/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you 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 io.netty.resolver;

import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
import io.netty.util.concurrent.Promise;
import io.netty.util.internal.UnstableApi;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;

/**
 * A {@link AbstractAddressResolver} that resolves {@link InetSocketAddress}.
 */
@UnstableApi
public class InetSocketAddressResolver extends AbstractAddressResolver<InetSocketAddress> {

    final NameResolver<InetAddress> nameResolver;

    /**
     * @param executor the {@link EventExecutor} which is used to notify the listeners of the {@link Future} returned
     *                 by {@link #resolve(java.net.SocketAddress)}
     * @param nameResolver the {@link NameResolver} used for name resolution
     */
    public InetSocketAddressResolver(EventExecutor executor, NameResolver<InetAddress> nameResolver) {
        super(executor, InetSocketAddress.class);
        this.nameResolver = nameResolver;
    }

    @Override
    protected boolean doIsResolved(InetSocketAddress address) {
        return !address.isUnresolved();
    }

    @Override
    protected void doResolve(final InetSocketAddress unresolvedAddress, final Promise<InetSocketAddress> promise)
            throws Exception {
        // Note that InetSocketAddress.getHostName() will never incur a reverse lookup here,
        // because an unresolved address always has a host name.
        nameResolver.resolve(unresolvedAddress.getHostName())
                .addListener(new FutureListener<InetAddress>() {
                    @Override
                    public void operationComplete(Future<InetAddress> future) throws Exception {
                        if (future.isSuccess()) {
                            promise.setSuccess(new InetSocketAddress(future.getNow(), unresolvedAddress.getPort()));
                        } else {
                            promise.setFailure(future.cause());
                        }
                    }
                });
    }

    @Override
    protected void doResolveAll(final InetSocketAddress unresolvedAddress,
                                final Promise<List<InetSocketAddress>> promise) throws Exception {
        // Note that InetSocketAddress.getHostName() will never incur a reverse lookup here,
        // because an unresolved address always has a host name.
        nameResolver.resolveAll(unresolvedAddress.getHostName())
                .addListener(new FutureListener<List<InetAddress>>() {
                    @Override
                    public void operationComplete(Future<List<InetAddress>> future) throws Exception {
                        if (future.isSuccess()) {
                            List<InetAddress> inetAddresses = future.getNow();
                            List<InetSocketAddress> socketAddresses =
                                    new ArrayList<InetSocketAddress>(inetAddresses.size());
                            for (InetAddress inetAddress : inetAddresses) {
                                socketAddresses.add(new InetSocketAddress(inetAddress, unresolvedAddress.getPort()));
                            }
                            promise.setSuccess(socketAddresses);
                        } else {
                            promise.setFailure(future.cause());
                        }
                    }
                });
    }

    @Override
    public void close() {
        nameResolver.close();
    }
}
