/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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
   *
   *   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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.hc.core5.http2.impl.nio.bootstrap;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hc.core5.function.Callback;
  import org.apache.hc.core5.function.Decorator;
  import org.apache.hc.core5.function.Supplier;
  import org.apache.hc.core5.http.config.CharCodingConfig;
  import org.apache.hc.core5.http.config.Http1Config;
  import org.apache.hc.core5.http.config.NamedElementChain;
  import org.apache.hc.core5.http.impl.DefaultConnectionReuseStrategy;
  import org.apache.hc.core5.http.impl.DefaultContentLengthStrategy;
  import org.apache.hc.core5.http.impl.Http1StreamListener;
  import org.apache.hc.core5.http.impl.HttpProcessors;
  import org.apache.hc.core5.http.impl.bootstrap.HttpAsyncServer;
  import org.apache.hc.core5.http.impl.bootstrap.StandardFilter;
  import org.apache.hc.core5.http.impl.nio.DefaultHttpRequestParserFactory;
  import org.apache.hc.core5.http.impl.nio.DefaultHttpResponseWriterFactory;
  import org.apache.hc.core5.http.impl.nio.ServerHttp1StreamDuplexerFactory;
  import org.apache.hc.core5.http.nio.AsyncFilterHandler;
  import org.apache.hc.core5.http.nio.AsyncServerExchangeHandler;
  import org.apache.hc.core5.http.nio.AsyncServerRequestHandler;
  import org.apache.hc.core5.http.nio.HandlerFactory;
  import org.apache.hc.core5.http.nio.ssl.TlsStrategy;
  import org.apache.hc.core5.http.nio.support.AsyncServerExpectationFilter;
  import org.apache.hc.core5.http.nio.support.AsyncServerFilterChainElement;
  import org.apache.hc.core5.http.nio.support.AsyncServerFilterChainExchangeHandlerFactory;
  import org.apache.hc.core5.http.nio.support.BasicAsyncServerExpectationDecorator;
  import org.apache.hc.core5.http.nio.support.BasicServerExchangeHandler;
  import org.apache.hc.core5.http.nio.support.DefaultAsyncResponseExchangeHandlerFactory;
  import org.apache.hc.core5.http.nio.support.TerminalAsyncServerFilter;
  import org.apache.hc.core5.http.protocol.HttpProcessor;
  import org.apache.hc.core5.http.protocol.LookupRegistry;
  import org.apache.hc.core5.http.protocol.RequestHandlerRegistry;
  import org.apache.hc.core5.http.protocol.UriPatternType;
  import org.apache.hc.core5.http2.HttpVersionPolicy;
  import org.apache.hc.core5.http2.config.H2Config;
  import org.apache.hc.core5.http2.impl.H2Processors;
  import org.apache.hc.core5.http2.impl.nio.H2StreamListener;
  import org.apache.hc.core5.http2.impl.nio.ServerH2StreamMultiplexerFactory;
  import org.apache.hc.core5.http2.impl.nio.ServerHttpProtocolNegotiationStarter;
  import org.apache.hc.core5.http2.ssl.H2ServerTlsStrategy;
  import org.apache.hc.core5.net.InetAddressUtils;
  import org.apache.hc.core5.reactor.IOEventHandlerFactory;
  import org.apache.hc.core5.reactor.IOReactorConfig;
  import org.apache.hc.core5.reactor.IOSession;
  import org.apache.hc.core5.reactor.IOSessionListener;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.Timeout;
  
  /**
   * HTTP/2 capable {@link HttpAsyncServer} bootstrap.
   *
   * @since 5.0
   */
  public class H2ServerBootstrap {
  
      private final List<HandlerEntry<Supplier<AsyncServerExchangeHandler>>> handlerList;
      private final List<FilterEntry<AsyncFilterHandler>> filters;
      private String canonicalHostName;
      private LookupRegistry<Supplier<AsyncServerExchangeHandler>> lookupRegistry;
      private IOReactorConfig ioReactorConfig;
      private HttpProcessor httpProcessor;
      private CharCodingConfig charCodingConfig;
      private HttpVersionPolicy versionPolicy;
      private H2Config h2Config;
      private Http1Config http1Config;
      private TlsStrategy tlsStrategy;
      private Timeout handshakeTimeout;
      private Decorator<IOSession> ioSessionDecorator;
      private Callback<Exception> exceptionCallback;
      private IOSessionListener sessionListener;
     private H2StreamListener h2StreamListener;
     private Http1StreamListener http1StreamListener;
 
     private H2ServerBootstrap() {
         this.handlerList = new ArrayList<>();
         this.filters = new ArrayList<>();
     }
 
     public static H2ServerBootstrap bootstrap() {
         return new H2ServerBootstrap();
     }
 
