/*
 * Copyright © 2021 Orange, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.transportpce.common.converter;

import com.google.common.collect.FluentIterable;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import org.opendaylight.mdsal.binding.dom.codec.spi.BindingDOMCodecServices;
import org.opendaylight.mdsal.binding.spec.reflect.BindingReflections;
import org.opendaylight.yangtools.yang.binding.DataObject;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.api.schema.stream.NormalizedNodeWriter;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONCodecFactory;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONCodecFactorySupplier;
import org.opendaylight.yangtools.yang.data.codec.gson.JSONNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.codec.gson.JsonParserStream;
import org.opendaylight.yangtools.yang.data.codec.gson.JsonWriterFactory;
import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNormalizedNodeStreamWriter;
import org.opendaylight.yangtools.yang.data.impl.schema.NormalizedNodeResult;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class JsonStringConverter<T extends DataObject> {
    private static final Logger LOG = LoggerFactory.getLogger(JsonStringConverter.class);
    private static final JsonParser PARSER = new JsonParser();
    private BindingDOMCodecServices bindingDOMCodecServices;


    public JsonStringConverter(BindingDOMCodecServices bindingDOMCodecServices) {
        this.bindingDOMCodecServices = bindingDOMCodecServices;
    }

    /**
     * Create a json string from dataobject T.
     * @param id InstanceIdentifier
     * @param dataObject T
     * @param supplier RFC7951 or DRAFT_LHOTKA_NETMOD_YANG_JSON_02
     * @return Json string representation of the object
     * @throws IOException if something went wrong.
     */
    public String createJsonStringFromDataObject(final InstanceIdentifier<T> id, T dataObject,
            JSONCodecFactorySupplier supplier) throws IOException {
        final SchemaPath scPath = SchemaPath.create(FluentIterable.from(id.getPathArguments())
                .transform(input -> BindingReflections.findQName(input.getType())), true);
        /*
         * This function needs : - context - scPath.getParent() -
         * scPath.getLastComponent().getNamespace(), -
         * JsonWriterFactory.createJsonWriter(writer)
         */

        JSONCodecFactory codecFactory = supplier
                .getShared(bindingDOMCodecServices.getRuntimeContext().getEffectiveModelContext());
        try (Writer writer = new StringWriter();
                JsonWriter jsonWriter = JsonWriterFactory.createJsonWriter(writer, 4);) {
            NormalizedNodeStreamWriter jsonStreamWriter = JSONNormalizedNodeStreamWriter.createExclusiveWriter(
                    codecFactory, scPath.getParent(), scPath.getLastComponent().getNamespace(), jsonWriter);
            try (NormalizedNodeWriter nodeWriter = NormalizedNodeWriter.forStreamWriter(jsonStreamWriter)) {
                nodeWriter.write(bindingDOMCodecServices.toNormalizedNode(id, dataObject).getValue());
                nodeWriter.flush();
            }
            JsonObject asJsonObject = PARSER.parse(writer.toString()).getAsJsonObject();
            return new Gson().toJson(asJsonObject);
        } catch (IOException e) {
            LOG.error("Cannot convert object {} to string ", dataObject);
            throw e;
        }
    }

    /**
     * Create a dataObject of T type from json string.
     * @param path YangInstanceIdentifier
     * @param jsonString String
     * @param supplier RFC7951 or DRAFT_LHOTKA_NETMOD_YANG_JSON_02
     * @return T the created object.
     */
    public T createDataObjectFromJsonString(YangInstanceIdentifier path, String jsonString,
            JSONCodecFactorySupplier supplier) {
        JsonReader reader = new JsonReader(new StringReader(jsonString));
        NormalizedNodeResult result = new NormalizedNodeResult();
        try (NormalizedNodeStreamWriter streamWriter = ImmutableNormalizedNodeStreamWriter.from(result);
                JsonParserStream jsonParser = JsonParserStream.create(streamWriter,
                        supplier
                                .getShared(bindingDOMCodecServices.getRuntimeContext().getEffectiveModelContext()))) {
            jsonParser.parse(reader);
            return (T) bindingDOMCodecServices
                    .fromNormalizedNode(path, result.getResult()).getValue();
        } catch (IOException e) {
            LOG.warn("An error occured during parsing Json input stream", e);
            return null;
        }
    }
}