// Copyright (C) 2009 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.gerrit.reviewdb.client.Change.CHANGE_ID_PATTERN;
import static com.google.gerrit.server.query.change.ChangeData.asChanges;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.primitives.Ints;
import com.google.gerrit.common.data.GroupReference;
import com.google.gerrit.common.errors.NotSignedInException;
import com.google.gerrit.extensions.common.AccountInfo;
import com.google.gerrit.extensions.registration.DynamicMap;
import com.google.gerrit.reviewdb.client.Account;
import com.google.gerrit.reviewdb.client.AccountGroup;
import com.google.gerrit.reviewdb.client.Branch;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.PatchLineCommentsUtil;
import com.google.gerrit.server.StarredChangesUtil;
import com.google.gerrit.server.account.AccountCache;
import com.google.gerrit.server.account.AccountResolver;
import com.google.gerrit.server.account.CapabilityControl;
import com.google.gerrit.server.account.GroupBackend;
import com.google.gerrit.server.account.GroupBackends;
import com.google.gerrit.server.account.VersionedAccountDestinations;
import com.google.gerrit.server.account.VersionedAccountQueries;
import com.google.gerrit.server.change.ChangeTriplet;
import com.google.gerrit.server.config.AllProjectsName;
import com.google.gerrit.server.config.AllUsersName;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.TrackingFooters;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.git.strategy.SubmitDryRun;
import com.google.gerrit.server.group.ListMembers;
import com.google.gerrit.server.index.FieldDef;
import com.google.gerrit.server.index.IndexConfig;
import com.google.gerrit.server.index.Schema;
import com.google.gerrit.server.index.change.ChangeField;
import com.google.gerrit.server.index.change.ChangeIndex;
import com.google.gerrit.server.index.change.ChangeIndexCollection;
import com.google.gerrit.server.index.change.ChangeIndexRewriter;
import com.google.gerrit.server.notedb.ChangeNotes;
import com.google.gerrit.server.patch.PatchListCache;
import com.google.gerrit.server.project.ChangeControl;
import com.google.gerrit.server.project.ListChildProjects;
import com.google.gerrit.server.project.ProjectCache;
import com.google.gerrit.server.query.LimitPredicate;
import com.google.gerrit.server.query.Predicate;
import com.google.gerrit.server.query.QueryBuilder;
import com.google.gerrit.server.query.QueryParseException;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.ProvisionException;
import com.google.inject.util.Providers;

import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.errors.RepositoryNotFoundException;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Repository;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.regex.Pattern;

/**
 * Parses a query string meant to be applied to change objects.
 */
public class ChangeQueryBuilder extends QueryBuilder<ChangeData> {
  public interface ChangeOperatorFactory
      extends OperatorFactory<ChangeData, ChangeQueryBuilder> {
  }

  private static final Pattern PAT_LEGACY_ID = Pattern.compile("^[1-9][0-9]*$");
  private static final Pattern PAT_CHANGE_ID = Pattern.compile(CHANGE_ID_PATTERN);
  private static final Pattern DEF_CHANGE = Pattern.compile(
      "^(?:[1-9][0-9]*|(?:[^~]+~[^~]+~)?[iI][0-9a-f]{4,}.*)$");

  // NOTE: As new search operations are added, please keep the
  // SearchSuggestOracle up to date.

