// Copyright (C) 2012 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.change;

import static com.google.gerrit.extensions.common.ListChangesOption.ALL_COMMITS;
import static com.google.gerrit.extensions.common.ListChangesOption.ALL_FILES;
import static com.google.gerrit.extensions.common.ListChangesOption.ALL_REVISIONS;
import static com.google.gerrit.extensions.common.ListChangesOption.CURRENT_ACTIONS;
import static com.google.gerrit.extensions.common.ListChangesOption.CURRENT_COMMIT;
import static com.google.gerrit.extensions.common.ListChangesOption.CURRENT_FILES;
import static com.google.gerrit.extensions.common.ListChangesOption.CURRENT_REVISION;
import static com.google.gerrit.extensions.common.ListChangesOption.DETAILED_ACCOUNTS;
import static com.google.gerrit.extensions.common.ListChangesOption.DETAILED_LABELS;
import static com.google.gerrit.extensions.common.ListChangesOption.DOWNLOAD_COMMANDS;
import static com.google.gerrit.extensions.common.ListChangesOption.DRAFT_COMMENTS;
import static com.google.gerrit.extensions.common.ListChangesOption.LABELS;
import static com.google.gerrit.extensions.common.ListChangesOption.MESSAGES;
import static com.google.gerrit.extensions.common.ListChangesOption.REVIEWED;
import static com.google.gerrit.extensions.common.ListChangesOption.WEB_LINKS;

import com.google.common.base.Joiner;
import com.google.common.base.Objects;
import com.google.common.base.Optional;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.common.collect.SetMultimap;
import com.google.common.collect.Sets;
import com.google.common.collect.Table;
import com.google.gerrit.common.data.LabelType;
import com.google.gerrit.common.data.LabelTypes;
import com.google.gerrit.common.data.LabelValue;
import com.google.gerrit.common.data.Permission;
import com.google.gerrit.common.data.PermissionRange;
import com.google.gerrit.common.data.SubmitRecord;
import com.google.gerrit.extensions.common.ActionInfo;
import com.google.gerrit.extensions.common.CommitInfo;
import com.google.gerrit.extensions.common.FetchInfo;
import com.google.gerrit.extensions.common.GitPerson;
import com.google.gerrit.extensions.common.ListChangesOption;
import com.google.gerrit.extensions.common.RevisionInfo;
import com.google.gerrit.extensions.config.DownloadCommand;
import com.google.gerrit.extensions.config.DownloadScheme;
import com.google.gerrit.extensions.registration.DynamicMap;
import com.google.gerrit.extensions.restapi.RestView;
import com.google.gerrit.extensions.restapi.Url;
import com.google.gerrit.extensions.webui.UiAction;
import com.google.gerrit.reviewdb.client.Account;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.ChangeMessage;
import com.google.gerrit.reviewdb.client.Patch;
import com.google.gerrit.reviewdb.client.PatchSet;
import com.google.gerrit.reviewdb.client.PatchSetApproval;
import com.google.gerrit.reviewdb.client.PatchSetInfo;
import com.google.gerrit.reviewdb.client.PatchSetInfo.ParentInfo;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.client.UserIdentity;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.AnonymousUser;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.WebLinks;
import com.google.gerrit.server.account.AccountInfo;
import com.google.gerrit.server.extensions.webui.UiActions;
import com.google.gerrit.server.git.LabelNormalizer;
import com.google.gerrit.server.patch.PatchListNotAvailableException;
import com.google.gerrit.server.patch.PatchSetInfoFactory;
import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
import com.google.gerrit.server.project.ChangeControl;
import com.google.gerrit.server.project.NoSuchProjectException;
import com.google.gerrit.server.project.ProjectControl;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.query.change.ChangeData.ChangedLines;
import com.google.gwtorm.server.OrmException;
import com.google.gwtorm.server.ResultSet;
import com.google.inject.Inject;
import com.google.inject.Provider;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.sql.Timestamp;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.ExecutionException;

public class ChangeJson {
  private static final Logger log = LoggerFactory.getLogger(ChangeJson.class);
  private static final ResultSet<ChangeMessage> NO_MESSAGES =
      new ResultSet<ChangeMessage>() {
        @Override
        public Iterator<ChangeMessage> iterator() {
          return toList().iterator();
        }

        @Override
        public List<ChangeMessage> toList() {
          return Collections.emptyList();
        }

