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 * 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
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 * <http://www.apache.org/>.
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package org.apache.http.conn.routing;

import java.net.InetAddress;

import org.apache.http.HttpHost;
import org.apache.http.util.Args;
import org.apache.http.util.Asserts;
import org.apache.http.util.LangUtils;

Helps tracking the steps in establishing a route.
Since:
4.0/**
 * Helps tracking the steps in establishing a route.
 *
 * @since 4.0
 */
public final class RouteTracker implements RouteInfo, Cloneable {

    
The target host to connect to. /** The target host to connect to. */
    private final HttpHost targetHost;

    
The local address to connect from. null indicates that the default should be used. /**
     * The local address to connect from.
     * {@code null} indicates that the default should be used.
     */
    private final InetAddress localAddress;

    // the attributes above are fixed at construction time
    // now follow attributes that indicate the established route

    
Whether the first hop of the route is established. /** Whether the first hop of the route is established. */
    private boolean connected;

    
The proxy chain, if any. /** The proxy chain, if any. */
    private HttpHost[] proxyChain;

    
Whether the the route is tunnelled end-to-end through proxies. /** Whether the the route is tunnelled end-to-end through proxies. */
    private TunnelType tunnelled;

    
Whether the route is layered over a tunnel. /** Whether the route is layered over a tunnel. */
    private LayerType layered;

    
Whether the route is secure. /** Whether the route is secure. */
    private boolean secure;

    
Creates a new route tracker.
The target and origin need to be specified at creation time.
Params:
target –    the host to which to route
local –  the local address to route from, or null for the default/**
     * Creates a new route tracker.
     * The target and origin need to be specified at creation time.
     *
     * @param target    the host to which to route
     * @param local     the local address to route from, or
     *                  {@code null} for the default
     */
    public RouteTracker(final HttpHost target, final InetAddress local) {
        Args.notNull(target, "Target host");
        this.targetHost   = target;
        this.localAddress = local;
        this.tunnelled    = TunnelType.PLAIN;
        this.layered      = LayerType.PLAIN;
    }

    
Since:
4.2/**
     * @since 4.2
     */
    public void reset() {
        this.connected = false;
        this.proxyChain = null;
        this.tunnelled = TunnelType.PLAIN;
        this.layered = LayerType.PLAIN;
        this.secure = false;
    }

    
Creates a new tracker for the given route.
Only target and origin are taken from the route,
everything else remains to be tracked.
Params:
route –     the route to track/**
     * Creates a new tracker for the given route.
     * Only target and origin are taken from the route,
     * everything else remains to be tracked.
     *
     * @param route     the route to track
     */
    public RouteTracker(final HttpRoute route) {
        this(route.getTargetHost(), route.getLocalAddress());
    }

    
Tracks connecting to the target.
Params:
secure –  true if the route is secure, false otherwise/**
     * Tracks connecting to the target.
     *
     * @param secure    {@code true} if the route is secure,
     *                  {@code false} otherwise
     */
    public final void connectTarget(final boolean secure) {
        Asserts.check(!this.connected, "Already connected");
        this.connected = true;
        this.secure = secure;
    }

    
Tracks connecting to the first proxy.
Params:
proxy –     the proxy connected to
secure –  true if the route is secure, false otherwise/**
     * Tracks connecting to the first proxy.
     *
     * @param proxy     the proxy connected to
     * @param secure    {@code true} if the route is secure,
     *                  {@code false} otherwise
     */
    public final void connectProxy(final HttpHost proxy, final boolean secure) {
        Args.notNull(proxy, "Proxy host");
        Asserts.check(!this.connected, "Already connected");
        this.connected  = true;
        this.proxyChain = new HttpHost[]{ proxy };
        this.secure     = secure;
    }

    
Tracks tunnelling to the target.
Params:
secure –  true if the route is secure, false otherwise/**
     * Tracks tunnelling to the target.
     *
     * @param secure    {@code true} if the route is secure,
     *                  {@code false} otherwise
     */
    public final void tunnelTarget(final boolean secure) {
        Asserts.check(this.connected, "No tunnel unless connected");
        Asserts.notNull(this.proxyChain, "No tunnel without proxy");
        this.tunnelled = TunnelType.TUNNELLED;
        this.secure    = secure;
    }

    
Tracks tunnelling to a proxy in a proxy chain.
This will extend the tracked proxy chain, but it does not mark
the route as tunnelled. Only end-to-end tunnels are considered there.
Params:
proxy –     the proxy tunnelled to
secure –  true if the route is secure, false otherwise/**
     * Tracks tunnelling to a proxy in a proxy chain.
     * This will extend the tracked proxy chain, but it does not mark
     * the route as tunnelled. Only end-to-end tunnels are considered there.
     *
     * @param proxy     the proxy tunnelled to
     * @param secure    {@code true} if the route is secure,
     *                  {@code false} otherwise
     */
    public final void tunnelProxy(final HttpHost proxy, final boolean secure) {
        Args.notNull(proxy, "Proxy host");
        Asserts.check(this.connected, "No tunnel unless connected");
        Asserts.notNull(this.proxyChain, "No tunnel without proxy");
        // prepare an extended proxy chain
        final HttpHost[] proxies = new HttpHost[this.proxyChain.length+1];
        System.arraycopy(this.proxyChain, 0,
                         proxies, 0, this.proxyChain.length);
        proxies[proxies.length-1] = proxy;

        this.proxyChain = proxies;
        this.secure     = secure;
    }

    
Tracks layering a protocol.
Params:
secure –  true if the route is secure, false otherwise/**
     * Tracks layering a protocol.
     *
     * @param secure    {@code true} if the route is secure,
     *                  {@code false} otherwise
     */
    public final void layerProtocol(final boolean secure) {
        // it is possible to layer a protocol over a direct connection,
        // although this case is probably not considered elsewhere
        Asserts.check(this.connected, "No layered protocol unless connected");
        this.layered = LayerType.LAYERED;
        this.secure  = secure;
    }

