// 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 static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Enums;
import com.google.common.collect.Lists;
import com.google.common.primitives.Ints;
import com.google.gerrit.common.data.GroupDescription;
import com.google.gerrit.common.data.GroupReference;
import com.google.gerrit.common.data.SubmitRecord;
import com.google.gerrit.common.errors.NotSignedInException;
import com.google.gerrit.extensions.registration.DynamicMap;
import com.google.gerrit.index.IndexConfig;
import com.google.gerrit.index.Schema;
import com.google.gerrit.index.SchemaUtil;
import com.google.gerrit.index.query.LimitPredicate;
import com.google.gerrit.index.query.Predicate;
import com.google.gerrit.index.query.QueryBuilder;
import com.google.gerrit.index.query.QueryParseException;
import com.google.gerrit.index.query.QueryRequiresAuthException;
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.CommentsUtil;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
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.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.git.GitRepositoryManager;
import com.google.gerrit.server.git.strategy.SubmitDryRun;
import com.google.gerrit.server.group.ListMembers;
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.mail.Address;
import com.google.gerrit.server.notedb.ChangeNotes;
import com.google.gerrit.server.notedb.NotesMigration;
import com.google.gerrit.server.notedb.ReviewerStateInternal;
import com.google.gerrit.server.patch.PatchListCache;
import com.google.gerrit.server.permissions.PermissionBackend;
import com.google.gerrit.server.project.ListChildProjects;
import com.google.gerrit.server.project.ProjectCache;
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 java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.function.Function;
import java.util.regex.Pattern;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.errors.RepositoryNotFoundException;
import org.eclipse.jgit.lib.Repository;

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

  /**
   * Converts a operand (operator value) passed to an operator into a {@link Predicate}.
   *
   * <p>Register a ChangeOperandFactory in a config Module like this (note, for an example we are
   * using the has predicate, when other predicate plugin operands are created they can be
   * registered in a similar manner):
   *
   * <p>bind(ChangeHasOperandFactory.class) .annotatedWith(Exports.named("your has operand"))
   * .to(YourClass.class);
   */
  private interface ChangeOperandFactory {
    Predicate<ChangeData> create(ChangeQueryBuilder builder) throws QueryParseException;
  }

  public interface ChangeHasOperandFactory extends ChangeOperandFactory {}

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

  static final int MAX_ACCOUNTS_PER_DEFAULT_FIELD = 10;

  // 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_ASSIGNEE = "assignee";
  public static final String FIELD_AUTHOR = "author";
  public static final String FIELD_EXACTAUTHOR = "exactauthor";
  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_EXACTCOMMITTER = "exactcommitter";
  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_PENDING_REVIEWER = "pendingreviewer";
  public static final String FIELD_PENDING_REVIEWER_BY_EMAIL = "pendingreviewerbyemail";
  public static final String FIELD_PRIVATE = "private";
  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_STARTED = "started";
  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_UNRESOLVED_COMMENT_COUNT = "unresolved";
  public static final String FIELD_VISIBLETO = "visibleto";
  public static final String FIELD_WATCHEDBY = "watchedby";
  public static final String FIELD_WIP = "wip";
  public static final String FIELD_REVERTOF = "revertof";

  public static final String ARG_ID_USER = "user";
  public static final String ARG_ID_GROUP = "group";
  public static final String ARG_ID_OWNER = "owner";
  public static final Account.Id OWNER_ACCOUNT_ID = new Account.Id(0);

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

  @VisibleForTesting
  public static class Arguments {
    final AccountCache accountCache;
    final AccountResolver accountResolver;
    final AllProjectsName allProjectsName;
    final AllUsersName allUsersName;
    final PermissionBackend permissionBackend;
    final ChangeData.Factory changeDataFactory;
    final ChangeIndex index;
    final ChangeIndexRewriter rewriter;
    final ChangeNotes.Factory notesFactory;
    final CommentsUtil commentsUtil;
    final ConflictsCache conflictsCache;
    final DynamicMap<ChangeHasOperandFactory> hasOperands;
    final DynamicMap<ChangeOperatorFactory> opFactories;
    final GitRepositoryManager repoManager;
    final GroupBackend groupBackend;
    final IdentifiedUser.GenericFactory userFactory;
    final IndexConfig indexConfig;
    final NotesMigration notesMigration;
    final PatchListCache patchListCache;
    final ProjectCache projectCache;
    final Provider<InternalChangeQuery> queryProvider;
    final Provider<ListChildProjects> listChildProjects;
    final Provider<ListMembers> listMembers;
    final Provider<ReviewDb> db;
    final StarredChangesUtil starredChangesUtil;
    final SubmitDryRun submitDryRun;

    private final Provider<CurrentUser> self;