        @Override
        public void close() {
        }
      };

  private final Provider<ReviewDb> db;
  private final LabelNormalizer labelNormalizer;
  private final Provider<CurrentUser> userProvider;
  private final AnonymousUser anonymous;
  private final IdentifiedUser.GenericFactory userFactory;
  private final ProjectControl.GenericFactory projectControlFactory;
  private final ChangeData.Factory changeDataFactory;
  private final PatchSetInfoFactory patchSetInfoFactory;
  private final ChangesCollection changes;
  private final FileInfoJson fileInfoJson;
  private final AccountInfo.Loader.Factory accountLoaderFactory;
  private final DynamicMap<DownloadScheme> downloadSchemes;
  private final DynamicMap<DownloadCommand> downloadCommands;
  private final DynamicMap<RestView<ChangeResource>> changeViews;
  private final Revisions revisions;

  private EnumSet<ListChangesOption> options;
  private AccountInfo.Loader accountLoader;
  private ChangeControl lastControl;
  private Set<Change.Id> reviewed;
  private LoadingCache<Project.NameKey, ProjectControl> projectControls;
  private Provider<WebLinks> webLinks;

  @Inject
  ChangeJson(
      Provider<ReviewDb> db,
      LabelNormalizer ln,
      Provider<CurrentUser> user,
      AnonymousUser au,
      IdentifiedUser.GenericFactory uf,
      ProjectControl.GenericFactory pcf,
      ChangeData.Factory cdf,
      PatchSetInfoFactory psi,
      ChangesCollection changes,
      FileInfoJson fileInfoJson,
      AccountInfo.Loader.Factory ailf,
      DynamicMap<DownloadScheme> downloadSchemes,
      DynamicMap<DownloadCommand> downloadCommands,
      DynamicMap<RestView<ChangeResource>> changeViews,
      Revisions revisions,
      Provider<WebLinks> webLinks) {
    this.db = db;
    this.labelNormalizer = ln;
    this.userProvider = user;
    this.anonymous = au;
    this.userFactory = uf;
    this.projectControlFactory = pcf;
    this.changeDataFactory = cdf;
    this.patchSetInfoFactory = psi;
    this.changes = changes;
    this.fileInfoJson = fileInfoJson;
    this.accountLoaderFactory = ailf;
    this.downloadSchemes = downloadSchemes;
    this.downloadCommands = downloadCommands;
    this.changeViews = changeViews;
    this.revisions = revisions;
    this.webLinks = webLinks;

    options = EnumSet.noneOf(ListChangesOption.class);
    projectControls = CacheBuilder.newBuilder()
      .concurrencyLevel(1)
      .build(new CacheLoader<Project.NameKey, ProjectControl>() {
        @Override
        public ProjectControl load(Project.NameKey key)
            throws NoSuchProjectException, IOException {
          return projectControlFactory.controlFor(key, userProvider.get());
        }
      });
  }

  public ChangeJson addOption(ListChangesOption o) {
    options.add(o);
    return this;
  }

  public ChangeJson addOptions(Collection<ListChangesOption> o) {
    options.addAll(o);
    return this;
  }

  public ChangeInfo format(ChangeResource rsrc) throws OrmException {
    return format(changeDataFactory.create(db.get(), rsrc.getControl()));
  }

  public ChangeInfo format(Change change) throws OrmException {
    return format(changeDataFactory.create(db.get(), change));
  }

  public ChangeInfo format(Change.Id id) throws OrmException {
    return format(changeDataFactory.create(db.get(), id));
  }

  public ChangeInfo format(ChangeData cd) throws OrmException {
    return format(cd, Optional.<PatchSet.Id> absent());
  }

  private ChangeInfo format(ChangeData cd, Optional<PatchSet.Id> limitToPsId)
      throws OrmException {
    accountLoader = accountLoaderFactory.create(has(DETAILED_ACCOUNTS));
    if (has(REVIEWED)) {
      ensureReviewedLoaded(Collections.singleton(cd));
    }
    ChangeInfo res = toChangeInfo(cd, limitToPsId);
    accountLoader.fill();
    return res;
  }

  public ChangeInfo format(RevisionResource rsrc) throws OrmException {
    ChangeData cd = changeDataFactory.create(db.get(), rsrc.getControl());
    return format(cd, Optional.of(rsrc.getPatchSet().getId()));
  }

  public List<List<ChangeInfo>> formatList2(List<List<ChangeData>> in)
      throws OrmException {
    accountLoader = accountLoaderFactory.create(has(DETAILED_ACCOUNTS));
    Iterable<ChangeData> all = Iterables.concat(in);
    ChangeData.ensureChangeLoaded(all);
    if (has(ALL_REVISIONS)) {
      ChangeData.ensureAllPatchSetsLoaded(all);
    } else {
      ChangeData.ensureCurrentPatchSetLoaded(all);
    }
    if (has(REVIEWED)) {
      ensureReviewedLoaded(all);
    }
    ChangeData.ensureCurrentApprovalsLoaded(all);