  public static final String FIELD_ADDED = "added";
  public static final String FIELD_AGE = "age";
  public static final String FIELD_AUTHOR = "author";
  public static final String FIELD_BEFORE = "before";
  public static final String FIELD_CHANGE = "change";
  public static final String FIELD_CHANGE_ID = "change_id";
  public static final String FIELD_COMMENT = "comment";
  public static final String FIELD_COMMENTBY = "commentby";
  public static final String FIELD_COMMIT = "commit";
  public static final String FIELD_COMMITTER = "committer";
  public static final String FIELD_CONFLICTS = "conflicts";
  public static final String FIELD_DELETED = "deleted";
  public static final String FIELD_DELTA = "delta";
  public static final String FIELD_DESTINATION = "destination";
  public static final String FIELD_DRAFTBY = "draftby";
  public static final String FIELD_EDITBY = "editby";
  public static final String FIELD_EXACTCOMMIT = "exactcommit";
  public static final String FIELD_FILE = "file";
  public static final String FIELD_FILEPART = "filepart";
  public static final String FIELD_GROUP = "group";
  public static final String FIELD_HASHTAG = "hashtag";
  public static final String FIELD_LABEL = "label";
  public static final String FIELD_LIMIT = "limit";
  public static final String FIELD_MERGE = "merge";
  public static final String FIELD_MERGEABLE = "mergeable2";
  public static final String FIELD_MESSAGE = "message";
  public static final String FIELD_OWNER = "owner";
  public static final String FIELD_OWNERIN = "ownerin";
  public static final String FIELD_PARENTPROJECT = "parentproject";
  public static final String FIELD_PATH = "path";
  public static final String FIELD_PROJECT = "project";
  public static final String FIELD_PROJECTS = "projects";
  public static final String FIELD_REF = "ref";
  public static final String FIELD_REVIEWEDBY = "reviewedby";
  public static final String FIELD_REVIEWER = "reviewer";
  public static final String FIELD_REVIEWERIN = "reviewerin";
  public static final String FIELD_STAR = "star";
  public static final String FIELD_STARBY = "starby";
  public static final String FIELD_STARREDBY = "starredby";
  public static final String FIELD_STATUS = "status";
  public static final String FIELD_SUBMISSIONID = "submissionid";
  public static final String FIELD_TR = "tr";
  public static final String FIELD_VISIBLETO = "visibleto";
  public static final String FIELD_WATCHEDBY = "watchedby";

  public static final String ARG_ID_USER = "user";
  public static final String ARG_ID_GROUP = "group";


  private static final QueryBuilder.Definition<ChangeData, ChangeQueryBuilder> mydef =
      new QueryBuilder.Definition<>(ChangeQueryBuilder.class);

  @VisibleForTesting
  public static class Arguments {
    final Provider<ReviewDb> db;
    final Provider<InternalChangeQuery> queryProvider;
    final ChangeIndexRewriter rewriter;
    final DynamicMap<ChangeOperatorFactory> opFactories;
    final IdentifiedUser.GenericFactory userFactory;
    final CapabilityControl.Factory capabilityControlFactory;
    final ChangeControl.GenericFactory changeControlGenericFactory;
    final ChangeNotes.Factory notesFactory;
    final ChangeData.Factory changeDataFactory;
    final FieldDef.FillArgs fillArgs;
    final PatchLineCommentsUtil plcUtil;
    final AccountResolver accountResolver;
    final GroupBackend groupBackend;
    final AllProjectsName allProjectsName;
    final AllUsersName allUsersName;
    final PatchListCache patchListCache;
    final GitRepositoryManager repoManager;
    final ProjectCache projectCache;
    final Provider<ListChildProjects> listChildProjects;
    final SubmitDryRun submitDryRun;
    final ConflictsCache conflictsCache;
    final TrackingFooters trackingFooters;
    final ChangeIndex index;
    final IndexConfig indexConfig;
    final Provider<ListMembers> listMembers;
    final StarredChangesUtil starredChangesUtil;
    final AccountCache accountCache;
    final boolean allowsDrafts;

    private final Provider<CurrentUser> self;

    @Inject
    @VisibleForTesting
    public Arguments(Provider<ReviewDb> db,
        Provider<InternalChangeQuery> queryProvider,
        ChangeIndexRewriter rewriter,
        DynamicMap<ChangeOperatorFactory> opFactories,
        IdentifiedUser.GenericFactory userFactory,
        Provider<CurrentUser> self,
        CapabilityControl.Factory capabilityControlFactory,
        ChangeControl.GenericFactory changeControlGenericFactory,
        ChangeNotes.Factory notesFactory,
        ChangeData.Factory changeDataFactory,
        FieldDef.FillArgs fillArgs,
        PatchLineCommentsUtil plcUtil,
        AccountResolver accountResolver,
        GroupBackend groupBackend,
        AllProjectsName allProjectsName,
        AllUsersName allUsersName,
        PatchListCache patchListCache,
        GitRepositoryManager repoManager,
        ProjectCache projectCache,
        Provider<ListChildProjects> listChildProjects,
        ChangeIndexCollection indexes,
        SubmitDryRun submitDryRun,
        ConflictsCache conflictsCache,
        TrackingFooters trackingFooters,
        IndexConfig indexConfig,
        Provider<ListMembers> listMembers,
        StarredChangesUtil starredChangesUtil,
        AccountCache accountCache,
        @GerritServerConfig Config cfg) {
      this(db, queryProvider, rewriter, opFactories, userFactory, self,
          capabilityControlFactory, changeControlGenericFactory, notesFactory,
          changeDataFactory, fillArgs, plcUtil, accountResolver, groupBackend,
          allProjectsName, allUsersName, patchListCache, repoManager,
          projectCache, listChildProjects, submitDryRun, conflictsCache,
          trackingFooters, indexes != null ? indexes.getSearchIndex() : null,
          indexConfig, listMembers, starredChangesUtil, accountCache,
          cfg == null ? true : cfg.getBoolean("change", "allowDrafts", true));
    }

