package org.json;

/*
Copyright (c) 2015 JSON.org

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

The Software shall be used for Good, not Evil.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

import org.json.execption.JSONFoundExecption;

import java.io.Reader;
import java.io.StringReader;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.Iterator;
import java.util.concurrent.*;
import java.util.function.BiFunction;
import java.util.function.Function;


/**
 * This provides static methods to convert an XML text into a JSONObject, and to
 * covert a JSONObject into an XML text.
 *
 * @author JSON.org
 * @version 2016-08-10
 */
@SuppressWarnings("boxing")
public class XML {

    /** The Character '&'. */
    public static final Character AMP = '&';

    /** The Character '''. */
    public static final Character APOS = '\'';

    /** The Character '!'. */
    public static final Character BANG = '!';

    /** The Character '='. */
    public static final Character EQ = '=';

    /** The Character <pre>{@code '>'. }</pre>*/
    public static final Character GT = '>';

    /** The Character '&lt;'. */
    public static final Character LT = '<';

    /** The Character '?'. */
    public static final Character QUEST = '?';

    /** The Character '"'. */
    public static final Character QUOT = '"';

    /** The Character '/'. */
    public static final Character SLASH = '/';

    /**
     * Null attribute name
     */
    public static final String NULL_ATTR = "xsi:nil";

    public static final String TYPE_ATTR = "xsi:type";

    /**
     * Creates an iterator for navigating Code Points in a string instead of
     * characters. Once Java7 support is dropped, this can be replaced with
     * <code>
     * string.codePoints()
     * </code>
     * which is available in Java8 and above.
     *
     * @see <a href=
     *      "http://stackoverflow.com/a/21791059/6030888">http://stackoverflow.com/a/21791059/6030888</a>
     */
    private static Iterable<Integer> codePointIterator(final String string) {
        return new Iterable<Integer>() {
            @Override
            public Iterator<Integer> iterator() {
                return new Iterator<Integer>() {
                    private int nextIndex = 0;
                    private int length = string.length();

                    @Override
                    public boolean hasNext() {
                        return this.nextIndex < this.length;
                    }

                    @Override
                    public Integer next() {
                        int result = string.codePointAt(this.nextIndex);
                        this.nextIndex += Character.charCount(result);
                        return result;
                    }

                    @Override
                    public void remove() {
                        throw new UnsupportedOperationException();
                    }
                };
            }
        };
    }

    /**
     * Replace special characters with XML escapes:
     *
     * <pre>{@code
     * &amp; (ampersand) is replaced by &amp;amp;
     * &lt; (less than) is replaced by &amp;lt;
     * &gt; (greater than) is replaced by &amp;gt;
     * &quot; (double quote) is replaced by &amp;quot;
     * &apos; (single quote / apostrophe) is replaced by &amp;apos;
     * }</pre>
     *
     * @param string
     *            The string to be escaped.
     * @return The escaped string.
     */
    public static String escape(String string) {
        StringBuilder sb = new StringBuilder(string.length());
        for (final int cp : codePointIterator(string)) {
            switch (cp) {
            case '&':
                sb.append("&amp;");
                break;
            case '<':
                sb.append("&lt;");
                break;
            case '>':
                sb.append("&gt;");
                break;
            case '"':
                sb.append("&quot;");
                break;
            case '\'':
                sb.append("&apos;");
                break;
            default:
                if (mustEscape(cp)) {
                    sb.append("&#x");
                    sb.append(Integer.toHexString(cp));
                    sb.append(';');
                } else {
                    sb.appendCodePoint(cp);
                }
            }
        }
        return sb.toString();
    }

    /**
     * @param cp code point to test
     * @return true if the code point is not valid for an XML
     */
    private static boolean mustEscape(int cp) {
        /* Valid range from https://www.w3.org/TR/REC-xml/#charsets
         *
         * #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
         *
         * any Unicode character, excluding the surrogate blocks, FFFE, and FFFF.
         */
        // isISOControl is true when (cp >= 0 && cp <= 0x1F) || (cp >= 0x7F && cp <= 0x9F)
        // all ISO control characters are out of range except tabs and new lines
        return (Character.isISOControl(cp)
                && cp != 0x9
                && cp != 0xA
                && cp != 0xD
            ) || !(
                // valid the range of acceptable characters that aren't control
                (cp >= 0x20 && cp <= 0xD7FF)
                || (cp >= 0xE000 && cp <= 0xFFFD)
                || (cp >= 0x10000 && cp <= 0x10FFFF)
            )
        ;
    }

    /**
     * Removes XML escapes from the string.
     *
     * @param string
     *            string to remove escapes from
     * @return string with converted entities
     */
    public static String unescape(String string) {
        StringBuilder sb = new StringBuilder(string.length());
        for (int i = 0, length = string.length(); i < length; i++) {
            char c = string.charAt(i);
            if (c == '&') {
                final int semic = string.indexOf(';', i);
                if (semic > i) {
                    final String entity = string.substring(i + 1, semic);
                    sb.append(XMLTokener.unescapeEntity(entity));
                    // skip past the entity we just parsed.
                    i += entity.length() + 1;
                } else {
                    // this shouldn't happen in most cases since the parser
                    // errors on unclosed entries.
                    sb.append(c);
                }
            } else {
                // not part of an entity
                sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * Throw an exception if the string contains whitespace. Whitespace is not
     * allowed in tagNames and attributes.
     *
     * @param string
     *            A string.
     * @throws JSONException Thrown if the string contains whitespace or is empty.
     */
    public static void noSpace(String string) throws JSONException {
        int i, length = string.length();
        if (length == 0) {
            throw new JSONException("Empty string.");
        }
        for (i = 0; i < length; i += 1) {
            if (Character.isWhitespace(string.charAt(i))) {
                throw new JSONException("'" + string
                        + "' contains a space character.");
            }
        }
    }

