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/*
 * Copyright 2016-2021 the original author or 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 org.springframework.data.jpa.convert;

import java.util.ArrayList;
import java.util.EnumSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.Expression;
import javax.persistence.criteria.From;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import javax.persistence.metamodel.Attribute;
import javax.persistence.metamodel.Attribute.PersistentAttributeType;
import javax.persistence.metamodel.ManagedType;
import javax.persistence.metamodel.SingularAttribute;

import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.data.domain.Example;
import org.springframework.data.domain.ExampleMatcher;
import org.springframework.data.domain.ExampleMatcher.PropertyValueTransformer;
import org.springframework.data.jpa.repository.query.EscapeCharacter;
import org.springframework.data.support.ExampleMatcherAccessor;
import org.springframework.data.util.DirectFieldAccessFallbackBeanWrapper;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * {@link QueryByExamplePredicateBuilder} creates a single {@link CriteriaBuilder#and(Predicate...)} combined
 * {@link Predicate} for a given {@link Example}. 

 * The builder includes any {@link SingularAttribute} of the {@link Example#getProbe()} applying {@link String} and
 * {@literal null} matching strategies configured on the {@link Example}. Ignored paths are no matter of their actual
 * value not considered. 

 *
 * @author Christoph Strobl
 * @author Mark Paluch
 * @author Oliver Gierke
 * @author Jens Schauder
 * @since 1.10
 */
public class QueryByExamplePredicateBuilder {

	private static final Set ASSOCIATION_TYPES;

	static {
		ASSOCIATION_TYPES = EnumSet.of(PersistentAttributeType.MANY_TO_MANY, //
				PersistentAttributeType.MANY_TO_ONE, //
				PersistentAttributeType.ONE_TO_MANY, //
				PersistentAttributeType.ONE_TO_ONE);
	}

	/**
	 * Extract the {@link Predicate} representing the {@link Example}.
	 *
	 * @param root must not be {@literal null}.
	 * @param cb must not be {@literal null}.
	 * @param example must not be {@literal null}.
	 * @return never {@literal null}.
	 */
	public static  Predicate getPredicate(Root root, CriteriaBuilder cb, Example example) {
		return getPredicate(root, cb, example, EscapeCharacter.DEFAULT);
	}

	/**
	 * Extract the {@link Predicate} representing the {@link Example}.
	 *
	 * @param root must not be {@literal null}.
	 * @param cb must not be {@literal null}.
	 * @param example must not be {@literal null}.
	 * @param escapeCharacter Must not be {@literal null}.
	 * @return never {@literal null}.
	 */
	public static  Predicate getPredicate(Root root, CriteriaBuilder cb, Example example,
			EscapeCharacter escapeCharacter) {

		Assert.notNull(root, "Root must not be null!");
		Assert.notNull(cb, "CriteriaBuilder must not be null!");
		Assert.notNull(example, "Example must not be null!");

		ExampleMatcher matcher = example.getMatcher();

		List predicates = getPredicates("", cb, root, root.getModel(), example.getProbe(),
				example.getProbeType(), new ExampleMatcherAccessor(matcher), new PathNode("root", null, example.getProbe()),
				escapeCharacter);

		if (predicates.isEmpty()) {
			return cb.isTrue(cb.literal(true));
		}

		if (predicates.size() == 1) {
			return predicates.iterator().next();
		}

		Predicate[] array = predicates.toArray(new Predicate[0]);

		return matcher.isAllMatching() ? cb.and(array) : cb.or(array);
	}

	@SuppressWarnings({ "rawtypes", "unchecked" })
	static List getPredicates(String path, CriteriaBuilder cb, Path from, ManagedType type, Object value,
			Class probeType, ExampleMatcherAccessor exampleAccessor, PathNode currentNode,
			EscapeCharacter escapeCharacter) {

		List predicates = new ArrayList<>();
		DirectFieldAccessFallbackBeanWrapper beanWrapper = new DirectFieldAccessFallbackBeanWrapper(value);

		for (SingularAttribute attribute : type.getSingularAttributes()) {

			String currentPath = !StringUtils.hasText(path) ? attribute.getName() : path + "." + attribute.getName();

			if (exampleAccessor.isIgnoredPath(currentPath)) {
				continue;
			}

			PropertyValueTransformer transformer = exampleAccessor.getValueTransformerForPath(currentPath);
			Optional