# HttpResponseProcessor.java

    /*
     * Copyright (c) 2019, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     * WSO2 Inc. 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.
     */

    package org.apache.synapse.commons.emulator.http.consumer;

    import io.netty.buffer.Unpooled;
    import io.netty.channel.ChannelFutureListener;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.handler.codec.http.DefaultFullHttpResponse;
    import io.netty.handler.codec.http.FullHttpResponse;
    import io.netty.handler.codec.http.HttpHeaders;
    import io.netty.handler.codec.http.HttpResponseStatus;
    import io.netty.handler.codec.http.HttpVersion;
    import io.netty.handler.codec.http.ServerCookieEncoder;
    import io.netty.util.CharsetUtil;
    import org.apache.synapse.commons.emulator.http.dsl.dto.Header;
    import org.apache.synapse.commons.emulator.http.dsl.dto.consumer.IncomingMessage;
    import org.apache.synapse.commons.emulator.http.dsl.dto.consumer.OutgoingMessage;
    import org.apache.synapse.commons.emulator.http.dsl.HttpConsumerContext;
    import org.apache.synapse.commons.emulator.http.dsl.dto.Cookie;

    import java.util.Map;

    import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;

    public class HttpResponseProcessor {
        private HttpConsumerContext consumerContext;

        public HttpResponseProcessor(HttpConsumerContext consumerContext) {
            this.consumerContext = consumerContext;
        }

        public void process(HttpRequestContext requestContext, ChannelHandlerContext ctx) {
            OutgoingMessage outgoing = getMatchResource(requestContext);
            if (outgoing == null) {
                if (!write404NotFoundResponse(requestContext, ctx)) {
                    ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
                }
            } else {
                if (!writeResponse(requestContext, outgoing, ctx)) {
                    ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
                }
            }
        }

        private boolean writeResponse(HttpRequestContext requestContext, OutgoingMessage outgoing, ChannelHandlerContext
                ctx) {
            boolean keepAlive = requestContext.isKeepAlive();

            HttpVersion httpVersion = consumerContext.getHttpVersion();
            HttpResponseStatus httpResponseStatus = outgoing.getStatusCode();
            FullHttpResponse response = new DefaultFullHttpResponse(
                    httpVersion, httpResponseStatus,
                    Unpooled.copiedBuffer(outgoing.getBody(), CharsetUtil.UTF_8));

            populateHttpHeaders(response, outgoing);
            populateCookies(response, outgoing);

            if (!keepAlive) {
                response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, response.content().readableBytes());
                ctx.write(response).addListener(ChannelFutureListener.CLOSE);
            } else {
                response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, response.content().readableBytes());
                response.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
                ctx.write(response);
            }
            return keepAlive;
        }

        private void populateHttpHeaders(FullHttpResponse response, OutgoingMessage outgoing) {
            if (outgoing.getHeaders() != null) {
                for (Header header : outgoing.getHeaders()) {
                    response.headers().add(header.getName(), header.getValue());
                }
            }
            response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, response.content().readableBytes());
        }

        private void populateCookies(FullHttpResponse response, OutgoingMessage outgoing) {
            if (outgoing.getCookies() != null) {
                for (Cookie cookie : outgoing.getCookies()) {
                    response.headers().add(HttpHeaders.Names.SET_COOKIE, ServerCookieEncoder.encode(cookie.getName(),
                            cookie.getValue()));
                }
            }
        }

        private boolean write404NotFoundResponse(HttpRequestContext requestContext, ChannelHandlerContext ctx) {
            boolean keepAlive = requestContext.isKeepAlive();
            HttpVersion httpVersion = consumerContext.getHttpVersion();
            FullHttpResponse response = new DefaultFullHttpResponse(
                    httpVersion, NOT_FOUND);
            response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "text/plain; charset=UTF-8");

            if (!keepAlive) {
                ctx.write(response).addListener(ChannelFutureListener.CLOSE);
            } else {
                response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, response.content().readableBytes());
                response.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
                ctx.write(response);
            }
            return keepAlive;
        }

        private OutgoingMessage getMatchResource(HttpRequestContext requestContext) {
            for (Map.Entry<IncomingMessage, OutgoingMessage> entry : consumerContext.getInOutCorrelation().entrySet()) {
                if (entry.getKey().isMatch(requestContext)) {
                    return entry.getValue();
                }
            }
            return null;
        }
    }