/**
 * DataCleaner (community edition)
 * Copyright (C) 2014 Neopost - Customer Information Management
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.datacleaner.job.runner;

import java.util.List;

import org.datacleaner.job.concurrent.PreviousErrorsExistException;
import org.datacleaner.job.concurrent.TaskListener;
import org.datacleaner.job.concurrent.TaskRunnable;
import org.datacleaner.job.concurrent.TaskRunner;
import org.datacleaner.job.tasks.Task;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Wrapper for the TaskRunner that only submits jobs when no errors have been
 * reported yet. This makes sure that a job will finish early if an error is
 * reported.
 */
final class ErrorAwareTaskRunnerWrapper implements TaskRunner, ErrorAware {

    private static final Logger logger = LoggerFactory.getLogger(ErrorAwareTaskRunnerWrapper.class);

    // A per-job exception is used if previous exceptions have been
    // reported. This is to make sure that the error message
    // ("A previous exception has occurred") will only be saved once.
    private final PreviousErrorsExistException _previousErrorsExistException =
            new PreviousErrorsExistException("A previous exception has occurred");

    private final TaskRunner _taskRunner;
    private final ErrorAware _errorAware;

    public ErrorAwareTaskRunnerWrapper(final ErrorAware errorAware, final TaskRunner taskRunner) {
        _taskRunner = taskRunner;
        _errorAware = errorAware;
    }

    @Override
    public void run(final Task task, final TaskListener taskListener) {
        if (isErrornous()) {
            taskListener.onError(task, _previousErrorsExistException);
        } else if (isCancelled()) {
            logger.info("Ignoring task because job has been cancelled: {}", task);
            taskListener.onError(task, _previousErrorsExistException);
        } else {
            _taskRunner.run(task, taskListener);
        }
    }

    @Override
    public void run(final TaskRunnable taskRunnable) {
        run(taskRunnable.getTask(), taskRunnable.getListener());
    }

    @Override
    public void shutdown() {
        _taskRunner.shutdown();
    }

    @Override
    public boolean isErrornous() {
        return _errorAware.isErrornous();
    }

    @Override
    public List<Throwable> getErrors() {
        return _errorAware.getErrors();
    }

    @Override
    public boolean isCancelled() {
        return _errorAware.isCancelled();
    }

    @Override
    public void assistExecution() {
        if (!isErrornous() && !isCancelled()) {
            _taskRunner.assistExecution();
        }
    }
}