com.greensopinion.finance.services.transaction.TransactionNormalizer.java Source code

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Here is the source code for com.greensopinion.finance.services.transaction.TransactionNormalizer.java

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/*******************************************************************************
 * Copyright (c) 2015, 2016 David Green.
 *
 * Licensed 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 com.greensopinion.finance.services.transaction;

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

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Sets;
import com.greensopinion.finance.services.domain.Transaction;

public class TransactionNormalizer {
    /**
     * Removes transaction pairs that are self-canceling.
     */
    public List<Transaction> normalize(List<Transaction> transactions) {
        List<Transaction> normalizedTransactions = new ArrayList<>(transactions);

        ListMultimap<Long, Transaction> transactionByAbsoluteValue = ArrayListMultimap.create();
        for (Transaction transaction : transactions) {
            transactionByAbsoluteValue.put(Math.abs(transaction.getAmount()), transaction);
        }
        for (Long amount : transactionByAbsoluteValue.keySet()) {
            List<Transaction> list = transactionByAbsoluteValue.get(amount);
            Set<Transaction> canceledOut = Sets.newIdentityHashSet();
            for (Transaction transaction : list) {
                if (canceledOut.contains(transaction)) {
                    continue;
                }
                for (Transaction transaction2 : list) {
                    if (transaction.getAmount() == -transaction2.getAmount()
                            && !canceledOut.contains(transaction2)) {
                        canceledOut.add(transaction);
                        canceledOut.add(transaction2);
                        break;
                    }
                }
            }
            normalizedTransactions.removeAll(canceledOut);
        }

        return normalizedTransactions;
    }
}