    private Arguments(
        Provider<ReviewDb> db,
        Provider<InternalChangeQuery> queryProvider,
        ChangeIndexRewriter rewriter,
        DynamicMap<ChangeOperatorFactory> opFactories,
        IdentifiedUser.GenericFactory userFactory,
        Provider<CurrentUser> self,
        CapabilityControl.Factory capabilityControlFactory,
        ChangeControl.GenericFactory changeControlGenericFactory,
        ChangeNotes.Factory notesFactory,
        ChangeData.Factory changeDataFactory,
        FieldDef.FillArgs fillArgs,
        PatchLineCommentsUtil plcUtil,
        AccountResolver accountResolver,
        GroupBackend groupBackend,
        AllProjectsName allProjectsName,
        AllUsersName allUsersName,
        PatchListCache patchListCache,
        GitRepositoryManager repoManager,
        ProjectCache projectCache,
        Provider<ListChildProjects> listChildProjects,
        SubmitDryRun submitDryRun,
        ConflictsCache conflictsCache,
        TrackingFooters trackingFooters,
        ChangeIndex index,
        IndexConfig indexConfig,
        Provider<ListMembers> listMembers,
        StarredChangesUtil starredChangesUtil,
        AccountCache accountCache,
        boolean allowsDrafts) {
     this.db = db;
     this.queryProvider = queryProvider;
     this.rewriter = rewriter;
     this.opFactories = opFactories;
     this.userFactory = userFactory;
     this.self = self;
     this.capabilityControlFactory = capabilityControlFactory;
     this.notesFactory = notesFactory;
     this.changeControlGenericFactory = changeControlGenericFactory;
     this.changeDataFactory = changeDataFactory;
     this.fillArgs = fillArgs;
     this.plcUtil = plcUtil;
     this.accountResolver = accountResolver;
     this.groupBackend = groupBackend;
     this.allProjectsName = allProjectsName;
     this.allUsersName = allUsersName;
     this.patchListCache = patchListCache;
     this.repoManager = repoManager;
     this.projectCache = projectCache;
     this.listChildProjects = listChildProjects;
     this.submitDryRun = submitDryRun;
     this.conflictsCache = conflictsCache;
     this.trackingFooters = trackingFooters;
     this.index = index;
     this.indexConfig = indexConfig;
     this.listMembers = listMembers;
     this.starredChangesUtil = starredChangesUtil;
     this.accountCache = accountCache;
     this.allowsDrafts = allowsDrafts;
    }

    Arguments asUser(CurrentUser otherUser) {
      return new Arguments(db, queryProvider, rewriter, opFactories, userFactory,
          Providers.of(otherUser),
          capabilityControlFactory, changeControlGenericFactory, notesFactory,
          changeDataFactory, fillArgs, plcUtil, accountResolver, groupBackend,
          allProjectsName, allUsersName, patchListCache, repoManager,
          projectCache, listChildProjects, submitDryRun,
          conflictsCache, trackingFooters, index, indexConfig, listMembers,
          starredChangesUtil, accountCache, allowsDrafts);
    }

    Arguments asUser(Account.Id otherId) {
      try {
        CurrentUser u = self.get();
        if (u.isIdentifiedUser() && otherId.equals(u.getAccountId())) {
          return this;
        }
      } catch (ProvisionException e) {
        // Doesn't match current user, continue.
      }
      return asUser(userFactory.create(otherId));
    }

    IdentifiedUser getIdentifiedUser() throws QueryParseException {
      try {
        CurrentUser u = getUser();
        if (u.isIdentifiedUser()) {
          return u.asIdentifiedUser();
        }
        throw new QueryParseException(NotSignedInException.MESSAGE);
      } catch (ProvisionException e) {
        throw new QueryParseException(NotSignedInException.MESSAGE, e);
      }
    }

