# RequestProcessor.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;

    import com.google.gson.Gson;
    import com.google.gson.GsonBuilder;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.w3c.dom.Document;
    import org.w3c.dom.Node;
    import org.xml.sax.InputSource;
    import org.xml.sax.helpers.DefaultHandler;

    import java.io.StringReader;
    import java.io.StringWriter;
    import java.util.Map;
    import javax.xml.parsers.DocumentBuilder;
    import javax.xml.parsers.DocumentBuilderFactory;
    import javax.xml.transform.OutputKeys;
    import javax.xml.transform.Transformer;
    import javax.xml.transform.TransformerFactory;
    import javax.xml.transform.dom.DOMSource;
    import javax.xml.transform.stream.StreamResult;

    /**
     * Class responsible for removing the unwanted whitespaces in any type of inputs.
     */
    public class RequestProcessor {

        RequestProcessor() {
        }

        private static Log log = LogFactory.getLog(RequestProcessor.class.getName());

        /**
         * Remove irrelevant whitespaces from the input string.
         * If string is a XML or JSON reordered the structure of the string to normalize
         *
         * @param inputString string which needs to remove whitespaces
         * @return trim string not include irrelevant whitespaces
         */
        public static String trimStrings(String inputString) {

            //trim the string
            String trimedString = inputString.trim();

            //remove CDATA tag from the string if exists
            if (trimedString.startsWith("<![CDATA[")) {
                trimedString = trimedString.substring(9);
                int index = trimedString.indexOf("]]>");
                if (index == -1) {
                    throw new IllegalStateException("argument starts with <![CDATA[ but cannot find pairing ]]>");
                }
                trimedString = trimedString.substring(0, index);
            }

            trimedString = convertStringToRelatedDocumentType(trimedString);
            return trimedString.replaceAll("\\s", "");
        }

        /**
         * Check the input string is a XML type and generate a XML object and convert it to string.
         * Check the input string is a JSON type and generate a JSON object and convert it to string.
         *
         * @param domString inputString which about to convert
         * @return reordered trim string not include irrelevant whitespaces
         */
        private static String convertStringToRelatedDocumentType(String domString) {
            //Parser that produces DOM object trees from XML content
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

            //API to obtain DOM Document instance
            DocumentBuilder builder;

            String processedString;
            try {
                //Create DocumentBuilder with default configuration
                builder = factory.newDocumentBuilder();
                builder.setErrorHandler(new DefaultHandler());

                //Parse the content to Document object
                Document xmlDOM = builder.parse(new InputSource(new StringReader(domString)));
                processedString = nodeToString(xmlDOM);
                processedString = processedString.replaceAll("xmlns=\"\"", "");
            } catch (Exception e) {
                processedString = convertAsJSONString(domString);
            }

            return processedString;
        }

        /**
         * Convert XML document to string.
         *
         * @param node document node which represent XML
         * @return converted document element as a string
         */
        private static String nodeToString(Node node) {
            StringWriter stringWriter = new StringWriter();
            try {
                Transformer transformer = TransformerFactory.newInstance().newTransformer();
                transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                transformer.setOutputProperty(OutputKeys.INDENT, "yes");
                transformer.transform(new DOMSource(node), new StreamResult(stringWriter));
            } catch (Exception e) {
                log.error("nodeToString Transformer Exception", e);
            }
            return stringWriter.toString();
        }

        /**
         * Create JSON object using input string.
         * If failed return as it is.
         *
         * @param inputString input string which is not an XML
         * @return reordered string
         */
        private static String convertAsJSONString(String inputString) {
            try {
                Gson gson = new GsonBuilder()
                        .setPrettyPrinting()
                        .registerTypeAdapterFactory(new TreeMapTypeAdapterFactory())
                        .create();

                Map root = gson.fromJson(inputString, Map.class);
                return gson.toJson(root);
            } catch (Exception e) {
                return inputString;
            }
        }
    }