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/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.common.xcontent;

import org.elasticsearch.ElasticsearchParseException;
import org.elasticsearch.Version;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.bytes.BytesArray;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.compress.Compressor;
import org.elasticsearch.common.compress.CompressorFactory;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.xcontent.DeprecationHandler;
import org.elasticsearch.xcontent.NamedXContentRegistry;
import org.elasticsearch.xcontent.ToXContent;
import org.elasticsearch.xcontent.ToXContent.Params;
import org.elasticsearch.xcontent.XContent;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentFactory;
import org.elasticsearch.xcontent.XContentParseException;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentParserConfiguration;
import org.elasticsearch.xcontent.XContentType;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;

@SuppressWarnings("unchecked")
public class XContentHelper {

    /**
     * Creates a parser based on the bytes provided
     * @deprecated use {@link #createParser(XContentParserConfiguration, BytesReference, XContentType)}
     * to avoid content type auto-detection
     */
    @Deprecated
    public static XContentParser createParser(NamedXContentRegistry registry, DeprecationHandler deprecation, BytesReference bytes)
        throws IOException {
        return createParser(XContentParserConfiguration.EMPTY.withRegistry(registry).withDeprecationHandler(deprecation), bytes);
    }

    /**
     * Creates a parser based on the bytes provided
     * @deprecated use {@link #createParser(XContentParserConfiguration, BytesReference, XContentType)}
     * to avoid content type auto-detection
     */
    @Deprecated
    public static XContentParser createParser(XContentParserConfiguration config, BytesReference bytes) throws IOException {
        Compressor compressor = CompressorFactory.compressor(bytes);
        if (compressor != null) {
            InputStream compressedInput = compressor.threadLocalInputStream(bytes.streamInput());
            if (compressedInput.markSupported() == false) {
                compressedInput = new BufferedInputStream(compressedInput);
            }
            final XContentType contentType = XContentFactory.xContentType(compressedInput);
            return XContentFactory.xContent(contentType).createParser(config, compressedInput);
        } else {
            return XContentFactory.xContent(xContentType(bytes)).createParser(config, bytes.streamInput());
        }
    }

    /**
     * Creates a parser for the bytes provided
     * @deprecated use {@link #createParser(XContentParserConfiguration, BytesReference, XContentType)}
     */
    @Deprecated
    public static XContentParser createParser(
        NamedXContentRegistry registry,
        DeprecationHandler deprecation,
        BytesReference bytes,
        XContentType xContentType
    ) throws IOException {
        return createParser(
            XContentParserConfiguration.EMPTY.withRegistry(registry).withDeprecationHandler(deprecation),
            bytes,
            xContentType
        );
    }

    /**
     * Creates a parser for the bytes using the supplied content-type
     */
    public static XContentParser createParser(XContentParserConfiguration config, BytesReference bytes, XContentType xContentType)
        throws IOException {
        Objects.requireNonNull(xContentType);
        Compressor compressor = CompressorFactory.compressor(bytes);
        if (compressor != null) {
            InputStream compressedInput = compressor.threadLocalInputStream(bytes.streamInput());
            if (compressedInput.markSupported() == false) {
                compressedInput = new BufferedInputStream(compressedInput);
            }
            return XContentFactory.xContent(xContentType).createParser(config, compressedInput);
        } else {
            // TODO now that we have config we make a method on bytes to do this building wihout needing this check everywhere
            if (bytes.hasArray()) {
                return xContentType.xContent().createParser(config, bytes.array(), bytes.arrayOffset(), bytes.length());
            }
            return xContentType.xContent().createParser(config, bytes.streamInput());
        }
    }

    /**
     * Converts the given bytes into a map that is optionally ordered.
     * 

     * Important: This can lose precision on numbers with a decimal point. It
     * converts numbers like {@code "n": 1234.567} to a {@code double} which
     * only has 52 bits of precision in the mantissa. This will come up most
     * frequently when folks write nanosecond precision dates as a decimal
     * number.
     * @deprecated this method relies on auto-detection of content type. Use {@link #convertToMap(BytesReference, boolean, XContentType)}
     *             instead with the proper {@link XContentType}
     */
    @Deprecated
    public static Tuple> convertToMap(BytesReference bytes, boolean ordered)
        throws ElasticsearchParseException {
        return convertToMap(bytes, ordered, null);
    }