     /**
      * Sets canonical name (fully qualified domain name) of the server.
      *
      * @since 5.0
      */
     public final H2ServerBootstrap setCanonicalHostName(final String canonicalHostName) {
         this.canonicalHostName = canonicalHostName;
         return this;
     }
 
     /**
      * Sets I/O reactor configuration.
      */
     public final H2ServerBootstrap setIOReactorConfig(final IOReactorConfig ioReactorConfig) {
         this.ioReactorConfig = ioReactorConfig;
         return this;
     }
 
     /**
      * Assigns {@link HttpProcessor} instance.
      */
     public final H2ServerBootstrap setHttpProcessor(final HttpProcessor httpProcessor) {
         this.httpProcessor = httpProcessor;
         return this;
     }
 
     /**
      * Sets HTTP protocol version policy
      */
     public final H2ServerBootstrap setVersionPolicy(final HttpVersionPolicy versionPolicy) {
         this.versionPolicy = versionPolicy;
         return this;
     }
 
     /**
      * Sets HTTP/2 protocol parameters
      */
     public final H2ServerBootstrap setH2Config(final H2Config h2Config) {
         this.h2Config = h2Config;
         return this;
     }
 
     /**
      * Sets HTTP/1.1 protocol parameters
      */
     public final H2ServerBootstrap setHttp1Config(final Http1Config http1Config) {
         this.http1Config = http1Config;
         return this;
     }
 
     /**
      * Sets message char coding.
      */
     public final H2ServerBootstrap setCharset(final CharCodingConfig charCodingConfig) {
         this.charCodingConfig = charCodingConfig;
         return this;
     }
 
     /**
      * Assigns {@link TlsStrategy} instance.
      */
     public final H2ServerBootstrap setTlsStrategy(final TlsStrategy tlsStrategy) {
         this.tlsStrategy = tlsStrategy;
         return this;
     }
 
     public final H2ServerBootstrap setHandshakeTimeout(final Timeout handshakeTimeout) {
         this.handshakeTimeout = handshakeTimeout;
         return this;
     }
 
     /**
      * Assigns {@link IOSession} {@link Decorator} instance.
      */
     public final H2ServerBootstrap setIOSessionDecorator(final Decorator<IOSession> ioSessionDecorator) {
         this.ioSessionDecorator = ioSessionDecorator;
         return this;
     }
 
     /**
      * Assigns {@link Exception} {@link Callback} instance.
      */
     public final H2ServerBootstrap setExceptionCallback(final Callback<Exception> exceptionCallback) {
         this.exceptionCallback = exceptionCallback;
         return this;
     }
 
     /**
      * Assigns {@link IOSessionListener} instance.
      */
     public final H2ServerBootstrap setIOSessionListener(final IOSessionListener sessionListener) {
         this.sessionListener = sessionListener;
         return this;
     }
 
     /**
      * Assigns {@link H2StreamListener} instance.
      */
     public final H2ServerBootstrap setStreamListener(final H2StreamListener h2StreamListener) {
         this.h2StreamListener = h2StreamListener;
         return this;
     }
 
     /**
      * Assigns {@link Http1StreamListener} instance.
      */
     public final H2ServerBootstrap setStreamListener(final Http1StreamListener http1StreamListener) {
         this.http1StreamListener = http1StreamListener;
         return this;
     }
 
     /**
      * Assigns {@link LookupRegistry} instance.
      */
     public final H2ServerBootstrap setLookupRegistry(final LookupRegistry<Supplier<AsyncServerExchangeHandler>> lookupRegistry) {
         this.lookupRegistry = lookupRegistry;
         return this;
     }
 
     /**
      * Registers the given {@link AsyncServerExchangeHandler} {@link Supplier} as a default handler for URIs
      * matching the given pattern.
      *
      * @param uriPattern the pattern to register the handler for.
      * @param supplier the handler supplier.
      */
     public final H2ServerBootstrap register(final String uriPattern, final Supplier<AsyncServerExchangeHandler> supplier) {
         Args.notBlank(uriPattern, "URI pattern");
         Args.notNull(supplier, "Supplier");
         handlerList.add(new HandlerEntry<>(null, uriPattern, supplier));
         return this;
     }
 
