andreschaffer/event-sourcing-cqrs-examples

package bankservice.projection.accounttransactions;

import static com.google.common.collect.Lists.newArrayList;
import static java.util.Collections.emptyList;
import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.toList;

import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Stream;

public class InMemoryTransactionsRepository implements TransactionsRepository {

  private Map<UUID, List<TransactionProjection>> accountTransactions = new ConcurrentHashMap<>();

  @Override
  public List<TransactionProjection> listByAccount(UUID accountId) {
    return accountTransactions.getOrDefault(accountId, emptyList()).stream()
        .sorted(comparing(TransactionProjection::getVersion))
        .collect(toList());
  }

  @Override
  public void save(TransactionProjection transactionProjection) {
    accountTransactions.merge(
        transactionProjection.getAccountId(),
        newArrayList(transactionProjection),
        (oldValue, value) -> Stream.concat(oldValue.stream(), value.stream()).collect(toList()));
  }
}