/*
    * junixsocket
    *
    * Copyright 2009-2024 Christian Kohlschütter
    *
    * Licensed 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 org.newsclub.net.unix;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.net.InetAddress;
  import java.net.SocketAddress;
  import java.net.SocketException;
  import java.net.URI;
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.Objects;
  import java.util.Set;
  
  import org.eclipse.jdt.annotation.NonNull;
  import org.eclipse.jdt.annotation.NonNullByDefault;
  
  /**
   * An {@link AFSocketAddress} for AF_SYSTEM sockets.
   *
   * @author Christian Kohlschütter
   */
  public final class AFSYSTEMSocketAddress extends AFSocketAddress {
    private static final long serialVersionUID = 1L; // do not change!
  
    private static AFAddressFamily<AFSYSTEMSocketAddress> afSystem;
    private static final String SELECTOR_PROVIDER_CLASS =
        "org.newsclub.net.unix.darwin.system.AFSYSTEMSelectorProvider";
  
    /**
     * The AF_SYSTEM system address.
     *
     * @author Christian Kohlschütter
     */
    @NonNullByDefault
    public static final class SysAddr extends NamedInteger {
      private static final long serialVersionUID = 1L;
  
      /**
       * The sysaddr AF_SYS_CONTROL, also known as AF_SYS_KERN_CONTROL.
       */
      public static final SysAddr AF_SYS_CONTROL;
  
      private static final @NonNull SysAddr[] VALUES = init(new @NonNull SysAddr[] {
          AF_SYS_CONTROL = new SysAddr("AF_SYS_CONTROL", 2) //
      });
  
      private SysAddr(int id) {
        super(id);
      }
  
      private SysAddr(String name, int id) {
        super(name, id);
      }
  
      /**
       * Returns a {@link SysAddr} for the given custom value.
       *
       * @param v The value.
       * @return The {@link SysAddr} object.
       */
      public static SysAddr ofValue(int v) {
        return ofValue(VALUES, SysAddr::new, v);
      }
    }
  
    private AFSYSTEMSocketAddress(int port, final byte[] socketAddress, ByteBuffer nativeAddress)
        throws SocketException {
      super(port, socketAddress, nativeAddress, addressFamily());
    }
  
    private static AFSYSTEMSocketAddress newAFSocketAddress(int port, final byte[] socketAddress,
        ByteBuffer nativeAddress) throws SocketException {
      return newDeserializedAFSocketAddress(port, socketAddress, nativeAddress, addressFamily(),
          AFSYSTEMSocketAddress::new);
    }
  
    /**
     * Returns an {@link AFSYSTEMSocketAddress} that refers to a given AF_SYSTEM socket address (i.e.,
     * referring to a particular socket instance instead of a service address). A Java-only "IP port
     * number" is stored along the instance for compatibility reasons.
    *
    * @param javaPort The emulated "port" number (not part of AF_SYSTEM).
    * @param sysAddr 16-bit system address (e.g., AF_SYS_KERNCONTROL)
    * @param id Controller unique identifier
    * @param unit Developer private unit number, 0 means "unspecified".
    * @return A corresponding {@link AFSYSTEMSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFSYSTEMSocketAddress ofSysAddrIdUnit(int javaPort, SysAddr sysAddr, int id,
       int unit) throws SocketException {
     return resolveAddress(toBytes(sysAddr, id, unit), javaPort, addressFamily());
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} that refers to a given AF_SYSTEM socket address (i.e.,
    * referring to a particular socket instance instead of a service address).
    *
    * @param sysAddr 16-bit system address (e.g., AF_SYS_KERNCONTROL)
    * @param id Controller unique identifier
    * @param unit Developer private unit number
    * @return A corresponding {@link AFSYSTEMSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFSYSTEMSocketAddress ofSysAddrIdUnit(SysAddr sysAddr, int id, int unit)
       throws SocketException {
     return ofSysAddrIdUnit(0, sysAddr, id, unit);
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} given a special {@link InetAddress} that encodes the
    * byte sequence of an AF_SYSTEM socket address, like those returned by {@link #wrapAddress()}.
    *
    * @param address The "special" {@link InetAddress}.
    * @param port The port (use 0 for "none").
    * @return The {@link AFSYSTEMSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFSYSTEMSocketAddress unwrap(InetAddress address, int port) throws SocketException {
     return AFSocketAddress.unwrap(address, port, addressFamily());
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} given a special {@link InetAddress} hostname that
    * encodes the byte sequence of an AF_SYSTEM socket address, like those returned by
    * {@link #wrapAddress()}.
    *
    * @param hostname The "special" hostname, as provided by {@link InetAddress#getHostName()}.
    * @param port The port (use 0 for "none").
    * @return The {@link AFSYSTEMSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFSYSTEMSocketAddress unwrap(String hostname, int port) throws SocketException {
     return AFSocketAddress.unwrap(hostname, port, addressFamily());
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} given a generic {@link SocketAddress}.
    *
    * @param address The address to unwrap.
    * @return The {@link AFSYSTEMSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFSYSTEMSocketAddress unwrap(SocketAddress address) throws SocketException {
     Objects.requireNonNull(address);
     if (!isSupportedAddress(address)) {
       throw new SocketException("Unsupported address");
     }
     return (AFSYSTEMSocketAddress) address;
   }
 