    /**
     * Scan the content following the named tag, attaching it to the context.
     *
     * @param x
     *            The XMLTokener containing the source string.
     * @param context
     *            The JSONObject that will include the new material.
     * @param name
     *            The tag name.
     * @return true if the close tag is processed.
     * @throws JSONException
     */
    private static boolean parse(XMLTokener x, JSONObject context, String name, XMLParserConfiguration config)
            throws JSONException {
        char c;
        int i;
        JSONObject jsonObject = null;
        String string;
        String tagName;
        Object token;
        XMLXsiTypeConverter<?> xmlXsiTypeConverter;

        // Test for and skip past these forms:
        // <!-- ... -->
        // <! ... >
        // <![ ... ]]>
        // <? ... ?>
        // Report errors for these forms:
        // <>
        // <=
        // <<

        token = x.nextToken();

        // <!

        if (token == BANG) {
            c = x.next();
            if (c == '-') {
                if (x.next() == '-') {
                    //denoting this line is annotation
                    //ignore <!--  -->
                    x.skipPast("-->");
                    return false;
                }
                x.back();
            } else if (c == '[') {
                token = x.nextToken();
                if ("CDATA".equals(token)) {
                    if (x.next() == '[') {
                        string = x.nextCDATA();
                        if (string.length() > 0) {
                            context.accumulate(config.getcDataTagName(), string);
                        }
                        return false;
                    }
                }
                throw x.syntaxError("Expected 'CDATA['");
            }
            i = 1;
            do {
                token = x.nextMeta();
                if (token == null) {
                    throw x.syntaxError("Missing '>' after '<!'.");
                } else if (token == LT) {
                    i += 1;
                } else if (token == GT) {
                    i -= 1;
                }
            } while (i > 0);
            return false;
        } else if (token == QUEST) {

            // <?
            x.skipPast("?>");
            return false;
        } else if (token == SLASH) {

            // Close tag </

            token = x.nextToken();
            if (name == null) {
                throw x.syntaxError("Mismatched close tag " + token);
            }
            if (!token.equals(name)) {
                throw x.syntaxError("Mismatched " + name + " and " + token);
            }
            if (x.nextToken() != GT) {
                throw x.syntaxError("Misshaped close tag");
            }
            return true;

        } else if (token instanceof Character) {
            throw x.syntaxError("Misshaped tag");

            // Open tag <
            //if token is tagName
        } else {
            tagName = (String) token;
            token = null;
            jsonObject = new JSONObject();
            boolean nilAttributeFound = false;
            xmlXsiTypeConverter = null;
            for (;;) {
                if (token == null) {
                    token = x.nextToken();
                }
                // attribute = value
                if (token instanceof String) {
                    //why two consecutive String, then =
                    //maybe is loop cause, last loop
                    string = (String) token;
                    token = x.nextToken();
                    if (token == EQ) {
                        token = x.nextToken();
                        if (!(token instanceof String)) {
                            throw x.syntaxError("Missing value");
                        }

                        if (config.isConvertNilAttributeToNull()
                                && NULL_ATTR.equals(string)
                                && Boolean.parseBoolean((String) token)) {
                            nilAttributeFound = true;
                        } else if(config.getXsiTypeMap() != null && !config.getXsiTypeMap().isEmpty()
                                && TYPE_ATTR.equals(string)) {
                            xmlXsiTypeConverter = config.getXsiTypeMap().get(token);
                        } else if (!nilAttributeFound) {
                            jsonObject.accumulate(string,
                                    config.isKeepStrings()
                                            ? ((String) token)
                                            : stringToValue((String) token));
                        }
                        token = null;
                    } else {
                        jsonObject.accumulate(string, "");
                    }


                } else if (token == SLASH) {
                    // Empty tag <.../>
                    if (x.nextToken() != GT) {
                        throw x.syntaxError("Misshaped tag");
                    }
                    if (config.getForceList().contains(tagName)) {
                        // Force the value to be an array
                        if (nilAttributeFound) {
                            context.append(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            //in loop
                            context.append(tagName, jsonObject);
                        } else {
                            context.put(tagName, new JSONArray());
                        }
                    } else {
                        if (nilAttributeFound) {
                            context.accumulate(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            context.accumulate(tagName, jsonObject);
                        } else {
                            context.accumulate(tagName, "");
                        }
                    }
                    return false;

                } else if (token == GT) {
                    // Content, between <...> and </...>
                    // after a String, if it is >, then analysis inner content
                    for (;;) {
                        //loop goal: first time temporally save String, second time put into parent JSONObject
                        //if has nested element, do recursion
                        token = x.nextContent();
                        if (token == null) {
                            if (tagName != null) {
                                throw x.syntaxError("Unclosed tag " + tagName);
                            }
                            return false;
                        } else if (token instanceof String) {
                            string = (String) token;
                            if (string.length() > 0) {
                                if(xmlXsiTypeConverter != null) {
                                    jsonObject.accumulate(config.getcDataTagName(),
                                            stringToValue(string, xmlXsiTypeConverter));
                                } else {
                                    jsonObject.accumulate(config.getcDataTagName(),
                                            config.isKeepStrings() ? string : stringToValue(string));
                                }
                            }

