/*
 * ToroDB
 * Copyright © 2014 8Kdata Technology (www.8kdata.com)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.torodb.mongodb.repl.oplogreplier.fetcher;

import com.eightkdata.mongowp.server.api.oplog.OplogOperation;
import com.torodb.mongodb.repl.oplogreplier.FinishedOplogBatch;
import com.torodb.mongodb.repl.oplogreplier.NormalOplogBatch;
import com.torodb.mongodb.repl.oplogreplier.NotReadyForMoreOplogBatch;
import com.torodb.mongodb.repl.oplogreplier.OplogBatch;
import com.torodb.mongodb.repl.oplogreplier.RollbackReplicationException;
import com.torodb.mongodb.repl.oplogreplier.StopReplicationException;

import java.util.List;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class FilteredOplogFetcher implements OplogFetcher {

  private final Predicate<OplogOperation> filter;
  private final OplogFetcher delegate;

  public FilteredOplogFetcher(Predicate<OplogOperation> filter, OplogFetcher delegate) {
    this.filter = filter;
    this.delegate = delegate;
  }

  @Override
  public OplogBatch fetch() throws StopReplicationException, RollbackReplicationException {
    OplogBatch batch = delegate.fetch();

    List<OplogOperation> filteredBatch = batch.getOps().stream().filter(filter)
        .collect(Collectors.toList());

    if (filteredBatch.isEmpty()) {
      if (batch.isLastOne()) {
        return FinishedOplogBatch.getInstance();
      } else {
        return NotReadyForMoreOplogBatch.getInstance();
      }
    } else {
      if (batch.isLastOne()) {
        throw new AssertionError("Batchs produced by a finished oplog fetcher cannot "
            + "contain ops");
      }
      return new NormalOplogBatch(filteredBatch, batch.isReadyForMore());
    }
  }

  @Override
  public void close() {
    delegate.close();
  }

}