/* 
 * 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 parquet.filter2.compat;

import java.util.ArrayList;
import java.util.List;

import parquet.filter2.compat.FilterCompat.Filter;
import parquet.filter2.compat.FilterCompat.NoOpFilter;
import parquet.filter2.compat.FilterCompat.Visitor;
import parquet.filter2.predicate.FilterPredicate;
import parquet.filter2.predicate.SchemaCompatibilityValidator;
import parquet.filter2.statisticslevel.StatisticsFilter;
import parquet.hadoop.metadata.BlockMetaData;
import parquet.schema.MessageType;

import static parquet.Preconditions.checkNotNull;

/**
 * Given a {@link Filter} applies it to a list of BlockMetaData (row groups)
 * If the Filter is an {@link parquet.filter.UnboundRecordFilter} or the no op filter,
 * no filtering will be performed.
 */
public class RowGroupFilter implements Visitor<List<BlockMetaData>> {
    private final List<BlockMetaData> blocks;
    private final MessageType schema;

    public static List<BlockMetaData> filterRowGroups(Filter filter, List<BlockMetaData> blocks, MessageType schema) {
        checkNotNull(filter, "filter");
        return filter.accept(new RowGroupFilter(blocks, schema));
    }

    private RowGroupFilter(List<BlockMetaData> blocks, MessageType schema) {
        this.blocks = checkNotNull(blocks, "blocks");
        this.schema = checkNotNull(schema, "schema");
    }

    @Override
    public List<BlockMetaData> visit(FilterCompat.FilterPredicateCompat filterPredicateCompat) {
        FilterPredicate filterPredicate = filterPredicateCompat.getFilterPredicate();

        // check that the schema of the filter matches the schema of the file
        SchemaCompatibilityValidator.validate(filterPredicate, schema);

        List<BlockMetaData> filteredBlocks = new ArrayList<BlockMetaData>();

        for (BlockMetaData block : blocks) {
            if (!StatisticsFilter.canDrop(filterPredicate, block.getColumns())) {
                filteredBlocks.add(block);
            }
        }

        return filteredBlocks;
    }

    @Override
    public List<BlockMetaData> visit(FilterCompat.UnboundRecordFilterCompat unboundRecordFilterCompat) {
        return blocks;
    }

    @Override
    public List<BlockMetaData> visit(NoOpFilter noOpFilter) {
        return blocks;
    }
}