                        } else if (token == LT) {
                            // Nested element
                            // new <
                            //when subStruct come across opposite one, subStruct's recursion return true to subStruct
                            //when subStruct has been accumulated, return false to parentis done
                            if (parse(x, jsonObject, tagName, config)) {
                                if (config.getForceList().contains(tagName)) {
                                    // Force the value to be an array
                                    if (jsonObject.length() == 0) {
                                        context.put(tagName, new JSONArray());
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        context.append(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        context.append(tagName, jsonObject);
                                    }
                                } else {
                                    if (jsonObject.length() == 0) {
                                        //let values of same tagName, save as JSONArray
                                        context.accumulate(tagName, "");
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        //enter into subStruct and then return true, come here when subStruct is <name>value</name>
                                        //config.getcDataTagName():"content" is temporally saving key
                                        context.accumulate(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        //when subStruct has nested element like <address><zipcode>111</zipcode><street>Ave</street><address>
                                        context.accumulate(tagName, jsonObject);
                                    }
                                }

                                return false;
                            }
                        }
                    }
                } else {
                    throw x.syntaxError("Misshaped tag");
                }
            }
        }
    }




    /**
     * Scan the content following the named tag, attaching it to the context.
     *
     * @param x
     *            The XMLTokener containing the source string.
     * @param context
     *            The JSONObject that will include the new material.
     * @param name
     *            The tag name.
     * @param paths
     *            paths of JSONPointer
     * @param level
     *            depth level of xml/JSONObject
     * @param pLevel
     *            depth level of paths
     * @param replacement for Milestone 2
     *            JSONObject that is going to replace the path's object
     * @return true if the close tag is processed.
     * @throws JSONException
     */
    private static boolean parseWithPath(XMLTokener x, JSONObject context, String name, XMLParserConfiguration config, String[] paths, int level, int pLevel, JSONObject replacement)
            throws JSONException, JSONFoundExecption {
        char c;
        int i;
        JSONObject jsonObject = null;
        String string;
        String tagName;
        Object token;
        XMLXsiTypeConverter<?> xmlXsiTypeConverter;

        // Test for and skip past these forms:
        // <!-- ... -->
        // <! ... >
        // <![ ... ]]>
        // <? ... ?>
        // Report errors for these forms:
        // <>
        // <=
        // <<

        token = x.nextToken();

        // <!

        if (token == BANG) {
            c = x.next();
            if (c == '-') {
                if (x.next() == '-') {
                    //denoting this line is annotation
                    //ignore <!--  -->
                    x.skipPast("-->");
                    return false;
                }
                x.back();
            } else if (c == '[') {
                token = x.nextToken();
                if ("CDATA".equals(token)) {
                    if (x.next() == '[') {
                        string = x.nextCDATA();
                        if (string.length() > 0) {
                            context.accumulate(config.getcDataTagName(), string);
                        }
                        return false;
                    }
                }
                throw x.syntaxError("Expected 'CDATA['");
            }
            i = 1;
            do {
                token = x.nextMeta();
                if (token == null) {
                    throw x.syntaxError("Missing '>' after '<!'.");
                } else if (token == LT) {
                    i += 1;
                } else if (token == GT) {
                    i -= 1;
                }
            } while (i > 0);
            return false;
        } else if (token == QUEST) {

            // <?
            x.skipPast("?>");
            return false;
        } else if (token == SLASH) {

            // Close tag </

            token = x.nextToken();
            if (name == null) {
                throw x.syntaxError("Mismatched close tag " + token);
            }
            if (!token.equals(name)) {
                throw x.syntaxError("Mismatched " + name + " and " + token);
            }
            if (x.nextToken() != GT) {
                throw x.syntaxError("Misshaped close tag");
            }
            return true;

        } else if (token instanceof Character) {
            throw x.syntaxError("Misshaped tag");

            // Open tag <
            //if token is tagName
        } else {
            tagName = (String) token;
            token = null;
            jsonObject = new JSONObject();
            boolean nilAttributeFound = false;
            xmlXsiTypeConverter = null;

            //add by Sunsheng Su
            if(level == pLevel){
                if(paths[pLevel].equals(tagName)){
                    if(pLevel < paths.length-1){
                        pLevel++;
                    }

                    //for toJSONObject with replacement
                    if(replacement != null && pLevel == level){ //paths.length -1
                        x.skipPast("</" +tagName+ ">");
                        //from professor Cristina test demo and responses to Justin, replacement has the last key of paths
                        context.put(tagName, replacement.get(tagName));
                        return false;
                    }
                }
                //for toJSONObject with extract object, skip other tagNames
                else if(replacement == null){
                    x.skipPast("</" +tagName+ ">");
                    return false;
                }
            }

            for (;;) {
                if (token == null) {
                    token = x.nextToken();
                }
                // attribute = value
                if (token instanceof String) {
                    //for this xml
                    //<last_update_posted type="Actual">September 12, 2019</last_update_posted>
                    string = (String) token;
                    token = x.nextToken();
                    if (token == EQ) {
                        token = x.nextToken();
                        if (!(token instanceof String)) {
                            throw x.syntaxError("Missing value");
                        }

                        if (config.isConvertNilAttributeToNull()
                                && NULL_ATTR.equals(string)
                                && Boolean.parseBoolean((String) token)) {
                            nilAttributeFound = true;
                        } else if(config.getXsiTypeMap() != null && !config.getXsiTypeMap().isEmpty()
                                && TYPE_ATTR.equals(string)) {
                            xmlXsiTypeConverter = config.getXsiTypeMap().get(token);
                        } else if (!nilAttributeFound) {
                            jsonObject.accumulate(string,
                                    config.isKeepStrings()
                                            ? ((String) token)
                                            : stringToValue((String) token));
                        }
                        token = null;
                    } else {
                        jsonObject.accumulate(string, "");
                    }

