/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.core.util.queue;

import org.mule.runtime.core.util.journal.queue.LocalQueueTxJournalEntry;
import org.mule.runtime.core.util.journal.queue.LocalTxQueueTransactionJournal;
import org.mule.runtime.core.util.xa.ResourceManagerException;

import java.io.Serializable;
import java.util.Collection;

/**
 * {@link LocalQueueTransactionContext} implementation for a persistent queue.
 */
public class PersistentQueueTransactionContext implements LocalQueueTransactionContext {

  private static int lastId = 0;
  private final LocalTxQueueTransactionJournal transactionJournal;
  private final QueueProvider queueProvider;
  private int txId;

  public PersistentQueueTransactionContext(LocalTxQueueTransactionJournal localTxQueueTransactionJournal,
                                           QueueProvider queueProvider) {
    this.transactionJournal = localTxQueueTransactionJournal;
    this.queueProvider = queueProvider;
    this.txId = getNextId();
  }

  private synchronized static int getNextId() {
    int nextId = lastId++;
    if (nextId < 0) {
      nextId = lastId = 0;
    }
    return nextId;
  }

  public boolean offer(QueueStore queue, Serializable item, long offerTimeout) throws InterruptedException {
    this.transactionJournal.logAdd(txId, queue, item);
    return true;
  }

  public void untake(QueueStore queue, Serializable item) throws InterruptedException {
    this.transactionJournal.logAddFirst(txId, queue, item);
  }

  public void clear(QueueStore queue) throws InterruptedException {
    synchronized (queue) {
      while (poll(queue, 10) != null);
    }
  }

  public Serializable poll(QueueStore queue, long pollTimeout) throws InterruptedException {
    synchronized (queue) {
      Serializable value = queue.peek();
      if (value == null) {
        return null;
      }
      this.transactionJournal.logRemove(txId, queue, value);
      return queue.poll(pollTimeout);
    }
  }

  public Serializable peek(QueueStore queue) throws InterruptedException {
    return queue.peek();
  }

  public int size(final QueueStore queue) {
    int numberOfElementsAdded = 0;
    Collection<LocalQueueTxJournalEntry> logEntries = this.transactionJournal.getLogEntriesForTx(txId);
    for (LocalQueueTxJournalEntry logEntry : logEntries) {
      if (logEntry.getQueueName().equals(queue.getName()) && (logEntry.isAdd() || logEntry.isAddFirst())) {
        numberOfElementsAdded++;
      }
    }
    return queue.getSize() + numberOfElementsAdded;
  }

  @Override
  public void doCommit() throws ResourceManagerException {
    try {
      Collection<LocalQueueTxJournalEntry> logEntries = this.transactionJournal.getLogEntriesForTx(txId);
      for (LocalQueueTxJournalEntry entry : logEntries) {
        if (entry.isAdd()) {
          queueProvider.getQueue(entry.getQueueName()).putNow(entry.getValue());
        } else if (entry.isAddFirst()) {
          queueProvider.getQueue(entry.getQueueName()).untake(entry.getValue());
        }
      }
      this.transactionJournal.logCommit(txId);
    } catch (Exception e) {
      throw new ResourceManagerException(e);
    }
  }

  @Override
  public void doRollback() throws ResourceManagerException {
    Collection<LocalQueueTxJournalEntry> logEntries = this.transactionJournal.getLogEntriesForTx(txId);
    for (LocalQueueTxJournalEntry entry : logEntries) {
      if (entry.isRemove()) {
        try {
          queueProvider.getQueue(entry.getQueueName()).putNow(entry.getValue());
        } catch (InterruptedException e) {
          throw new ResourceManagerException(e);
        }
      }
    }
    this.transactionJournal.logRollback(txId);
  }

}