    /**
     * Exactly the same as {@link XContentHelper#convertToMap(BytesReference, boolean, XContentType, Set, Set)} but
     * none of the fields are filtered
     */
    public static Tuple> convertToMap(BytesReference bytes, boolean ordered, XContentType xContentType) {
        return convertToMap(bytes, ordered, xContentType, null, null);
    }

    /**
     * Converts the given bytes into a map that is optionally ordered. The provided {@link XContentType} must be non-null.
     * 

     * Important: This can lose precision on numbers with a decimal point. It
     * converts numbers like {@code "n": 1234.567} to a {@code double} which
     * only has 52 bits of precision in the mantissa. This will come up most
     * frequently when folks write nanosecond precision dates as a decimal
     * number.
     */
    public static Tuple> convertToMap(
        BytesReference bytes,
        boolean ordered,
        XContentType xContentType,
        @Nullable Set include,
        @Nullable Set exclude
    ) throws ElasticsearchParseException {
        try {
            final XContentType contentType;
            InputStream input;
            Compressor compressor = CompressorFactory.compressor(bytes);
            if (compressor != null) {
                InputStream compressedStreamInput = compressor.threadLocalInputStream(bytes.streamInput());
                if (compressedStreamInput.markSupported() == false) {
                    compressedStreamInput = new BufferedInputStream(compressedStreamInput);
                }
                input = compressedStreamInput;
                contentType = xContentType != null ? xContentType : XContentFactory.xContentType(input);
            } else if (bytes.hasArray()) {
                final byte[] raw = bytes.array();
                final int offset = bytes.arrayOffset();
                final int length = bytes.length();
                contentType = xContentType != null ? xContentType : XContentFactory.xContentType(raw, offset, length);
                return new Tuple<>(
                    Objects.requireNonNull(contentType),
                    convertToMap(XContentFactory.xContent(contentType), raw, offset, length, ordered, include, exclude)
                );
            } else {
                input = bytes.streamInput();
                contentType = xContentType != null ? xContentType : XContentFactory.xContentType(input);
            }
            try (InputStream stream = input) {
                return new Tuple<>(
                    Objects.requireNonNull(contentType),
                    convertToMap(XContentFactory.xContent(contentType), stream, ordered, include, exclude)
                );
            }
        } catch (IOException e) {
            throw new ElasticsearchParseException("Failed to parse content to map", e);
        }
    }

    /**
     * Convert a string in some {@link XContent} format to a {@link Map}. Throws an {@link ElasticsearchParseException} if there is any
     * error.
     */
    public static Map convertToMap(XContent xContent, String string, boolean ordered) throws ElasticsearchParseException {
        try (XContentParser parser = xContent.createParser(XContentParserConfiguration.EMPTY, string)) {
            return ordered ? parser.mapOrdered() : parser.map();
        } catch (IOException e) {
            throw new ElasticsearchParseException("Failed to parse content to map", e);
        }
    }

    /**
     * The same as {@link XContentHelper#convertToMap(XContent, byte[], int, int, boolean, Set, Set)} but none of the
     * fields are filtered.
     */
    public static Map convertToMap(XContent xContent, InputStream input, boolean ordered)
        throws ElasticsearchParseException {
        return convertToMap(xContent, input, ordered, null, null);
    }

    /**
     * Convert a string in some {@link XContent} format to a {@link Map}. Throws an {@link ElasticsearchParseException} if there is any
     * error. Note that unlike {@link #convertToMap(BytesReference, boolean)}, this doesn't automatically uncompress the input.
     *
     * Additionally, fields may be included or excluded from the parsing.
     */
    public static Map convertToMap(
        XContent xContent,
        InputStream input,
        boolean ordered,
        @Nullable Set include,
        @Nullable Set exclude
    ) throws ElasticsearchParseException {
        try (
            XContentParser parser = xContent.createParser(XContentParserConfiguration.EMPTY.withFiltering(include, exclude, false), input)
        ) {
            return ordered ? parser.mapOrdered() : parser.map();
        } catch (IOException e) {
            throw new ElasticsearchParseException("Failed to parse content to map", e);
        }
    }

    /**
     * Convert a byte array in some {@link XContent} format to a {@link Map}. Throws an {@link ElasticsearchParseException} if there is any
     * error. Note that unlike {@link #convertToMap(BytesReference, boolean)}, this doesn't automatically uncompress the input.
     */
    public static Map convertToMap(XContent xContent, byte[] bytes, int offset, int length, boolean ordered)
        throws ElasticsearchParseException {
        return convertToMap(xContent, bytes, offset, length, ordered, null, null);
    }