    List<List<ChangeInfo>> res = Lists.newArrayListWithCapacity(in.size());
    Map<Change.Id, ChangeInfo> out = Maps.newHashMap();
    for (List<ChangeData> changes : in) {
      res.add(toChangeInfo(out, changes));
    }
    accountLoader.fill();
    return res;
  }

  private boolean has(ListChangesOption option) {
    return options.contains(option);
  }

  private List<ChangeInfo> toChangeInfo(Map<Change.Id, ChangeInfo> out,
      List<ChangeData> changes) throws OrmException {
    List<ChangeInfo> info = Lists.newArrayListWithCapacity(changes.size());
    for (ChangeData cd : changes) {
      ChangeInfo i = out.get(cd.getId());
      if (i == null) {
        i = toChangeInfo(cd, Optional.<PatchSet.Id> absent());
        out.put(cd.getId(), i);
      }
      info.add(i);
    }
    return info;
  }

  private ChangeInfo toChangeInfo(ChangeData cd,
      Optional<PatchSet.Id> limitToPsId) throws OrmException {
    ChangeInfo out = new ChangeInfo();
    Change in = cd.change();
    out.project = in.getProject().get();
    out.branch = in.getDest().getShortName();
    out.topic = in.getTopic();
    out.changeId = in.getKey().get();
    out.mergeable = in.getStatus() != Change.Status.MERGED ? in.isMergeable() : null;
    ChangedLines changedLines = cd.changedLines();
    if (changedLines != null) {
      out.insertions = changedLines.insertions;
      out.deletions = changedLines.deletions;
    }
    out.subject = in.getSubject();
    out.status = in.getStatus();
    out.owner = accountLoader.get(in.getOwner());
    out.created = in.getCreatedOn();
    out.updated = in.getLastUpdatedOn();
    out._number = in.getId().get();
    out._sortkey = in.getSortKey();
    out.starred = userProvider.get().getStarredChanges().contains(in.getId())
        ? true
        : null;
    out.reviewed = in.getStatus().isOpen()
        && has(REVIEWED)
        && reviewed.contains(cd.getId()) ? true : null;
    out.labels = labelsFor(cd, has(LABELS), has(DETAILED_LABELS));

    if (out.labels != null && has(DETAILED_LABELS)) {
      // If limited to specific patch sets but not the current patch set, don't
      // list permitted labels, since users can't vote on those patch sets.
      if (!limitToPsId.isPresent()
          || limitToPsId.get().equals(in.currentPatchSetId())) {
        out.permittedLabels = permittedLabels(cd);
      }
      out.removableReviewers = removableReviewers(cd, out.labels.values());
    }
    if (has(MESSAGES)) {
      out.messages = messages(cd);
    }
    out.finish();

    if (has(ALL_REVISIONS)
        || has(CURRENT_REVISION)
        || limitToPsId.isPresent()) {
      out.revisions = revisions(cd, limitToPsId, out.project);
      if (out.revisions != null) {
        for (Map.Entry<String, RevisionInfo> entry : out.revisions.entrySet()) {
          if (entry.getValue().isCurrent) {
            out.currentRevision = entry.getKey();
            break;
          }
        }
      }
    }

    if (has(CURRENT_ACTIONS) && userProvider.get().isIdentifiedUser()) {
      out.actions = Maps.newTreeMap();
      for (UiAction.Description d : UiActions.from(
          changeViews,
          changes.parse(control(cd)),
          userProvider)) {
        out.actions.put(d.getId(), new ActionInfo(d));
      }
    }
    lastControl = null;
    return out;
  }

  private ChangeControl control(ChangeData cd) throws OrmException {
    if (lastControl != null
        && cd.getId().equals(lastControl.getChange().getId())) {
      return lastControl;
    }
    ChangeControl ctrl;
    try {
      if (cd.hasChangeControl()) {
        ctrl = cd.changeControl().forUser(userProvider.get());
      } else {
        ctrl = projectControls.get(cd.change().getProject())
            .controlFor(cd.change());
      }
    } catch (ExecutionException e) {
      throw new OrmException(e);
    }
    lastControl = ctrl;
    return ctrl;
  }