    CurrentUser getUser() throws QueryParseException {
      try {
        return self.get();
      } catch (ProvisionException e) {
        throw new QueryParseException(NotSignedInException.MESSAGE, e);
      }
    }

    Schema<ChangeData> getSchema() {
      return index != null ? index.getSchema() : null;
    }
  }

  private final Arguments args;

  @Inject
  ChangeQueryBuilder(Arguments args) {
    super(mydef);
    this.args = args;
    setupDynamicOperators();
  }

  @VisibleForTesting
  protected ChangeQueryBuilder(
      Definition<ChangeData, ? extends QueryBuilder<ChangeData>> def,
      Arguments args) {
    super(def);
    this.args = args;
  }

  private void setupDynamicOperators() {
    for (DynamicMap.Entry<ChangeOperatorFactory> e : args.opFactories) {
      String name = e.getExportName() + "_" + e.getPluginName();
      opFactories.put(name, e.getProvider().get());
    }
  }

  public ChangeQueryBuilder asUser(CurrentUser user) {
    return new ChangeQueryBuilder(builderDef, args.asUser(user));
  }

  @Operator
  public Predicate<ChangeData> age(String value) {
    return new AgePredicate(value);
  }

  @Operator
  public Predicate<ChangeData> before(String value) throws QueryParseException {
    return new BeforePredicate(value);
  }

  @Operator
  public Predicate<ChangeData> until(String value) throws QueryParseException {
    return before(value);
  }

  @Operator
  public Predicate<ChangeData> after(String value) throws QueryParseException {
    return new AfterPredicate(value);
  }

  @Operator
  public Predicate<ChangeData> since(String value) throws QueryParseException {
    return after(value);
  }

  @Operator
  public Predicate<ChangeData> change(String query) throws QueryParseException {
    if (PAT_LEGACY_ID.matcher(query).matches()) {
      return new LegacyChangeIdPredicate(Change.Id.parse(query));
    } else if (PAT_CHANGE_ID.matcher(query).matches()) {
      return new ChangeIdPredicate(parseChangeId(query));
    }
    Optional<ChangeTriplet> triplet = ChangeTriplet.parse(query);
    if (triplet.isPresent()) {
      return Predicate.and(
          project(triplet.get().project().get()),
          branch(triplet.get().branch().get()),
          new ChangeIdPredicate(parseChangeId(triplet.get().id().get())));
    }

    throw new QueryParseException("Invalid change format");
  }

  @Operator
  public Predicate<ChangeData> comment(String value) {
    return new CommentPredicate(args.index, value);
  }

  @Operator
  public Predicate<ChangeData> status(String statusName) {
    if ("reviewed".equalsIgnoreCase(statusName)) {
      return IsReviewedPredicate.create();
    }
    return ChangeStatusPredicate.parse(statusName);
  }

  public Predicate<ChangeData> status_open() {
    return ChangeStatusPredicate.open();
  }

  @Operator
  public Predicate<ChangeData> has(String value) throws QueryParseException {
    if ("star".equalsIgnoreCase(value)) {
      return starredby(self());
    }

    if ("stars".equalsIgnoreCase(value)) {
      return new HasStarsPredicate(self());
    }

    if ("draft".equalsIgnoreCase(value)) {
      return draftby(self());
    }

    if ("edit".equalsIgnoreCase(value)) {
      return new EditByPredicate(self());
    }
    throw new IllegalArgumentException();
  }

  @Operator
  public Predicate<ChangeData> is(String value) throws QueryParseException {
    if ("starred".equalsIgnoreCase(value)) {
      return starredby(self());
    }

    if ("watched".equalsIgnoreCase(value)) {
      return new IsWatchedByPredicate(args, false);
    }

    if ("visible".equalsIgnoreCase(value)) {
      return is_visible();
    }

    if ("reviewed".equalsIgnoreCase(value)) {
      return IsReviewedPredicate.create();
    }

    if ("owner".equalsIgnoreCase(value)) {
      return new OwnerPredicate(self());
    }

    if ("reviewer".equalsIgnoreCase(value)) {
      return ReviewerPredicate.create(args, self());
    }

    if ("mergeable".equalsIgnoreCase(value)) {
      return new IsMergeablePredicate(args.fillArgs);
    }

    try {
      return status(value);
    } catch (IllegalArgumentException e) {
      // not status: alias?
    }

    throw error("Invalid query");
  }

  @Operator
  public Predicate<ChangeData> commit(String id) {
    return new CommitPredicate(id);
  }

