package org.apache.maven.index.reader;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 *
 *   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.
 */

import java.util.Map;
import java.util.TreeSet;

import com.google.common.base.Function;
import org.apache.maven.index.reader.Record.Type;

import static com.google.common.collect.Iterables.concat;
import static com.google.common.collect.Iterables.transform;
import static java.util.Collections.singletonList;
import static org.apache.maven.index.reader.Utils.allGroups;
import static org.apache.maven.index.reader.Utils.descriptor;
import static org.apache.maven.index.reader.Utils.rootGroup;
import static org.apache.maven.index.reader.Utils.rootGroups;

/**
 * Helpers to transform records from one to another representation, and, some helpers for publishing using Guava.
 */
public final class TestUtils
{
  private TestUtils() {
    // nothing
  }

  private static final RecordCompactor RECORD_COMPACTOR = new RecordCompactor();

  private static final RecordExpander RECORD_EXPANDER = new RecordExpander();

  public static Function<Record, Map<String, String>> compactFunction =
      new Function<Record, Map<String, String>>()
      {
        public Map<String, String> apply(final Record input) {
          return RECORD_COMPACTOR.apply(input);
        }
      };

  public static Function<Map<String, String>, Record> expandFunction =
      new Function<Map<String, String>, Record>()
      {
        public Record apply(final Map<String, String> input) {
          return RECORD_EXPANDER.apply(input);
        }
      };

  /**
   * Helper method, that "decorates" the stream of records to be written out with "special" Maven Indexer records, so
   * all the caller is needed to provide {@link Iterable} or {@link Record}s <strong>to be</strong> on the index, with
   * record type {@link Type#ARTIFACT_ADD}. This method will create the output as "proper" Maven Indexer record
   * stream, by adding the {@link Type#DESCRIPTOR}, {@link Type#ROOT_GROUPS} and {@link Type#ALL_GROUPS} special
   * records.
   */
  public static Iterable<Record> decorate(final Iterable<Record> iterable,
                                          final String repoId)
  {
    final TreeSet<String> allGroupsSet = new TreeSet<String>();
    final TreeSet<String> rootGroupsSet = new TreeSet<String>();
    return transform(
        concat(
            singletonList(descriptor(repoId)),
            iterable,
            singletonList(allGroups(allGroupsSet)), // placeholder, will be recreated at the end with proper content
            singletonList(rootGroups(rootGroupsSet)) // placeholder, will be recreated at the end with proper content
        ),
        new Function<Record, Record>()
        {
          public Record apply(final Record rec) {
            if (Type.DESCRIPTOR == rec.getType()) {
              return rec;
            }
            else if (Type.ALL_GROUPS == rec.getType()) {
              return allGroups(allGroupsSet);
            }
            else if (Type.ROOT_GROUPS == rec.getType()) {
              return rootGroups(rootGroupsSet);
            }
            else {
              final String groupId = rec.get(Record.GROUP_ID);
              if (groupId != null) {
                allGroupsSet.add(groupId);
                rootGroupsSet.add(rootGroup(groupId));
              }
              return rec;
            }
          }
        }
    );
  }
}