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GEARS Runtime Common

There is a newer version: 1.17.5

package com.xlrit.gears.base.choice;

import java.util.List;
import java.util.Optional;
import java.util.function.Function;
import java.util.stream.Stream;

import jakarta.persistence.EntityManager;
import jakarta.persistence.Tuple;
import jakarta.persistence.TypedQuery;

import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor
public abstract class JpaChoices implements Choices {
	public static final String PARAM_FILTER = "filter";

	protected final EntityManager entityManager;
	protected final Function toChoice;

	@Override
	public Kind kind() {
		return Kind.DYNAMIC;
	}

	@Override
	public int count() {
		TypedQuery query = createCountQuery();
		Long count = query.getSingleResult();
		return count == null ? 0 : count.intValue();
	}

	@Override
	public Optional find(String id) {
		TypedQuery query = createItemQuery(id);
		List resultList = query.getResultList();
		if (resultList.isEmpty()) return Optional.empty();
		if (resultList.size() > 1) throw new RuntimeException("Item query must return 0 or 1 result, but got " + resultList.size() + ": " + getQueryString(query));
		return Optional.of(toChoice.apply(resultList.get(0)));
	}

	@Override
	public Stream items(String filter, int start, int count) {
		TypedQuery query = createItemsQuery(filter);
		return query
			.setFirstResult(start)
			.setMaxResults(count)
			.getResultStream()
			.map(toChoice);
	}

	protected abstract TypedQuery createCountQuery();
	protected abstract TypedQuery createItemsQuery(String filter);
	protected abstract TypedQuery createItemQuery(String id);

	@SuppressWarnings("rawtypes")
	private static String getQueryString(TypedQuery typedQuery) {
		if (typedQuery instanceof org.hibernate.query.Query query)
			return query.getQueryString();
		return "(query unknown)";
	}
}