   @Override
   public String toString() {
     int port = getPort();
 
     byte[] bytes = getBytes();
     if (bytes.length != (8 * 4)) {
       return getClass().getName() + "[" + (port == 0 ? "" : "port=" + port) + ";UNKNOWN" + "]";
     }
 
     ByteBuffer bb = ByteBuffer.wrap(bytes);
     SysAddr sysAddr = SysAddr.ofValue(bb.getInt());
     int id = bb.getInt();
     int unit = bb.getInt();
 
     return getClass().getName() + "[" + (port == 0 ? "" : "port=" + port + ";") + sysAddr + ";id="
         + id + ";unit=" + unit + "]";
   }
 
   /**
    * Returns the "SysAddr" part of the address.
    *
    * @return The SysAddr part.
    */
   public @NonNull SysAddr getSysAddr() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     return SysAddr.ofValue(bb.getInt(0));
   }
 
   /**
    * Returns the "id" part of the address.
    *
    * @return The id part.
    */
   public int getId() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     return bb.getInt(4);
   }
 
   /**
    * Returns the "unit" part of the address.
    *
    * @return The unit part.
    */
   public int getUnit() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     return bb.getInt(8);
   }
 
   @Override
   public boolean hasFilename() {
     return false;
   }
 
   @Override
   public File getFile() throws FileNotFoundException {
     throw new FileNotFoundException("no file");
   }
 
   /**
    * Checks if an {@link InetAddress} can be unwrapped to an {@link AFSYSTEMSocketAddress}.
    *
    * @param addr The instance to check.
    * @return {@code true} if so.
    * @see #wrapAddress()
    * @see #unwrap(InetAddress, int)
    */
   public static boolean isSupportedAddress(InetAddress addr) {
     return AFSocketAddress.isSupportedAddress(addr, addressFamily());
   }
 
   /**
    * Checks if a {@link SocketAddress} can be unwrapped to an {@link AFSYSTEMSocketAddress}.
    *
    * @param addr The instance to check.
    * @return {@code true} if so.
    * @see #unwrap(InetAddress, int)
    */
   public static boolean isSupportedAddress(SocketAddress addr) {
     return (addr instanceof AFSYSTEMSocketAddress);
   }
 
   @SuppressWarnings("cast")
   private static byte[] toBytes(SysAddr sysAddr, int id, int unit) {
     ByteBuffer bb = ByteBuffer.allocate(8 * 4);
     bb.putInt(sysAddr.value());
     bb.putInt(id);
     bb.putInt(unit);
     bb.putInt(0);
     bb.putInt(0);
     bb.putInt(0);
     bb.putInt(0);
     bb.putInt(0);
     return (byte[]) bb.flip().array();
   }
 
   /**
    * Returns the corresponding {@link AFAddressFamily}.
    *
    * @return The address family instance.
    */
   @SuppressWarnings("null")
   public static synchronized AFAddressFamily<AFSYSTEMSocketAddress> addressFamily() {
     if (afSystem == null) {
       afSystem = AFAddressFamily.registerAddressFamily("system", //
           AFSYSTEMSocketAddress.class, new AFSocketAddressConfig<AFSYSTEMSocketAddress>() {
 
             private final AFSocketAddressConstructor<AFSYSTEMSocketAddress> addrConstr =
                 isUseDeserializationForInit() ? AFSYSTEMSocketAddress::newAFSocketAddress
                     : AFSYSTEMSocketAddress::new;
 
