/*
    * Copyright 2024 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.channel.uring;
  
  import io.netty.channel.unix.Buffer;
  
  import java.nio.ByteBuffer;
  
  /**
   * <pre>{@code
   * struct msghdr {
   *     void         *msg_name;       // optional address
   *     socklen_t    msg_namelen;     // size of address
   *     struct       iovec*msg_iov;   // scatter/gather array
   *     size_t       msg_iovlen;      // # elements in msg_iov
   *     void*        msg_control;     // ancillary data, see below
   *     size_t       msg_controllen;  // ancillary data buffer len
   *     int          msg_flags;       // flags on received message
   * };
   * }</pre>
   */
  final class MsgHdr {
  
      private MsgHdr() { }
  
      static void set(ByteBuffer memory, ByteBuffer sockAddrMemory, int addressSize, ByteBuffer iovMemory, int iovLength,
                      ByteBuffer msgControl, int cmsgHdrDataOffset, short segmentSize) {
          int memoryPosition = memory.position();
          memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_NAMELEN, addressSize);
  
          int msgControlLen = 0;
          long msgControlAddr;
          if (segmentSize > 0) {
              msgControlLen = Native.CMSG_LEN;
              CmsgHdr.write(msgControl, cmsgHdrDataOffset, Native.CMSG_LEN, Native.SOL_UDP,
                      Native.UDP_SEGMENT, segmentSize);
              msgControlAddr = Buffer.memoryAddress(msgControl) + msgControl.position();
          } else {
              // Set to 0 if we not explicit requested GSO.
              msgControlAddr = 0;
          }
          if (Native.SIZEOF_SIZE_T == 4) {
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_NAME, (int) Buffer.memoryAddress(sockAddrMemory));
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, (int) Buffer.memoryAddress(iovMemory));
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, (int) msgControlAddr);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, msgControlLen);
          } else {
              assert Native.SIZEOF_SIZE_T == 8;
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_NAME, Buffer.memoryAddress(sockAddrMemory));
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, Buffer.memoryAddress(iovMemory));
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, msgControlAddr);
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, msgControlLen);
          }
          // No flags (we assume the memory was memset before)
      }
  
      static void prepSendFd(ByteBuffer memory, int fd, ByteBuffer msgControl,
                             int cmsgHdrDataOffset, ByteBuffer iovMemory, int iovLength) {
          int memoryPosition = memory.position();
          long msgControlAddr = Buffer.memoryAddress(msgControl);
          CmsgHdr.writeScmRights(msgControl, cmsgHdrDataOffset, fd);
          if (Native.SIZEOF_SIZE_T == 4) {
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, (int) msgControlAddr);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, Native.MSG_CONTROL_LEN_FOR_FD);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, (int) Buffer.memoryAddress(iovMemory));
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
          } else {
              assert Native.SIZEOF_SIZE_T == 8;
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, msgControlAddr);
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, Native.MSG_CONTROL_LEN_FOR_FD);
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, Buffer.memoryAddress(iovMemory));
              memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
          }
      }
  
      static void prepReadFd(ByteBuffer memory, ByteBuffer msgControl, int cmsgHdrDataOffset,
                             ByteBuffer iovMemory, int iovLength) {
          int memoryPosition = memory.position();
          long msgControlAddr = Buffer.memoryAddress(msgControl);
          if (Native.SIZEOF_SIZE_T == 4) {
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, (int) msgControlAddr);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, Native.MSG_CONTROL_LEN_FOR_FD);
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, (int) Buffer.memoryAddress(iovMemory));
              memory.putInt(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
         } else {
             assert Native.SIZEOF_SIZE_T == 8;
             memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROL, msgControlAddr);
             memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_CONTROLLEN, Native.MSG_CONTROL_LEN_FOR_FD);
             memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOV, Buffer.memoryAddress(iovMemory));
             memory.putLong(memoryPosition + Native.MSGHDR_OFFSETOF_MSG_IOVLEN, iovLength);
         }
     }
 
     static int getCmsgData(ByteBuffer memory, ByteBuffer msgControl, int cmsgHdrDataOffset) {
         return CmsgHdr.readScmRights(msgControl, cmsgHdrDataOffset);
     }
 }