                } else if (token == SLASH) {
                    // Empty tag <.../>
                    if (x.nextToken() != GT) {
                        throw x.syntaxError("Misshaped tag");
                    }
                    if (config.getForceList().contains(tagName)) {
                        // Force the value to be an array
                        if (nilAttributeFound) {
                            context.append(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            //in loop
                            context.append(tagName, jsonObject);
                        } else {
                            context.put(tagName, new JSONArray());
                        }
                    } else {
                        if (nilAttributeFound) {
                            context.accumulate(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            context.accumulate(tagName, jsonObject);
                        } else {
                            context.accumulate(tagName, "");
                        }
                    }
                    return false;

                } else if (token == GT) {
                    // Content, between <...> and </...>
                    // after a String, if it is >, then analysis inner content
                    for (;;) {
                        //loop goal: first time temporally save String, second time put into parent JSONObject
                        //if has nested element, do recursion
                        token = x.nextContent();
                        if (token == null) {
                            if (tagName != null) {
                                throw x.syntaxError("Unclosed tag " + tagName);
                            }
                            return false;
                        } else if (token instanceof String) {
                            string = (String) token;
                            if (string.length() > 0) {
                                if(xmlXsiTypeConverter != null) {
                                    jsonObject.accumulate(config.getcDataTagName(),
                                            stringToValue(string, xmlXsiTypeConverter));
                                } else {
                                    jsonObject.accumulate(config.getcDataTagName(),
                                            config.isKeepStrings() ? string : stringToValue(string));
                                }
                            }

                        } else if (token == LT) {
                            // still has <, denoting Nested element
                            // new <
                            //when subStruct come across opposite one, subStruct's recursion return true to subStruct. So, the tagName's content will be add
                            //when subStruct has been accumulated, return false to calling position
                            //address -> "<" -> street -> "<" -> /street -> true to add street into JSONObject -> false -> address
                            //address -> "<" -> zipcode -> "<" -> /zipcode -> true to add zipcode into JSONObject -> false -> address
                            //address -> "<" -> /address -> true to add address(JSONObject[street,zipcode]) to JSONObject(upper level)

                            if (parseWithPath(x, jsonObject, tagName, config, paths, level+1, pLevel, replacement)) {
                                if (config.getForceList().contains(tagName)) {
                                    // Force the value to be an array
                                    if (jsonObject.length() == 0) {
                                        context.put(tagName, new JSONArray());
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        context.append(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        context.append(tagName, jsonObject);
                                    }
                                } else {
                                    if (jsonObject.length() == 0) {
                                        //let values of same tagName, save as JSONArray
                                        context.accumulate(tagName, "");
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        //todo why jsonObject.length == 1 1:array reason 2:same name with content
                                        //enter into subStruct and then return true, come here when subStruct is <name>value</name>
                                        //config.getcDataTagName(): key:"content" is temporally saved with String
                                        context.accumulate(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        //when subStruct has nested element like <address><zipcode>111</zipcode><street>Ave</street><address>
                                        context.accumulate(tagName, jsonObject);
                                    }
                                }

                                //add by Sunsheng Su
                                //pLevel == path.length-1 (no need)
                                //pLevel not equal to level unless pLevel reach the last one
                                //this block code only executed when tagName has been found totally, including children
                                if(replacement == null  && pLevel == paths.length-1 && level == pLevel-1){
                                    //for normal path, , like /a/b/c, this is b level and to get tagName c
                                    if (paths[pLevel].split("[^0-9]").length != 1){
                                        throw new JSONFoundExecption( jsonObject.opt(paths[pLevel]));
                                    }
                                    //for path with index, like /a/b/c/1, this is c level, and accumulate until 1.
                                    else{
                                        int index = Integer.parseInt(paths[pLevel]);
                                        if(index == 0){
                                            throw new JSONFoundExecption( jsonObject.opt(config.getcDataTagName()));
                                        }
                                        else if(context.get(paths[pLevel-1]) instanceof JSONArray){
                                            if(context.getJSONArray(paths[pLevel-1]).length() == index+1)
                                                throw new JSONFoundExecption( jsonObject.opt(config.getcDataTagName()));
                                        }
                                    }
                                }
                                return false;
                            }
                        }
                    }
                } else {
                    throw x.syntaxError("Misshaped tag");
                }
            }
        }
    }

    /**
     * This method tries to convert the given string value to the target object
     * @param string String to convert
     * @param typeConverter value converter to convert string to integer, boolean e.t.c
     * @return JSON value of this string or the string
     */
    public static Object stringToValue(String string, XMLXsiTypeConverter<?> typeConverter) {
        if(typeConverter != null) {
            return typeConverter.convert(string);
        }
        return stringToValue(string);
    }

    /**
     * This method is the same as {@link JSONObject#stringToValue(String)}.
     *
     * @param string String to convert
     * @return JSON value of this string or the string
     */
    // To maintain compatibility with the Android API, this method is a direct copy of
    // the one in JSONObject. Changes made here should be reflected there.
    // This method should not make calls out of the XML object.
    public static Object stringToValue(String string) {
        if ("".equals(string)) {
            return string;
        }

        // check JSON key words true/false/null
        if ("true".equalsIgnoreCase(string)) {
            return Boolean.TRUE;
        }
        if ("false".equalsIgnoreCase(string)) {
            return Boolean.FALSE;
        }
        if ("null".equalsIgnoreCase(string)) {
            return JSONObject.NULL;
        }

        /*
         * If it might be a number, try converting it. If a number cannot be
         * produced, then the value will just be a string.
         */

        char initial = string.charAt(0);
        if ((initial >= '0' && initial <= '9') || initial == '-') {
            try {
                return stringToNumber(string);
            } catch (Exception ignore) {
            }
        }
        return string;
    }

