package cn.enilu.guns.bean.vo.query;

import cn.enilu.guns.utils.Lists;
import org.apache.commons.lang3.StringUtils;
import org.springframework.data.jpa.domain.Specification;

import javax.persistence.criteria.*;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

/**
 * descript
 *
 * @author ：enilu
 * @date ：Created in 2019/6/30 16:04
 */
public class DynamicSpecifications {


    public static <T> Specification<T> bySearchFilter(final Collection<SearchFilter> filters, final Class<T> entityClazz) {
        return new Specification<T>() {
            @Override
            public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
                if (filters!=null && !filters.isEmpty()) {

                    List<Predicate> predicates = Lists.newArrayList();
                    for (SearchFilter filter : filters) {
                        // nested path translate, 如Task的名为"user.name"的filedName, 转换为Task.user.name属性
                        String[] names = StringUtils.split(filter.fieldName, ".");
                        Path expression = root.get(names[0]);
                        for (int i = 1; i < names.length; i++) {
                            expression = expression.get(names[i]);
                        }
                        // logic operator
                        switch (filter.operator) {
                            case EQ:
                                predicates.add(builder.equal(expression, filter.value));
                                break;
                            case LIKE:
                                predicates.add(builder.like(expression, "%" + filter.value + "%"));
                                break;
                            case GT:
                                predicates.add(builder.greaterThan(expression, (Comparable) filter.value));
                                break;
                            case LT:
                                predicates.add(builder.lessThan(expression, (Comparable) filter.value));
                                break;
                            case GTE:
                                predicates.add(builder.greaterThanOrEqualTo(expression, (Comparable) filter.value));
                                break;
                            case LTE:
                                predicates.add(builder.lessThanOrEqualTo(expression, (Comparable) filter.value));
                                break;
                            case IN:
                                predicates.add(expression.in((ArrayList)filter.value));
                                break;
                            case ISNULL:
                                predicates.add(expression.isNull());
                                break;
                            case ISNOTNULL:
                                predicates.add(expression.isNotNull());
                                break;
                        }
                    }

                    // 将所有条件用 and 联合起来
                    if (!predicates.isEmpty()) {
                        return builder.and(predicates.toArray(new Predicate[predicates.size()]));
                    }
                }

                return builder.conjunction();
            }
        };
    }
}
