/*
    * 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.Locale;
  import java.util.Objects;
  import java.util.Set;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * An {@link AFSocketAddress} for VSOCK sockets.
   *
   * @author Christian Kohlschütter
   */
  public final class AFVSOCKSocketAddress extends AFSocketAddress {
    private static final long serialVersionUID = 1L; // do not change!
  
    private static final Pattern PAT_VSOCK_URI_HOST_AND_PORT = Pattern.compile(
        "^(?<port>any|[0-9a-fx\\-]+)(\\.(?<cid>any|hypervisor|local|host|[0-9a-fx\\-]+))?(?:\\:(?<javaPort>[0-9]+))?$");
  
    private static AFAddressFamily<AFVSOCKSocketAddress> afVsock;
  
    /**
     * "Any address for binding".
     */
    public static final int VMADDR_CID_ANY = -1;
  
    /**
     * Reserved for services built into the hypervisor.
     */
    public static final int VMADDR_CID_HYPERVISOR = 0;
  
    /**
     * The well-known address for local communication (loopback).
     */
    public static final int VMADDR_CID_LOCAL = 1;
  
    /**
     * The well-known address of the host.
     */
    public static final int VMADDR_CID_HOST = 2;
  
    /**
     * Any port number for binding.
     */
    public static final int VMADDR_PORT_ANY = -1;
  
    private AFVSOCKSocketAddress(int port, final byte[] socketAddress, ByteBuffer nativeAddress)
        throws SocketException {
      super(port, socketAddress, nativeAddress, addressFamily());
    }
  
    private static AFVSOCKSocketAddress newAFSocketAddress(int port, final byte[] socketAddress,
        ByteBuffer nativeAddress) throws SocketException {
      return newDeserializedAFSocketAddress(port, socketAddress, nativeAddress, addressFamily(),
          AFVSOCKSocketAddress::new);
    }
  
    /**
     * Returns an {@link AFVSOCKSocketAddress} that refers to a given VSOCK port and CID; the "java
     * port" is set to -1.
     *
     * @param port The VSOCK port
     * @param cid The CID.
     * @return A corresponding {@link AFVSOCKSocketAddress} instance.
     * @throws SocketException if the operation fails.
     */
    public static AFVSOCKSocketAddress ofPortAndCID(int port, int cid) throws SocketException {
      return ofPortAndCID(-1, port, cid);
    }
  
    /**
     * Returns an {@link AFVSOCKSocketAddress} that refers to a given VSOCK port on the hypervisor;
    * the "java port" is set to -1.
    *
    * @param port The VSOCK port
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofHypervisorPort(int port) throws SocketException {
     return ofPortAndCID(port, VMADDR_CID_HYPERVISOR);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress}, especially useful for binding, that refers to "any"
    * port on the hypervisor; the "java port" is set to -1.
    *
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofAnyHypervisorPort() throws SocketException {
     return ofPortAndCID(VMADDR_PORT_ANY, VMADDR_CID_HYPERVISOR);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} that refers to the given port with the local/loopback
    * CID; the "java port" is set to -1.
    *
    * @param port The VSOCK port.
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofLocalPort(int port) throws SocketException {
     return ofPortAndCID(port, VMADDR_CID_LOCAL);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress}, especially useful for binding, that refers to "any"
    * port with the local/loopback CID; the "java port" is set to -1.
    *
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofAnyLocalPort() throws SocketException {
     return ofPortAndCID(VMADDR_PORT_ANY, VMADDR_CID_LOCAL);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} that refers to a given VSOCK port on the host; the
    * "java port" is set to -1.
    *
    * @param port The VSOCK port
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofHostPort(int port) throws SocketException {
     return ofPortAndCID(port, VMADDR_CID_HOST);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress}, especially useful for binding, that refers to "any"
    * port on the host; the "java port" is set to -1.
    *
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofAnyHostPort() throws SocketException {
     return ofPortAndCID(VMADDR_PORT_ANY, VMADDR_CID_HOST);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress}, especially useful for binding, that refers to "any"
    * port and CID; the "java port" is set to -1.
    *
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofAnyPort() throws SocketException {
     return ofPortAndCID(VMADDR_PORT_ANY, VMADDR_CID_ANY);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress}, especially useful for binding, that refers to the
    * given port with "any CID"; the "java port" is set to -1.
    *
    * @param port The VSOCK port.
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofPortWithAnyCID(int port) throws SocketException {
     return ofPortAndCID(port, VMADDR_CID_ANY);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} that refers to a given port and CID.
    *
    * @param javaPort The Java port number.
    * @param vsockPort The vsock port.
    * @param cid The CID.
    * @return A corresponding {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails.
    */
   public static AFVSOCKSocketAddress ofPortAndCID(int javaPort, int vsockPort, int cid)
       throws SocketException {
     return resolveAddress(toBytes(vsockPort, cid), javaPort, addressFamily());
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} given a special {@link InetAddress} that encodes the
    * byte sequence of an AF_VSOCK 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 AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFVSOCKSocketAddress unwrap(InetAddress address, int port) throws SocketException {
     return AFSocketAddress.unwrap(address, port, addressFamily());
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} given a special {@link InetAddress} hostname that
    * encodes the byte sequence of an AF_VSOCK 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 AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFVSOCKSocketAddress unwrap(String hostname, int port) throws SocketException {
     return AFSocketAddress.unwrap(hostname, port, addressFamily());
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} given a generic {@link SocketAddress}.
    *
    * @param address The address to unwrap.
    * @return The {@link AFVSOCKSocketAddress} instance.
    * @throws SocketException if the operation fails, for example when an unsupported address is
    *           specified.
    */
   public static AFVSOCKSocketAddress unwrap(SocketAddress address) throws SocketException {
     Objects.requireNonNull(address);
     if (!isSupportedAddress(address)) {
       throw new SocketException("Unsupported address");
     }
     return (AFVSOCKSocketAddress) address;
   }
 