     /**
      * Registers the given {@link AsyncServerExchangeHandler} {@link Supplier} as a handler for URIs
      * matching the given host and the pattern.
      *
      * @param hostname the host name
      * @param uriPattern the pattern to register the handler for.
      * @param supplier the handler supplier.
      */
     public final H2ServerBootstrap registerVirtual(final String hostname, final String uriPattern, final Supplier<AsyncServerExchangeHandler> supplier) {
         Args.notBlank(hostname, "Hostname");
         Args.notBlank(uriPattern, "URI pattern");
         Args.notNull(supplier, "Supplier");
         handlerList.add(new HandlerEntry<>(hostname, uriPattern, supplier));
         return this;
     }
 
     /**
      * Registers the given {@link AsyncServerRequestHandler} as a default handler for URIs
      * matching the given pattern.
      *
      * @param uriPattern the pattern to register the handler for.
      * @param requestHandler the handler.
      */
     public final <T> H2ServerBootstrap register(
             final String uriPattern,
             final AsyncServerRequestHandler<T> requestHandler) {
         register(uriPattern, () -> new BasicServerExchangeHandler<>(requestHandler));
         return this;
     }
 
     /**
      * Registers the given {@link AsyncServerRequestHandler} as a handler for URIs
      * matching the given host and the pattern.
      *
      * @param hostname the host name
      * @param uriPattern the pattern to register the handler for.
      * @param requestHandler the handler.
      */
     public final <T> H2ServerBootstrap registerVirtual(
             final String hostname,
             final String uriPattern,
             final AsyncServerRequestHandler<T> requestHandler) {
         registerVirtual(hostname, uriPattern, () -> new BasicServerExchangeHandler<>(requestHandler));
         return this;
     }
 
     /**
      * Adds the filter before the filter with the given name.
      */
     public final H2ServerBootstrap addFilterBefore(final String existing, final String name, final AsyncFilterHandler filterHandler) {
         Args.notBlank(existing, "Existing");
         Args.notBlank(name, "Name");
         Args.notNull(filterHandler, "Filter handler");
         filters.add(new FilterEntry<>(FilterEntry.Position.BEFORE, name, filterHandler, existing));
         return this;
     }
 
     /**
      * Adds the filter after the filter with the given name.
      */
     public final H2ServerBootstrap addFilterAfter(final String existing, final String name, final AsyncFilterHandler filterHandler) {
         Args.notBlank(existing, "Existing");
         Args.notBlank(name, "Name");
         Args.notNull(filterHandler, "Filter handler");
         filters.add(new FilterEntry<>(FilterEntry.Position.AFTER, name, filterHandler, existing));
         return this;
     }
 
     /**
      * Replace an existing filter with the given name with new filter.
      */
     public final H2ServerBootstrap replaceFilter(final String existing, final AsyncFilterHandler filterHandler) {
         Args.notBlank(existing, "Existing");
         Args.notNull(filterHandler, "Filter handler");
         filters.add(new FilterEntry<>(FilterEntry.Position.REPLACE, existing, filterHandler, existing));
         return this;
     }
 
     /**
      * Add an filter to the head of the processing list.
      */
     public final H2ServerBootstrap addFilterFirst(final String name, final AsyncFilterHandler filterHandler) {
         Args.notNull(name, "Name");
         Args.notNull(filterHandler, "Filter handler");
         filters.add(new FilterEntry<>(FilterEntry.Position.FIRST, name, filterHandler, null));
         return this;
     }
 
     /**
      * Add an filter to the tail of the processing list.
      */
     public final H2ServerBootstrap addFilterLast(final String name, final AsyncFilterHandler filterHandler) {
         Args.notNull(name, "Name");
         Args.notNull(filterHandler, "Filter handler");
         filters.add(new FilterEntry<>(FilterEntry.Position.LAST, name, filterHandler, null));
         return this;
     }
 