    /**
     * direct copy of {@link JSONObject#stringToNumber(String)} to maintain Android support.
     */
    private static Number stringToNumber(final String val) throws NumberFormatException {
        char initial = val.charAt(0);
        if ((initial >= '0' && initial <= '9') || initial == '-') {
            // decimal representation
            if (isDecimalNotation(val)) {
                // Use a BigDecimal all the time so we keep the original
                // representation. BigDecimal doesn't support -0.0, ensure we
                // keep that by forcing a decimal.
                try {
                    BigDecimal bd = new BigDecimal(val);
                    if(initial == '-' && BigDecimal.ZERO.compareTo(bd)==0) {
                        return Double.valueOf(-0.0);
                    }
                    return bd;
                } catch (NumberFormatException retryAsDouble) {
                    // this is to support "Hex Floats" like this: 0x1.0P-1074
                    try {
                        Double d = Double.valueOf(val);
                        if(d.isNaN() || d.isInfinite()) {
                            throw new NumberFormatException("val ["+val+"] is not a valid number.");
                        }
                        return d;
                    } catch (NumberFormatException ignore) {
                        throw new NumberFormatException("val ["+val+"] is not a valid number.");
                    }
                }
            }
            // block items like 00 01 etc. Java number parsers treat these as Octal.
            if(initial == '0' && val.length() > 1) {
                char at1 = val.charAt(1);
                if(at1 >= '0' && at1 <= '9') {
                    throw new NumberFormatException("val ["+val+"] is not a valid number.");
                }
            } else if (initial == '-' && val.length() > 2) {
                char at1 = val.charAt(1);
                char at2 = val.charAt(2);
                if(at1 == '0' && at2 >= '0' && at2 <= '9') {
                    throw new NumberFormatException("val ["+val+"] is not a valid number.");
                }
            }
            // integer representation.
            // This will narrow any values to the smallest reasonable Object representation
            // (Integer, Long, or BigInteger)

            // BigInteger down conversion: We use a similar bitLength compare as
            // BigInteger#intValueExact uses. Increases GC, but objects hold
            // only what they need. i.e. Less runtime overhead if the value is
            // long lived.
            BigInteger bi = new BigInteger(val);
            if(bi.bitLength() <= 31){
                return Integer.valueOf(bi.intValue());
            }
            if(bi.bitLength() <= 63){
                return Long.valueOf(bi.longValue());
            }
            return bi;
        }
        throw new NumberFormatException("val ["+val+"] is not a valid number.");
    }

    /**
     * direct copy of {@link JSONObject#isDecimalNotation(String)} to maintain Android support.
     */
    private static boolean isDecimalNotation(final String val) {
        return val.indexOf('.') > -1 || val.indexOf('e') > -1
                || val.indexOf('E') > -1 || "-0".equals(val);
    }


    /**
     * Convert a well-formed (but not necessarily valid) XML string into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * @param string
     *            The source string.
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(String string) throws JSONException {
        return toJSONObject(string, XMLParserConfiguration.ORIGINAL);
    }

    /**
     * Convert a well-formed (but not necessarily valid) XML into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * @param reader The XML source reader.
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(Reader reader) throws JSONException {
        return toJSONObject(reader, XMLParserConfiguration.ORIGINAL);
    }

    /**
     * Convert a well-formed (but not necessarily valid) XML into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * All values are converted as strings, for 1, 01, 29.0 will not be coerced to
     * numbers but will instead be the exact value as seen in the XML document.
     *
     * @param reader The XML source reader.
     * @param keepStrings If true, then values will not be coerced into boolean
     *  or numeric values and will instead be left as strings
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(Reader reader, boolean keepStrings) throws JSONException {
        if(keepStrings) {
            return toJSONObject(reader, XMLParserConfiguration.KEEP_STRINGS);
        }
        return toJSONObject(reader, XMLParserConfiguration.ORIGINAL);
    }

    /**
     * Convert a well-formed (but not necessarily valid) XML into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * All values are converted as strings, for 1, 01, 29.0 will not be coerced to
     * numbers but will instead be the exact value as seen in the XML document.
     *
     * @param reader The XML source reader.
     * @param config Configuration options for the parser
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(Reader reader, XMLParserConfiguration config) throws JSONException {
        JSONObject jo = new JSONObject();
        XMLTokener x = new XMLTokener(reader);
        while (x.more()) {
            x.skipPast("<");
            if(x.more()) {
                parse(x, jo, null, config);
            }
        }
        return jo;
    }

    /**
     * Convert a well-formed (but not necessarily valid) XML string into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * All values are converted as strings, for 1, 01, 29.0 will not be coerced to
     * numbers but will instead be the exact value as seen in the XML document.
     *
     * @param string
     *            The source string.
     * @param keepStrings If true, then values will not be coerced into boolean
     *  or numeric values and will instead be left as strings
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(String string, boolean keepStrings) throws JSONException {
        return toJSONObject(new StringReader(string), keepStrings);
    }

    /**
     * Convert a well-formed (but not necessarily valid) XML string into a
     * JSONObject. Some information may be lost in this transformation because
     * JSON is a data format and XML is a document format. XML uses elements,
     * attributes, and content text, while JSON uses unordered collections of
     * name/value pairs and arrays of values. JSON does not does not like to
     * distinguish between elements and attributes. Sequences of similar
     * elements are represented as JSONArrays. Content text may be placed in a
     * "content" member. Comments, prologs, DTDs, and <pre>{@code
     * &lt;[ [ ]]>}</pre>
     * are ignored.
     *
     * All values are converted as strings, for 1, 01, 29.0 will not be coerced to
     * numbers but will instead be the exact value as seen in the XML document.
     *
     * @param string
     *            The source string.
     * @param config Configuration options for the parser.
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(String string, XMLParserConfiguration config) throws JSONException {
        return toJSONObject(new StringReader(string), config);
    }