  @Operator
  public Predicate<ChangeData> conflicts(String value) throws OrmException,
      QueryParseException {
    return new ConflictsPredicate(args, value, parseChange(value));
  }

  @Operator
  public Predicate<ChangeData> p(String name) {
    return project(name);
  }

  @Operator
  public Predicate<ChangeData> project(String name) {
    if (name.startsWith("^")) {
      return new RegexProjectPredicate(name);
    }
    return new ProjectPredicate(name);
  }

  @Operator
  public Predicate<ChangeData> projects(String name) {
    return new ProjectPrefixPredicate(name);
  }

  @Operator
  public Predicate<ChangeData> parentproject(String name) {
    return new ParentProjectPredicate(args.projectCache, args.listChildProjects,
        args.self, name);
  }

  @Operator
  public Predicate<ChangeData> branch(String name) {
    if (name.startsWith("^")) {
      return ref("^" + RefNames.fullName(name.substring(1)));
    }
    return ref(RefNames.fullName(name));
  }

  @Operator
  public Predicate<ChangeData> hashtag(String hashtag) {
    return new HashtagPredicate(hashtag);
  }

  @Operator
  public Predicate<ChangeData> topic(String name) {
    return new ExactTopicPredicate(name);
  }

  @Operator
  public Predicate<ChangeData> intopic(String name) {
    if (name.startsWith("^")) {
      return new RegexTopicPredicate(name);
    }
    if (name.isEmpty()) {
      return new ExactTopicPredicate(name);
    }
    return new FuzzyTopicPredicate(name, args.index);
  }

  @Operator
  public Predicate<ChangeData> ref(String ref) {
    if (ref.startsWith("^")) {
      return new RegexRefPredicate(ref);
    }
    return new RefPredicate(ref);
  }

  @Operator
  public Predicate<ChangeData> f(String file) {
    return file(file);
  }

  @Operator
  public Predicate<ChangeData> file(String file) {
    if (file.startsWith("^")) {
      return new RegexPathPredicate(file);
    }
    return EqualsFilePredicate.create(args, file);
  }

  @Operator
  public Predicate<ChangeData> path(String path) {
    if (path.startsWith("^")) {
      return new RegexPathPredicate(path);
    }
    return new EqualsPathPredicate(FIELD_PATH, path);
  }

  @Operator
  public Predicate<ChangeData> label(String name) throws QueryParseException,
      OrmException {
    Set<Account.Id> accounts = null;
    AccountGroup.UUID group = null;

    // Parse for:
    // label:CodeReview=1,user=jsmith or
    // label:CodeReview=1,jsmith or
    // label:CodeReview=1,group=android_approvers or
    // label:CodeReview=1,android_approvers
    //  user/groups without a label will first attempt to match user
    String[] splitReviewer = name.split(",", 2);
    name = splitReviewer[0];        // remove all but the vote piece, e.g.'CodeReview=1'

    if (splitReviewer.length == 2) {
      // process the user/group piece
      PredicateArgs lblArgs = new PredicateArgs(splitReviewer[1]);

      for (Map.Entry<String, String> pair : lblArgs.keyValue.entrySet()) {
        if (pair.getKey().equalsIgnoreCase(ARG_ID_USER)) {
          accounts = parseAccount(pair.getValue());
        } else if (pair.getKey().equalsIgnoreCase(ARG_ID_GROUP)) {
          group = parseGroup(pair.getValue()).getUUID();
        } else {
          throw new QueryParseException(
              "Invalid argument identifier '"   + pair.getKey() + "'");
        }
      }

      for (String value : lblArgs.positional) {
       if (accounts != null || group != null) {
          throw new QueryParseException("more than one user/group specified (" +
              value + ")");
        }
        try {
          accounts = parseAccount(value);
        } catch (QueryParseException qpex) {
          // If it doesn't match an account, see if it matches a group
          // (accounts get precedence)
          try {
            group = parseGroup(value).getUUID();
          } catch (QueryParseException e) {
            throw error("Neither user nor group " + value + " found");
          }
        }
      }
    }

