/*
    * Copyright 2014 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.http2;
  
  import io.netty.util.collection.CharObjectHashMap;
  
  import static io.netty.handler.codec.http2.Http2CodecUtil.DEFAULT_HEADER_LIST_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_CONCURRENT_STREAMS;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_FRAME_SIZE_LOWER_BOUND;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_FRAME_SIZE_UPPER_BOUND;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_HEADER_LIST_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_HEADER_TABLE_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_INITIAL_WINDOW_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MAX_UNSIGNED_INT;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MIN_CONCURRENT_STREAMS;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MIN_HEADER_LIST_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MIN_HEADER_TABLE_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.MIN_INITIAL_WINDOW_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.NUM_STANDARD_SETTINGS;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_ENABLE_CONNECT_PROTOCOL;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_ENABLE_PUSH;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_HEADER_TABLE_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_INITIAL_WINDOW_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_MAX_CONCURRENT_STREAMS;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_MAX_FRAME_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.SETTINGS_MAX_HEADER_LIST_SIZE;
  import static io.netty.handler.codec.http2.Http2CodecUtil.isMaxFrameSizeValid;
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  import static java.lang.Integer.toHexString;
  
  /**
   * Settings for one endpoint in an HTTP/2 connection. Each of the values are optional as defined in
   * the spec for the SETTINGS frame. Permits storage of arbitrary key/value pairs but provides helper
   * methods for standard settings.
   */
  public final class Http2Settings extends CharObjectHashMap<Long> {
      /**
       * Default capacity based on the number of standard settings from the HTTP/2 spec, adjusted so that adding all of
       * the standard settings will not cause the map capacity to change.
       */
      private static final int DEFAULT_CAPACITY = (int) (NUM_STANDARD_SETTINGS / DEFAULT_LOAD_FACTOR) + 1;
      private static final Long FALSE = 0L;
      private static final Long TRUE = 1L;
  
      public Http2Settings() {
          this(DEFAULT_CAPACITY);
      }
  
      public Http2Settings(int initialCapacity, float loadFactor) {
          super(initialCapacity, loadFactor);
      }
  
      public Http2Settings(int initialCapacity) {
          super(initialCapacity);
      }
  
      /**
       * Adds the given setting key/value pair. For standard settings defined by the HTTP/2 spec, performs
       * validation on the values.
       *
       * @throws IllegalArgumentException if verification for a standard HTTP/2 setting fails.
       */
      @Override
      public Long put(char key, Long value) {
          verifyStandardSetting(key, value);
          return super.put(key, value);
      }
  
      /**
       * Gets the {@code SETTINGS_HEADER_TABLE_SIZE} value. If unavailable, returns {@code null}.
       */
      public Long headerTableSize() {
          return get(SETTINGS_HEADER_TABLE_SIZE);
      }
  
      /**
       * Sets the {@code SETTINGS_HEADER_TABLE_SIZE} value.
       *
       * @throws IllegalArgumentException if verification of the setting fails.
       */
      public Http2Settings headerTableSize(long value) {
          put(SETTINGS_HEADER_TABLE_SIZE, Long.valueOf(value));
          return this;
      }
  
      /**
      * Gets the {@code SETTINGS_ENABLE_PUSH} value. If unavailable, returns {@code null}.
      */
     public Boolean pushEnabled() {
         Long value = get(SETTINGS_ENABLE_PUSH);
         if (value == null) {
             return null;
         }
         return TRUE.equals(value);
     }
 
     /**
      * Sets the {@code SETTINGS_ENABLE_PUSH} value.
      */
     public Http2Settings pushEnabled(boolean enabled) {
         put(SETTINGS_ENABLE_PUSH, enabled ? TRUE : FALSE);
         return this;
     }
 
     /**
      * Gets the {@code SETTINGS_MAX_CONCURRENT_STREAMS} value. If unavailable, returns {@code null}.
      */
     public Long maxConcurrentStreams() {
         return get(SETTINGS_MAX_CONCURRENT_STREAMS);
     }
 
