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

package com.plannaplan.services;

import java.util.ArrayList;
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.Commision;
import com.plannaplan.entities.Exchange;
import com.plannaplan.entities.Groups;
import com.plannaplan.entities.User;
import com.plannaplan.models.EmailExchangesData;
import com.plannaplan.models.MatchData;
import com.plannaplan.repositories.ExchangeRepository;

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

/**
 * Service to manage Exchanges
 */
@Service
public class ExchangeService {

    @Autowired
    private ExchangeRepository repo;

    @Autowired
    private AssignmentService assignmentService;

    @Autowired
    private UserService userService;

    @Autowired
    private EmailService emailService;

    /**
     * @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);
    }

    /**
     * @return list of all exchanges in database
     */
    public List<Exchange> getAllExchanges() {
        return this.repo.findAll();
    }

    /**
     * @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);
    }

    /**
     * method to perform Exchange algorythm. It search for matches and swap
     * assignments between latests user commisions if it can be performed. After
     * swap we block users matches that contains switched groups. After algorythm
     * email is being sent to all users with information about performed exchanges
     */
    public void performExchange() {
        final List<MatchData> matchData = this.getMatches();
        final List<Long> performedAssignmentExchanges = new ArrayList<>();
        final EmailExchangesData emailData = new EmailExchangesData();
        final List<Exchange> exchangesToDelete = new ArrayList<>();

        matchData.forEach(m -> {
            final Assignment assignmentOne = m.getAssignmentOne();
            final Assignment assignmentTwo = m.getAssignmentTwo();

            final Exchange exchange1 = m.getExchangeOne();
            final Exchange exchange2 = m.getExchangeTwo();

            if (!(performedAssignmentExchanges.contains(assignmentOne.getId())
                    || performedAssignmentExchanges.contains(assignmentTwo.getId()))) {
                final Commision commisionOne = assignmentOne.getCommision();
                final User userOne = commisionOne.getCommisionOwner();
                final Commision commisionTwo = assignmentTwo.getCommision();
                final User userTwo = commisionTwo.getCommisionOwner();

                assignmentOne.setCommision(commisionTwo);
                assignmentTwo.setCommision(commisionOne);

                userOne.removeGroup(assignmentOne.getGroup().getId());
                userTwo.removeGroup(assignmentTwo.getGroup().getId());

                userOne.claimGroup(assignmentTwo.getGroup());
                userTwo.claimGroup(assignmentOne.getGroup());

                this.assignmentService.save(assignmentOne);
                this.assignmentService.save(assignmentTwo);

                this.userService.save(userOne);
                this.userService.save(userTwo);

                performedAssignmentExchanges.add(assignmentOne.getId());
                performedAssignmentExchanges.add(assignmentTwo.getId());

                emailData.addExchange(exchange1.getOwnedAssignment().getCommision().getCommisionOwner(), exchange1);
                emailData.addExchange(exchange2.getOwnedAssignment().getCommision().getCommisionOwner(), exchange2);
            }

            exchangesToDelete.add(exchange1);
            exchangesToDelete.add(exchange2);
        });
        this.emailService.sendExchangesResults(emailData);
        this.repo.deleteAll(exchangesToDelete);
    }

    /**
     * @return list of matches found in database
     */
    public List<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, exchangeTwo);
        }).collect(Collectors.toList());

        final Set<MatchData> uniqData = new HashSet<>(matches);
        final List<MatchData> matchDataListSorted = uniqData.stream().sorted((m1, m2) -> -1 * m1.compare(m2))
                .collect(Collectors.toList());

        return matchDataListSorted;
    }
}