/*
    * Copyright 2018 LINE Corporation
    *
    * LINE Corporation licenses this file to you 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:
    *
    *   https://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.linecorp.centraldogma.server.internal.storage.repository.cache;
  
  import static com.linecorp.centraldogma.internal.Util.validateJsonFilePath;
  import static com.linecorp.centraldogma.server.internal.storage.repository.RepositoryCache.logger;
  import static java.util.Objects.requireNonNull;
  
  import java.util.List;
  import java.util.Objects;
  import java.util.concurrent.CompletableFuture;
  
  import com.google.common.base.MoreObjects.ToStringHelper;
  
  import com.linecorp.centraldogma.common.MergeQuery;
  import com.linecorp.centraldogma.common.MergeSource;
  import com.linecorp.centraldogma.common.MergedEntry;
  import com.linecorp.centraldogma.common.Revision;
  import com.linecorp.centraldogma.server.storage.repository.AbstractCacheableCall;
  import com.linecorp.centraldogma.server.storage.repository.Repository;
  
  final class CacheableMergeQueryCall<T> extends AbstractCacheableCall<MergedEntry<T>> {
  
      private final Revision revision;
      private final MergeQuery<T> query;
      private final int hashCode;
  
      CacheableMergeQueryCall(Repository repo, Revision revision, MergeQuery<T> query) {
          super(repo);
          this.revision = requireNonNull(revision, "revision");
          this.query = requireNonNull(query, "query");
          // Only JSON files can currently be merged.
          query.mergeSources().forEach(path -> validateJsonFilePath(path.path(), "path"));
  
          hashCode = Objects.hash(revision, query) * 31 + System.identityHashCode(repo);
  
          assert !revision.isRelative();
      }
  
      @Override
      public int weigh(MergedEntry<T> value) {
          int weight = 0;
          final List<MergeSource> mergeSources = query.mergeSources();
          weight += mergeSources.size();
          for (MergeSource mergeSource : mergeSources) {
              weight += mergeSource.path().length();
          }
          final List<String> expressions = query.expressions();
          weight += expressions.size();
          for (String expression : expressions) {
              weight += expression.length();
          }
          if (value != null) {
              weight += value.contentAsText().length();
          }
          return weight;
      }
  
      @Override
      public CompletableFuture<MergedEntry<T>> execute() {
          logger.debug("Cache miss: {}", this);
          return repo().mergeFiles(revision, query);
      }
  
      @Override
      public int hashCode() {
          return hashCode;
      }
  
      @Override
      public boolean equals(Object o) {
          if (!super.equals(o)) {
              return false;
          }
  
          final CacheableMergeQueryCall<?> that = (CacheableMergeQueryCall<?>) o;
          return revision.equals(that.revision) &&
                 query.equals(that.query);
      }
  
      @Override
      protected void toString(ToStringHelper helper) {
          helper.add("revision", revision)
                .add("query", query);
      }
 }