/*
 * Copyright 2017-2020 original authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.micronaut.jackson.convert;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import io.micronaut.core.convert.ArgumentConversionContext;
import io.micronaut.core.convert.ConversionService;
import io.micronaut.core.convert.value.ConvertibleValues;
import io.micronaut.core.util.CollectionUtils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.Set;

Simple facade over a Jackson ObjectNode to make it a ConvertibleValues. 
Author:
Graeme Rocher
Type parameters:
<V> – The generic type for values
Since:
1.0/**
 * Simple facade over a Jackson {@link ObjectNode} to make it a {@link ConvertibleValues}.
 *
 * @param <V> The generic type for values
 *
 * @author Graeme Rocher
 * @since 1.0
 */
public class ObjectNodeConvertibleValues<V> implements ConvertibleValues<V> {

    private final ObjectNode objectNode;
    private final ConversionService<?> conversionService;

    
Params:
objectNode –        The node that maps to JSON object structure
conversionService – To convert the JSON node into given type/**
     * @param objectNode        The node that maps to JSON object structure
     * @param conversionService To convert the JSON node into given type
     */
    public ObjectNodeConvertibleValues(ObjectNode objectNode, ConversionService<?> conversionService) {
        this.objectNode = objectNode;
        this.conversionService = conversionService;
    }

    @Override
    public Set<String> names() {
        Iterator<String> fieldNames = objectNode.fieldNames();
        return CollectionUtils.iteratorToSet(fieldNames);
    }

    @Override
    public Collection<V> values() {
        List<V> values = new ArrayList<>();
        for (JsonNode jsonNode : objectNode) {
            values.add((V) jsonNode);
        }
        return Collections.unmodifiableCollection(values);
    }

    @Override
    public <T> Optional<T> get(CharSequence name, ArgumentConversionContext<T> conversionContext) {
        String fieldName = name.toString();
        JsonNode jsonNode = objectNode.get(fieldName);
        if (jsonNode == null) {
            return Optional.empty();
        } else {
            return conversionService.convert(jsonNode, conversionContext);
        }
    }
}