    // expand a group predicate into multiple user predicates
    if (group != null) {
      Set<Account.Id> allMembers =
          new HashSet<>(Lists.transform(
              args.listMembers.get().setRecursive(true).apply(group),
              new Function<AccountInfo, Account.Id>() {
                @Override
                public Account.Id apply(AccountInfo accountInfo) {
                  return new Account.Id(accountInfo._accountId);
                }
              }));
      int maxLimit = args.indexConfig.maxLimit();
      if (allMembers.size() > maxLimit) {
        // limit the number of query terms otherwise Gerrit will barf
        accounts = ImmutableSet.copyOf(Iterables.limit(allMembers, maxLimit));
      } else {
        accounts = allMembers;
      }
    }

    return new LabelPredicate(args.projectCache,
        args.changeControlGenericFactory, args.userFactory, args.db,
        name, accounts, group);
  }

  @Operator
  public Predicate<ChangeData> message(String text) {
    return new MessagePredicate(args.index, text);
  }

  @Operator
  public Predicate<ChangeData> star(String label) throws QueryParseException {
    return new StarPredicate(self(), label);
  }

  @Operator
  public Predicate<ChangeData> starredby(String who)
      throws QueryParseException, OrmException {
    return starredby(parseAccount(who));
  }

  private Predicate<ChangeData> starredby(Set<Account.Id> who)
      throws QueryParseException {
    List<Predicate<ChangeData>> p = Lists.newArrayListWithCapacity(who.size());
    for (Account.Id id : who) {
      p.add(starredby(id));
    }
    return Predicate.or(p);
  }

  @SuppressWarnings("deprecation")
  private Predicate<ChangeData> starredby(Account.Id who)
      throws QueryParseException {
    if (args.getSchema().hasField(ChangeField.STAR)) {
      return new StarPredicate(who, StarredChangesUtil.DEFAULT_LABEL);
    }

    if (args.getSchema().hasField(ChangeField.STARREDBY)) {
      return new IsStarredByPredicate(who);
    }

    try {
      // starred changes are not contained in the index, we must read them from
      // git
      return new IsStarredByLegacyPredicate(who, args.starredChangesUtil
          .byAccount(who, StarredChangesUtil.DEFAULT_LABEL));
    } catch (OrmException e) {
      throw new QueryParseException("Failed to query starred changes.", e);
    }
  }

  @Operator
  public Predicate<ChangeData> watchedby(String who)
      throws QueryParseException, OrmException {
    Set<Account.Id> m = parseAccount(who);
    List<IsWatchedByPredicate> p = Lists.newArrayListWithCapacity(m.size());

    Account.Id callerId;
    try {
      CurrentUser caller = args.self.get();
      callerId = caller.isIdentifiedUser() ? caller.getAccountId() : null;
    } catch (ProvisionException e) {
      callerId = null;
    }

    for (Account.Id id : m) {
      // Each child IsWatchedByPredicate includes a visibility filter for the
      // corresponding user, to ensure that predicate subtree only returns
      // changes visible to that user. The exception is if one of the users is
      // the caller of this method, in which case visibility is already being
      // checked at the top level.
      p.add(new IsWatchedByPredicate(args.asUser(id), !id.equals(callerId)));
    }
    return Predicate.or(p);
  }

  @Operator
  public Predicate<ChangeData> draftby(String who) throws QueryParseException,
      OrmException {
    Set<Account.Id> m = parseAccount(who);
    List<Predicate<ChangeData>> p = Lists.newArrayListWithCapacity(m.size());
    for (Account.Id id : m) {
      p.add(draftby(id));
    }
    return Predicate.or(p);
  }

  @SuppressWarnings("deprecation")
  private Predicate<ChangeData> draftby(Account.Id who) {
    return args.getSchema().hasField(ChangeField.DRAFTBY)
        ? new HasDraftByPredicate(who)
        : new HasDraftByLegacyPredicate(args, who);
  }

  @Operator
  public Predicate<ChangeData> visibleto(String who)
      throws QueryParseException, OrmException {
    if ("self".equals(who)) {
      return is_visible();
    }
    Set<Account.Id> m = args.accountResolver.findAll(args.db.get(), who);
    if (!m.isEmpty()) {
      List<Predicate<ChangeData>> p = Lists.newArrayListWithCapacity(m.size());
      for (Account.Id id : m) {
        return visibleto(args.userFactory.create(id));
      }
      return Predicate.or(p);
    }