    @Override
    public final HttpHost getTargetHost() {
        return this.targetHost;
    }

    @Override
    public final InetAddress getLocalAddress() {
        return this.localAddress;
    }

    @Override
    public final int getHopCount() {
        int hops = 0;
        if (this.connected) {
            if (proxyChain == null) {
                hops = 1;
            } else {
                hops = proxyChain.length + 1;
            }
        }
        return hops;
    }

    @Override
    public final HttpHost getHopTarget(final int hop) {
        Args.notNegative(hop, "Hop index");
        final int hopcount = getHopCount();
        Args.check(hop < hopcount, "Hop index exceeds tracked route length");
        HttpHost result = null;
        if (hop < hopcount-1) {
            result = this.proxyChain[hop];
        } else {
            result = this.targetHost;
        }

        return result;
    }

    @Override
    public final HttpHost getProxyHost() {
        return (this.proxyChain == null) ? null : this.proxyChain[0];
    }

    public final boolean isConnected() {
        return this.connected;
    }

    @Override
    public final TunnelType getTunnelType() {
        return this.tunnelled;
    }

    @Override
    public final boolean isTunnelled() {
        return (this.tunnelled == TunnelType.TUNNELLED);
    }

    @Override
    public final LayerType getLayerType() {
        return this.layered;
    }

    @Override
    public final boolean isLayered() {
        return (this.layered == LayerType.LAYERED);
    }

    @Override
    public final boolean isSecure() {
        return this.secure;
    }

    
Obtains the tracked route. If a route has been tracked, it is connected. If not connected, nothing has been tracked so far. 
Returns:
 the tracked route, or null if nothing has been tracked so far/**
     * Obtains the tracked route.
     * If a route has been tracked, it is {@link #isConnected connected}.
     * If not connected, nothing has been tracked so far.
     *
     * @return  the tracked route, or
     *          {@code null} if nothing has been tracked so far
     */
    public final HttpRoute toRoute() {
        return !this.connected ?
            null : new HttpRoute(this.targetHost, this.localAddress,
                                 this.proxyChain, this.secure,
                                 this.tunnelled, this.layered);
    }

    
Compares this tracked route to another.
Params:
o –         the object to compare with
Returns:
 true if the argument is the same tracked route, false/**
     * Compares this tracked route to another.
     *
     * @param o         the object to compare with
     *
     * @return  {@code true} if the argument is the same tracked route,
     *          {@code false}
     */
    @Override
    public final boolean equals(final Object o) {
        if (o == this) {
            return true;
        }
        if (!(o instanceof RouteTracker)) {
            return false;
        }

        final RouteTracker that = (RouteTracker) o;
        return
            // Do the cheapest checks first
            (this.connected == that.connected) &&
            (this.secure    == that.secure) &&
            (this.tunnelled == that.tunnelled) &&
            (this.layered   == that.layered) &&
            LangUtils.equals(this.targetHost, that.targetHost) &&
            LangUtils.equals(this.localAddress, that.localAddress) &&
            LangUtils.equals(this.proxyChain, that.proxyChain);
    }

    
Generates a hash code for this tracked route. Route trackers are modifiable and should therefore not be used as lookup keys. Use toRoute to obtain an unmodifiable representation of the tracked route. 
Returns:
 the hash code/**
     * Generates a hash code for this tracked route.
     * Route trackers are modifiable and should therefore not be used
     * as lookup keys. Use {@link #toRoute toRoute} to obtain an
     * unmodifiable representation of the tracked route.
     *
     * @return  the hash code
     */
    @Override
    public final int hashCode() {
        int hash = LangUtils.HASH_SEED;
        hash = LangUtils.hashCode(hash, this.targetHost);
        hash = LangUtils.hashCode(hash, this.localAddress);
        if (this.proxyChain != null) {
            for (final HttpHost element : this.proxyChain) {
                hash = LangUtils.hashCode(hash, element);
            }
        }
        hash = LangUtils.hashCode(hash, this.connected);
        hash = LangUtils.hashCode(hash, this.secure);
        hash = LangUtils.hashCode(hash, this.tunnelled);
        hash = LangUtils.hashCode(hash, this.layered);
        return hash;
    }

    
Obtains a description of the tracked route.
Returns:
 a human-readable representation of the tracked route/**
     * Obtains a description of the tracked route.
     *
     * @return  a human-readable representation of the tracked route
     */
    @Override
    public final String toString() {
        final StringBuilder cab = new StringBuilder(50 + getHopCount()*30);

        cab.append("RouteTracker[");
        if (this.localAddress != null) {
            cab.append(this.localAddress);
            cab.append("->");
        }
        cab.append('{');
        if (this.connected) {
            cab.append('c');
        }
        if (this.tunnelled == TunnelType.TUNNELLED) {
            cab.append('t');
        }
        if (this.layered == LayerType.LAYERED) {
            cab.append('l');
        }
        if (this.secure) {
            cab.append('s');
        }
        cab.append("}->");
        if (this.proxyChain != null) {
            for (final HttpHost element : this.proxyChain) {
                cab.append(element);
                cab.append("->");
            }
        }
        cab.append(this.targetHost);
        cab.append(']');

        return cab.toString();
    }


    // default implementation of clone() is sufficient
    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

}