  private List<SubmitRecord> submitRecords(ChangeData cd) throws OrmException {
    if (cd.getSubmitRecords() != null) {
      return cd.getSubmitRecords();
    }
    ChangeControl ctl = control(cd);
    if (ctl == null) {
      return ImmutableList.of();
    }
    PatchSet ps = cd.currentPatchSet();
    if (ps == null) {
      return ImmutableList.of();
    }
    cd.setSubmitRecords(ctl.canSubmit(db.get(), ps, cd, true, false, true));
    return cd.getSubmitRecords();
  }

  private Map<String, LabelInfo> labelsFor(ChangeData cd, boolean standard,
      boolean detailed) throws OrmException {
    if (!standard && !detailed) {
      return null;
    }

    ChangeControl ctl = control(cd);
    if (ctl == null) {
      return null;
    }

    LabelTypes labelTypes = ctl.getLabelTypes();
    if (cd.change().getStatus().isOpen()) {
      return labelsForOpenChange(cd, labelTypes, standard, detailed);
    } else {
      return labelsForClosedChange(cd, labelTypes, standard, detailed);
    }
  }

  private Map<String, LabelInfo> labelsForOpenChange(ChangeData cd,
      LabelTypes labelTypes, boolean standard, boolean detailed)
      throws OrmException {
    Map<String, LabelInfo> labels = initLabels(cd, labelTypes, standard);
    if (detailed) {
      setAllApprovals(cd, labels);
    }
    for (Map.Entry<String, LabelInfo> e : labels.entrySet()) {
      LabelType type = labelTypes.byLabel(e.getKey());
      if (type == null) {
        continue;
      }
      if (standard) {
        for (PatchSetApproval psa : cd.currentApprovals()) {
          if (type.matches(psa)) {
            short val = psa.getValue();
            Account.Id accountId = psa.getAccountId();
            setLabelScores(type, e.getValue(), val, accountId);
          }
        }
      }
      if (detailed) {
        setLabelValues(type, e.getValue());
      }
    }
    return labels;
  }

  private Map<String, LabelInfo> initLabels(ChangeData cd,
      LabelTypes labelTypes, boolean standard) throws OrmException {
    // Don't use Maps.newTreeMap(Comparator) due to OpenJDK bug 100167.
    Map<String, LabelInfo> labels =
        new TreeMap<String, LabelInfo>(labelTypes.nameComparator());
    for (SubmitRecord rec : submitRecords(cd)) {
      if (rec.labels == null) {
        continue;
      }
      for (SubmitRecord.Label r : rec.labels) {
        LabelInfo p = labels.get(r.label);
        if (p == null || p._status.compareTo(r.status) < 0) {
          LabelInfo n = new LabelInfo();
          n._status = r.status;
          if (standard) {
            switch (r.status) {
              case OK:
                n.approved = accountLoader.get(r.appliedBy);
                break;
              case REJECT:
                n.rejected = accountLoader.get(r.appliedBy);
                n.blocking = true;
                break;
              default:
                break;
            }
          }

          n.optional = n._status == SubmitRecord.Label.Status.MAY ? true : null;
          labels.put(r.label, n);
        }
      }
    }
    return labels;
  }

  private void setLabelScores(LabelType type,
      LabelInfo label, short score, Account.Id accountId)
      throws OrmException {
    if (label.approved != null || label.rejected != null) {
      return;
    }

    if (type.getMin() == null || type.getMax() == null) {
      // Can't set score for unknown or misconfigured type.
      return;
    }

    if (score != 0) {
      if (score == type.getMin().getValue()) {
        label.rejected = accountLoader.get(accountId);
      } else if (score == type.getMax().getValue()) {
        label.approved = accountLoader.get(accountId);
      } else if (score < 0) {
        label.disliked = accountLoader.get(accountId);
        label.value = score;
      } else if (score > 0 && label.disliked == null) {
        label.recommended = accountLoader.get(accountId);
        label.value = score;
      }
    }
  }

  private void setAllApprovals(ChangeData cd,
      Map<String, LabelInfo> labels) throws OrmException {
    ChangeControl baseCtrl = control(cd);
    if (baseCtrl == null) {
      return;
    }