    // If its not an account, maybe its a group?
    //
    Collection<GroupReference> suggestions = args.groupBackend.suggest(who, null);
    if (!suggestions.isEmpty()) {
      HashSet<AccountGroup.UUID> ids = new HashSet<>();
      for (GroupReference ref : suggestions) {
        ids.add(ref.getUUID());
      }
      return visibleto(new SingleGroupUser(args.capabilityControlFactory, ids));
    }

    throw error("No user or group matches \"" + who + "\".");
  }

  public Predicate<ChangeData> visibleto(CurrentUser user) {
    return new ChangeIsVisibleToPredicate(args.db, args.notesFactory,
        args.changeControlGenericFactory, user);
  }

  public Predicate<ChangeData> is_visible() throws QueryParseException {
    return visibleto(args.getUser());
  }

  @Operator
  public Predicate<ChangeData> o(String who)
      throws QueryParseException, OrmException {
    return owner(who);
  }

  @Operator
  public Predicate<ChangeData> owner(String who) throws QueryParseException,
      OrmException {
    return owner(parseAccount(who));
  }

  private Predicate<ChangeData> owner(Set<Account.Id> who) {
    List<OwnerPredicate> p = Lists.newArrayListWithCapacity(who.size());
    for (Account.Id id : who) {
      p.add(new OwnerPredicate(id));
    }
    return Predicate.or(p);
  }

  @Operator
  public Predicate<ChangeData> ownerin(String group)
      throws QueryParseException {
    GroupReference g = GroupBackends.findBestSuggestion(args.groupBackend, group);
    if (g == null) {
      throw error("Group " + group + " not found");
    }
    return new OwnerinPredicate(args.userFactory, g.getUUID());
  }

  @Operator
  public Predicate<ChangeData> r(String who)
      throws QueryParseException, OrmException {
    return reviewer(who);
  }

  @Operator
  public Predicate<ChangeData> reviewer(String who)
      throws QueryParseException, OrmException {
    Set<Account.Id> m = parseAccount(who);
    List<Predicate<ChangeData>> p = Lists.newArrayListWithCapacity(m.size());
    for (Account.Id id : m) {
      p.add(ReviewerPredicate.create(args, id));
    }
    return Predicate.or(p);
  }

  @Operator
  public Predicate<ChangeData> reviewerin(String group)
      throws QueryParseException {
    GroupReference g = GroupBackends.findBestSuggestion(args.groupBackend, group);
    if (g == null) {
      throw error("Group " + group + " not found");
    }
    return new ReviewerinPredicate(args.userFactory, g.getUUID());
  }

  @Operator
  public Predicate<ChangeData> tr(String trackingId) {
    return new TrackingIdPredicate(args.trackingFooters, trackingId);
  }

  @Operator
  public Predicate<ChangeData> bug(String trackingId) {
    return tr(trackingId);
  }

  @Operator
  public Predicate<ChangeData> limit(String query) throws QueryParseException {
    Integer limit = Ints.tryParse(query);
    if (limit == null) {
      throw error("Invalid limit: " + query);
    }
    return new LimitPredicate<>(FIELD_LIMIT, limit);
  }

  @Operator
  public Predicate<ChangeData> added(String value)
      throws QueryParseException {
    return new AddedPredicate(value);
  }

  @Operator
  public Predicate<ChangeData> deleted(String value)
      throws QueryParseException {
    return new DeletedPredicate(value);
  }

  @Operator
  public Predicate<ChangeData> size(String value)
      throws QueryParseException {
    return delta(value);
  }

  @Operator
  public Predicate<ChangeData> delta(String value)
      throws QueryParseException {
    return new DeltaPredicate(value);
  }

  @Operator
  public Predicate<ChangeData> commentby(String who)
      throws QueryParseException, OrmException {
    return commentby(parseAccount(who));
  }

  private Predicate<ChangeData> commentby(Set<Account.Id> who) {
    List<CommentByPredicate> p = Lists.newArrayListWithCapacity(who.size());
    for (Account.Id id : who) {
      p.add(new CommentByPredicate(id));
    }
    return Predicate.or(p);
  }

  @Operator
  public Predicate<ChangeData> from(String who)
      throws QueryParseException, OrmException {
    Set<Account.Id> ownerIds = parseAccount(who);
    return Predicate.or(owner(ownerIds), commentby(ownerIds));
  }