             @Override
             protected AFSYSTEMSocketAddress parseURI(URI u, int port) throws SocketException {
               return AFSYSTEMSocketAddress.of(u, port);
             }
 
             @Override
             protected AFSocketAddressConstructor<AFSYSTEMSocketAddress> addressConstructor() {
               return addrConstr;
             }
 
             @Override
             protected String selectorProviderClassname() {
               return SELECTOR_PROVIDER_CLASS;
             }
 
             @Override
             protected Set<String> uriSchemes() {
               return new HashSet<>(Arrays.asList("afsystem"));
             }
           });
       try {
         Class.forName(SELECTOR_PROVIDER_CLASS);
       } catch (ClassNotFoundException e) {
         // ignore
       }
     }
     return afSystem;
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} for the given URI, if possible.
    *
    * @param uri The URI.
    * @return The address.
    * @throws SocketException if the operation fails.
    */
   @SuppressWarnings("PMD.ShortMethodName")
   public static AFSYSTEMSocketAddress of(URI uri) throws SocketException {
     return of(uri, -1);
   }
 
   /**
    * Returns an {@link AFSYSTEMSocketAddress} for the given URI, if possible.
    *
    * @param uri The URI.
    * @param overridePort The port to forcibly use, or {@code -1} for "don't override".
    * @return The address.
    * @throws SocketException if the operation fails.
    */
   @SuppressWarnings({
       "PMD.CognitiveComplexity", "PMD.CyclomaticComplexity", "PMD.ExcessiveMethodLength",
       "PMD.NcssCount", "PMD.NPathComplexity", "PMD.ShortMethodName"})
   public static AFSYSTEMSocketAddress of(URI uri, int overridePort) throws SocketException {
     switch (uri.getScheme()) {
       case "afsystem":
         break;
       default:
         throw new SocketException("Unsupported URI scheme: " + uri.getScheme());
     }
 
     String host;
     if ((host = uri.getHost()) == null || host.isEmpty()) {
       String ssp = uri.getSchemeSpecificPart();
       if (ssp == null || !ssp.startsWith("//")) {
         throw new SocketException("Unsupported URI: " + uri);
       }
       ssp = ssp.substring(2);
       int i = ssp.indexOf('/');
       host = i == -1 ? ssp : ssp.substring(0, i);
       if (host.isEmpty()) {
         throw new SocketException("Unsupported URI: " + uri);
       }
     }
 
     ByteBuffer bb = ByteBuffer.allocate(8 * 4);
     for (String p : host.split("\\.")) {
       int v;
       try {
         v = parseUnsignedInt(p, 10);
       } catch (NumberFormatException e) {
         throw (SocketException) new SocketException("Unsupported URI: " + uri).initCause(e);
       }
       bb.putInt(v);
     }
     bb.flip();
     if (bb.remaining() > 8 * 4) {
       throw new SocketException("Unsupported URI: " + uri);
     }
     /* SysAddr sa = */ SysAddr.ofValue(bb.getInt());
     /* int id = */ bb.getInt();
     /* int unit = */ bb.getInt();
 
     while (bb.remaining() > 0) {
       if (bb.getInt() != 0) {
         throw new SocketException("Unsupported URI: " + uri);
       }
     }
 
     return
 
     resolveAddress(bb.array(), uri.getPort(), addressFamily());
   }
 
   @Override
   @SuppressWarnings({"PMD.CognitiveComplexity", "PMD.CompareObjectsWithEquals"})
   public URI toURI(String scheme, URI template) throws IOException {
     switch (scheme) {
       case "afsystem":
         break;
       default:
         return super.toURI(scheme, template);
     }
 
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     StringBuilder sb = new StringBuilder();
     while (bb.remaining() > 0) {
       sb.append(toUnsignedString(bb.getInt()));
       if (bb.remaining() > 0) {
         sb.append('.');
       }
     }
 
     return new HostAndPort(sb.toString(), getPort()).toURI(scheme, template);
   }
 }