    /**
     * Convert a byte array in some {@link XContent} format to a {@link Map}. Throws an {@link ElasticsearchParseException} if there is any
     * error. Note that unlike {@link #convertToMap(BytesReference, boolean)}, this doesn't automatically uncompress the input.
     *
     * Unlike {@link XContentHelper#convertToMap(XContent, byte[], int, int, boolean)} this optionally accepts fields to include or exclude
     * during XContent parsing.
     */
    public static Map convertToMap(
        XContent xContent,
        byte[] bytes,
        int offset,
        int length,
        boolean ordered,
        @Nullable Set include,
        @Nullable Set exclude
    ) throws ElasticsearchParseException {
        try (
            XContentParser parser = xContent.createParser(
                XContentParserConfiguration.EMPTY.withFiltering(include, exclude, false),
                bytes,
                offset,
                length
            )
        ) {
            return ordered ? parser.mapOrdered() : parser.map();
        } catch (IOException e) {
            throw new ElasticsearchParseException("Failed to parse content to map", e);
        }
    }

    @Deprecated
    public static String convertToJson(BytesReference bytes, boolean reformatJson) throws IOException {
        return convertToJson(bytes, reformatJson, false);
    }

    @Deprecated
    public static String convertToJson(BytesReference bytes, boolean reformatJson, boolean prettyPrint) throws IOException {
        return convertToJson(bytes, reformatJson, prettyPrint, XContentFactory.xContentType(bytes.toBytesRef().bytes));
    }

    public static String convertToJson(BytesReference bytes, boolean reformatJson, XContentType xContentType) throws IOException {
        return convertToJson(bytes, reformatJson, false, xContentType);
    }

    /**
     * Accepts a JSON string, parses it and prints it without pretty-printing it. This is useful
     * where a piece of JSON is formatted for legibility, but needs to be stripped of unnecessary
     * whitespace e.g. for comparison in a test.
     *
     * @param json the JSON to format
     * @return reformatted JSON
     * @throws IOException if the reformatting fails, e.g. because the JSON is not well-formed
     */
    public static String stripWhitespace(String json) throws IOException {
        return convertToJson(new BytesArray(json), true, XContentType.JSON);
    }

    public static String convertToJson(BytesReference bytes, boolean reformatJson, boolean prettyPrint, XContentType xContentType)
        throws IOException {
        Objects.requireNonNull(xContentType);
        if (xContentType.canonical() == XContentType.JSON && reformatJson == false) {
            return bytes.utf8ToString();
        }

        if (bytes.hasArray()) {
            try (
                XContentParser parser = XContentFactory.xContent(xContentType)
                    .createParser(XContentParserConfiguration.EMPTY, bytes.array(), bytes.arrayOffset(), bytes.length())
            ) {
                return toJsonString(prettyPrint, parser);
            }
        } else {
            try (
                InputStream stream = bytes.streamInput();
                XContentParser parser = XContentFactory.xContent(xContentType).createParser(XContentParserConfiguration.EMPTY, stream)
            ) {
                return toJsonString(prettyPrint, parser);
            }
        }
    }

    private static String toJsonString(boolean prettyPrint, XContentParser parser) throws IOException {
        parser.nextToken();
        XContentBuilder builder = XContentFactory.jsonBuilder();
        if (prettyPrint) {
            builder.prettyPrint();
        }
        builder.copyCurrentStructure(parser);
        return Strings.toString(builder);
    }

    /**
     * Updates the provided changes into the source. If the key exists in the changes, it overrides the one in source
     * unless both are Maps, in which case it recursively updated it.
     *
     * @param source                 the original map to be updated
     * @param changes                the changes to update into updated
     * @param checkUpdatesAreUnequal should this method check if updates to the same key (that are not both maps) are
     *                               unequal?  This is just a .equals check on the objects, but that can take some time on long strings.
     * @return true if the source map was modified
     */
    public static boolean update(Map source, Map changes, boolean checkUpdatesAreUnequal) {
        boolean modified = false;
        for (Map.Entry changesEntry : changes.entrySet()) {
            if (source.containsKey(changesEntry.getKey()) == false) {
                // safe to copy, change does not exist in source
                source.put(changesEntry.getKey(), changesEntry.getValue());
                modified = true;
                continue;
            }
            Object old = source.get(changesEntry.getKey());
            if (old instanceof Map && changesEntry.getValue() instanceof Map) {
                // recursive merge maps
                modified |= update(
                    (Map) source.get(changesEntry.getKey()),
                    (Map) changesEntry.getValue(),
                    checkUpdatesAreUnequal && modified == false
                );
                continue;
            }
            // update the field
            source.put(changesEntry.getKey(), changesEntry.getValue());
            if (modified) {
                continue;
            }
            if (checkUpdatesAreUnequal == false) {
                modified = true;
                continue;
            }
            modified = Objects.equals(old, changesEntry.getValue()) == false;
        }
        return modified;
    }