     public HttpAsyncServer create() {
         final String actualCanonicalHostName = canonicalHostName != null ? canonicalHostName : InetAddressUtils.getCanonicalLocalHostName();
         final RequestHandlerRegistry<Supplier<AsyncServerExchangeHandler>> registry = new RequestHandlerRegistry<>(
                 actualCanonicalHostName,
                 () -> lookupRegistry != null ? lookupRegistry :
                         UriPatternType.newMatcher(UriPatternType.URI_PATTERN));
         for (final HandlerEntry<Supplier<AsyncServerExchangeHandler>> entry: handlerList) {
             registry.register(entry.hostname, entry.uriPattern, entry.handler);
         }
 
         final HandlerFactory<AsyncServerExchangeHandler> handlerFactory;
         if (!filters.isEmpty()) {
             final NamedElementChain<AsyncFilterHandler> filterChainDefinition = new NamedElementChain<>();
             filterChainDefinition.addLast(
                     new TerminalAsyncServerFilter(new DefaultAsyncResponseExchangeHandlerFactory(registry)),
                     StandardFilter.MAIN_HANDLER.name());
             filterChainDefinition.addFirst(
                     new AsyncServerExpectationFilter(),
                     StandardFilter.EXPECT_CONTINUE.name());
 
             for (final FilterEntry<AsyncFilterHandler> entry: filters) {
                 switch (entry.position) {
                     case AFTER:
                         filterChainDefinition.addAfter(entry.existing, entry.filterHandler, entry.name);
                         break;
                     case BEFORE:
                         filterChainDefinition.addBefore(entry.existing, entry.filterHandler, entry.name);
                         break;
                     case REPLACE:
                         filterChainDefinition.replace(entry.existing, entry.filterHandler);
                         break;
                     case FIRST:
                         filterChainDefinition.addFirst(entry.filterHandler, entry.name);
                         break;
                     case LAST:
                         // Don't add last, after TerminalAsyncServerFilter, as that does not delegate to the chain
                         // Instead, add the filter just before it, making it effectively the last filter
                         filterChainDefinition.addBefore(StandardFilter.MAIN_HANDLER.name(), entry.filterHandler, entry.name);
                         break;
                 }
             }
 
             NamedElementChain<AsyncFilterHandler>.Node current = filterChainDefinition.getLast();
             AsyncServerFilterChainElement execChain = null;
             while (current != null) {
                 execChain = new AsyncServerFilterChainElement(current.getValue(), execChain);
                 current = current.getPrevious();
             }
 
             handlerFactory = new AsyncServerFilterChainExchangeHandlerFactory(execChain, exceptionCallback);
         } else {
             handlerFactory = new DefaultAsyncResponseExchangeHandlerFactory(registry, handler -> new BasicAsyncServerExpectationDecorator(handler, exceptionCallback));
         }
 
         final ServerH2StreamMultiplexerFactory http2StreamHandlerFactory = new ServerH2StreamMultiplexerFactory(
                 httpProcessor != null ? httpProcessor : H2Processors.server(),
                 handlerFactory,
                 h2Config != null ? h2Config : H2Config.DEFAULT,
                 charCodingConfig != null ? charCodingConfig : CharCodingConfig.DEFAULT,
                 h2StreamListener);
 
         final TlsStrategy actualTlsStrategy = tlsStrategy != null ? tlsStrategy : new H2ServerTlsStrategy();
 
         final ServerHttp1StreamDuplexerFactory http1StreamHandlerFactory = new ServerHttp1StreamDuplexerFactory(
                 httpProcessor != null ? httpProcessor : HttpProcessors.server(),
                 handlerFactory,
                 http1Config != null ? http1Config : Http1Config.DEFAULT,
                 charCodingConfig != null ? charCodingConfig : CharCodingConfig.DEFAULT,
                 DefaultConnectionReuseStrategy.INSTANCE,
                 DefaultHttpRequestParserFactory.INSTANCE,
                 DefaultHttpResponseWriterFactory.INSTANCE,
                 DefaultContentLengthStrategy.INSTANCE,
                 DefaultContentLengthStrategy.INSTANCE,
                 http1StreamListener);
 
         final IOEventHandlerFactory ioEventHandlerFactory = new ServerHttpProtocolNegotiationStarter(
                 http1StreamHandlerFactory,
                 http2StreamHandlerFactory,
                 versionPolicy != null ? versionPolicy : HttpVersionPolicy.NEGOTIATE,
                 actualTlsStrategy,
                 handshakeTimeout);
 
         return new HttpAsyncServer(ioEventHandlerFactory, ioReactorConfig, ioSessionDecorator, exceptionCallback,
                 sessionListener, actualCanonicalHostName);
     }
 
 }