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/*
 * Copyright (C) 2015 HaiYang Li
 *
 * 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 com.landawn.abacus.http;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.charset.Charset;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

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

import com.landawn.abacus.exception.UncheckedIOException;
import com.landawn.abacus.logging.Logger;
import com.landawn.abacus.logging.LoggerFactory;
import com.landawn.abacus.util.IOUtil;
import com.landawn.abacus.util.N;
import com.landawn.abacus.util.Objectory;
import com.landawn.abacus.util.Strings;

/**
 *
 * @author Haiyang Li
 * @since 0.8
 */
public class EchoServlet extends AbstractHttpServlet {

    private static final long serialVersionUID = -8506987801604338536L;

    private static final Logger logger = LoggerFactory.getLogger(EchoServlet.class);

    public static final String IS_GET_FIRST = "isGetFirst";

    private boolean isGetFirst;

    /**
     *
     * @throws ServletException the servlet exception
     */
    @Override
    public void init() throws ServletException {
        super.init();
    }

    /**
     *
     * @param config
     * @throws ServletException the servlet exception
     */
    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        isGetFirst = Boolean.valueOf(getInitParameter(config, IS_GET_FIRST));
    }

    /**
     *
     * @param req
     * @param resp
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) {
        execute(req, resp);
    }

    /**
     *
     * @param req
     * @param resp
     */
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) {
        execute(req, resp);
    }

    /**
     *
     * @param req
     * @param resp
     */
    @Override
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) {
        execute(req, resp);
    }

    /**
     *
     * @param req
     * @param resp
     */
    @Override
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) {
        execute(req, resp);
    }

    /**
     *
     * @param request
     * @param response
     * @throws UncheckedIOException the unchecked IO exception
     */
    protected void execute(HttpServletRequest request, HttpServletResponse response) throws UncheckedIOException {
        final ContentFormat requestContentFormat = getRequestContentFormat(request);
        final Charset requestCharset = HttpUtil.getCharset(getContentType(request));

        Map paramMap = null;
        InputStream is = null;
        OutputStream os = null;

        try {
            final Enumeration headerNames = request.getHeaderNames();
            if (headerNames != null) {
                final Map headers = new LinkedHashMap<>();
                String headerName = null;

                while (headerNames.hasMoreElements()) {
                    headerName = headerNames.nextElement();
                    response.setHeader(headerName, request.getHeader(headerName));
                    headers.put(headerName, request.getHeader(headerName));
                }

                logger.info("Request Headers: " + N.toJSON(headers));
            }

            byte[] bytes = N.EMPTY_BYTE_ARRAY;

            if (isGetFirst) {
                paramMap = request.getParameterMap();

                if (N.isEmpty(paramMap)) {
                    is = getInputStream(request, requestContentFormat);
                }
            } else {
                is = getInputStream(request, requestContentFormat);

                paramMap = request.getParameterMap();
            }

            if (N.isEmpty(paramMap)) {
                bytes = IOUtil.readAllBytes(is);

                logger.info("Request body: " + new String(bytes, requestCharset));

                os = getOutputStream(response, requestContentFormat, requestCharset);

                IOUtil.write(os, bytes);
            } else {
                final StringBuilder sb = Objectory.createStringBuilder();

                try {
                    int i = 0;
                    for (Entry entry : paramMap.entrySet()) {
                        if (i++ > 0) {
                            sb.append('&');
                        }

                        sb.append(entry.getKey());
                        sb.append('=');
                        sb.append(N.isEmpty(entry.getValue()) ? Strings.EMPTY_STRING
                                : (entry.getValue().length == 1 ? N.toString(entry.getValue()[0]) : N.toString(entry.getValue())));
                    }

                    final String queryParts = sb.toString();

                    if (Strings.isEmpty(queryParts)) {
                        logger.info("Request query: " + N.toJSON(queryParts));
                    }

                    os = getOutputStream(response, requestContentFormat, requestCharset);

                    IOUtil.write(os, queryParts);
                } finally {
                    Objectory.recycle(sb);
                }
            }

            if (os != null) {
                flush(os);
            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        } finally {
            IOUtil.close(is);
            IOUtil.close(os);
        }
    }
}