   /**
    * Returns the "VSOCK port" part of this address.
    *
    * @return The VSOCK port identifier
    * @see #getPort()
    */
   public int getVSOCKPort() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     int a = bb.getInt(1 * 4);
     return a;
   }
 
   /**
    * Returns the "VSOCK CID" part of this address.
    *
    * @return The VSOCK CID identifier.
    */
   public int getVSOCKCID() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     int a = bb.getInt(2 * 4);
     return a;
   }
 
   /**
    * Returns the "VSOCK reserved1" part of this address.
    *
    * @return The "reserved1" identifier, which should be 0.
    */
   public int getVSOCKReserved1() {
     ByteBuffer bb = ByteBuffer.wrap(getBytes());
     int a = bb.getInt(0 * 4);
     return a;
   }
 
   @Override
   public String toString() {
     int port = getPort();
 
     byte[] bytes = getBytes();
     if (bytes.length != (3 * 4)) {
       return getClass().getName() + "[" + (port == 0 ? "" : "port=" + port) + ";UNKNOWN" + "]";
     }
 
     ByteBuffer bb = ByteBuffer.wrap(bytes);
     int reserved1 = bb.getInt();
     int vsockPort = bb.getInt();
     int cid = bb.getInt();
 
     String vsockPortString;
     if (vsockPort >= -1) {
       vsockPortString = Integer.toString(vsockPort);
     } else {
       vsockPortString = String.format(Locale.ENGLISH, "0x%08x", vsockPort);
     }
 
     String typeString = (reserved1 == 0 ? "" : "reserved1=" + reserved1 + ";") + "vsockPort="
         + vsockPortString + ";cid=" + cid;
 
     return getClass().getName() + "[" + (port == 0 ? "" : "port=" + port + ";") + typeString + "]";
   }
 
   @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 AFVSOCKSocketAddress}.
    *
    * @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 AFVSOCKSocketAddress}.
    *
    * @param addr The instance to check.
    * @return {@code true} if so.
    * @see #unwrap(InetAddress, int)
    */
   public static boolean isSupportedAddress(SocketAddress addr) {
     return (addr instanceof AFVSOCKSocketAddress);
   }
 
   @SuppressWarnings("cast")
   private static byte[] toBytes(int port, int cid) {
     ByteBuffer bb = ByteBuffer.allocate(3 * 4);
     bb.putInt(0); // svm_reserved1
     bb.putInt(port); // svm_port
     bb.putInt(cid); // svm_cid
     return (byte[]) bb.flip().array();
   }
 
   /**
    * Returns the corresponding {@link AFAddressFamily}.
    *
    * @return The address family instance.
    */
   @SuppressWarnings("null")
   public static synchronized AFAddressFamily<AFVSOCKSocketAddress> addressFamily() {
     if (afVsock == null) {
       afVsock = AFAddressFamily.registerAddressFamily("vsock", //
           AFVSOCKSocketAddress.class, new AFSocketAddressConfig<AFVSOCKSocketAddress>() {
 
             private final AFSocketAddressConstructor<AFVSOCKSocketAddress> addrConstr =
                 isUseDeserializationForInit() ? AFVSOCKSocketAddress::newAFSocketAddress
                     : AFVSOCKSocketAddress::new;
 
             @Override
             protected AFVSOCKSocketAddress parseURI(URI u, int port) throws SocketException {
               return AFVSOCKSocketAddress.of(u, port);
             }
 
             @Override
             protected AFSocketAddressConstructor<AFVSOCKSocketAddress> addressConstructor() {
               return addrConstr;
             }
 
             @Override
             protected String selectorProviderClassname() {
               return "org.newsclub.net.unix.vsock.AFVSOCKSelectorProvider";
             }
 
             @Override
             protected Set<String> uriSchemes() {
               return new HashSet<>(Arrays.asList("vsock", "http+vsock", "https+vsock"));
             }
           });
       try {
         Class.forName("org.newsclub.net.unix.vsock.AFVSOCKSelectorProvider");
       } catch (ClassNotFoundException e) {
         // ignore
       }
     }
     return afVsock;
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} for the given URI, if possible.
    *
    * @param uri The URI.
    * @return The address.
    * @throws SocketException if the operation fails.
    */
   @SuppressWarnings("PMD.ShortMethodName")
   public static AFVSOCKSocketAddress of(URI uri) throws SocketException {
     return of(uri, -1);
   }
 
