/*
 * Copyright (c) 2019 PANTHEON.tech, s.r.o. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.controller.remote.rpc;

import static java.util.Objects.requireNonNull;

import akka.dispatch.OnComplete;
import com.google.common.util.concurrent.AbstractFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import scala.concurrent.ExecutionContext;
import scala.concurrent.Future;

abstract class AbstractRemoteFuture<T, E extends Exception> extends AbstractFuture<T> {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractRemoteFuture.class);

    private final @NonNull SchemaPath type;

    AbstractRemoteFuture(final @NonNull SchemaPath type, final Future<Object> requestFuture) {
        this.type = requireNonNull(type);
        requestFuture.onComplete(new FutureUpdater(), ExecutionContext.Implicits$.MODULE$.global());
    }

    @Override
    public final T get() throws InterruptedException, ExecutionException {
        try {
            return super.get();
        } catch (ExecutionException e) {
            throw mapException(e);
        }
    }

    @Override
    public final T get(final long timeout, final TimeUnit unit)
            throws InterruptedException, ExecutionException, TimeoutException {
        try {
            return super.get(timeout, unit);
        } catch (final ExecutionException e) {
            throw mapException(e);
        }
    }

    @Override
    protected final boolean set(final T value) {
        final boolean ret = super.set(value);
        if (ret) {
            LOG.debug("Future {} for action {} successfully completed", this, type);
        }
        return ret;
    }

    final void failNow(final Throwable error) {
        LOG.debug("Failing future {} for operation {}", this, type, error);
        setException(error);
    }

    abstract @Nullable T processReply(Object reply);

    abstract @NonNull Class<E> exceptionClass();

    abstract @NonNull E wrapCause(Throwable cause);

    private ExecutionException mapException(final ExecutionException ex) {
        final Throwable cause = ex.getCause();
        return exceptionClass().isInstance(cause) ? ex : new ExecutionException(ex.getMessage(), wrapCause(cause));
    }

    private final class FutureUpdater extends OnComplete<Object> {
        @Override
        public void onComplete(final Throwable error, final Object reply) {
            if (error == null) {
                final T result = processReply(reply);
                if (result != null) {
                    LOG.debug("Received response for operation {}: result is {}", type, result);
                    set(result);
                } else {
                    failNow(new IllegalStateException("Incorrect reply type " + reply + " from Akka"));
                }
            } else {
                failNow(error);
            }
        }
    }
}