// Copyright (C) 2021 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.approval;

import com.google.gerrit.entities.LabelId;
import com.google.gerrit.entities.LabelType;
import com.google.gerrit.entities.Project;
import com.google.gerrit.index.query.Predicate;
import com.google.gerrit.server.project.ProjectCache;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;
import java.util.Collection;
import java.util.Objects;
import java.util.Optional;

/** Predicate that matches patch set approvals we want to copy based on the value. */
public class MagicValuePredicate extends ApprovalPredicate {
  enum MagicValue {
    MIN,
    MAX,
    ANY
  }

  public interface Factory {
    MagicValuePredicate create(MagicValue value);
  }

  private final MagicValue value;
  private final ProjectCache projectCache;

  @Inject
  MagicValuePredicate(ProjectCache projectCache, @Assisted MagicValue value) {
    this.projectCache = projectCache;
    this.value = value;
  }

  @Override
  public boolean match(ApprovalContext ctx) {
    Optional<LabelType> lt =
        getLabelType(ctx.changeNotes().getProjectName(), ctx.patchSetApproval().labelId());
    short pValue;
    switch (value) {
      case ANY:
        return true;
      case MIN:
        if (!lt.isPresent()) {
          return false;
        }
        pValue = lt.get().getMaxNegative();
        break;
      case MAX:
        if (!lt.isPresent()) {
          return false;
        }
        pValue = lt.get().getMaxPositive();
        break;
      default:
        throw new IllegalArgumentException("unrecognized label value: " + value);
    }
    return pValue == ctx.patchSetApproval().value();
  }

  private Optional<LabelType> getLabelType(Project.NameKey project, LabelId labelId) {
    return projectCache
        .get(project)
        .orElseThrow(() -> new IllegalStateException(project + " absent"))
        .getLabelTypes()
        .byLabel(labelId);
  }

  @Override
  public Predicate<ApprovalContext> copy(
      Collection<? extends Predicate<ApprovalContext>> children) {
    return new MagicValuePredicate(projectCache, value);
  }

  @Override
  public int hashCode() {
    return Objects.hash(value);
  }

  @Override
  public boolean equals(Object other) {
    if (!(other instanceof MagicValuePredicate)) {
      return false;
    }
    return ((MagicValuePredicate) other).value.equals(value);
  }
}