/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.conn;


import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.ProxySelector;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;

import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.conn.params.ConnRouteParams;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.routing.HttpRoutePlanner;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Args;
import org.apache.http.util.Asserts;


Default implementation of an HttpRoutePlanner. This implementation is based on ProxySelector. By default, it will pick up the proxy settings of the JVM, either from system properties or from the browser running the application. Additionally, it interprets some parameters, though not the DEFAULT_PROXY. 

The following parameters can be used to customize the behavior of this
class:

 
ConnRoutePNames.LOCAL_ADDRESS
 
ConnRoutePNames.FORCED_ROUTE

Since:
4.0
Deprecated:
(4.3) use SystemDefaultRoutePlanner/**
 * Default implementation of an {@link HttpRoutePlanner}.
 * This implementation is based on {@link java.net.ProxySelector}.
 * By default, it will pick up the proxy settings of the JVM, either
 * from system properties or from the browser running the application.
 * Additionally, it interprets some
 * {@link org.apache.http.conn.params.ConnRoutePNames parameters},
 * though not the {@link
 * org.apache.http.conn.params.ConnRoutePNames#DEFAULT_PROXY DEFAULT_PROXY}.
 * <p>
 * The following parameters can be used to customize the behavior of this
 * class:
 * <ul>
 *  <li>{@link org.apache.http.conn.params.ConnRoutePNames#LOCAL_ADDRESS}</li>
 *  <li>{@link org.apache.http.conn.params.ConnRoutePNames#FORCED_ROUTE}</li>
 * </ul>
 *
 * @since 4.0
 *
 * @deprecated (4.3) use {@link SystemDefaultRoutePlanner}
 */
@Deprecated
public class ProxySelectorRoutePlanner implements HttpRoutePlanner {

    
The scheme registry. /** The scheme registry. */
    protected final SchemeRegistry schemeRegistry; // @Contract(threading = ThreadingBehavior.SAFE)

    
The proxy selector to use, or null for system default. /** The proxy selector to use, or {@code null} for system default. */
    protected ProxySelector proxySelector;

    
Creates a new proxy selector route planner.
Params:
schreg –    the scheme registry
prosel –  the proxy selector, or null for the system default/**
     * Creates a new proxy selector route planner.
     *
     * @param schreg    the scheme registry
     * @param prosel    the proxy selector, or
     *                  {@code null} for the system default
     */
    public ProxySelectorRoutePlanner(final SchemeRegistry schreg,
                                     final ProxySelector prosel) {
        Args.notNull(schreg, "SchemeRegistry");
        schemeRegistry = schreg;
        proxySelector  = prosel;
    }

    
Obtains the proxy selector to use.
Returns:
the proxy selector, or null for the system default/**
     * Obtains the proxy selector to use.
     *
     * @return the proxy selector, or {@code null} for the system default
     */
    public ProxySelector getProxySelector() {
        return this.proxySelector;
    }

    
Sets the proxy selector to use.
Params:
prosel –  the proxy selector, or null to use the system default/**
     * Sets the proxy selector to use.
     *
     * @param prosel    the proxy selector, or
     *                  {@code null} to use the system default
     */
    public void setProxySelector(final ProxySelector prosel) {
        this.proxySelector = prosel;
    }

    @Override
    public HttpRoute determineRoute(final HttpHost target,
                                    final HttpRequest request,
                                    final HttpContext context)
        throws HttpException {

        Args.notNull(request, "HTTP request");

        // If we have a forced route, we can do without a target.
        HttpRoute route =
            ConnRouteParams.getForcedRoute(request.getParams());
        if (route != null) {
            return route;
        }

        // If we get here, there is no forced route.
        // So we need a target to compute a route.

        Asserts.notNull(target, "Target host");

        final InetAddress local =
            ConnRouteParams.getLocalAddress(request.getParams());
        final HttpHost proxy = determineProxy(target, request, context);

        final Scheme schm =
            this.schemeRegistry.getScheme(target.getSchemeName());
        // as it is typically used for TLS/SSL, we assume that
        // a layered scheme implies a secure connection
        final boolean secure = schm.isLayered();

        if (proxy == null) {
            route = new HttpRoute(target, local, secure);
        } else {
            route = new HttpRoute(target, local, proxy, secure);
        }
        return route;
    }

