/*
    * Copyright 2021 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:
    *
    *   https://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.netty5.handler.ssl;
  
  import io.netty.internal.tcnative.SSL;
  import io.netty5.util.AsciiString;
  
  import java.util.HashMap;
  import java.util.Map;
  
  /**
   * {@link OpenSslSessionCache} that is used by the client-side.
   */
  final class OpenSslClientSessionCache extends OpenSslSessionCache {
      // TODO: Should we support to have a List of OpenSslSessions for a Host/Port key and so be able to
      // support sessions for different protocols / ciphers to the same remote peer ?
      private final Map<HostPort, NativeSslSession> sessions = new HashMap<>();
  
      OpenSslClientSessionCache(OpenSslEngineMap engineMap) {
          super(engineMap);
      }
  
      @Override
      protected boolean sessionCreated(NativeSslSession session) {
          assert Thread.holdsLock(this);
          HostPort hostPort = keyFor(session.getPeerHost(), session.getPeerPort());
          if (hostPort == null || sessions.containsKey(hostPort)) {
              return false;
          }
          sessions.put(hostPort, session);
          return true;
      }
  
      @Override
      protected void sessionRemoved(NativeSslSession session) {
          assert Thread.holdsLock(this);
          HostPort hostPort = keyFor(session.getPeerHost(), session.getPeerPort());
          if (hostPort == null) {
              return;
          }
          sessions.remove(hostPort);
      }
  
      @Override
      void setSession(long ssl, String host, int port) {
          HostPort hostPort = keyFor(host, port);
          if (hostPort == null) {
              return;
          }
          final NativeSslSession session;
          final boolean reused;
          synchronized (this) {
              session = sessions.get(hostPort);
              if (session == null) {
                  return;
              }
              if (!session.isValid()) {
                  removeSessionWithId(session.sessionId());
                  return;
              }
              // Try to set the session, if true is returned OpenSSL incremented the reference count
              // of the underlying SSL_SESSION*.
              reused = SSL.setSession(ssl, session.session());
          }
  
          if (reused) {
              if (session.shouldBeSingleUse()) {
                  // Should only be used once
                  session.invalidate();
              }
              session.updateLastAccessedTime();
          }
      }
  
      private static HostPort keyFor(String host, int port) {
          if (host == null && port < 1) {
              return null;
          }
          return new HostPort(host, port);
      }
  
      @Override
      synchronized void clear() {
          super.clear();
          sessions.clear();
      }
 
     /**
      * Host / Port tuple used to find a {@link OpenSslSession} in the cache.
      */
     private static final class HostPort {
         private final int hash;
         private final String host;
         private final int port;
 
         HostPort(String host, int port) {
             this.host = host;
             this.port = port;
             // Calculate a hashCode that does ignore case.
             hash = 31 * AsciiString.hashCode(host) + port;
         }
 
         @Override
         public int hashCode() {
             return hash;
         }
 
         @Override
         public boolean equals(Object obj) {
             if (!(obj instanceof HostPort)) {
                 return false;
             }
             HostPort other = (HostPort) obj;
             return port == other.port && host.equalsIgnoreCase(other.host);
         }
 
         @Override
         public String toString() {
             return "HostPort{" +
                     "host='" + host + '\'' +
                     ", port=" + port +
                     '}';
         }
     }
 }