package com.brains.jpa.hibernate.jpahibernatedemo;

import java.util.List;

import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import com.brains.jpa.hibernate.jpahibernatedemo.entity.Course;

import jakarta.persistence.EntityManager;
import jakarta.persistence.TypedQuery;
import jakarta.persistence.criteria.CriteriaBuilder;
import jakarta.persistence.criteria.CriteriaQuery;
import jakarta.persistence.criteria.Join;
import jakarta.persistence.criteria.JoinType;
import jakarta.persistence.criteria.Predicate;
import jakarta.persistence.criteria.Root;
import jakarta.transaction.Transactional;

@SpringBootTest(classes = JpaHibernateDemoApplication.class)
class CriteriaJoinQueryTest {

	private Logger logger = LoggerFactory.getLogger(getClass());
	
	@Autowired
	EntityManager em;
	
	@Test
	@Transactional
	void join() {
		//"Select * From Course c join c.students s"
		// 1. Use Criteria builder to create CriteriaQuery returning the expected result
		CriteriaBuilder cb = em.getCriteriaBuilder();
		CriteriaQuery<Course> cq = cb.createQuery(Course.class);
		
		// 2. Define root for the tables which are involved in the query
		Root<Course> courseRoot = cq.from(Course.class); // 'From Course c' part of main query
		
		// 3. Define Predicates for adding conditions
		Join<Object, Object> join = courseRoot.join("students");

		// 4. Add predicate to criteria query
		
		// 5. Build the typed query using entity manager and criteria query
		TypedQuery<Course> query = em.createQuery(cq.select(courseRoot));
		List<Course> resultList = query.getResultList();
		logger.info("join");
		logger.info("Size: -> {}", resultList.size());
		logger.info("Courses: -> {}", resultList);
	}
	
	@Test
	@Transactional
	void left_join() {
		//"Select * From Course c left join c.students s"
		// 1. Use Criteria builder to create CriteriaQuery returning the expected result
		CriteriaBuilder cb = em.getCriteriaBuilder();
		CriteriaQuery<Course> cq = cb.createQuery(Course.class);
		
		// 2. Define root for the tables which are involved in the query
		Root<Course> courseRoot = cq.from(Course.class); // 'From Course c' part of main query
		
		// 3. Define Predicates for adding conditions
		Join<Object, Object> join = courseRoot.join("students", JoinType.LEFT);

		// 4. Add predicate to criteria query
		
		// 5. Build the typed query using entity manager and criteria query
		TypedQuery<Course> query = em.createQuery(cq.select(courseRoot));
		List<Course> resultList = query.getResultList();
		logger.info("left_join");
		logger.info("Size: -> {}", resultList.size());
		logger.info("Courses: -> {}", resultList);
	}
}