/*
    * ====================================================================
    * 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.conn.routing;
  
  import java.net.InetAddress;
  
  import org.apache.http.annotation.NotThreadSafe;
  import org.apache.http.util.LangUtils;
  
  import org.apache.http.HttpHost;
  
  /**
   * Helps tracking the steps in establishing a route.
   *
   * @since 4.0
   */
  @NotThreadSafe
  public final class RouteTracker implements RouteInfo, Cloneable {
  
      /** The target host to connect to. */
      private final HttpHost targetHost;
  
      /**
       * The local address to connect from.
       * <code>null</code> 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. */
      private boolean connected;
  
      /** The proxy chain, if any. */
      private HttpHost[] proxyChain;
  
      /** Whether the the route is tunnelled end-to-end through proxies. */
      private TunnelType tunnelled;
  
      /** Whether the route is layered over a tunnel. */
      private LayerType layered;
  
      /** Whether the route is secure. */
      private boolean secure;
  
      /**
       * 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</code> for the default
       */
      public RouteTracker(HttpHost target, InetAddress local) {
          if (target == null) {
              throw new IllegalArgumentException("Target host may not be null.");
          }
          this.targetHost   = target;
          this.localAddress = local;
          this.tunnelled    = TunnelType.PLAIN;
          this.layered      = LayerType.PLAIN;
      }
  
      /**
       * @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.
      *
      * @param route     the route to track
      */
     public RouteTracker(HttpRoute route) {
         this(route.getTargetHost(), route.getLocalAddress());
     }
 
     /**
      * Tracks connecting to the target.
      *
      * @param secure    <code>true</code> if the route is secure,
      *                  <code>false</code> otherwise
      */
     public final void connectTarget(boolean secure) {
         if (this.connected) {
             throw new IllegalStateException("Already connected.");
         }
         this.connected = true;
         this.secure = secure;
     }
 
     /**
      * Tracks connecting to the first proxy.
      *
      * @param proxy     the proxy connected to
      * @param secure    <code>true</code> if the route is secure,
      *                  <code>false</code> otherwise
      */
     public final void connectProxy(HttpHost proxy, boolean secure) {
         if (proxy == null) {
             throw new IllegalArgumentException("Proxy host may not be null.");
         }
         if (this.connected) {
             throw new IllegalStateException("Already connected.");
         }
         this.connected  = true;
         this.proxyChain = new HttpHost[]{ proxy };
         this.secure     = secure;
     }
 
     /**
      * Tracks tunnelling to the target.
      *
      * @param secure    <code>true</code> if the route is secure,
      *                  <code>false</code> otherwise
      */
     public final void tunnelTarget(boolean secure) {
         if (!this.connected) {
             throw new IllegalStateException("No tunnel unless connected.");
         }
         if (this.proxyChain == null) {
             throw new IllegalStateException("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.
      *
      * @param proxy     the proxy tunnelled to
      * @param secure    <code>true</code> if the route is secure,
      *                  <code>false</code> otherwise
      */
     public final void tunnelProxy(HttpHost proxy, boolean secure) {
         if (proxy == null) {
             throw new IllegalArgumentException("Proxy host may not be null.");
         }
         if (!this.connected) {
             throw new IllegalStateException("No tunnel unless connected.");
         }
         if (this.proxyChain == null) {
             throw new IllegalStateException("No proxy tunnel without proxy.");
         }
 
         // prepare an extended proxy chain
         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.
      *
      * @param secure    <code>true</code> if the route is secure,
      *                  <code>false</code> otherwise
      */
     public final void layerProtocol(boolean secure) {
         // it is possible to layer a protocol over a direct connection,
         // although this case is probably not considered elsewhere
         if (!this.connected) {
             throw new IllegalStateException
                 ("No layered protocol unless connected.");
         }
         this.layered = LayerType.LAYERED;
         this.secure  = secure;
     }
 
     public final HttpHost getTargetHost() {
         return this.targetHost;
     }
 
     public final InetAddress getLocalAddress() {
         return this.localAddress;
     }
 
     public final int getHopCount() {
         int hops = 0;
         if (this.connected) {
             if (proxyChain == null)
                 hops = 1;
             else
                 hops = proxyChain.length + 1;
         }
         return hops;
     }
 
     public final HttpHost getHopTarget(int hop) {
         if (hop < 0)
             throw new IllegalArgumentException
                 ("Hop index must not be negative: " + hop);
         final int hopcount = getHopCount();
         if (hop >= hopcount) {
             throw new IllegalArgumentException
                 ("Hop index " + hop +
                  " exceeds tracked route length " + hopcount +".");
         }
 
         HttpHost result = null;
         if (hop < hopcount-1)
             result = this.proxyChain[hop];
         else
             result = this.targetHost;
 
         return result;
     }
 
     public final HttpHost getProxyHost() {
         return (this.proxyChain == null) ? null : this.proxyChain[0];
     }
 
     public final boolean isConnected() {
         return this.connected;
     }
 
     public final TunnelType getTunnelType() {
         return this.tunnelled;
     }
 
     public final boolean isTunnelled() {
         return (this.tunnelled == TunnelType.TUNNELLED);
     }
 
     public final LayerType getLayerType() {
         return this.layered;
     }
 
     public final boolean isLayered() {
         return (this.layered == LayerType.LAYERED);
     }
 
     public final boolean isSecure() {
         return this.secure;
     }
 
     /**
      * 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</code> 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.
      *
      * @param o         the object to compare with
      *
      * @return  <code>true</code> if the argument is the same tracked route,
      *          <code>false</code>
      */
     @Override
     public final boolean equals(Object o) {
         if (o == this)
             return true;
         if (!(o instanceof RouteTracker))
             return false;
 
         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 {@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 (int i = 0; i < this.proxyChain.length; i++) {
                 hash = LangUtils.hashCode(hash, this.proxyChain[i]);
             }
         }
         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.
      *
      * @return  a human-readable representation of the tracked route
      */
     @Override
     public final String toString() {
         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 (int i=0; i<this.proxyChain.length; i++) {
                 cab.append(this.proxyChain[i]);
                 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();
     }
 
 }