/*
 * Copyright 2002-2017 the original author or authors.
 *
 * 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.springframework.http.server.reactive;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.cookie.Cookie;
import io.netty.handler.codec.http.cookie.DefaultCookie;
import io.reactivex.netty.protocol.http.server.HttpServerResponse;
import io.reactivex.netty.protocol.http.server.ResponseContentWriter;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import rx.Observable;
import rx.RxReactiveStreams;
import rx.functions.Func1;

import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.NettyDataBufferFactory;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseCookie;
import org.springframework.util.Assert;

/**
 * Adapt {@link ServerHttpResponse} to the RxNetty {@link HttpServerResponse}.
 * For internal use within the framework.
 * 
 * @author Rossen Stoyanchev
 * @author Stephane Maldini
 * @author Sebastien Deleuze
 * @since 5.0
 */
public class RxNettyServerHttpResponse extends AbstractServerHttpResponse {

	private final HttpServerResponse<ByteBuf> response;

	private static final ByteBuf FLUSH_SIGNAL = Unpooled.buffer(0, 0);

	// 8 Kb flush threshold to avoid blocking RxNetty when the send buffer has reached the high watermark
	private static final long FLUSH_THRESHOLD = 8192;

	public RxNettyServerHttpResponse(HttpServerResponse<ByteBuf> response,
			NettyDataBufferFactory dataBufferFactory) {
		super(dataBufferFactory);
		Assert.notNull(response, "'response' must not be null.");

		this.response = response;
	}


	public HttpServerResponse<?> getRxNettyResponse() {
		return this.response;
	}


	@Override
	protected void applyStatusCode() {
		HttpStatus statusCode = this.getStatusCode();
		if (statusCode != null) {
			this.response.setStatus(HttpResponseStatus.valueOf(statusCode.value()));
		}
	}

	@Override
	protected Mono<Void> writeWithInternal(Publisher<? extends DataBuffer> body) {
		Observable<ByteBuf> content = RxReactiveStreams.toObservable(body)
				.map(NettyDataBufferFactory::toByteBuf);
		return Flux.from(RxReactiveStreams.toPublisher(this.response.write(content, new FlushSelector(FLUSH_THRESHOLD))))
				.then();
	}

	@Override
	protected Mono<Void> writeAndFlushWithInternal(
			Publisher<? extends Publisher<? extends DataBuffer>> body) {
		Flux<ByteBuf> bodyWithFlushSignals = Flux.from(body).
				flatMap(publisher -> Flux.from(publisher).
						map(NettyDataBufferFactory::toByteBuf).
						concatWith(Mono.just(FLUSH_SIGNAL)));
		Observable<ByteBuf> content = RxReactiveStreams.toObservable(bodyWithFlushSignals);
		ResponseContentWriter<ByteBuf> writer = this.response.write(content, bb -> bb == FLUSH_SIGNAL);
		return Flux.from(RxReactiveStreams.toPublisher(writer)).then();
	}

	@Override
	protected void applyHeaders() {
		for (String name : getHeaders().keySet()) {
			for (String value : getHeaders().get(name)) {
				this.response.addHeader(name, value);
			}
		}
	}

	@Override
	protected void applyCookies() {
		for (String name : getCookies().keySet()) {
			for (ResponseCookie httpCookie : getCookies().get(name)) {
				Cookie cookie = new DefaultCookie(name, httpCookie.getValue());
				if (!httpCookie.getMaxAge().isNegative()) {
					cookie.setMaxAge(httpCookie.getMaxAge().getSeconds());
				}
				httpCookie.getDomain().ifPresent(cookie::setDomain);
				httpCookie.getPath().ifPresent(cookie::setPath);
				cookie.setSecure(httpCookie.isSecure());
				cookie.setHttpOnly(httpCookie.isHttpOnly());
				this.response.addCookie(cookie);
			}
		}
	}

	private class FlushSelector implements Func1<ByteBuf, Boolean> {

		private final long flushEvery;
		private long count;

		public FlushSelector(long flushEvery) {
			this.flushEvery = flushEvery;
		}

		@Override
		public Boolean call(ByteBuf byteBuf) {
			this.count += byteBuf.readableBytes();
			if (this.count >= this.flushEvery) {
				this.count = 0;
				return true;
			}
			return false;
		}
	}


	/*
	While the underlying implementation of {@link ZeroCopyHttpOutputMessage} seems to
	work; it does bypass {@link #applyBeforeCommit} and more importantly it doesn't change
	its {@linkplain #state()). Therefore it's commented out, for now.

	We should revisit this code once
	https://github.com/ReactiveX/RxNetty/issues/194 has been fixed.


	@Override
	public Mono<Void> writeWith(File file, long position, long count) {
		Channel channel = this.response.unsafeNettyChannel();

		HttpResponse httpResponse =
				new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
		io.netty.handler.codec.http.HttpHeaders headers = httpResponse.headers();

		for (Map.Entry<String, List<String>> header : getHeaders().entrySet()) {
			String headerName = header.getKey();
			for (String headerValue : header.getValue()) {
				headers.add(headerName, headerValue);
			}
		}
		Mono<Void> responseWrite = MonoChannelFuture.from(channel.write(httpResponse));

		FileRegion fileRegion = new DefaultFileRegion(file, position, count);
		Mono<Void> fileWrite = MonoChannelFuture.from(channel.writeAndFlush(fileRegion));

		return Flux.concat(applyBeforeCommit(), responseWrite, fileWrite).then();
	}
*/
}