    // All users ever added, even if they can't vote on one or all labels.
    Set<Account.Id> allUsers = Sets.newHashSet();
    ListMultimap<PatchSet.Id, PatchSetApproval> allApprovals =
        cd.approvals();
    for (PatchSetApproval psa : allApprovals.values()) {
      allUsers.add(psa.getAccountId());
    }

    List<PatchSetApproval> currentList =
        allApprovals.get(baseCtrl.getChange().currentPatchSetId());
    // Most recent, normalized vote on each label for the current patch set by
    // each user (may be 0).
    Table<Account.Id, String, PatchSetApproval> current = HashBasedTable.create(
        allUsers.size(), baseCtrl.getLabelTypes().getLabelTypes().size());
    for (PatchSetApproval psa :
        labelNormalizer.normalize(baseCtrl, currentList).getNormalized()) {
      current.put(psa.getAccountId(), psa.getLabel(), psa);
    }

    for (Account.Id accountId : allUsers) {
      IdentifiedUser user = userFactory.create(accountId);
      ChangeControl ctl = baseCtrl.forUser(user);
      for (Map.Entry<String, LabelInfo> e : labels.entrySet()) {
        LabelType lt = ctl.getLabelTypes().byLabel(e.getKey());
        if (lt == null) {
          // Ignore submit record for undefined label; likely the submit rule
          // author didn't intend for the label to show up in the table.
          continue;
        }
        Integer value;
        Timestamp date = null;
        PatchSetApproval psa = current.get(accountId, lt.getName());
        if (psa != null) {
          value = Integer.valueOf(psa.getValue());
          date = psa.getGranted();
        } else {
          // Either the user cannot vote on this label, or there just wasn't a
          // dummy approval for this label. Explicitly check whether the user
          // can vote on this label.
          value = labelNormalizer.canVote(ctl, lt, accountId) ? 0 : null;
        }
        e.getValue().addApproval(approvalInfo(accountId, value, date));
      }
    }
  }

  private Map<String, LabelInfo> labelsForClosedChange(ChangeData cd,
      LabelTypes labelTypes, boolean standard, boolean detailed)
      throws OrmException {
    Set<Account.Id> allUsers = Sets.newHashSet();
    for (PatchSetApproval psa : cd.approvals().values()) {
      allUsers.add(psa.getAccountId());
    }

    Set<String> labelNames = Sets.newHashSet();
    Multimap<Account.Id, PatchSetApproval> current = HashMultimap.create();
    for (PatchSetApproval a : cd.currentApprovals()) {
      LabelType type = labelTypes.byLabel(a.getLabelId());
      if (type != null && a.getValue() != 0) {
        labelNames.add(type.getName());
        current.put(a.getAccountId(), a);
      }
    }

    // We can only approximately reconstruct what the submit rule evaluator
    // would have done. These should really come from a stored submit record.
    //
    // Don't use Maps.newTreeMap(Comparator) due to OpenJDK bug 100167.
    Map<String, LabelInfo> labels =
        new TreeMap<String, LabelInfo>(labelTypes.nameComparator());
    for (String name : labelNames) {
      LabelType type = labelTypes.byLabel(name);
      LabelInfo li = new LabelInfo();
      if (detailed) {
        setLabelValues(type, li);
      }
      labels.put(type.getName(), li);
    }

    for (Account.Id accountId : allUsers) {
      Map<String, ApprovalInfo> byLabel =
          Maps.newHashMapWithExpectedSize(labels.size());

      if (detailed) {
        for (Map.Entry<String, LabelInfo> entry : labels.entrySet()) {
          ApprovalInfo ai = approvalInfo(accountId, 0, null);
          byLabel.put(entry.getKey(), ai);
          entry.getValue().addApproval(ai);
        }
      }
      for (PatchSetApproval psa : current.get(accountId)) {
        LabelType type = labelTypes.byLabel(psa.getLabelId());
        if (type == null) {
          continue;
        }

        short val = psa.getValue();
        ApprovalInfo info = byLabel.get(type.getName());
        if (info != null) {
          info.value = Integer.valueOf(val);
          info.date = psa.getGranted();
        }

