/*
    * 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.IOException;
  import java.lang.reflect.InvocationTargetException;
  import java.net.SocketAddress;
  import java.net.SocketException;
  import java.net.URI;
  import java.nio.channels.ServerSocketChannel;
  import java.nio.channels.SocketChannel;
  import java.nio.channels.UnsupportedAddressTypeException;
  import java.nio.channels.spi.SelectorProvider;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import org.eclipse.jdt.annotation.NonNull;
  import org.eclipse.jdt.annotation.Nullable;
  import org.newsclub.net.unix.AFSocketAddress.AFSocketAddressConstructor;
  
  /**
   * Describes an address family supported by junixsocket.
   *
   * @param <A> The corresponding {@link AFSocketAddress} subclass.
   * @author Christian Kohlschütter
   */
  public final class AFAddressFamily<A extends AFSocketAddress> {
    private static final Map<String, AFAddressFamily<?>> AF_MAP = Collections.synchronizedMap(
        new HashMap<>());
    private static final Map<String, AFAddressFamily<?>> URI_SCHEMES = Collections.synchronizedMap(
        new HashMap<>());
    private static final AtomicBoolean DEFERRED_INIT_DONE = new AtomicBoolean(false);
  
    private final int domain;
    private AFSocketAddressConstructor<A> addressConstructor;
    private @Nullable Class<A> addressClass;
    private final String juxString;
    private final String juxInetAddressSuffix;
    private final String addressClassname;
  
    private String selectorProviderClassname;
  
    private AFSocket.Constructor<A> socketConstructor;
    private AFServerSocket.Constructor<A> serverSocketConstructor;
    private AFSocketAddressConfig<A> addressConfig;
  
    private SelectorProvider selectorProvider = null;
  
    static {
      NativeUnixSocket.isLoaded(); // trigger init
    }
  
    private AFAddressFamily(String juxString, int domain, String addressClassname) {
      this.juxString = juxString;
      this.domain = domain; // FIXME validate
      this.addressClassname = addressClassname;
      this.juxInetAddressSuffix = "." + juxString + AFInetAddress.INETADDR_SUFFIX;
    }
  
    @SuppressWarnings("unchecked")
    static synchronized <A extends AFSocketAddress> @NonNull AFAddressFamily<A> registerAddressFamily(
        String juxString, int domain, String addressClassname) {
      AFAddressFamily<?> af = AF_MAP.get(juxString);
      if (af != null) {
        if (af.getDomain() != domain) {
          throw new IllegalStateException("Wrong domain for address family " + juxString + ": " + af
              .getDomain() + " vs. " + domain);
        }
        return (AFAddressFamily<A>) af;
      }
  
      af = new AFAddressFamily<>(juxString, domain, addressClassname);
      AF_MAP.put(juxString, af);
  
      return (AFAddressFamily<A>) af;
    }
  
    static synchronized void triggerInit() {
      for (AFAddressFamily<?> af : new HashSet<>(AF_MAP.values())) {
       if (af.addressClassname != null) {
         try {
           Class<?> clz = Class.forName(af.addressClassname);
           clz.getMethod("addressFamily").invoke(null);
         } catch (Exception e) {
           // ignore
         }
       }
     }
   }
 
   static synchronized AFAddressFamily<?> getAddressFamily(String juxString) {
     return AF_MAP.get(juxString);
   }
 
   static AFAddressFamily<?> getAddressFamily(URI uri) {
     checkDeferredInit();
     Objects.requireNonNull(uri, "uri");
     String scheme = uri.getScheme();
     return URI_SCHEMES.get(scheme);
   }
 
   static void checkDeferredInit() {
     if (DEFERRED_INIT_DONE.compareAndSet(false, true)) {
       NativeUnixSocket.isLoaded();
       AFAddressFamily.triggerInit();
     }
   }
 
   int getDomain() {
     return domain;
   }
 
   String getJuxString() {
     return juxString;
   }
 
   AFSocketAddressConstructor<A> getAddressConstructor() {
     if (addressConstructor == null) {
       throw new UnsupportedAddressTypeException();
     }
     return addressConstructor;
   }
 
   private synchronized void checkProvider() {
     if (socketConstructor == null && selectorProvider == null) {
       try {
         getSelectorProvider();
       } catch (IllegalStateException e) {
         // ignore
       }
     }
   }
 
