// Copyright (C) 2013 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.common.base.Preconditions.checkArgument;

import com.google.auto.value.AutoValue;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
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.entities.Change;
import com.google.gerrit.entities.PatchSetApproval;
import com.google.gerrit.server.notedb.ChangeNotes;
import com.google.gerrit.server.project.ProjectCache;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.Collection;
import java.util.List;

/**
 * Normalizes votes on labels according to project config.
 *
 * <p>Votes are recorded in the database for a user based on the state of the project at that time:
 * what labels are defined for the project. The label definition can change between the time a vote
 * is originally made and a later point, for example when a change is submitted. This class
 * normalizes old votes against current project configuration.
 */
@Singleton
public class LabelNormalizer {
  @AutoValue
  public abstract static class Result {
    @VisibleForTesting
    static Result create(
        List<PatchSetApproval> unchanged,
        List<PatchSetApproval> updated,
        List<PatchSetApproval> deleted) {
      return new AutoValue_LabelNormalizer_Result(
          ImmutableList.copyOf(unchanged),
          ImmutableList.copyOf(updated),
          ImmutableList.copyOf(deleted));
    }

    public abstract ImmutableList<PatchSetApproval> unchanged();

    public abstract ImmutableList<PatchSetApproval> updated();

    public abstract ImmutableList<PatchSetApproval> deleted();

    public Iterable<PatchSetApproval> getNormalized() {
      return Iterables.concat(unchanged(), updated());
    }
  }

  private final ProjectCache projectCache;

  @Inject
  LabelNormalizer(ProjectCache projectCache) {
    this.projectCache = projectCache;
  }

  /**
   * @param notes change notes containing the given approvals.
   * @param approvals list of approvals.
   * @return copies of approvals normalized to the defined ranges for the label type. Approvals for
   *     unknown labels are not included in the output.
   */
  public Result normalize(ChangeNotes notes, Collection<PatchSetApproval> approvals)
      throws IOException {
    List<PatchSetApproval> unchanged = Lists.newArrayListWithCapacity(approvals.size());
    List<PatchSetApproval> updated = Lists.newArrayListWithCapacity(approvals.size());
    List<PatchSetApproval> deleted = Lists.newArrayListWithCapacity(approvals.size());
    LabelTypes labelTypes = projectCache.checkedGet(notes.getProjectName()).getLabelTypes(notes);
    for (PatchSetApproval psa : approvals) {
      Change.Id changeId = psa.key().patchSetId().changeId();
      checkArgument(
          changeId.equals(notes.getChangeId()),
          "Approval %s does not match change %s",
          psa.key(),
          notes.getChange().getKey());
      if (psa.isLegacySubmit()) {
        unchanged.add(psa);
        continue;
      }
      LabelType label = labelTypes.byLabel(psa.labelId());
      if (label == null) {
        deleted.add(psa);
        continue;
      }
      PatchSetApproval copy = applyTypeFloor(label, psa);
      if (copy.value() != psa.value()) {
        updated.add(copy);
      } else {
        unchanged.add(psa);
      }
    }
    return Result.create(unchanged, updated, deleted);
  }

  private PatchSetApproval applyTypeFloor(LabelType lt, PatchSetApproval a) {
    PatchSetApproval.Builder b = a.toBuilder();
    LabelValue atMin = lt.getMin();
    if (atMin != null && a.value() < atMin.getValue()) {
      b.value(atMin.getValue());
    }
    LabelValue atMax = lt.getMax();
    if (atMax != null && a.value() > atMax.getValue()) {
      b.value(atMax.getValue());
    }
    return b.build();
  }
}