        LabelInfo li = labels.get(type.getName());
        if (!standard) {
          continue;
        }

        setLabelScores(type, li, val, accountId);
      }
    }
    return labels;
  }

  private ApprovalInfo approvalInfo(Account.Id id, Integer value, Timestamp date) {
    ApprovalInfo ai = new ApprovalInfo(id);
    ai.value = value;
    ai.date = date;
    accountLoader.put(ai);
    return ai;
  }

  private static boolean isOnlyZero(Collection<String> values) {
    return values.isEmpty() || (values.size() == 1 && values.contains(" 0"));
  }

  private void setLabelValues(LabelType type, LabelInfo label) {
    label.values = Maps.newLinkedHashMap();
    for (LabelValue v : type.getValues()) {
      label.values.put(v.formatValue(), v.getText());
    }
    if (isOnlyZero(label.values.keySet())) {
      label.values = null;
    }
  }

  private Map<String, Collection<String>> permittedLabels(ChangeData cd)
      throws OrmException {
    ChangeControl ctl = control(cd);
    if (ctl == null) {
      return null;
    }

    LabelTypes labelTypes = ctl.getLabelTypes();
    SetMultimap<String, String> permitted = LinkedHashMultimap.create();
    for (SubmitRecord rec : submitRecords(cd)) {
      if (rec.labels == null) {
        continue;
      }
      for (SubmitRecord.Label r : rec.labels) {
        LabelType type = labelTypes.byLabel(r.label);
        if (type == null) {
          continue;
        }
        PermissionRange range = ctl.getRange(Permission.forLabel(r.label));
        for (LabelValue v : type.getValues()) {
          if (range.contains(v.getValue())) {
            permitted.put(r.label, v.formatValue());
          }
        }
      }
    }
    List<String> toClear =
      Lists.newArrayListWithCapacity(permitted.keySet().size());
    for (Map.Entry<String, Collection<String>> e
        : permitted.asMap().entrySet()) {
      if (isOnlyZero(e.getValue())) {
        toClear.add(e.getKey());
      }
    }
    for (String label : toClear) {
      permitted.removeAll(label);
    }
    return permitted.asMap();
  }

  private Collection<ChangeMessageInfo> messages(ChangeData cd)
      throws OrmException {
    List<ChangeMessage> messages =
        db.get().changeMessages().byChange(cd.getId()).toList();
    if (messages.isEmpty()) {
      return Collections.emptyList();
    }

    // chronological order
    Collections.sort(messages, new Comparator<ChangeMessage>() {
      @Override
      public int compare(ChangeMessage a, ChangeMessage b) {
        return a.getWrittenOn().compareTo(b.getWrittenOn());
      }
    });

    List<ChangeMessageInfo> result =
        Lists.newArrayListWithCapacity(messages.size());
    for (ChangeMessage message : messages) {
      PatchSet.Id patchNum = message.getPatchSetId();

      ChangeMessageInfo cmi = new ChangeMessageInfo();
      cmi.id = message.getKey().get();
      cmi.author = accountLoader.get(message.getAuthor());
      cmi.date = message.getWrittenOn();
      cmi.message = message.getMessage();
      cmi._revisionNumber = patchNum != null ? patchNum.get() : null;
      result.add(cmi);
    }
    return result;
  }

  private Collection<AccountInfo> removableReviewers(ChangeData cd,
      Collection<LabelInfo> labels) throws OrmException {
    ChangeControl ctl = control(cd);
    if (ctl == null) {
      return null;
    }

    Set<Account.Id> fixed = Sets.newHashSetWithExpectedSize(labels.size());
    Set<Account.Id> removable = Sets.newHashSetWithExpectedSize(labels.size());
    for (LabelInfo label : labels) {
      if (label.all == null) {
        continue;
      }
      for (ApprovalInfo ai : label.all) {
        if (ctl.canRemoveReviewer(ai._id, Objects.firstNonNull(ai.value, 0))) {
          removable.add(ai._id);
        } else {
          fixed.add(ai._id);
        }
      }
    }
    removable.removeAll(fixed);

    List<AccountInfo> result = Lists.newArrayListWithCapacity(removable.size());
    for (Account.Id id : removable) {
      result.add(accountLoader.get(id));
    }
    return result;
  }

  private void ensureReviewedLoaded(Iterable<ChangeData> all)
      throws OrmException {
    reviewed = Sets.newHashSet();
    if (userProvider.get().isIdentifiedUser()) {
      Account.Id self = ((IdentifiedUser) userProvider.get()).getAccountId();
      for (List<ChangeData> batch : Iterables.partition(all, 50)) {
        List<ResultSet<ChangeMessage>> m =
            Lists.newArrayListWithCapacity(batch.size());
        for (ChangeData cd : batch) {
          PatchSet.Id ps = cd.change().currentPatchSetId();
          if (ps != null && cd.change().getStatus().isOpen()) {
            m.add(db.get().changeMessages().byPatchSet(ps));
          } else {
            m.add(NO_MESSAGES);
          }
        }
        for (int i = 0; i < m.size(); i++) {
          if (isChangeReviewed(self, batch.get(i), m.get(i).toList())) {
            reviewed.add(batch.get(i).getId());
          }
        }
      }
    }
  }

