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/**
 * Copyright 2013 Google Inc.
 *
 * 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.google.bitcoin.utils;

import com.google.bitcoin.core.Transaction;
import com.google.bitcoin.core.TransactionBroadcaster;
import com.google.bitcoin.core.VerificationException;
import com.google.bitcoin.core.Wallet;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.SettableFuture;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.locks.ReentrantLock;

/**
 * A mock transaction broadcaster can be used in unit tests as a stand-in for a PeerGroup. It catches any transactions
 * broadcast through it and makes them available via the {@link #broadcasts} member. Reading from that
 * {@link LinkedBlockingQueue} will block the thread until a transaction is available.
 */
public class MockTransactionBroadcaster implements TransactionBroadcaster {
    private final ReentrantLock lock = Threading.lock("mock tx broadcaster");
    private final Wallet wallet;

    public static class TxFuturePair {
        public Transaction tx;
        public SettableFuture future;

        public TxFuturePair(Transaction tx, SettableFuture future) {
            this.tx = tx;
            this.future = future;
        }
    }

    private final LinkedBlockingQueue broadcasts = new LinkedBlockingQueue();

    public MockTransactionBroadcaster(Wallet wallet) {
        // This code achieves nothing directly, but it sets up the broadcaster/peergroup > wallet lock ordering
        // so inversions can be caught.
        lock.lock();
        try {
            this.wallet = wallet;
            wallet.getPendingTransactions();
        } finally {
            lock.unlock();
        }
    }

    @Override
    public SettableFuture broadcastTransaction(Transaction tx) {
        // Use a lock just to catch lock ordering inversions e.g. wallet->broadcaster.
        lock.lock();
        try {
            SettableFuture result = SettableFuture.create();
            broadcasts.put(new TxFuturePair(tx, result));
            Futures.addCallback(result, new FutureCallback() {
                @Override
                public void onSuccess(Transaction result) {
                    try {
                        wallet.receivePending(result, null);
                    } catch (VerificationException e) {
                        throw new RuntimeException(e);
                    }
                }

                @Override
                public void onFailure(Throwable t) {
                }
            });
            return result;
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            lock.unlock();
        }
    }

    public Transaction waitForTransaction() {
        return waitForTxFuture().tx;
    }

    public TxFuturePair waitForTxFuture() {
        try {
            return broadcasts.take();
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    public int size() {
        return broadcasts.size();
    }
}