/*
    * Copyright 2012 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.netty.handler.codec.spdy;
  
  import io.netty.channel.ChannelPromise;
  import io.netty.util.internal.PlatformDependent;
  
  import java.util.Comparator;
  import java.util.Map;
  import java.util.Queue;
  import java.util.TreeMap;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import static io.netty.handler.codec.spdy.SpdyCodecUtil.*;
  
  final class SpdySession {
  
      private final AtomicInteger activeLocalStreams  = new AtomicInteger();
      private final AtomicInteger activeRemoteStreams = new AtomicInteger();
      private final Map<Integer, StreamState> activeStreams = PlatformDependent.newConcurrentHashMap();
      private final StreamComparator streamComparator = new StreamComparator();
      private final AtomicInteger sendWindowSize;
      private final AtomicInteger receiveWindowSize;
  
      SpdySession(int sendWindowSize, int receiveWindowSize) {
          this.sendWindowSize = new AtomicInteger(sendWindowSize);
          this.receiveWindowSize = new AtomicInteger(receiveWindowSize);
      }
  
      int numActiveStreams(boolean remote) {
          if (remote) {
              return activeRemoteStreams.get();
          } else {
              return activeLocalStreams.get();
          }
      }
  
      boolean noActiveStreams() {
          return activeStreams.isEmpty();
      }
  
      boolean isActiveStream(int streamId) {
          return activeStreams.containsKey(streamId);
      }
  
      // Stream-IDs should be iterated in priority order
      Map<Integer, StreamState> activeStreams() {
          Map<Integer, StreamState> streams = new TreeMap<Integer, StreamState>(streamComparator);
          streams.putAll(activeStreams);
          return streams;
      }
  
      void acceptStream(
              int streamId, byte priority, boolean remoteSideClosed, boolean localSideClosed,
              int sendWindowSize, int receiveWindowSize, boolean remote) {
          if (!remoteSideClosed || !localSideClosed) {
              StreamState state = activeStreams.put(streamId, new StreamState(
                      priority, remoteSideClosed, localSideClosed, sendWindowSize, receiveWindowSize));
              if (state == null) {
                  if (remote) {
                      activeRemoteStreams.incrementAndGet();
                  } else {
                      activeLocalStreams.incrementAndGet();
                  }
              }
          }
      }
  
      private StreamState removeActiveStream(int streamId, boolean remote) {
          StreamState state = activeStreams.remove(streamId);
          if (state != null) {
              if (remote) {
                  activeRemoteStreams.decrementAndGet();
              } else {
                  activeLocalStreams.decrementAndGet();
              }
          }
          return state;
      }
  
      void removeStream(int streamId, Throwable cause, boolean remote) {
          StreamState state = removeActiveStream(streamId, remote);
          if (state != null) {
              state.clearPendingWrites(cause);
          }
     }
 
     boolean isRemoteSideClosed(int streamId) {
         StreamState state = activeStreams.get(streamId);
         return state == null || state.isRemoteSideClosed();
     }
 
     void closeRemoteSide(int streamId, boolean remote) {
         StreamState state = activeStreams.get(streamId);
         if (state != null) {
             state.closeRemoteSide();
             if (state.isLocalSideClosed()) {
                 removeActiveStream(streamId, remote);
             }
         }
     }
 
     boolean isLocalSideClosed(int streamId) {
         StreamState state = activeStreams.get(streamId);
         return state == null || state.isLocalSideClosed();
     }
 
     void closeLocalSide(int streamId, boolean remote) {
         StreamState state = activeStreams.get(streamId);
         if (state != null) {
             state.closeLocalSide();
             if (state.isRemoteSideClosed()) {
                 removeActiveStream(streamId, remote);
             }
         }
     }
 
     /*
      * hasReceivedReply and receivedReply are only called from channelRead()
      * no need to synchronize access to the StreamState
      */
     boolean hasReceivedReply(int streamId) {
         StreamState state = activeStreams.get(streamId);
         return state != null && state.hasReceivedReply();
     }
 
     void receivedReply(int streamId) {
         StreamState state = activeStreams.get(streamId);
         if (state != null) {
             state.receivedReply();
         }
     }
 
     int getSendWindowSize(int streamId) {
         if (streamId == SPDY_SESSION_STREAM_ID) {
             return sendWindowSize.get();
         }
 
         StreamState state = activeStreams.get(streamId);
         return state != null ? state.getSendWindowSize() : -1;
     }
 
     int updateSendWindowSize(int streamId, int deltaWindowSize) {
         if (streamId == SPDY_SESSION_STREAM_ID) {
             return sendWindowSize.addAndGet(deltaWindowSize);
         }
 
         StreamState state = activeStreams.get(streamId);
         return state != null ? state.updateSendWindowSize(deltaWindowSize) : -1;
     }
 
     int updateReceiveWindowSize(int streamId, int deltaWindowSize) {
         if (streamId == SPDY_SESSION_STREAM_ID) {
             return receiveWindowSize.addAndGet(deltaWindowSize);
         }
 
         StreamState state = activeStreams.get(streamId);
         if (state == null) {
             return -1;
         }
         if (deltaWindowSize > 0) {
             state.setReceiveWindowSizeLowerBound(0);
         }
         return state.updateReceiveWindowSize(deltaWindowSize);
     }
 
     int getReceiveWindowSizeLowerBound(int streamId) {
         if (streamId == SPDY_SESSION_STREAM_ID) {
             return 0;
         }
 