  private boolean isChangeReviewed(Account.Id self, ChangeData cd,
      List<ChangeMessage> msgs) throws OrmException {
    // Sort messages to keep the most recent ones at the beginning.
    Collections.sort(msgs, new Comparator<ChangeMessage>() {
      @Override
      public int compare(ChangeMessage a, ChangeMessage b) {
        return b.getWrittenOn().compareTo(a.getWrittenOn());
      }
    });

    Account.Id changeOwnerId = cd.change().getOwner();
    for (ChangeMessage cm : msgs) {
      if (self.equals(cm.getAuthor())) {
        return true;
      } else if (changeOwnerId.equals(cm.getAuthor())) {
        return false;
      }
    }
    return false;
  }

  private Map<String, RevisionInfo> revisions(ChangeData cd,
      Optional<PatchSet.Id> limitToPsId, String project) throws OrmException {
    ChangeControl ctl = control(cd);
    if (ctl == null) {
      return null;
    }

    Collection<PatchSet> src;
    if (has(ALL_REVISIONS)) {
      src = cd.patches();
    } else {
      PatchSet ps;
      if (limitToPsId.isPresent()) {
        ps = cd.patch(limitToPsId.get());
        if (ps == null) {
          throw new OrmException("missing patch set " + limitToPsId.get());
        }
      } else {
        ps = cd.currentPatchSet();
        if (ps == null) {
          throw new OrmException(
              "missing current patch set for change " + cd.getId());
        }
      }
      src = Collections.singletonList(ps);
    }

    Map<String, RevisionInfo> res = Maps.newLinkedHashMap();
    for (PatchSet in : src) {
      if (ctl.isPatchVisible(in, db.get())) {
        res.put(in.getRevision().get(), toRevisionInfo(cd, in, project));
      }
    }
    return res;
  }

  private RevisionInfo toRevisionInfo(ChangeData cd, PatchSet in, String project)
      throws OrmException {
    RevisionInfo out = new RevisionInfo();
    out.isCurrent = in.getId().equals(cd.change().currentPatchSetId());
    out._number = in.getId().get();
    out.draft = in.isDraft() ? true : null;
    out.fetch = makeFetchMap(cd, in);

    if (has(ALL_COMMITS) || (out.isCurrent && has(CURRENT_COMMIT))) {
      try {
        out.commit = toCommit(in);
      } catch (PatchSetInfoNotAvailableException e) {
        log.warn("Cannot load PatchSetInfo " + in.getId(), e);
      }
    }

    if (has(ALL_FILES) || (out.isCurrent && has(CURRENT_FILES))) {
      try {
        out.files = fileInfoJson.toFileInfoMap(cd.change(), in);
        out.files.remove(Patch.COMMIT_MSG);
      } catch (PatchListNotAvailableException e) {
        log.warn("Cannot load PatchList " + in.getId(), e);
      }
    }

    if ((out.isCurrent || (out.draft != null && out.draft))
        && has(CURRENT_ACTIONS)
        && userProvider.get().isIdentifiedUser()) {
      out.actions = Maps.newTreeMap();
      for (UiAction.Description d : UiActions.from(
          revisions,
          new RevisionResource(changes.parse(control(cd)), in),
          userProvider)) {
        out.actions.put(d.getId(), new ActionInfo(d));
      }
    }

    if (has(DRAFT_COMMENTS)
        && userProvider.get().isIdentifiedUser()) {
      IdentifiedUser user = (IdentifiedUser)userProvider.get();
      out.hasDraftComments =
          db.get().patchComments()
              .draftByPatchSetAuthor(in.getId(), user.getAccountId())
              .iterator().hasNext()
          ? true
          : null;
    }

    if (has(WEB_LINKS)) {
      out.webLinks = Lists.newArrayList();
      for (WebLinks.Link link : webLinks.get().getPatchSetLinks(
          project, in.getRevision().get())) {
        out.webLinks.add(new RevisionInfo.WebLinkInfo(link.name, link.url));
      }
    }
    return out;
  }