  @Operator
  public Predicate<ChangeData> query(String name) throws QueryParseException {
    try (Repository git = args.repoManager.openRepository(args.allUsersName)) {
      VersionedAccountQueries q = VersionedAccountQueries.forUser(self());
      q.load(git);
      String query = q.getQueryList().getQuery(name);
      if (query != null) {
        return parse(query);
      }
    } catch (RepositoryNotFoundException e) {
      throw new QueryParseException("Unknown named query (no " +
          args.allUsersName + " repo): " + name, e);
    } catch (IOException | ConfigInvalidException e) {
      throw new QueryParseException("Error parsing named query: " + name, e);
    }
    throw new QueryParseException("Unknown named query: " + name);
  }

  @Operator
  public Predicate<ChangeData> reviewedby(String who)
      throws QueryParseException, OrmException {
    return IsReviewedPredicate.create(parseAccount(who));
  }

  @Operator
  public Predicate<ChangeData> destination(String name)
      throws QueryParseException {
    try (Repository git = args.repoManager.openRepository(args.allUsersName)) {
      VersionedAccountDestinations d =
          VersionedAccountDestinations.forUser(self());
      d.load(git);
      Set<Branch.NameKey> destinations =
          d.getDestinationList().getDestinations(name);
      if (destinations != null) {
        return new DestinationPredicate(destinations, name);
      }
    } catch (RepositoryNotFoundException e) {
      throw new QueryParseException("Unknown named destination (no " +
          args.allUsersName + " repo): " + name, e);
    } catch (IOException | ConfigInvalidException e) {
      throw new QueryParseException("Error parsing named destination: " + name, e);
    }
    throw new QueryParseException("Unknown named destination: " + name);
  }

  @Operator
  public Predicate<ChangeData> author(String who) {
    return new AuthorPredicate(who);
  }

  @Operator
  public Predicate<ChangeData> committer(String who) {
    return new CommitterPredicate(who);
  }

  @Override
  protected Predicate<ChangeData> defaultField(String query) throws QueryParseException {
    if (query.startsWith("refs/")) {
      return ref(query);
    } else if (DEF_CHANGE.matcher(query).matches()) {
      try {
        return change(query);
      } catch (QueryParseException e) {
        // Skip.
      }
    }

    // Adapt the capacity of this list when adding more default predicates.
    List<Predicate<ChangeData>> predicates = Lists.newArrayListWithCapacity(11);
    try {
      predicates.add(commit(query));
    } catch (IllegalArgumentException e) {
      // Skip.
    }
    try {
      predicates.add(owner(query));
    } catch (OrmException | QueryParseException e) {
      // Skip.
    }
    try {
      predicates.add(reviewer(query));
    } catch (OrmException | QueryParseException e) {
      // Skip.
    }
    predicates.add(file(query));
    try {
      predicates.add(label(query));
    } catch (OrmException | QueryParseException e) {
      // Skip.
    }
    predicates.add(message(query));
    predicates.add(comment(query));
    predicates.add(projects(query));
    predicates.add(ref(query));
    predicates.add(branch(query));
    predicates.add(topic(query));
    // Adapt the capacity of the "predicates" list when adding more default
    // predicates.
    return Predicate.or(predicates);
  }

  private Set<Account.Id> parseAccount(String who)
      throws QueryParseException, OrmException {
    if ("self".equals(who)) {
      return Collections.singleton(self());
    }
    Set<Account.Id> matches = args.accountResolver.findAll(args.db.get(), who);
    if (matches.isEmpty()) {
      throw error("User " + who + " not found");
    }
    return matches;
  }

  private GroupReference parseGroup(String group) throws QueryParseException {
    GroupReference g = GroupBackends.findBestSuggestion(args.groupBackend,
        group);
    if (g == null) {
      throw error("Group " + group + " not found");
    }
    return g;
  }

  private List<Change> parseChange(String value) throws OrmException,
      QueryParseException {
    if (PAT_LEGACY_ID.matcher(value).matches()) {
      return asChanges(
          args.queryProvider.get().byLegacyChangeId(Change.Id.parse(value)));
    } else if (PAT_CHANGE_ID.matcher(value).matches()) {
      List<Change> changes =
          asChanges(args.queryProvider.get().byKeyPrefix(parseChangeId(value)));
      if (changes.isEmpty()) {
        throw error("Change " + value + " not found");
      }
      return changes;
    }

    throw error("Change " + value + " not found");
  }

  private static String parseChangeId(String value) {
    if (value.charAt(0) == 'i') {
      value = "I" + value.substring(1);
    }
    return value;
  }

  private Account.Id self() throws QueryParseException {
    return args.getIdentifiedUser().getAccountId();
  }
}