backend/buisnesslogic/src/main/java/com/plannaplan/repositories/GroupRepository.java

package com.plannaplan.repositories;

import java.util.List;
import java.util.Optional;

import com.plannaplan.entities.Groups;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

/**
 *  GroupRepository.find:
 *      Return list of:
 *      SELECT * FROM Groups WHERE time = i AND room = j AND capacity = k .
 * 
 *      Where i, j, k, ?1, ?2, ?3 are equale to variables. 
 * 
 *  GroupRepository.getByCourse:
 *      Return list of:
 *      SELECT * FROM Groups WHERE course_id = i .
 * 
 *      Where i, ?1 are equale to variables. 
 */
@Repository
public interface GroupRepository extends JpaRepository<Groups, Long> {
    @Query("FROM Groups WHERE time = ?1 AND room = ?2 AND capacity = ?3")
    Optional<Groups> find(@Param("time") int time, @Param("room") String room, @Param("capacity") int capacity);

    @Query("FROM Groups WHERE course_id = ?1")
    List<Groups> getByCourse(@Param("id") Long id);

    @Query("SELECT COUNT(*) AS assinged_times FROM Assignment WHERE isPastAssignment=false GROUP BY group HAVING group_id=?1")
    Optional<Number> getAssignedAmount(Long groupId);

    /**
     * PLAIN SQL QUERY: SELECT group_id, COUNT(*) assinged_times FROM assignment
     * WHERE is_past_assignment=0 GROUP BY group_id HAVING group_id IN (:ids)")
     * 
     * @param groupIds list of groups ids
     * @return list of objects arrays where first object is Groups instance and
     *         second is Long that is taken places value
     */
    @Query("SELECT group, COUNT(*) AS assinged_times FROM Assignment a WHERE a.isPastAssignment=false GROUP BY a.group HAVING group_id IN (:ids)")
    List<Object[]> getAssignedAmounts(@Param("ids") List<Long> groupIds);

}