         StreamState state = activeStreams.get(streamId);
         return state != null ? state.getReceiveWindowSizeLowerBound() : 0;
     }
 
     void updateAllSendWindowSizes(int deltaWindowSize) {
         for (StreamState state: activeStreams.values()) {
             state.updateSendWindowSize(deltaWindowSize);
         }
     }
 
     void updateAllReceiveWindowSizes(int deltaWindowSize) {
         for (StreamState state: activeStreams.values()) {
             state.updateReceiveWindowSize(deltaWindowSize);
             if (deltaWindowSize < 0) {
                 state.setReceiveWindowSizeLowerBound(deltaWindowSize);
             }
         }
     }
 
     boolean putPendingWrite(int streamId, PendingWrite pendingWrite) {
         StreamState state = activeStreams.get(streamId);
         return state != null && state.putPendingWrite(pendingWrite);
     }
 
     PendingWrite getPendingWrite(int streamId) {
         if (streamId == SPDY_SESSION_STREAM_ID) {
             for (Map.Entry<Integer, StreamState> e: activeStreams().entrySet()) {
                 StreamState state = e.getValue();
                 if (state.getSendWindowSize() > 0) {
                     PendingWrite pendingWrite = state.getPendingWrite();
                     if (pendingWrite != null) {
                         return pendingWrite;
                     }
                 }
             }
             return null;
         }
 
         StreamState state = activeStreams.get(streamId);
         return state != null ? state.getPendingWrite() : null;
     }
 
     PendingWrite removePendingWrite(int streamId) {
         StreamState state = activeStreams.get(streamId);
         return state != null ? state.removePendingWrite() : null;
     }
 
     private static final class StreamState {
 
         private final byte priority;
         private boolean remoteSideClosed;
         private boolean localSideClosed;
         private boolean receivedReply;
         private final AtomicInteger sendWindowSize;
         private final AtomicInteger receiveWindowSize;
         private int receiveWindowSizeLowerBound;
         private final Queue<PendingWrite> pendingWriteQueue = new ConcurrentLinkedQueue<PendingWrite>();
 
         StreamState(
                 byte priority, boolean remoteSideClosed, boolean localSideClosed,
                 int sendWindowSize, int receiveWindowSize) {
             this.priority = priority;
             this.remoteSideClosed = remoteSideClosed;
             this.localSideClosed = localSideClosed;
             this.sendWindowSize = new AtomicInteger(sendWindowSize);
             this.receiveWindowSize = new AtomicInteger(receiveWindowSize);
         }
 
         byte getPriority() {
             return priority;
         }
 
         boolean isRemoteSideClosed() {
             return remoteSideClosed;
         }
 
         void closeRemoteSide() {
             remoteSideClosed = true;
         }
 
         boolean isLocalSideClosed() {
             return localSideClosed;
         }
 
         void closeLocalSide() {
             localSideClosed = true;
         }
 
         boolean hasReceivedReply() {
             return receivedReply;
         }
 
         void receivedReply() {
             receivedReply = true;
         }
 
         int getSendWindowSize() {
             return sendWindowSize.get();
         }
 
         int updateSendWindowSize(int deltaWindowSize) {
             return sendWindowSize.addAndGet(deltaWindowSize);
         }
 
         int updateReceiveWindowSize(int deltaWindowSize) {
             return receiveWindowSize.addAndGet(deltaWindowSize);
         }
 
         int getReceiveWindowSizeLowerBound() {
             return receiveWindowSizeLowerBound;
         }
 
         void setReceiveWindowSizeLowerBound(int receiveWindowSizeLowerBound) {
             this.receiveWindowSizeLowerBound = receiveWindowSizeLowerBound;
         }
 
         boolean putPendingWrite(PendingWrite msg) {
             return pendingWriteQueue.offer(msg);
         }
 
         PendingWrite getPendingWrite() {
             return pendingWriteQueue.peek();
         }
 
         PendingWrite removePendingWrite() {
             return pendingWriteQueue.poll();
         }
 
         void clearPendingWrites(Throwable cause) {
             for (;;) {
                 PendingWrite pendingWrite = pendingWriteQueue.poll();
                 if (pendingWrite == null) {
                     break;
                 }
                 pendingWrite.fail(cause);
             }
         }
     }
 
     private final class StreamComparator implements Comparator<Integer> {
 
         StreamComparator() { }
 
         @Override
         public int compare(Integer id1, Integer id2) {
             StreamState state1 = activeStreams.get(id1);
             StreamState state2 = activeStreams.get(id2);
 
             int result = state1.getPriority() - state2.getPriority();
             if (result != 0) {
                 return result;
             }
 
             return id1 - id2;
         }
     }
 
     public static final class PendingWrite {
         final SpdyDataFrame spdyDataFrame;
         final ChannelPromise promise;
 
         PendingWrite(SpdyDataFrame spdyDataFrame, ChannelPromise promise) {
             this.spdyDataFrame = spdyDataFrame;
             this.promise = promise;
         }
 
         void fail(Throwable cause) {
             spdyDataFrame.release();
             promise.setFailure(cause);
         }
     }
 }