    
Determines a proxy for the given target.
Params:
target –  the planned target, never null
request –  the request to be sent, never null
context –  the context, or null
Throws:
HttpException – 
        in case of system proxy settings that cannot be handled
Returns:
 the proxy to use, or null for a direct route/**
     * Determines a proxy for the given target.
     *
     * @param target    the planned target, never {@code null}
     * @param request   the request to be sent, never {@code null}
     * @param context   the context, or {@code null}
     *
     * @return  the proxy to use, or {@code null} for a direct route
     *
     * @throws HttpException
     *         in case of system proxy settings that cannot be handled
     */
    protected HttpHost determineProxy(final HttpHost    target,
                                      final HttpRequest request,
                                      final HttpContext context)
        throws HttpException {

        // the proxy selector can be 'unset', so we better deal with null here
        ProxySelector psel = this.proxySelector;
        if (psel == null) {
            psel = ProxySelector.getDefault();
        }
        if (psel == null) {
            return null;
        }

        URI targetURI = null;
        try {
            targetURI = new URI(target.toURI());
        } catch (final URISyntaxException usx) {
            throw new HttpException
                ("Cannot convert host to URI: " + target, usx);
        }
        final List<Proxy> proxies = psel.select(targetURI);

        final Proxy p = chooseProxy(proxies, target, request, context);

        HttpHost result = null;
        if (p.type() == Proxy.Type.HTTP) {
            // convert the socket address to an HttpHost
            if (!(p.address() instanceof InetSocketAddress)) {
                throw new HttpException
                    ("Unable to handle non-Inet proxy address: "+p.address());
            }
            final InetSocketAddress isa = (InetSocketAddress) p.address();
            // assume default scheme (http)
            result = new HttpHost(getHost(isa), isa.getPort());
        }

        return result;
    }

    
Obtains a host from an InetSocketAddress. 
Params:
isa –       the socket address
Returns:
 a host string, either as a symbolic name or
         as a literal IP address string

(TODO: determine format for IPv6 addresses, with or without [brackets])
/**
     * Obtains a host from an {@link InetSocketAddress}.
     *
     * @param isa       the socket address
     *
     * @return  a host string, either as a symbolic name or
     *          as a literal IP address string
     * <p>
     * (TODO: determine format for IPv6 addresses, with or without [brackets])
     * </p>
     */
    protected String getHost(final InetSocketAddress isa) {

        //@@@ Will this work with literal IPv6 addresses, or do we
        //@@@ need to wrap these in [] for the string representation?
        //@@@ Having it in this method at least allows for easy workarounds.
       return isa.isUnresolved() ?
            isa.getHostName() : isa.getAddress().getHostAddress();

    }

    
Chooses a proxy from a list of available proxies. The default implementation just picks the first non-SOCKS proxy from the list. If there are only SOCKS proxies, Proxy.NO_PROXY is returned. Derived classes may implement more advanced strategies, such as proxy rotation if there are multiple options. 
Params:
proxies –  the list of proxies to choose from, never null or empty
target –  the planned target, never null
request –  the request to be sent, never null
context –  the context, or null
Returns:
 a proxy type/**
     * Chooses a proxy from a list of available proxies.
     * The default implementation just picks the first non-SOCKS proxy
     * from the list. If there are only SOCKS proxies,
     * {@link Proxy#NO_PROXY Proxy.NO_PROXY} is returned.
     * Derived classes may implement more advanced strategies,
     * such as proxy rotation if there are multiple options.
     *
     * @param proxies   the list of proxies to choose from,
     *                  never {@code null} or empty
     * @param target    the planned target, never {@code null}
     * @param request   the request to be sent, never {@code null}
     * @param context   the context, or {@code null}
     *
     * @return  a proxy type
     */
    protected Proxy chooseProxy(final List<Proxy> proxies,
                                final HttpHost    target,
                                final HttpRequest request,
                                final HttpContext context) {
        Args.notEmpty(proxies, "List of proxies");

        Proxy result = null;

        // check the list for one we can use
        for (int i=0; (result == null) && (i < proxies.size()); i++) {

            final Proxy p = proxies.get(i);
            switch (p.type()) {

            case DIRECT:
            case HTTP:
                result = p;
                break;

            case SOCKS:
                // SOCKS hosts are not handled on the route level.
                // The socket may make use of the SOCKS host though.
                break;
            }
        }

        if (result == null) {
            //@@@ log as warning or info that only a socks proxy is available?
            // result can only be null if all proxies are socks proxies
            // socks proxies are not handled on the route planning level
            result = Proxy.NO_PROXY;
        }

        return result;
    }

}