    /**
     * Merges the defaults provided as the second parameter into the content of the first. Only does recursive merge
     * for inner maps.
     */
    public static void mergeDefaults(Map content, Map defaults) {
        for (Map.Entry defaultEntry : defaults.entrySet()) {
            if (content.containsKey(defaultEntry.getKey()) == false) {
                // copy it over, it does not exists in the content
                content.put(defaultEntry.getKey(), defaultEntry.getValue());
            } else {
                // in the content and in the default, only merge compound ones (maps)
                if (content.get(defaultEntry.getKey()) instanceof Map && defaultEntry.getValue() instanceof Map) {
                    mergeDefaults((Map) content.get(defaultEntry.getKey()), (Map) defaultEntry.getValue());
                } else if (content.get(defaultEntry.getKey()) instanceof List && defaultEntry.getValue() instanceof List) {
                    List defaultList = (List) defaultEntry.getValue();
                    List contentList = (List) content.get(defaultEntry.getKey());

                    if (allListValuesAreMapsOfOne(defaultList) && allListValuesAreMapsOfOne(contentList)) {
                        // all are in the form of [ {"key1" : {}}, {"key2" : {}} ], merge based on keys
                        Map> processed = new LinkedHashMap<>();
                        for (Object o : contentList) {
                            Map map = (Map) o;
                            Map.Entry entry = map.entrySet().iterator().next();
                            processed.put(entry.getKey(), map);
                        }
                        for (Object o : defaultList) {
                            Map map = (Map) o;
                            Map.Entry entry = map.entrySet().iterator().next();
                            if (processed.containsKey(entry.getKey())) {
                                mergeDefaults(processed.get(entry.getKey()), map);
                            } else {
                                // put the default entries after the content ones.
                                processed.put(entry.getKey(), map);
                            }
                        }

                        content.put(defaultEntry.getKey(), new ArrayList<>(processed.values()));
                    } else {
                        // if both are lists, simply combine them, first the defaults, then the content
                        // just make sure not to add the same value twice
                        List mergedList = new ArrayList<>(defaultList);

                        for (Object o : contentList) {
                            if (mergedList.contains(o) == false) {
                                mergedList.add(o);
                            }
                        }
                        content.put(defaultEntry.getKey(), mergedList);
                    }
                }
            }
        }
    }

    private static boolean allListValuesAreMapsOfOne(List list) {
        for (Object o : list) {
            if ((o instanceof Map) == false) {
                return false;
            }
            if (((Map) o).size() != 1) {
                return false;
            }
        }
        return true;
    }

    /**
     * Writes a "raw" (bytes) field, handling cases where the bytes are compressed, and tries to optimize writing using
     * {@link XContentBuilder#rawField(String, InputStream)}.
     * @deprecated use {@link #writeRawField(String, BytesReference, XContentType, XContentBuilder, Params)} to avoid content type
     * auto-detection
     */
    @Deprecated
    public static void writeRawField(String field, BytesReference source, XContentBuilder builder, ToXContent.Params params)
        throws IOException {
        Compressor compressor = CompressorFactory.compressor(source);
        if (compressor != null) {
            try (InputStream compressedStreamInput = compressor.threadLocalInputStream(source.streamInput())) {
                builder.rawField(field, compressedStreamInput);
            }
        } else {
            try (InputStream stream = source.streamInput()) {
                builder.rawField(field, stream);
            }
        }
    }

    /**
     * Writes a "raw" (bytes) field, handling cases where the bytes are compressed, and tries to optimize writing using
     * {@link XContentBuilder#rawField(String, InputStream, XContentType)}.
     */
    public static void writeRawField(
        String field,
        BytesReference source,
        XContentType xContentType,
        XContentBuilder builder,
        ToXContent.Params params
    ) throws IOException {
        Objects.requireNonNull(xContentType);
        Compressor compressor = CompressorFactory.compressor(source);
        if (compressor != null) {
            try (InputStream compressedStreamInput = compressor.threadLocalInputStream(source.streamInput())) {
                builder.rawField(field, compressedStreamInput, xContentType);
            }
        } else {
            try (InputStream stream = source.streamInput()) {
                builder.rawField(field, stream, xContentType);
            }
        }
    }