    @Inject
    @VisibleForTesting
    public Arguments(
        Provider<ReviewDb> db,
        Provider<InternalChangeQuery> queryProvider,
        ChangeIndexRewriter rewriter,
        DynamicMap<ChangeOperatorFactory> opFactories,
        DynamicMap<ChangeHasOperandFactory> hasOperands,
        IdentifiedUser.GenericFactory userFactory,
        Provider<CurrentUser> self,
        PermissionBackend permissionBackend,
        ChangeNotes.Factory notesFactory,
        ChangeData.Factory changeDataFactory,
        CommentsUtil commentsUtil,
        AccountResolver accountResolver,
        GroupBackend groupBackend,
        AllProjectsName allProjectsName,
        AllUsersName allUsersName,
        PatchListCache patchListCache,
        GitRepositoryManager repoManager,
        ProjectCache projectCache,
        Provider<ListChildProjects> listChildProjects,
        ChangeIndexCollection indexes,
        SubmitDryRun submitDryRun,
        ConflictsCache conflictsCache,
        IndexConfig indexConfig,
        Provider<ListMembers> listMembers,
        StarredChangesUtil starredChangesUtil,
        AccountCache accountCache,
        NotesMigration notesMigration) {
      this(
          db,
          queryProvider,
          rewriter,
          opFactories,
          hasOperands,
          userFactory,
          self,
          permissionBackend,
          notesFactory,
          changeDataFactory,
          commentsUtil,
          accountResolver,
          groupBackend,
          allProjectsName,
          allUsersName,
          patchListCache,
          repoManager,
          projectCache,
          listChildProjects,
          submitDryRun,
          conflictsCache,
          indexes != null ? indexes.getSearchIndex() : null,
          indexConfig,
          listMembers,
          starredChangesUtil,
          accountCache,
          notesMigration);
    }

    private Arguments(
        Provider<ReviewDb> db,
        Provider<InternalChangeQuery> queryProvider,
        ChangeIndexRewriter rewriter,
        DynamicMap<ChangeOperatorFactory> opFactories,
        DynamicMap<ChangeHasOperandFactory> hasOperands,
        IdentifiedUser.GenericFactory userFactory,
        Provider<CurrentUser> self,
        PermissionBackend permissionBackend,
        ChangeNotes.Factory notesFactory,
        ChangeData.Factory changeDataFactory,
        CommentsUtil commentsUtil,
        AccountResolver accountResolver,
        GroupBackend groupBackend,
        AllProjectsName allProjectsName,
        AllUsersName allUsersName,
        PatchListCache patchListCache,
        GitRepositoryManager repoManager,
        ProjectCache projectCache,
        Provider<ListChildProjects> listChildProjects,
        SubmitDryRun submitDryRun,
        ConflictsCache conflictsCache,
        ChangeIndex index,
        IndexConfig indexConfig,
        Provider<ListMembers> listMembers,
        StarredChangesUtil starredChangesUtil,
        AccountCache accountCache,
        NotesMigration notesMigration) {
      this.db = db;
      this.queryProvider = queryProvider;
      this.rewriter = rewriter;
      this.opFactories = opFactories;
      this.userFactory = userFactory;
      this.self = self;
      this.permissionBackend = permissionBackend;
      this.notesFactory = notesFactory;
      this.changeDataFactory = changeDataFactory;
      this.commentsUtil = commentsUtil;
      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.index = index;
      this.indexConfig = indexConfig;
      this.listMembers = listMembers;
      this.starredChangesUtil = starredChangesUtil;
      this.accountCache = accountCache;
      this.hasOperands = hasOperands;
      this.notesMigration = notesMigration;
    }

    Arguments asUser(CurrentUser otherUser) {
      return new Arguments(
          db,
          queryProvider,
          rewriter,
          opFactories,
          hasOperands,
          userFactory,
          Providers.of(otherUser),
          permissionBackend,
          notesFactory,
          changeDataFactory,
          commentsUtil,
          accountResolver,
          groupBackend,
          allProjectsName,
          allUsersName,
          patchListCache,
          repoManager,
          projectCache,
          listChildProjects,
          submitDryRun,
          conflictsCache,
          index,
          indexConfig,
          listMembers,
          starredChangesUtil,
          accountCache,
          notesMigration);
    }