   AFSocket.Constructor<A> getSocketConstructor() {
     checkProvider();
     if (socketConstructor == null) {
       throw new UnsupportedAddressTypeException();
     }
     return socketConstructor;
   }
 
   AFServerSocket.Constructor<A> getServerSocketConstructor() {
     checkProvider();
     if (serverSocketConstructor == null) {
       throw new UnsupportedAddressTypeException();
     }
     return serverSocketConstructor;
   }
 
   Class<A> getSocketAddressClass() {
     if (addressClass == null) {
       throw new UnsupportedAddressTypeException();
     }
     return addressClass;
   }
 
   String getJuxInetAddressSuffix() {
     return juxInetAddressSuffix;
   }
 
   /**
    * Registers an address family.
    *
    * @param <A> The supported address type.
    * @param juxString The sockaddr_* identifier as registered in native code.
    * @param addressClass The supported address subclass.
    * @param config The address-specific config object.
    * @return The corresponding {@link AFAddressFamily} instance.
    */
   @SuppressWarnings({"unchecked", "rawtypes"})
   public static synchronized <A extends AFSocketAddress> AFAddressFamily<A> registerAddressFamily(
       String juxString, //
       Class<A> addressClass, AFSocketAddressConfig<A> config) {
     AFAddressFamily<?> af = getAddressFamily(juxString);
     if (af == null) {
       throw new IllegalStateException("Address family not supported by native code: " + juxString);
     }
     if (af.addressClassname != null && !addressClass.getName().equals(af.addressClassname)) {
       throw new IllegalStateException("Unexpected classname for address family " + juxString + ": "
           + addressClass.getName() + "; expected: " + af.addressClassname);
     }
     if (af.addressConstructor != null || af.addressClass != null) {
       throw new IllegalStateException("Already registered: " + juxString);
     }
     af.addressConfig = (AFSocketAddressConfig) config;
     af.addressConstructor = (AFSocketAddressConstructor) config.addressConstructor();
     af.addressClass = (Class) addressClass;
     synchronized (af) { // work-around for likely false positive Spotbugs error
       af.selectorProviderClassname = config.selectorProviderClassname();
     }
 
     for (String scheme : config.uriSchemes()) {
       if (scheme.isEmpty()) {
         throw new IllegalStateException("Invalid URI scheme; cannot register " + scheme + " for "
             + juxString);
 
       }
       if (URI_SCHEMES.containsKey(scheme)) {
         throw new IllegalStateException("URI scheme already registered; cannot register " + scheme
             + " for " + juxString);
       }
       URI_SCHEMES.put(scheme, af);
     }
 
     return (AFAddressFamily<A>) af;
   }
 
   /**
    * Registers an implementation.
    *
    * @param <A> The supported address type.
    * @param juxString The sockaddr_* identifier as registered in native code.
    * @param addressFamily The supported address family as registered via
    *          {@link #registerAddressFamily(String, Class, AFSocketAddressConfig)}.
    * @param config The address family-specific configuration object.
    * @return The corresponding {@link AFAddressFamily} instance.
    */
   @SuppressWarnings({"unchecked", "rawtypes", "PMD.ExcessiveParameterList"})
   public static synchronized <A extends AFSocketAddress> AFAddressFamily<A> registerAddressFamilyImpl(
       String juxString, //
       AFAddressFamily<A> addressFamily, //
       AFAddressFamilyConfig<A> config) {
     Objects.requireNonNull(addressFamily);
     Objects.requireNonNull(config);
 
     AFAddressFamily<?> af = getAddressFamily(juxString);
     if (af == null) {
       throw new IllegalStateException("Unknown address family: " + juxString);
     }
     if (addressFamily != af) { // NOPMD.CompareObjectsWithEquals
       throw new IllegalStateException("Address family inconsistency: " + juxString);
     }
     if (af.socketConstructor != null) {
       throw new IllegalStateException("Already registered: " + juxString);
     }
     af.socketConstructor = (AFSocket.Constructor) config.socketConstructor();
     af.serverSocketConstructor = (AFServerSocket.Constructor) config.serverSocketConstructor();
 