    /**
     * Returns the bytes that represent the XContent output of the provided {@link ToXContent} object, using the provided
     * {@link XContentType}. Wraps the output into a new anonymous object according to the value returned
     * by the {@link ToXContent#isFragment()} method returns.
     */
    public static BytesReference toXContent(ToXContent toXContent, XContentType xContentType, boolean humanReadable) throws IOException {
        return toXContent(toXContent, xContentType, ToXContent.EMPTY_PARAMS, humanReadable);
    }

    /**
     * Returns the bytes that represent the XContent output of the provided {@link ToXContent} object, using the provided
     * {@link XContentType}. Wraps the output into a new anonymous object according to the value returned
     * by the {@link ToXContent#isFragment()} method returns.
     */
    public static BytesReference toXContent(ToXContent toXContent, XContentType xContentType, Params params, boolean humanReadable)
        throws IOException {
        try (XContentBuilder builder = XContentBuilder.builder(xContentType.xContent())) {
            builder.humanReadable(humanReadable);
            if (toXContent.isFragment()) {
                builder.startObject();
            }
            toXContent.toXContent(builder, params);
            if (toXContent.isFragment()) {
                builder.endObject();
            }
            return BytesReference.bytes(builder);
        }
    }

    /**
     * Guesses the content type based on the provided bytes which may be compressed.
     *
     * @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
     * The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
     * This method is deprecated to prevent usages of it from spreading further without specific reasons.
     */
    @Deprecated
    public static XContentType xContentTypeMayCompressed(BytesReference bytes) {
        Compressor compressor = CompressorFactory.compressor(bytes);
        if (compressor != null) {
            try {
                InputStream compressedStreamInput = compressor.threadLocalInputStream(bytes.streamInput());
                if (compressedStreamInput.markSupported() == false) {
                    compressedStreamInput = new BufferedInputStream(compressedStreamInput);
                }
                return XContentFactory.xContentType(compressedStreamInput);
            } catch (IOException e) {
                assert false : "Should not happen, we're just reading bytes from memory";
                throw new UncheckedIOException(e);
            }
        } else {
            return XContentHelper.xContentType(bytes);
        }
    }

    /**
     * Guesses the content type based on the provided bytes.
     *
     * @deprecated the content type should not be guessed except for few cases where we effectively don't know the content type.
     * The REST layer should move to reading the Content-Type header instead. There are other places where auto-detection may be needed.
     * This method is deprecated to prevent usages of it from spreading further without specific reasons.
     */
    @Deprecated
    public static XContentType xContentType(BytesReference bytes) {
        if (bytes.hasArray()) {
            return XContentFactory.xContentType(bytes.array(), bytes.arrayOffset(), bytes.length());
        }
        try {
            final InputStream inputStream = bytes.streamInput();
            assert inputStream.markSupported();
            return XContentFactory.xContentType(inputStream);
        } catch (IOException e) {
            assert false : "Should not happen, we're just reading bytes from memory";
            throw new UncheckedIOException(e);
        }
    }

    /**
     * Returns the contents of an object as an unparsed BytesReference
     *
     * This is useful for things like mappings where we're copying bytes around but don't
     * actually need to parse their contents, and so avoids building large maps of maps
     * unnecessarily
     */
    public static BytesReference childBytes(XContentParser parser) throws IOException {
        if (parser.currentToken() != XContentParser.Token.START_OBJECT) {
            if (parser.nextToken() != XContentParser.Token.START_OBJECT) {
                throw new XContentParseException(
                    parser.getTokenLocation(),
                    "Expected [START_OBJECT] but got [" + parser.currentToken() + "]"
                );
            }
        }
        XContentBuilder builder = XContentBuilder.builder(parser.contentType().xContent());
        builder.copyCurrentStructure(parser);
        return BytesReference.bytes(builder);
    }

    /**
     * Serialises new XContentType VND_ values in a bwc manner
     * TODO remove in ES v9
     * @param out stream output of the destination node
     * @param xContentType an instance to serialize
     */
    public static void writeTo(StreamOutput out, XContentType xContentType) throws IOException {
        if (out.getVersion().before(Version.V_8_0_0)) {
            // when sending an enumeration to  















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