/*
    * Copyright 2020 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.quic;
  
  import io.netty.util.internal.PlatformDependent;
  import org.jetbrains.annotations.Nullable;
  
  import java.net.Inet4Address;
  import java.net.Inet6Address;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.UnknownHostException;
  import java.nio.ByteBuffer;
  
  final class SockaddrIn {
      static final byte[] IPV4_MAPPED_IPV6_PREFIX = {
              0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, (byte) 0xff, (byte) 0xff };
      static final int IPV4_ADDRESS_LENGTH = 4;
      static final int IPV6_ADDRESS_LENGTH = 16;
      static final byte[] SOCKADDR_IN6_EMPTY_ARRAY = new byte[Quiche.SIZEOF_SOCKADDR_IN6];
      static final byte[] SOCKADDR_IN_EMPTY_ARRAY = new byte[Quiche.SIZEOF_SOCKADDR_IN];
  
      private SockaddrIn() { }
  
      static int cmp(long memory, long memory2) {
          return Quiche.sockaddr_cmp(memory, memory2);
      }
  
      static int setAddress(ByteBuffer memory, InetSocketAddress address) {
          InetAddress addr = address.getAddress();
          return setAddress(addr instanceof Inet6Address, memory, address);
      }
  
      static int setAddress(boolean ipv6, ByteBuffer memory, InetSocketAddress address) {
          if (ipv6) {
              return SockaddrIn.setIPv6(memory, address.getAddress(), address.getPort());
          } else {
              return SockaddrIn.setIPv4(memory, address.getAddress(), address.getPort());
          }
      }
  
      /**
       *
       * struct sockaddr_in {
       *      sa_family_t    sin_family; // address family: AF_INET
       *      in_port_t      sin_port;   // port in network byte order
       *      struct in_addr sin_addr;   // internet address
       * };
       *
       * // Internet address.
       * struct in_addr {
       *     uint32_t       s_addr;     // address in network byte order
       * };
       *
       */
      static int setIPv4(ByteBuffer memory, InetAddress address, int port) {
          int position = memory.position();
          try {
              // memset
              memory.put(SOCKADDR_IN_EMPTY_ARRAY);
  
              memory.putShort(position + Quiche.SOCKADDR_IN_OFFSETOF_SIN_FAMILY, Quiche.AF_INET);
              memory.putShort(position + Quiche.SOCKADDR_IN_OFFSETOF_SIN_PORT, (short) port);
  
              byte[] bytes = address.getAddress();
              int offset = 0;
              if (bytes.length == IPV6_ADDRESS_LENGTH) {
                  // IPV6 mapped IPV4 address, we only need the last 4 bytes.
                  offset = IPV4_MAPPED_IPV6_PREFIX.length;
              }
              assert bytes.length == offset + IPV4_ADDRESS_LENGTH;
              memory.position(position + Quiche.SOCKADDR_IN_OFFSETOF_SIN_ADDR + Quiche.IN_ADDRESS_OFFSETOF_S_ADDR);
              memory.put(bytes, offset, IPV4_ADDRESS_LENGTH);
              return Quiche.SIZEOF_SOCKADDR_IN;
          } finally {
              memory.position(position);
          }
      }
  
      /**
       * struct sockaddr_in6 {
       *     sa_family_t     sin6_family;   // AF_INET6
       *     in_port_t       sin6_port;     // port number
       *     uint32_t        sin6_flowinfo; // IPv6 flow information
       *     struct in6_addr sin6_addr;     // IPv6 address
       *     uint32_t        sin6_scope_id; /* Scope ID (new in 2.4)
      * };
      *
      * struct in6_addr {
      *     unsigned char s6_addr[16];   // IPv6 address
      * };
      */
     static int setIPv6(ByteBuffer memory, InetAddress address, int port) {
         int position = memory.position();
         try {
             // memset
             memory.put(SOCKADDR_IN6_EMPTY_ARRAY);
 
             memory.putShort(position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_FAMILY, Quiche.AF_INET6);
             memory.putShort(position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_PORT, (short) port);
 
             // Skip sin6_flowinfo as we did memset before
             byte[] bytes = address.getAddress();
             int offset = Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_ADDR + Quiche.IN6_ADDRESS_OFFSETOF_S6_ADDR;
 
             if (bytes.length == IPV4_ADDRESS_LENGTH) {
                 memory.position(position + offset);
                 memory.put(IPV4_MAPPED_IPV6_PREFIX);
 
                 memory.position(position + offset + IPV4_MAPPED_IPV6_PREFIX.length);
                 memory.put(bytes, 0, IPV4_ADDRESS_LENGTH);
 
                 // Skip sin6_scope_id as we did memset before
             } else {
                 memory.position(position + offset);
                 memory.put(bytes, 0, IPV6_ADDRESS_LENGTH);
 
                 memory.putInt(position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_SCOPE_ID,
                         ((Inet6Address) address).getScopeId());
             }
             return Quiche.SIZEOF_SOCKADDR_IN6;
         } finally {
             memory.position(position);
         }
     }
 
     @Nullable
     static InetSocketAddress getIPv4(ByteBuffer memory, byte[] tmpArray) {
         assert tmpArray.length == IPV4_ADDRESS_LENGTH;
         int position = memory.position();
 
         try {
             int port = memory.getShort(position + Quiche.SOCKADDR_IN_OFFSETOF_SIN_PORT) & 0xFFFF;
             memory.position(position + Quiche.SOCKADDR_IN_OFFSETOF_SIN_ADDR + Quiche.IN_ADDRESS_OFFSETOF_S_ADDR);
             memory.get(tmpArray);
             try {
                 return new InetSocketAddress(InetAddress.getByAddress(tmpArray), port);
             } catch (UnknownHostException ignore) {
                 return null;
             }
         } finally {
             memory.position(position);
         }
     }
 
     @Nullable
     static InetSocketAddress getIPv6(ByteBuffer memory, byte[] ipv6Array, byte[] ipv4Array) {
         assert ipv6Array.length == IPV6_ADDRESS_LENGTH;
         assert ipv4Array.length == IPV4_ADDRESS_LENGTH;
         int position = memory.position();
 
         try {
             int port = memory.getShort(
                     position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_PORT) & 0xFFFF;
             memory.position(position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_ADDR + Quiche.IN6_ADDRESS_OFFSETOF_S6_ADDR);
             memory.get(ipv6Array);
             if (PlatformDependent.equals(
                     ipv6Array, 0, IPV4_MAPPED_IPV6_PREFIX, 0, IPV4_MAPPED_IPV6_PREFIX.length)) {
                 System.arraycopy(ipv6Array, IPV4_MAPPED_IPV6_PREFIX.length, ipv4Array, 0, IPV4_ADDRESS_LENGTH);
                 try {
                     return new InetSocketAddress(Inet4Address.getByAddress(ipv4Array), port);
                 } catch (UnknownHostException ignore) {
                     return null;
                 }
             } else {
                 int scopeId = memory.getInt(position + Quiche.SOCKADDR_IN6_OFFSETOF_SIN6_SCOPE_ID);
                 try {
                     return new InetSocketAddress(Inet6Address.getByAddress(null, ipv6Array, scopeId), port);
                 } catch (UnknownHostException ignore) {
                     return null;
                 }
             }
         } finally {
             memory.position(position);
         }
     }
 }