backend/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java

package com.plannaplan.services;

import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;

import com.plannaplan.entities.Assignment;
import com.plannaplan.entities.Exchange;
import com.plannaplan.entities.Groups;
import com.plannaplan.models.MatchData;
import com.plannaplan.repositories.ExchangeRepository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class ExchangeService {

    @Autowired
    private ExchangeRepository repo;

    /**
     * @param exchange Instance to save in database
     * @return Exchange Instance contains database id
     */
    public Exchange save(Exchange exchange) {
	return this.repo.save(exchange);
    }

    /**
     * @param id Id of exchange in database
     * @return Optional Exchange if found
     */
    public Optional<Exchange> getById(Long id) {
	return this.repo.findById(id);
    }

    /**
     * @param id Id of user
     * @return List of exchanges that belong to user
     */
    public List<Exchange> getByUserId(Long id) {
	return this.repo.getByUserId(id);
    }

    /**
     * @param entity Exchange entity which we would like to delete
     */
    public void deleteExchange(Exchange entity) {
	this.repo.delete(entity);
    }

    /**
     * @param assignment Assignment to trade for
     * @param group      Desired group
     * @return Optional with Exchange if exist
     */
    public Optional<Exchange> checkForExchange(Assignment assignment, Groups group) {
	return this.repo.checkForExchange(assignment, group);
    }

    public void performExchange() {

    }

   public Set<MatchData> getMatches(){
       final List<MatchData> matches = this.repo.getMatches().stream().map(m -> {
	       final Exchange exchangeOne = (Exchange) m[0];
	       final Exchange exchangeTwo = (Exchange) m[1];
	       return new MatchData(exchangeOne.getOwnedAssignment(), exchangeTwo.getOwnedAssignment());
	   }).collect(Collectors.toList());

       final Set<MatchData> filterMatches = new HashSet<>(matches);
       return filterMatches;
   }
}