    /**
     *  milestone 2
     *  Read an XML file into a JSON object, and extract some smaller sub-object inside,
     *  given a certain path (use JSONPointer).
     * @param reader
     *            The source string.
     * @param path Configuration options for the parser.
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static Object toJSONObject(Reader reader, JSONPointer path) {
        try {
            getJsonObjectWithPath(reader, path, null);
        } catch (JSONFoundExecption e) {
//            System.out.println(e.getMessage());
            if (e.getCode().equals("200")) {
                return e.getJsonObject();
            }
        }
        return null;
    }

    /*
    *
    * @param level: JSON level depth
    * @param pLevel: path level depth
    * @param replace: JSONObject for Milestone 2
    * */
    private static JSONObject getJsonObjectWithPath(Reader reader, JSONPointer path, JSONObject replace) throws JSONFoundExecption {
        JSONObject jo = new JSONObject();
        XMLTokener x = new XMLTokener(reader);
        String[] paths = path.toString().split("/");
        paths = Arrays.copyOfRange(paths, 1, paths.length);

        while (x.more()) {
            x.skipPast("<");
            if (x.more()) {
                parseWithPath(x, jo, null, XMLParserConfiguration.ORIGINAL, paths, 0, 0, replace);
            }
        }
        return jo;
    }

    /**
     *  milestone 2
     *  Read an XML file into a JSON object, replace a sub-object on a certain key path
     *  with another JSON object that you construct,
     *
     * @param reader
     *            The source string.
     * @param path Configuration options for the parser.
     * @param replacement Configuration options for the parser.
     * @return A JSONObject containing the structured data from the XML string.
     * @throws JSONException Thrown if there is an errors while parsing the string
     */
    public static JSONObject toJSONObject(Reader reader, JSONPointer path, JSONObject replacement) {

        JSONObject jo = null;
        try {
            jo = getJsonObjectWithPath(reader, path, replacement);
        } catch (JSONFoundExecption e) {
            e.printStackTrace();
        }
        return jo;
    }


    /**
     * Convert a JSONObject into a well-formed, element-normal XML string.
     *
     * @param object
     *            A JSONObject.
     * @return A string.
     * @throws JSONException Thrown if there is an error parsing the string
     */
    public static String toString(Object object) throws JSONException {
        return toString(object, null, XMLParserConfiguration.ORIGINAL);
    }

    /**
     * Convert a JSONObject into a well-formed, element-normal XML string.
     *
     * @param object
     *            A JSONObject.
     * @param tagName
     *            The optional name of the enclosing tag.
     * @return A string.
     * @throws JSONException Thrown if there is an error parsing the string
     */
    public static String toString(final Object object, final String tagName) {
        return toString(object, tagName, XMLParserConfiguration.ORIGINAL);
    }

    /**
     * Convert a JSONObject into a well-formed, element-normal XML string.
     *
     * @param object
     *            A JSONObject.
     * @param tagName
     *            The optional name of the enclosing tag.
     * @param config
     *            Configuration that can control output to XML.
     * @return A string.
     * @throws JSONException Thrown if there is an error parsing the string
     */
    public static String toString(final Object object, final String tagName, final XMLParserConfiguration config)
            throws JSONException {
        StringBuilder sb = new StringBuilder();
        JSONArray ja;
        JSONObject jo;
        String string;

        if (object instanceof JSONObject) {

            // Emit <tagName>
            if (tagName != null) {
                sb.append('<');
                sb.append(tagName);
                sb.append('>');
            }

            // Loop thru the keys.
            // don't use the new entrySet accessor to maintain Android Support
            jo = (JSONObject) object;
            for (final String key : jo.keySet()) {
                Object value = jo.opt(key);
                if (value == null) {
                    value = "";
                } else if (value.getClass().isArray()) {
                    value = new JSONArray(value);
                }

                // Emit content in body
                if (key.equals(config.getcDataTagName())) {
                    if (value instanceof JSONArray) {
                        ja = (JSONArray) value;
                        int jaLength = ja.length();
                        // don't use the new iterator API to maintain support for Android
						for (int i = 0; i < jaLength; i++) {
                            if (i > 0) {
                                sb.append('\n');
                            }
                            Object val = ja.opt(i);
                            sb.append(escape(val.toString()));
                        }
                    } else {
                        sb.append(escape(value.toString()));
                    }

                    // Emit an array of similar keys

                } else if (value instanceof JSONArray) {
                    ja = (JSONArray) value;
                    int jaLength = ja.length();
                    // don't use the new iterator API to maintain support for Android
					for (int i = 0; i < jaLength; i++) {
                        Object val = ja.opt(i);
                        if (val instanceof JSONArray) {
                            sb.append('<');
                            sb.append(key);
                            sb.append('>');
                            sb.append(toString(val, null, config));
                            sb.append("</");
                            sb.append(key);
                            sb.append('>');
                        } else {
                            sb.append(toString(val, key, config));
                        }
                    }
                } else if ("".equals(value)) {
                    sb.append('<');
                    sb.append(key);
                    sb.append("/>");

                    // Emit a new tag <k>

                } else {
                    sb.append(toString(value, key, config));
                }
            }
            if (tagName != null) {

                // Emit the </tagName> close tag
                sb.append("</");
                sb.append(tagName);
                sb.append('>');
            }
            return sb.toString();

