content: /*
   * Copyright 2021-2024 Aklivity Inc.
   *
   * Aklivity 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.
   */
  package io.aklivity.zilla.runtime.binding.http.internal.hpack;
  
  import static io.aklivity.zilla.runtime.binding.http.internal.hpack.HpackLiteralHeaderFieldFW.LiteralType.WITHOUT_INDEXING;
  
  import java.util.function.Consumer;
  
  import org.agrona.DirectBuffer;
  import org.agrona.MutableDirectBuffer;
  
  import io.aklivity.zilla.runtime.binding.http.internal.types.Flyweight;
  
  /*
   * Flyweight for HPACK Header Field
   */
  public class HpackHeaderFieldFW extends Flyweight
  {
  
      private final HpackIntegerFW indexedRO = new HpackIntegerFW(7);
      private final HpackLiteralHeaderFieldFW literalRO = new HpackLiteralHeaderFieldFW();
      private final HpackIntegerFW updateRO = new HpackIntegerFW(5);
  
      @Override
      public int limit()
      {
          switch (type())
          {
          case INDEXED :
              return indexedRO.limit();
          case LITERAL :
              return literalRO.limit();
          case UPDATE:
              return updateRO.limit();
          default:
              return 0;
          }
      }
  
      public boolean error()
      {
          return type() == HeaderFieldType.LITERAL && literal().error();
      }
  
      public enum HeaderFieldType
      {
          INDEXED,        // Indexed Header Field Representation
          LITERAL,        // Literal Header Field Representation
          UPDATE,         // Dynamic Table Size Update
          UNKNOWN
      }
  
      public HeaderFieldType type()
      {
          byte b = buffer().getByte(offset());
  
          if ((b & 0b1000_0000) == 0b1000_0000)
          {
              return HeaderFieldType.INDEXED;
          }
          else if ((b & 0b1100_0000) == 0b0100_0000 || (b & 0b1111_0000) == 0 || (b & 0b1111_0000) == 0b0001_0000)
          {
              return HeaderFieldType.LITERAL;
          }
          else if ((b & 0b1110_0000) == 0b0010_0000)
          {
              return HeaderFieldType.UPDATE;
          }
  
          return HeaderFieldType.UNKNOWN;
      }
  
      public int index()
      {
          assert type() == HeaderFieldType.INDEXED;
  
          return indexedRO.integer();
      }
  
      public int tableSize()
      {
          assert type() == HeaderFieldType.UPDATE;
  
          return updateRO.integer();
      }
  
      public HpackLiteralHeaderFieldFW literal()
      {
          assert type() == HeaderFieldType.LITERAL;
  
          return literalRO;
      }
  
      @Override
      public HpackHeaderFieldFW wrap(DirectBuffer buffer, int offset, int maxLimit)
      {
          super.wrap(buffer, offset, maxLimit);
  
          switch (type())
          {
          case INDEXED :
              indexedRO.wrap(buffer(), offset, maxLimit());
              break;
          case LITERAL :
              literalRO.wrap(buffer(), offset, maxLimit());
              break;
          case UPDATE:
              updateRO.wrap(buffer(), offset, maxLimit());
              break;
          default:
              break;
          }
  
          checkLimit(limit(), maxLimit);
          return this;
      }
  
      public static final class Builder extends Flyweight.Builder<HpackHeaderFieldFW>
      {
          private final HpackIntegerFW.Builder indexedRW = new HpackIntegerFW.Builder(7);
          private final HpackLiteralHeaderFieldFW.Builder literalRW = new HpackLiteralHeaderFieldFW.Builder();
  
          public Builder()
          {
              super(new HpackHeaderFieldFW());
          }
  
          @Override
          public HpackHeaderFieldFW.Builder wrap(MutableDirectBuffer buffer, int offset, int maxLimit)
          {
              super.wrap(buffer, offset, maxLimit);
              return this;
          }
  
          public HpackHeaderFieldFW.Builder indexed(int index)
          {
              buffer().putByte(offset(), (byte) 0x80);
              indexedRW.wrap(buffer(), offset(), maxLimit());
              indexedRW.integer(index).build();
              limit(indexedRW.limit());
              return this;
          }
  
          public HpackHeaderFieldFW.Builder literal(Consumer<HpackLiteralHeaderFieldFW.Builder> mutator)
          {
              literalRW.wrap(buffer(), offset(), maxLimit());
              mutator.accept(literalRW);
              limit(literalRW.build().limit());
              return this;
          }
  
          public HpackHeaderFieldFW.Builder literal(String name, String value)
          {
              return literal(x -> x.type(WITHOUT_INDEXING).name(name).value(value));
          }
  
      }
  
  }
  