  CommitInfo toCommit(PatchSet in)
      throws PatchSetInfoNotAvailableException {
    PatchSetInfo info = patchSetInfoFactory.get(db.get(), in.getId());
    CommitInfo commit = new CommitInfo();
    commit.parents = Lists.newArrayListWithCapacity(info.getParents().size());
    commit.author = toGitPerson(info.getAuthor());
    commit.committer = toGitPerson(info.getCommitter());
    commit.subject = info.getSubject();
    commit.message = info.getMessage();
    for (ParentInfo parent : info.getParents()) {
      CommitInfo i = new CommitInfo();
      i.commit = parent.id.get();
      i.subject = parent.shortMessage;
      commit.parents.add(i);
    }
    return commit;
  }

  private Map<String, FetchInfo> makeFetchMap(ChangeData cd, PatchSet in)
      throws OrmException {
    Map<String, FetchInfo> r = Maps.newLinkedHashMap();

    for (DynamicMap.Entry<DownloadScheme> e : downloadSchemes) {
      String schemeName = e.getExportName();
      DownloadScheme scheme = e.getProvider().get();
      if (!scheme.isEnabled()
          || (scheme.isAuthRequired() && !userProvider.get().isIdentifiedUser())) {
        continue;
      }

      ChangeControl ctl = control(cd);
      if (!scheme.isAuthSupported()
          && !ctl.forUser(anonymous).isPatchVisible(in, db.get())) {
        continue;
      }

      String projectName = ctl.getProject().getNameKey().get();
      String url = scheme.getUrl(projectName);
      String refName = in.getRefName();
      FetchInfo fetchInfo = new FetchInfo(url, refName);
      r.put(schemeName, fetchInfo);

      if (has(DOWNLOAD_COMMANDS)) {
        for (DynamicMap.Entry<DownloadCommand> e2 : downloadCommands) {
          String commandName = e2.getExportName();
          DownloadCommand command = e2.getProvider().get();
          String c = command.getCommand(scheme, projectName, refName);
          if (c != null) {
            addCommand(fetchInfo, commandName, c);
          }
        }
      }
    }

    return r;
  }

  private void addCommand(FetchInfo fetchInfo, String commandName, String c) {
    if (fetchInfo.commands == null) {
      fetchInfo.commands = Maps.newTreeMap();
    }
    fetchInfo.commands.put(commandName, c);
  }

  private static GitPerson toGitPerson(UserIdentity committer) {
    GitPerson p = new GitPerson();
    p.name = committer.getName();
    p.email = committer.getEmail();
    p.date = committer.getDate();
    p.tz = committer.getTimeZone();
    return p;
  }

  public static class ChangeInfo {
    public final String kind = "gerritcodereview#change";
    public String id;
    public String project;
    public String branch;
    public String topic;
    public String changeId;
    public String subject;
    public Change.Status status;
    public Timestamp created;
    public Timestamp updated;
    public Boolean starred;
    public Boolean reviewed;
    public Boolean mergeable;
    public Integer insertions;
    public Integer deletions;

    public String _sortkey;
    public int _number;

    public AccountInfo owner;

    public Map<String, ActionInfo> actions;
    public Map<String, LabelInfo> labels;
    public Map<String, Collection<String>> permittedLabels;
    public Collection<AccountInfo> removableReviewers;
    public Collection<ChangeMessageInfo> messages;

    public String currentRevision;
    public Map<String, RevisionInfo> revisions;
    public Boolean _moreChanges;

    void finish() {
      id = Joiner.on('~').join(
          Url.encode(project),
          Url.encode(branch),
          Url.encode(changeId));
    }
  }

  public static class LabelInfo {
    transient SubmitRecord.Label.Status _status;

    public AccountInfo approved;
    public AccountInfo rejected;
    public AccountInfo recommended;
    public AccountInfo disliked;
    public List<ApprovalInfo> all;

    public Map<String, String> values;

    public Short value;
    public Boolean optional;
    public Boolean blocking;

    void addApproval(ApprovalInfo ai) {
      if (all == null) {
        all = Lists.newArrayList();
      }
      all.add(ai);
    }
  }

  public static class ApprovalInfo extends AccountInfo {
    public Integer value;
    public Timestamp date;

    ApprovalInfo(Account.Id id) {
      super(id);
    }
  }

  public static class ChangeMessageInfo {
    public String id;
    public AccountInfo author;
    public Timestamp date;
    public String message;
    public Integer _revisionNumber;
  }
}