fr.adbonnin.cz2128.json.repository.ValueSetRepository Maven / Gradle / Ivy

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Repository library based on FasterXML / Jackson.
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package fr.adbonnin.cz2128.json.repository;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;
import fr.adbonnin.cz2128.json.JsonProvider;
import fr.adbonnin.cz2128.json.iterator.ValueArrayIterator;

import java.io.IOException;
import java.util.*;
import java.util.function.Predicate;
import java.util.stream.StreamSupport;

import static java.util.Objects.requireNonNull;

public class ValueSetRepository extends SetRepository {

    private final ObjectMapper mapper;

    public ValueSetRepository(JsonProvider provider, ObjectMapper mapper, Class type) {
        this(provider, mapper, mapper.readerFor(type));
    }

    public ValueSetRepository(JsonProvider provider, ObjectMapper mapper, TypeReference type) {
        this(provider, mapper, mapper.readerFor(type));
    }

    public ValueSetRepository(JsonProvider provider, ObjectMapper mapper, ObjectReader reader) {
        super(provider, reader);
        this.mapper = requireNonNull(mapper);
    }

    public ObjectMapper getMapper() {
        return mapper;
    }

    @Override
    public  ValueSetRepository of(Class type) {
        return new ValueSetRepository<>(getProvider(), mapper, type);
    }

    @Override
    public  ValueSetRepository of(TypeReference type) {
        return new ValueSetRepository<>(getProvider(), mapper, type);
    }

    @Override
    public  ValueSetRepository of(ObjectReader reader) {
        return new ValueSetRepository<>(getProvider(), mapper, reader);
    }

    @Override
    protected long saveAll(JsonParser parser, JsonGenerator generator, Iterator elements) throws IOException {
        long updates = 0;
        generator.writeStartArray();

        final Map newElements = StreamSupport.stream(Spliterators.spliteratorUnknownSize(elements, Spliterator.ORDERED), false)
            .collect(LinkedHashMap::new, (map, item) -> map.put(item, item), Map::putAll);

        // Update old elements
        final ValueArrayIterator itr = new ValueArrayIterator<>(parser, getReader());
        while (itr.hasNext()) {
            final T oldElement = itr.next();

            if (!newElements.containsKey(oldElement)) {
                mapper.writeValue(generator, oldElement);
                continue;
            }

            final T newElement = newElements.remove(oldElement);
            mapper.writeValue(generator, newElement);
            ++updates;
        }

        // Create new elements
        for (T newElement : newElements.values()) {
            mapper.writeValue(generator, newElement);
            ++updates;
        }

        generator.writeEndArray();
        return updates;
    }

    @Override
    protected long deleteAll(JsonParser parser, JsonGenerator generator, Predicate predicate) throws IOException {
        long deleted = 0;
        generator.writeStartArray();

        final ValueArrayIterator itr = new ValueArrayIterator<>(parser, getReader());
        while (itr.hasNext()) {
            final T element = itr.next();

            if (predicate.test(element)) {
                ++deleted;
            }
            else {
                mapper.writeValue(generator, element);
            }
        }

        generator.writeEndArray();
        return deleted;
    }
}