        }

        if (object != null && (object instanceof JSONArray ||  object.getClass().isArray())) {
            if(object.getClass().isArray()) {
                ja = new JSONArray(object);
            } else {
                ja = (JSONArray) object;
            }
            int jaLength = ja.length();
            // don't use the new iterator API to maintain support for Android
			for (int i = 0; i < jaLength; i++) {
                Object val = ja.opt(i);
                // XML does not have good support for arrays. If an array
                // appears in a place where XML is lacking, synthesize an
                // <array> element.
                sb.append(toString(val, tagName == null ? "array" : tagName, config));
            }
            return sb.toString();
        }

        string = (object == null) ? "null" : escape(object.toString());
        return (tagName == null) ? "\"" + string + "\""
                : (string.length() == 0) ? "<" + tagName + "/>" : "<" + tagName
                        + ">" + string + "</" + tagName + ">";

    }


    /**
     * Milestone 3
     *
     * reload original parse function and add a new parameter "Function keyTransformer"
     *
     * Scan the content following the named tag, attaching it to the context.
     *
     * @param x
     *            The XMLTokener containing the source string.
     * @param context
     *            The JSONObject that will include the new material.
     * @param name
     *            The tag name.
     * @param keyTransformer
     *            key to new key
     * @return true if the close tag is processed.
     * @throws JSONException
     */
    private static boolean parse(XMLTokener x, JSONObject context, String name, XMLParserConfiguration config, Function keyTransformer)
            throws JSONException {
        char c;
        int i;
        JSONObject jsonObject = null;
        String string;
        String tagName;
        Object token;
        XMLXsiTypeConverter<?> xmlXsiTypeConverter;

        // Test for and skip past these forms:
        // <!-- ... -->
        // <! ... >
        // <![ ... ]]>
        // <? ... ?>
        // Report errors for these forms:
        // <>
        // <=
        // <<

        token = x.nextToken();

        // <!

        if (token == BANG) {
            c = x.next();
            if (c == '-') {
                if (x.next() == '-') {
                    //denoting this line is annotation
                    //ignore <!--  -->
                    x.skipPast("-->");
                    return false;
                }
                x.back();
            } else if (c == '[') {
                token = x.nextToken();
                if ("CDATA".equals(token)) {
                    if (x.next() == '[') {
                        string = x.nextCDATA();
                        if (string.length() > 0) {
                            context.accumulate(config.getcDataTagName(), string);
                        }
                        return false;
                    }
                }
                throw x.syntaxError("Expected 'CDATA['");
            }
            i = 1;
            do {
                token = x.nextMeta();
                if (token == null) {
                    throw x.syntaxError("Missing '>' after '<!'.");
                } else if (token == LT) {
                    i += 1;
                } else if (token == GT) {
                    i -= 1;
                }
            } while (i > 0);
            return false;
        } else if (token == QUEST) {

            // <?
            x.skipPast("?>");
            return false;
        } else if (token == SLASH) {

            // Close tag </

            token = x.nextToken();
            if (name == null) {
                throw x.syntaxError("Mismatched close tag " + token);
            }
            if (!token.equals(name)) {
                throw x.syntaxError("Mismatched " + name + " and " + token);
            }
            if (x.nextToken() != GT) {
                throw x.syntaxError("Misshaped close tag");
            }
            return true;

        } else if (token instanceof Character) {
            throw x.syntaxError("Misshaped tag");

            // Open tag <
            //if token is tagName
        } else {
            tagName = (String) token;
            token = null;
            jsonObject = new JSONObject();
            boolean nilAttributeFound = false;
            xmlXsiTypeConverter = null;
            for (;;) {
                if (token == null) {
                    token = x.nextToken();
                }
                // attribute = value
                if (token instanceof String) {
                    //For Milestone 3
                    //for this xml
                    //<last_update_posted type="Actual">September 12, 2019</last_update_posted>
                    //add type to Jsonobject
                    //"last_update_posted": {
                    //      "type": "Actual",
                    //      "content": "September 12, 2019"
                    //    },
                    string = (String) token;
                    string = (String) keyTransformer.apply(string);

                    token = x.nextToken();
                    if (token == EQ) {
                        token = x.nextToken();
                        if (!(token instanceof String)) {
                            throw x.syntaxError("Missing value");
                        }

                        if (config.isConvertNilAttributeToNull()
                                && NULL_ATTR.equals(string)
                                && Boolean.parseBoolean((String) token)) {
                            nilAttributeFound = true;
                        } else if(config.getXsiTypeMap() != null && !config.getXsiTypeMap().isEmpty()
                                && TYPE_ATTR.equals(string)) {
                            xmlXsiTypeConverter = config.getXsiTypeMap().get(token);
                        } else if (!nilAttributeFound) {
                            jsonObject.accumulate(string,
                                    config.isKeepStrings()
                                            ? ((String) token)
                                            : stringToValue((String) token));
                        }
                        token = null;
                    } else {
                        jsonObject.accumulate(string, "");
                    }


                } else if (token == SLASH) {
                    // Empty tag <.../>
                    if (x.nextToken() != GT) {
                        throw x.syntaxError("Misshaped tag");
                    }
                    if (config.getForceList().contains(tagName)) {
                        // Force the value to be an array
                        if (nilAttributeFound) {
                            context.append(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            //in loop
                            context.append(tagName, jsonObject);
                        } else {
                            context.put(tagName, new JSONArray());
                        }
                    } else {
                        if (nilAttributeFound) {
                            context.accumulate(tagName, JSONObject.NULL);
                        } else if (jsonObject.length() > 0) {
                            context.accumulate(tagName, jsonObject);
                        } else {
                            context.accumulate(tagName, "");
                        }
                    }
                    return false;