     /**
      * Sets the {@code SETTINGS_MAX_CONCURRENT_STREAMS} value.
      *
      * @throws IllegalArgumentException if verification of the setting fails.
      */
     public Http2Settings maxConcurrentStreams(long value) {
         put(SETTINGS_MAX_CONCURRENT_STREAMS, Long.valueOf(value));
         return this;
     }
 
     /**
      * Gets the {@code SETTINGS_INITIAL_WINDOW_SIZE} value. If unavailable, returns {@code null}.
      */
     public Integer initialWindowSize() {
         return getIntValue(SETTINGS_INITIAL_WINDOW_SIZE);
     }
 
     /**
      * Sets the {@code SETTINGS_INITIAL_WINDOW_SIZE} value.
      *
      * @throws IllegalArgumentException if verification of the setting fails.
      */
     public Http2Settings initialWindowSize(int value) {
         put(SETTINGS_INITIAL_WINDOW_SIZE, Long.valueOf(value));
         return this;
     }
 
     /**
      * Gets the {@code SETTINGS_MAX_FRAME_SIZE} value. If unavailable, returns {@code null}.
      */
     public Integer maxFrameSize() {
         return getIntValue(SETTINGS_MAX_FRAME_SIZE);
     }
 
     /**
      * Sets the {@code SETTINGS_MAX_FRAME_SIZE} value.
      *
      * @throws IllegalArgumentException if verification of the setting fails.
      */
     public Http2Settings maxFrameSize(int value) {
         put(SETTINGS_MAX_FRAME_SIZE, Long.valueOf(value));
         return this;
     }
 
     /**
      * Gets the {@code SETTINGS_MAX_HEADER_LIST_SIZE} value. If unavailable, returns {@code null}.
      */
     public Long maxHeaderListSize() {
         return get(SETTINGS_MAX_HEADER_LIST_SIZE);
     }
 
     /**
      * Sets the {@code SETTINGS_MAX_HEADER_LIST_SIZE} value.
      *
      * @throws IllegalArgumentException if verification of the setting fails.
      */
     public Http2Settings maxHeaderListSize(long value) {
         put(SETTINGS_MAX_HEADER_LIST_SIZE, Long.valueOf(value));
         return this;
     }
 
     /**
      * Gets the {@code SETTINGS_ENABLE_CONNECT_PROTOCOL} value. If unavailable, returns {@code null}.
      */
     public Boolean connectProtocolEnabled() {
         Long value = get(SETTINGS_ENABLE_CONNECT_PROTOCOL);
         if (value == null) {
             return null;
         }
         return TRUE.equals(value);
     }
 
     /**
      * Sets the {@code SETTINGS_ENABLE_CONNECT_PROTOCOL} value.
      */
     public Http2Settings connectProtocolEnabled(boolean enabled) {
         put(SETTINGS_ENABLE_CONNECT_PROTOCOL, enabled ? TRUE : FALSE);
         return this;
     }
 
     /**
      * Clears and then copies the given settings into this object.
      */
     public Http2Settings copyFrom(Http2Settings settings) {
         clear();
         putAll(settings);
         return this;
     }
 
     /**
      * A helper method that returns {@link Long#intValue()} on the return of {@link #get(char)}, if present. Note that
      * if the range of the value exceeds {@link Integer#MAX_VALUE}, the {@link #get(char)} method should
      * be used instead to avoid truncation of the value.
      */
     public Integer getIntValue(char key) {
         Long value = get(key);
         if (value == null) {
             return null;
         }
         return value.intValue();
     }
 
