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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.sql.calcite.filtration;

import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import io.druid.query.filter.AndDimFilter;
import io.druid.query.filter.DimFilter;
import io.druid.query.filter.NotDimFilter;
import io.druid.query.filter.OrDimFilter;

import java.util.List;

public abstract class BottomUpTransform implements Function
{
  protected abstract DimFilter process(final DimFilter filter);

  private DimFilter checkedProcess(final DimFilter filter)
  {
    final DimFilter retVal = process(Preconditions.checkNotNull(filter, "filter"));
    return Preconditions.checkNotNull(retVal, "process(filter) result in %s", getClass().getSimpleName());
  }

  @Override
  public Filtration apply(final Filtration filtration)
  {
    if (filtration.getDimFilter() != null) {
      final Filtration retVal = Filtration.create(apply0(filtration.getDimFilter()), filtration.getIntervals());
      return filtration.equals(retVal) ? retVal : apply(retVal);
    } else {
      return filtration;
    }
  }

  private DimFilter apply0(final DimFilter filter)
  {
    if (filter instanceof AndDimFilter) {
      final List oldFilters = ((AndDimFilter) filter).getFields();
      final List newFilters = Lists.newArrayList();
      for (DimFilter oldFilter : oldFilters) {
        final DimFilter newFilter = apply0(oldFilter);
        if (newFilter != null) {
          newFilters.add(newFilter);
        }
      }
      if (!newFilters.equals(oldFilters)) {
        return checkedProcess(new AndDimFilter(newFilters));
      } else {
        return checkedProcess(filter);
      }
    } else if (filter instanceof OrDimFilter) {
      final List oldFilters = ((OrDimFilter) filter).getFields();
      final List newFilters = Lists.newArrayList();
      for (DimFilter oldFilter : oldFilters) {
        final DimFilter newFilter = apply0(oldFilter);
        if (newFilter != null) {
          newFilters.add(newFilter);
        }
      }
      if (!newFilters.equals(oldFilters)) {
        return checkedProcess(new OrDimFilter(newFilters));
      } else {
        return checkedProcess(filter);
      }
    } else if (filter instanceof NotDimFilter) {
      final DimFilter oldFilter = ((NotDimFilter) filter).getField();
      final DimFilter newFilter = apply0(oldFilter);
      if (!oldFilter.equals(newFilter)) {
        return checkedProcess(new NotDimFilter(newFilter));
      } else {
        return checkedProcess(filter);
      }
    } else {
      return checkedProcess(filter);
    }
  }
}