   /**
    * Returns an {@link AFVSOCKSocketAddress} 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 AFVSOCKSocketAddress of(URI uri, int overridePort) throws SocketException {
     switch (uri.getScheme()) {
       case "vsock":
       case "http+vsock":
       case "https+vsock":
         break;
       default:
         throw new SocketException("Unsupported URI scheme: " + uri.getScheme());
     }
 
     String host = uri.getHost();
     if (host == null) {
       host = uri.getAuthority();
       if (host != null) {
         int at = host.indexOf('@');
         if (at >= 0) {
           host = host.substring(at + 1);
         }
       }
     }
     if (host == null) {
       throw new SocketException("Cannot get hostname from URI: " + uri);
     }
 
     try {
       Matcher m = PAT_VSOCK_URI_HOST_AND_PORT.matcher(host);
       if (!m.matches()) {
         throw new SocketException("Invalid VSOCK URI: " + uri);
       }
 
       String cidStr = m.group("cid");
       String portStr = m.group("port");
       String javaPortStr = m.group("javaPort");
 
       int cid;
       switch (cidStr == null ? "" : cidStr) {
         case "":
         case "any":
           cid = VMADDR_CID_ANY;
           break;
         case "hypervisor":
           cid = VMADDR_CID_HYPERVISOR;
           break;
         case "local":
           cid = VMADDR_CID_LOCAL;
           break;
         case "host":
           cid = VMADDR_CID_HOST;
           break;
         default:
           cid = parseInt(cidStr);
           break;
       }
 
       int port;
       switch (portStr == null ? "" : portStr) {
         case "any":
         case "":
           port = VMADDR_PORT_ANY;
           break;
         default:
           port = parseInt(portStr);
           break;
       }
 
       int javaPort = overridePort != -1 ? overridePort : uri.getPort();
       if (javaPortStr != null && !javaPortStr.isEmpty()) {
         javaPort = parseInt(javaPortStr);
       }
 
       return ofPortAndCID(javaPort, port, cid);
     } catch (IllegalArgumentException e) {
       throw (SocketException) new SocketException("Invalid VSOCK URI: " + uri).initCause(e);
     }
   }
 
   @Override
   @SuppressWarnings({"PMD.CognitiveComplexity", "PMD.CompareObjectsWithEquals"})
   public URI toURI(String scheme, URI template) throws IOException {
     switch (scheme) {
       case "vsock":
       case "http+vsock":
       case "https+vsock":
         break;
       default:
         return super.toURI(scheme, template);
     }
 
     byte[] bytes = getBytes();
     if (bytes.length != (3 * 4)) {
       return super.toURI(scheme, template);
     }
 
     StringBuilder sb = new StringBuilder();
 
     String portStr;
     int port;
     switch ((port = getVSOCKPort())) {
       case VMADDR_PORT_ANY:
         portStr = "any";
         break;
       default:
         portStr = toUnsignedString(port);
         break;
     }
 
     sb.append(portStr);
     sb.append('.');
     String cidStr;
     int cid;
     switch ((cid = getVSOCKCID())) {
       case VMADDR_CID_ANY:
         cidStr = "any";
         break;
       case VMADDR_CID_HYPERVISOR:
         cidStr = "hypervisor";
         break;
       case VMADDR_CID_LOCAL:
         cidStr = "local";
         break;
       case VMADDR_CID_HOST:
         cidStr = "host";
         break;
       default:
         cidStr = toUnsignedString(cid);
         break;
     }
 
     sb.append(cidStr);
 
     return new HostAndPort(sb.toString(), getPort()).toURI(scheme, template);
   }
 
   private static int parseInt(String v) {
     if (v.startsWith("0x")) {
       return parseUnsignedInt(v.substring(2), 16);
     } else if (v.startsWith("-")) {
       return Integer.parseInt(v);
     } else {
       return parseUnsignedInt(v, 10);
     }
   }
 
   /**
    * Checks if the given address could cover another address.
    *
    * By default, this is only true if both addresses are regarded equal using
    * {@link #equals(Object)}.
    *
    * However, implementations may support "wildcard" addresses, and this method would compare a
    * wildcard address against some non-wildcard address, for example.
    *
    * @param covered The other address that could be covered by this address.
    * @return {@code true} if the other address could be covered.
    */
   @Override
   public boolean covers(AFSocketAddress covered) {
     if (super.covers(covered)) {
       return true;
     } else if (covered instanceof AFVSOCKSocketAddress) {
       AFVSOCKSocketAddress other = (AFVSOCKSocketAddress) covered;
 
       if (getVSOCKCID() == VMADDR_CID_ANY) {
         if (getVSOCKPort() == VMADDR_PORT_ANY) {
           return true;
         } else {
           return getVSOCKPort() == other.getVSOCKPort();
         }
       } else if (getVSOCKPort() == VMADDR_PORT_ANY) {
         return getVSOCKCID() == other.getVSOCKCID();
       }
     }
 
     return equals(covered);
   }
 }