                } else if (token == GT) {
                    // Content, between <...> and </...>
                    // after a String, if it is >, then analysis inner content
                    for (;;) {
                        //loop goal: first time temporally save String, second time put into parent JSONObject
                        //if has nested element, do recursion
                        token = x.nextContent();
                        if (token == null) {
                            if (tagName != null) {
                                throw x.syntaxError("Unclosed tag " + tagName);
                            }
                            return false;
                        } else if (token instanceof String) {
                            string = (String) token;
                            if (string.length() > 0) {
                                if(xmlXsiTypeConverter != null) {
                                    jsonObject.accumulate(config.getcDataTagName(),
                                            stringToValue(string, xmlXsiTypeConverter));
                                } else {
                                    if(jsonObject.length()>0){
                                        //For Milestone 3
                                        //here to deal with real content tagName, not configTagName
                                        //<last_update_posted type="Actual">September 12, 2019</last_update_posted>
                                        //"last_update_posted": {
                                        //      "type": "Actual",
                                        //      "content": "September 12, 2019"
                                        //    },
                                        String configTagName = (String) keyTransformer.apply(config.getcDataTagName());
                                        jsonObject.accumulate(configTagName,
                                                config.isKeepStrings() ? string : stringToValue(string));
                                    }
                                    else {
                                        jsonObject.accumulate(config.getcDataTagName(),
                                                config.isKeepStrings() ? string : stringToValue(string));
                                    }
                                }
                            }

                        } else if (token == LT) {
                            // Nested element
                            // new <
                            //when subStruct come across opposite one, subStruct's recursion return true to subStruct
                            //when subStruct has been accumulated, return false to parentis done
                            if (parse(x, jsonObject, tagName, config, keyTransformer)) {
                                //For Milestone 3
                                //deal with global tagName for most cases
                                tagName = (String) keyTransformer.apply(tagName);

                                if (config.getForceList().contains(tagName)) {
                                    // Force the value to be an array
                                    if (jsonObject.length() == 0) {
                                        context.put(tagName, new JSONArray());
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        context.append(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        context.append(tagName, jsonObject);
                                    }
                                } else {
                                    if (jsonObject.length() == 0) {
                                        //let values of same tagName, save as JSONArray
                                        context.accumulate(tagName, "");
                                    } else if (jsonObject.length() == 1
                                            && jsonObject.opt(config.getcDataTagName()) != null) {
                                        //enter into subStruct and then return true, come here when subStruct is <name>value</name>
                                        //config.getcDataTagName():"content" is temporally saving key
                                        context.accumulate(tagName, jsonObject.opt(config.getcDataTagName()));
                                    } else {
                                        //when subStruct has nested element like <address><zipcode>111</zipcode><street>Ave</street><address>
                                        context.accumulate(tagName, jsonObject);
                                    }
                                }

                                return false;
                            }
                        }
                    }
                } else {
                    throw x.syntaxError("Misshaped tag");
                }
            }
        }
    }

    /*
    * Milestone 3
    * Read an XML file into a JSON object, and add the prefix "swe262_" to all of its keys.
    *
    * YOURTYPEHERE should be a function (or "functional" in Java)
    * that takes as input a String  denoting a key and returns another String that is the transformation of the key
    *
    *  functions provided by the client code, so they can be quite powerful
    * and include all sorts of string matching and transformation logic.
    *
    * The goal here is that you do the transformation during the parsing of the XML file, not in another pass afterwards.
    * "foo" --> "swe262_foo"
    * "foo" --> "oof"
    *
    * https://canvas.eee.uci.edu/courses/42906/pages/project
     * */
    public static JSONObject toJSONObject(Reader reader, Function keyTransformer){
        keyTransformer.apply("b");
        JSONObject jo = new JSONObject();
        XMLTokener x = new XMLTokener(reader);
        while (x.more()) {
            x.skipPast("<");
            if (x.more()) {
                parse(x, jo, null, XMLParserConfiguration.ORIGINAL, keyTransformer);
            }
        }

        return jo;
    }

    /*
    * Milestone 5
    * Add asynchronous methods to the library that allow the client code to proceed
    * example: XML.toJSONObject(aReader, (JSONObject jo) -> {jo.write(aWriter);}, (Exception e) -> { something went wrong });
    *
    * */
    static ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(2);//LinkedBlockingQueue
    public static CustomFuture<String> toJSONObject(Reader reader, BiFunction<JSONObject, String, String> fun, Function<Throwable, Object> fail) throws ExecutionException, InterruptedException {
        Function futureFun = (a) -> {
            Object msg = null;
            System.out.println("Async: " + Thread.currentThread().getName() + " is transforming xml to JSON in the background.");
            try{
                JSONObject jsonObject = toJSONObject(reader, XMLParserConfiguration.ORIGINAL);
                System.out.println("Async: xml to toJSONObject done");
                msg  = fun.apply(jsonObject, "M5_inner");
            }catch (Exception e){
                System.out.println("Async: Exception happens!");
                msg = fail.apply(e);
            }catch (Error e){
                System.out.println("Async: Error happens!");
                msg = fail.apply(e);
            }
            return msg;
        };
        CustomFuture<String> customFuture = new CustomFuture(futureFun);
        executor.submit(customFuture);
        return customFuture;
    }

//    public static CompletableFuture<String> toJSONObject(Reader reader, BiFunction<JSONObject, String, String> fun, Function<Throwable, Object> fail) throws ExecutionException, InterruptedException {
//        CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> {
//            String msg = null;
//            System.out.println("Async: " + Thread.currentThread().getName() + " is transforming xml to JSON in the background.");
//            try {
//                JSONObject jsonObject = toJSONObject(reader, XMLParserConfiguration.ORIGINAL);
//                System.out.println("Async: xml to toJSONObject done");
//                msg = fun.apply(jsonObject, "M5_inner");
//            } catch (Throwable e) {
//                System.out.println("Async: Something wrong happens!");
//                msg = (String) fail.apply(e);
//            }
//            return msg;
//        });
//        return completableFuture;
//    }

}