields) {
    return IndexedChangeQuery.createOptions(indexConfig, start, limit, requestedFields);
  }

  @Override
  public void setDynamicBean(String plugin, DynamicBean dynamicBean) {
    dynamicBeans.put(plugin, dynamicBean);
  }

  public DynamicBean getDynamicBean(String plugin) {
    return dynamicBeans.get(plugin);
  }

  @Override
  public List<PluginDefinedInfo> create(ChangeData cd) {
    List<PluginDefinedInfo> plugins = new ArrayList<>(attributeFactoriesByPlugin.size());
    for (Map.Entry<String, ChangeAttributeFactory> e : attributeFactoriesByPlugin.entries()) {
      String plugin = e.getKey();
      PluginDefinedInfo pda = null;
      try {
        pda = e.getValue().create(cd, this, plugin);
      } catch (RuntimeException ex) {
        // Log once a minute, to avoid spamming logs with one stack trace per change.
        logger.atWarning().atMostEvery(1, MINUTES).withCause(ex).log(
            "error populating attribute on change %s from plugin %s", cd.getId(), plugin);
      }
      if (pda != null) {
        pda.name = plugin;
        plugins.add(pda);
      }
    }
    if (plugins.isEmpty()) {
      plugins = null;
    }
    return plugins;
  }

  @Override
  protected Predicate<ChangeData> enforceVisibility(Predicate<ChangeData> pred) {
    return new AndChangeSource(
        pred,
        new ChangeIsVisibleToPredicate(
            notesFactory,
            userProvider.get(),
            permissionBackend,
            projectCache,
            anonymousUserProvider),
        start);
  }

  @Override
  protected String formatForLogging(ChangeData changeData) {
    return changeData.getId().toString();
  }
}