     FileDescriptorCast.registerCastingProviders(config);
 
     return (AFAddressFamily<A>) af;
   }
 
   @SuppressWarnings("unchecked")
   AFSocketImplExtensions<A> initImplExtensions(AncillaryDataSupport ancillaryDataSupport) {
     switch (getDomain()) {
       case NativeUnixSocket.DOMAIN_TIPC:
         return (AFSocketImplExtensions<A>) new AFTIPCSocketImplExtensions(ancillaryDataSupport);
       case NativeUnixSocket.DOMAIN_VSOCK:
         return (AFSocketImplExtensions<A>) new AFVSOCKSocketImplExtensions(ancillaryDataSupport);
       case NativeUnixSocket.DOMAIN_SYSTEM:
         return (AFSocketImplExtensions<A>) new AFSYSTEMSocketImplExtensions(ancillaryDataSupport);
       default:
         throw new UnsupportedOperationException();
     }
   }
 
   /**
    * Creates a new, unconnected, unbound socket compatible with this socket address.
    *
    * @return The socket instance.
    * @throws IOException on error.
    */
   public AFSocket<?> newSocket() throws IOException {
     try {
       return getSocketConstructor().newInstance(null, null);
     } catch (UnsupportedOperationException e) {
       throw (SocketException) new SocketException().initCause(e);
     }
   }
 
   /**
    * Creates a new, unconnected, unbound server socket compatible with this socket address.
    *
    * @return The server socket instance.
    * @throws IOException on error.
    */
   public AFServerSocket<?> newServerSocket() throws IOException {
     try {
       return getServerSocketConstructor().newInstance(null);
     } catch (UnsupportedOperationException e) {
       throw (SocketException) new SocketException().initCause(e);
     }
   }
 
   /**
    * Creates a new, unconnected, unbound {@link SocketChannel} compatible with this socket address.
    *
    * @return The socket instance.
    * @throws IOException on error.
    */
   public AFSocketChannel<?> newSocketChannel() throws IOException {
     return newSocket().getChannel();
   }
 
   /**
    * Creates a new, unconnected, unbound {@link ServerSocketChannel} compatible with this socket
    * address.
    *
    * @return The socket instance.
    * @throws IOException on error.
    */
   public AFServerSocketChannel<?> newServerSocketChannel() throws IOException {
     return newServerSocket().getChannel();
   }
 
   AFSocketAddress parseURI(URI u, int overridePort) throws SocketException {
     if (addressConfig == null) {
       throw new SocketException("Cannot instantiate addresses of type " + addressClass);
     }
     return addressConfig.parseURI(u, overridePort);
   }
 
   /**
    * Returns the set of supported URI schemes that can be parsed to some {@link AFSocketAddress}.
    *
    * The set is dependent on which {@link AFSocketAddress} implementations are registered with
    * junixsocket.
    *
    * @return The set of supported URI schemes.
    */
   public static synchronized Set<String> uriSchemes() {
     checkDeferredInit();
     return Collections.unmodifiableSet(URI_SCHEMES.keySet());
   }
 
   /**
    * Returns the {@link SelectorProvider} associated with this address family, or {@code null} if no
    * such instance is registered.
    *
    * @return The {@link SelectorProvider}.
    * @throws IllegalStateException on error.
    */
   public synchronized SelectorProvider getSelectorProvider() {
     if (selectorProvider != null) {
       return selectorProvider;
     }
     if (selectorProviderClassname == null) {
       return null;
     }
     try {
       selectorProvider = (SelectorProvider) Class.forName(selectorProviderClassname).getMethod(
           "provider", new Class<?>[0]).invoke(null);
     } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException
         | ClassNotFoundException | RuntimeException e) {
       throw new IllegalStateException("Cannot instantiate selector provider for "
           + addressClassname, e);
     }
     return selectorProvider;
   }
 
   /**
    * Returns an appropriate SocketAddress to be used when calling bind with a null argument.
    *
    * @return The new socket address, or {@code null}.
    * @throws IOException on error.
    */
   public SocketAddress nullBindAddress() throws IOException {
     return addressConfig.nullBindAddress();
   }
 }