     private static void verifyStandardSetting(int key, Long value) {
         checkNotNull(value, "value");
         switch (key) {
             case SETTINGS_HEADER_TABLE_SIZE:
                 if (value < MIN_HEADER_TABLE_SIZE || value > MAX_HEADER_TABLE_SIZE) {
                     throw new IllegalArgumentException("Setting HEADER_TABLE_SIZE is invalid: " + value +
                             ", expected [" + MIN_HEADER_TABLE_SIZE + ", " + MAX_HEADER_TABLE_SIZE + ']');
                 }
                 break;
             case SETTINGS_ENABLE_PUSH:
                 if (value != 0L && value != 1L) {
                     throw new IllegalArgumentException("Setting ENABLE_PUSH is invalid: " + value +
                             ", expected [0, 1]");
                 }
                 break;
             case SETTINGS_MAX_CONCURRENT_STREAMS:
                 if (value < MIN_CONCURRENT_STREAMS || value > MAX_CONCURRENT_STREAMS) {
                     throw new IllegalArgumentException("Setting MAX_CONCURRENT_STREAMS is invalid: " + value +
                             ", expected [" + MIN_CONCURRENT_STREAMS + ", " + MAX_CONCURRENT_STREAMS + ']');
                 }
                 break;
             case SETTINGS_INITIAL_WINDOW_SIZE:
                 if (value < MIN_INITIAL_WINDOW_SIZE || value > MAX_INITIAL_WINDOW_SIZE) {
                     throw new IllegalArgumentException("Setting INITIAL_WINDOW_SIZE is invalid: " + value +
                             ", expected [" + MIN_INITIAL_WINDOW_SIZE + ", " + MAX_INITIAL_WINDOW_SIZE + ']');
                 }
                 break;
             case SETTINGS_MAX_FRAME_SIZE:
                 if (!isMaxFrameSizeValid(value.intValue())) {
                     throw new IllegalArgumentException("Setting MAX_FRAME_SIZE is invalid: " + value +
                             ", expected [" + MAX_FRAME_SIZE_LOWER_BOUND + ", " + MAX_FRAME_SIZE_UPPER_BOUND + ']');
                 }
                 break;
             case SETTINGS_MAX_HEADER_LIST_SIZE:
                 if (value < MIN_HEADER_LIST_SIZE || value > MAX_HEADER_LIST_SIZE) {
                     throw new IllegalArgumentException("Setting MAX_HEADER_LIST_SIZE is invalid: " + value +
                             ", expected [" + MIN_HEADER_LIST_SIZE + ", " + MAX_HEADER_LIST_SIZE + ']');
                 }
                 break;
             case SETTINGS_ENABLE_CONNECT_PROTOCOL:
                 if (value != 0L && value != 1L) {
                     throw new IllegalArgumentException("Setting ENABLE_CONNECT_PROTOCOL is invalid: " + value +
                             ", expected [0, 1]");
                 }
                 break;
             default:
                 // Non-standard HTTP/2 setting
                 if (value < 0 || value > MAX_UNSIGNED_INT) {
                     throw new IllegalArgumentException("Non-standard setting 0x" + toHexString(key) + " is invalid: " +
                             value + ", expected unsigned 32-bit value");
                 }
                 break;
         }
     }
 
     @Override
     protected String keyToString(char key) {
         switch (key) {
             case SETTINGS_HEADER_TABLE_SIZE:
                 return "HEADER_TABLE_SIZE";
             case SETTINGS_ENABLE_PUSH:
                 return "ENABLE_PUSH";
             case SETTINGS_MAX_CONCURRENT_STREAMS:
                 return "MAX_CONCURRENT_STREAMS";
             case SETTINGS_INITIAL_WINDOW_SIZE:
                 return "INITIAL_WINDOW_SIZE";
             case SETTINGS_MAX_FRAME_SIZE:
                 return "MAX_FRAME_SIZE";
             case SETTINGS_MAX_HEADER_LIST_SIZE:
                 return "MAX_HEADER_LIST_SIZE";
             case SETTINGS_ENABLE_CONNECT_PROTOCOL:
                 return "ENABLE_CONNECT_PROTOCOL";
             default:
                 // Unknown keys.
                 return "0x" + toHexString(key);
         }
     }
 
     public static Http2Settings defaultSettings() {
         return new Http2Settings().maxHeaderListSize(DEFAULT_HEADER_LIST_SIZE);
     }
 }