package ca.uhn.fhir.rest.server.servlet;

/*
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * Copyright (C) 2014 - 2017 University Health Network
 * %%
 * 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.
 * #L%
 */
import static org.apache.commons.lang3.StringUtils.isNotBlank;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.zip.GZIPInputStream;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.io.IOUtils;
import org.apache.http.entity.ContentType;

import ca.uhn.fhir.context.ConfigurationException;
import ca.uhn.fhir.rest.method.BaseMethodBinding;
import ca.uhn.fhir.rest.method.BaseMethodBinding.IRequestReader;
import ca.uhn.fhir.rest.method.RequestDetails;
import ca.uhn.fhir.rest.server.Constants;
import ca.uhn.fhir.rest.server.RestfulServer;
import ca.uhn.fhir.rest.server.exceptions.InvalidRequestException;

public class ServletRequestDetails extends RequestDetails {

        private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(ServletRequestDetails.class);
        /**
         * @see BaseMethodBinding#loadRequestContents(RequestDetails)
         */
        private static volatile IRequestReader ourRequestReader;
        private RestfulServer myServer;
        private HttpServletRequest myServletRequest;
        private HttpServletResponse myServletResponse;
        private byte[] requestContents;

        public ServletRequestDetails() {
                super();
                setResponse(new ServletRestfulResponse(this));
        }

        @Override
        protected byte[] getByteStreamRequestContents() {
                /*
                 * This is weird, but this class is used both in clients and in servers, and we want to avoid needing to depend on
                 * servlet-api in clients since there is no point. So we dynamically load a class that does the servlet processing
                 * in servers. Down the road it may make sense to just split the method binding classes into server and client
                 * versions, but this isn't actually a huge deal I don't think.
                 */
                IRequestReader reader = ourRequestReader;
                if (reader == null) {
                        try {
                                Class.forName("javax.servlet.ServletInputStream");
                                String className = BaseMethodBinding.class.getName() + "$" + "ActiveRequestReader";
                                try {
                                        reader = (IRequestReader) Class.forName(className).newInstance();
                                } catch (Exception e1) {
                                        throw new ConfigurationException("Failed to instantiate class " + className, e1);
                                }
                        } catch (ClassNotFoundException e) {
                                String className = BaseMethodBinding.class.getName() + "$" + "InactiveRequestReader";
                                try {
                                        reader = (IRequestReader) Class.forName(className).newInstance();
                                } catch (Exception e1) {
                                        throw new ConfigurationException("Failed to instantiate class " + className, e1);
                                }
                        }
                        ourRequestReader = reader;
                }

                try {
                        InputStream inputStream = reader.getInputStream(this);
                        requestContents = IOUtils.toByteArray(inputStream);

                        if (myServer.isUncompressIncomingContents()) {
                                String contentEncoding = myServletRequest.getHeader(Constants.HEADER_CONTENT_ENCODING);
                                if ("gzip".equals(contentEncoding)) {
                                        ourLog.debug("Uncompressing (GZip) incoming content");
                                        if (requestContents.length > 0) {
                                                GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(requestContents));
                                                requestContents = IOUtils.toByteArray(gis);
                                        }
                                }
                        }
                        // FIXME resource leak
                        return requestContents;
                } catch (IOException e) {
                        ourLog.error("Could not load request resource", e);
                        throw new InvalidRequestException(String.format("Could not load request resource: %s", e.getMessage()));
                }
        }

        @Override
        public String getHeader(String name) {
                return getServletRequest().getHeader(name);
        }

        @Override
        public List<String> getHeaders(String name) {
                Enumeration<String> headers = getServletRequest().getHeaders(name);
                return headers == null ? Collections.<String> emptyList() : Collections.list(getServletRequest().getHeaders(name));
        }

        @Override
        public InputStream getInputStream() throws IOException {
                return getServletRequest().getInputStream();
        }

        @Override
        public Reader getReader() throws IOException {
                return getServletRequest().getReader();
        }

        @Override
        public RestfulServer getServer() {
                return myServer;
        }

        @Override
        public String getServerBaseForRequest() {
                return getServer().getServerBaseForRequest(getServletRequest());
        }

        public HttpServletRequest getServletRequest() {
                return myServletRequest;
        }

        public HttpServletResponse getServletResponse() {
                return myServletResponse;
        }

        public void setServer(RestfulServer theServer) {
                this.myServer = theServer;
        }

        public void setServletRequest(HttpServletRequest myServletRequest) {
                this.myServletRequest = myServletRequest;
        }

        public void setServletResponse(HttpServletResponse myServletResponse) {
                this.myServletResponse = myServletResponse;
        }

        @Override
        public Charset getCharset() {
                String ct = getHeader(Constants.HEADER_CONTENT_TYPE);

                Charset charset = null;
                if (isNotBlank(ct)) {
                        ContentType parsedCt = ContentType.parse(ct);
                        charset = parsedCt.getCharset();
                }
                return charset;
        }

}