/*
 * 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.
 */

package org.apache.druid.segment.serde;

import com.google.common.base.Supplier;
import org.apache.druid.collections.bitmap.BitmapFactory;
import org.apache.druid.collections.bitmap.ImmutableBitmap;
import org.apache.druid.segment.column.BitmapIndex;
import org.apache.druid.segment.data.GenericIndexed;

import javax.annotation.Nullable;

/**
 * Provides {@link BitmapIndex} for some dictionary encoded column, where the dictionary and bitmaps are stored in some
 * {@link GenericIndexed}.
 */
public class StringBitmapIndexColumnPartSupplier implements Supplier<BitmapIndex>
{
  private final BitmapFactory bitmapFactory;
  private final GenericIndexed<ImmutableBitmap> bitmaps;
  private final GenericIndexed<String> dictionary;

  public StringBitmapIndexColumnPartSupplier(
      BitmapFactory bitmapFactory,
      GenericIndexed<ImmutableBitmap> bitmaps,
      GenericIndexed<String> dictionary
  )
  {
    this.bitmapFactory = bitmapFactory;
    this.bitmaps = bitmaps;
    this.dictionary = dictionary;
  }

  @Override
  public BitmapIndex get()
  {
    return new BitmapIndex()
    {
      @Override
      public int getCardinality()
      {
        return dictionary.size();
      }

      @Override
      public String getValue(int index)
      {
        return dictionary.get(index);
      }

      @Override
      public boolean hasNulls()
      {
        return dictionary.indexOf(null) >= 0;
      }

      @Override
      public BitmapFactory getBitmapFactory()
      {
        return bitmapFactory;
      }

      @Override
      public int getIndex(@Nullable String value)
      {
        // GenericIndexed.indexOf satisfies contract needed by BitmapIndex.indexOf
        return dictionary.indexOf(value);
      }

      @Override
      public ImmutableBitmap getBitmap(int idx)
      {
        if (idx < 0) {
          return bitmapFactory.makeEmptyImmutableBitmap();
        }

        final ImmutableBitmap bitmap = bitmaps.get(idx);
        return bitmap == null ? bitmapFactory.makeEmptyImmutableBitmap() : bitmap;
      }
    };
  }
}