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

    CurrentUser getUser() throws QueryRequiresAuthException {
      try {
        return self.get();
      } catch (ProvisionException e) {
        throw new QueryRequiresAuthException(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 Arguments getArgs() {
    return args;
  }

  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 {
    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())));
    }
    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));
    }

    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());
    }

    if ("unresolved".equalsIgnoreCase(value)) {
      return new IsUnresolvedPredicate();
    }

    // for plugins the value will be operandName_pluginName
    String[] names = value.split("_");
    if (names.length == 2) {
      ChangeHasOperandFactory op = args.hasOperands.get(names[1], names[0]);
      if (op != null) {
        return op.create(this);
      }
    }

    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)) {
      if (args.getSchema().hasField(ChangeField.WIP)) {
        return Predicate.and(
            Predicate.not(new BooleanPredicate(ChangeField.WIP)),
            ReviewerPredicate.reviewer(args, self()));
      }
      return ReviewerPredicate.reviewer(args, self());
    }

    if ("cc".equalsIgnoreCase(value)) {
      return ReviewerPredicate.cc(self());
    }

    if ("mergeable".equalsIgnoreCase(value)) {
      return new BooleanPredicate(ChangeField.MERGEABLE);
    }

    if ("private".equalsIgnoreCase(value)) {
      if (args.getSchema().hasField(ChangeField.PRIVATE)) {
        return new BooleanPredicate(ChangeField.PRIVATE);
      }
      throw new QueryParseException(
          "'is:private' operator is not supported by change index version");
    }

    if ("assigned".equalsIgnoreCase(value)) {
      return Predicate.not(new AssigneePredicate(new Account.Id(ChangeField.NO_ASSIGNEE)));
    }

    if ("unassigned".equalsIgnoreCase(value)) {
      return new AssigneePredicate(new Account.Id(ChangeField.NO_ASSIGNEE));
    }

    if ("submittable".equalsIgnoreCase(value)) {
      return new SubmittablePredicate(SubmitRecord.Status.OK);
    }

    if ("ignored".equalsIgnoreCase(value)) {
      return star("ignore");
    }

    if ("started".equalsIgnoreCase(value)) {
      if (args.getSchema().hasField(ChangeField.STARTED)) {
        return new BooleanPredicate(ChangeField.STARTED);
      }
      throw new QueryParseException(
          "'is:started' operator is not supported by change index version");
    }

    if ("wip".equalsIgnoreCase(value)) {
      if (args.getSchema().hasField(ChangeField.WIP)) {
        return new BooleanPredicate(ChangeField.WIP);
      }
      throw new QueryParseException("'is:wip' operator is not supported by change index version");
    }

    return status(value);
  }

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

  @Operator
  public Predicate<ChangeData> conflicts(String value) throws OrmException, QueryParseException {
    List<Change> changes = parseChange(value);
    List<Predicate<ChangeData>> or = new ArrayList<>(changes.size());
    for (Change c : changes) {
      or.add(ConflictsPredicate.create(args, value, c));
    }
    return Predicate.or(or);
  }

  @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, IOException, ConfigInvalidException {
    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
    // Special case: votes by owners can be tracked with ",owner":
    // label:Code-Review+2,owner
    // label:Code-Review+2,user=owner
    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)) {
          if (pair.getValue().equals(ARG_ID_OWNER)) {
            accounts = Collections.singleton(OWNER_ACCOUNT_ID);
          } else {
            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 {
          if (value.equals(ARG_ID_OWNER)) {
            accounts = Collections.singleton(OWNER_ACCOUNT_ID);
          } else {
            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", e);
          }
        }
      }
    }

    if (group != null) {
      accounts = getMembers(group);
    }

    // If the vote piece looks like Code-Review=NEED with a valid non-numeric
    // submit record status, interpret as a submit record query.
    int eq = name.indexOf('=');
    if (args.getSchema().hasField(ChangeField.SUBMIT_RECORD) && eq > 0) {
      String statusName = name.substring(eq + 1).toUpperCase();
      if (!isInt(statusName)) {
        SubmitRecord.Label.Status status =
            Enums.getIfPresent(SubmitRecord.Label.Status.class, statusName).orNull();
        if (status == null) {
          throw error("Invalid label status " + statusName + " in " + name);
        }
        return SubmitRecordPredicate.create(name.substring(0, eq), status, accounts);
      }
    }

    return new LabelPredicate(args, name, accounts, group);
  }

  private static boolean isInt(String s) {
    if (s == null) {
      return false;
    }
    if (s.startsWith("+")) {
      s = s.substring(1);
    }
    return Ints.tryParse(s) != null;
  }

  @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, IOException, ConfigInvalidException {
    return starredby(parseAccount(who));
  }

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

  private Predicate<ChangeData> starredby(Account.Id who) {
    return new StarPredicate(who, StarredChangesUtil.DEFAULT_LABEL);
  }

  @Operator
  public Predicate<ChangeData> watchedby(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    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, IOException, ConfigInvalidException {
    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);
  }

  private Predicate<ChangeData> draftby(Account.Id who) {
    return new HasDraftByPredicate(who);
  }

  private boolean isSelf(String who) {
    return "self".equals(who) || "me".equals(who);
  }

  @Operator
  public Predicate<ChangeData> visibleto(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    if (isSelf(who)) {
      return is_visible();
    }
    Set<Account.Id> m = args.accountResolver.findAll(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(ids));
    }

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

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

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

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

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

  private Predicate<ChangeData> ownerDefaultField(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    Set<Account.Id> accounts = parseAccount(who);
    if (accounts.size() > MAX_ACCOUNTS_PER_DEFAULT_FIELD) {
      return Predicate.any();
    }
    return owner(accounts);
  }

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

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

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

    AccountGroup.UUID groupId = g.getUUID();
    GroupDescription.Basic groupDescription = args.groupBackend.get(groupId);
    if (!(groupDescription instanceof GroupDescription.Internal)) {
      return new OwnerinPredicate(args.userFactory, groupId);
    }

    Set<Account.Id> accounts = getMembers(groupId);
    List<OwnerPredicate> p = Lists.newArrayListWithCapacity(accounts.size());
    for (Account.Id id : accounts) {
      p.add(new OwnerPredicate(id));
    }
    return Predicate.or(p);
  }

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

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

  private Predicate<ChangeData> reviewerDefaultField(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    return reviewer(who, true);
  }

  private Predicate<ChangeData> reviewer(String who, boolean forDefaultField)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    Predicate<ChangeData> byState =
        reviewerByState(who, ReviewerStateInternal.REVIEWER, forDefaultField);
    if (Objects.equals(byState, Predicate.<ChangeData>any())) {
      return Predicate.any();
    }
    if (args.getSchema().hasField(ChangeField.WIP)) {
      return Predicate.and(Predicate.not(new BooleanPredicate(ChangeField.WIP)), byState);
    }
    return byState;
  }

  @Operator
  public Predicate<ChangeData> cc(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    return reviewerByState(who, ReviewerStateInternal.CC, false);
  }

  @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(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, IOException, ConfigInvalidException {
    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, IOException, ConfigInvalidException {
    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, IOException, ConfigInvalidException {
    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 && !destinations.isEmpty()) {
        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) throws QueryParseException {
    if (args.getSchema().hasField(ChangeField.EXACT_AUTHOR)) {
      return getAuthorOrCommitterPredicate(
          who.trim(), ExactAuthorPredicate::new, AuthorPredicate::new);
    }
    return getAuthorOrCommitterFullTextPredicate(who.trim(), AuthorPredicate::new);
  }

  @Operator
  public Predicate<ChangeData> committer(String who) throws QueryParseException {
    if (args.getSchema().hasField(ChangeField.EXACT_COMMITTER)) {
      return getAuthorOrCommitterPredicate(
          who.trim(), ExactCommitterPredicate::new, CommitterPredicate::new);
    }
    return getAuthorOrCommitterFullTextPredicate(who.trim(), CommitterPredicate::new);
  }

  @Operator
  public Predicate<ChangeData> submittable(String str) throws QueryParseException {
    SubmitRecord.Status status =
        Enums.getIfPresent(SubmitRecord.Status.class, str.toUpperCase()).orNull();
    if (status == null) {
      throw error("invalid value for submittable:" + str);
    }
    return new SubmittablePredicate(status);
  }

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

  @Operator
  public Predicate<ChangeData> revertof(String value) throws QueryParseException {
    if (args.getSchema().hasField(ChangeField.REVERT_OF)) {
      return new RevertOfPredicate(value);
    }
    throw new QueryParseException("'revertof' operator is not supported by change index version");
  }

  @Override
  protected Predicate<ChangeData> defaultField(String query) throws QueryParseException {
    if (query.startsWith("refs/")) {
      return ref(query);
    } else if (DEF_CHANGE.matcher(query).matches()) {
      List<Predicate<ChangeData>> predicates = Lists.newArrayListWithCapacity(2);
      try {
        predicates.add(change(query));
      } catch (QueryParseException e) {
        // Skip.
      }

      // For PAT_LEGACY_ID, it may also be the prefix of some commits.
      if (query.length() >= 6 && PAT_LEGACY_ID.matcher(query).matches()) {
        predicates.add(commit(query));
      }

      return Predicate.or(predicates);
    }

    // Adapt the capacity of this list when adding more default predicates.
    List<Predicate<ChangeData>> predicates = Lists.newArrayListWithCapacity(11);
    try {
      Predicate<ChangeData> p = ownerDefaultField(query);
      if (!Objects.equals(p, Predicate.<ChangeData>any())) {
        predicates.add(p);
      }
    } catch (OrmException | IOException | ConfigInvalidException | QueryParseException e) {
      // Skip.
    }
    try {
      Predicate<ChangeData> p = reviewerDefaultField(query);
      if (!Objects.equals(p, Predicate.<ChangeData>any())) {
        predicates.add(p);
      }
    } catch (OrmException | IOException | ConfigInvalidException | QueryParseException e) {
      // Skip.
    }
    predicates.add(file(query));
    try {
      predicates.add(label(query));
    } catch (OrmException | IOException | ConfigInvalidException | QueryParseException e) {
      // Skip.
    }
    predicates.add(commit(query));
    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 Predicate<ChangeData> getAuthorOrCommitterPredicate(
      String who,
      Function<String, Predicate<ChangeData>> exactPredicateFunc,
      Function<String, Predicate<ChangeData>> fullPredicateFunc)
      throws QueryParseException {
    if (Address.tryParse(who) != null) {
      return exactPredicateFunc.apply(who);
    }
    return getAuthorOrCommitterFullTextPredicate(who, fullPredicateFunc);
  }

  private Predicate<ChangeData> getAuthorOrCommitterFullTextPredicate(
      String who, Function<String, Predicate<ChangeData>> fullPredicateFunc)
      throws QueryParseException {
    Set<String> parts = SchemaUtil.getNameParts(who);
    if (parts.isEmpty()) {
      throw error("invalid value");
    }

    List<Predicate<ChangeData>> predicates =
        parts.stream().map(fullPredicateFunc).collect(toList());
    return Predicate.and(predicates);
  }

  private Set<Account.Id> getMembers(AccountGroup.UUID g) throws OrmException {
    Set<Account.Id> accounts;
    Set<Account.Id> allMembers =
        args.listMembers.get().setRecursive(true).apply(g).stream()
            .map(a -> new Account.Id(a._accountId))
            .collect(toSet());
    int maxTerms = args.indexConfig.maxTerms();
    if (allMembers.size() > maxTerms) {
      // limit the number of query terms otherwise Gerrit will barf
      accounts = allMembers.stream().limit(maxTerms).collect(toSet());
    } else {
      accounts = allMembers;
    }
    return accounts;
  }

  private Set<Account.Id> parseAccount(String who)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    if (isSelf(who)) {
      return Collections.singleton(self());
    }
    Set<Account.Id> matches = args.accountResolver.findAll(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();
  }

  public Predicate<ChangeData> reviewerByState(
      String who, ReviewerStateInternal state, boolean forDefaultField)
      throws QueryParseException, OrmException, IOException, ConfigInvalidException {
    Predicate<ChangeData> reviewerByEmailPredicate = null;
    if (args.index.getSchema().hasField(ChangeField.REVIEWER_BY_EMAIL)) {
      Address address = Address.tryParse(who);
      if (address != null) {
        reviewerByEmailPredicate = ReviewerByEmailPredicate.forState(address, state);
      }
    }

    Predicate<ChangeData> reviewerPredicate = null;
    try {
      Set<Account.Id> accounts = parseAccount(who);
      if (!forDefaultField || accounts.size() <= MAX_ACCOUNTS_PER_DEFAULT_FIELD) {
        reviewerPredicate =
            Predicate.or(
                accounts.stream()
                    .map(id -> ReviewerPredicate.forState(id, state))
                    .collect(toList()));
      }
    } catch (QueryParseException e) {
      // Propagate this exception only if we can't use 'who' to query by email
      if (reviewerByEmailPredicate == null) {
        throw e;
      }
    }

    if (reviewerPredicate != null && reviewerByEmailPredicate != null) {
      return Predicate.or(reviewerPredicate, reviewerByEmailPredicate);
    } else if (reviewerPredicate != null) {
      return reviewerPredicate;
    } else if (reviewerByEmailPredicate != null) {
      return reviewerByEmailPredicate;
    } else {
      return Predicate.any();
    }
  }
}