package com.plannaplan.services;

import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.plannaplan.entities.Exchange;
import com.plannaplan.entities.User;
import com.plannaplan.models.EmailAcceptedData;
import com.plannaplan.models.EmailExchangesData;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.stereotype.Service;

/**
 * Service to send emails
 */
@Service
public class EmailService {

    @Autowired
    private JavaMailSender emailSender;

    @Autowired
    private UserService userService;

    @Value("${plannaplan.email}")
    private String appEmail;

    public EmailService() {
    }

    /**
     * send simple text email
     * 
     * @param destination destitnaion mail
     * @param message     text to be send
     */
    public void sendMail(String destination, String message) {
        SimpleMailMessage mailMessage = new SimpleMailMessage();
        mailMessage.setFrom(appEmail);
        mailMessage.setTo(destination);
        mailMessage.setSubject("[Plan na plan] INFO");
        mailMessage.setText(message);
        emailSender.send(mailMessage);
    }

    /**
     * sends email with infromation about accepted groups
     * 
     * @param user user to send a mail
     * @param data EmailAcceptedData instance containing informations about accepted
     *             and removed groups
     */
    public void sendAcceptationResult(User user, EmailAcceptedData data) {
        SimpleMailMessage mailMessage = new SimpleMailMessage();
        mailMessage.setFrom(appEmail);
        mailMessage.setTo(user.getEmail());
        mailMessage.setSubject("[PlanNaPlan] Akceptacja przedmiotów");
        mailMessage.setText(data.getEmailMessage());
        emailSender.send(mailMessage);
    }

    /**
     * method to send email for students whose groups were swaped
     * 
     * @param data EmailExchangesData instance that contains pair of datas user and
     *             list of performed exhanges
     */
    public void sendExchangesResults(EmailExchangesData data) {
        for (Map.Entry<Long, List<Exchange>> entry : data.getDataEntry()) {
            final User user = this.userService.getById(entry.getKey()).get();
            String response = "Znaleźliśmy dla Ciebie osobę, która zamieniła się z Tobą przedmiotami!!!\n Zamienione przedmioty: \n";

            final Iterator<Exchange> interator = entry.getValue().iterator();

            while (interator.hasNext()) {
                final Exchange exchange = interator.next();
                final String courseFrom = exchange.getDesiredAssignment().getCourseId() != null
                        ? exchange.getDesiredAssignment().getCourseId().getName()
                        : "Nieznane zajęcie";
                final String courseTo = exchange.getOwnedAssignment().getGroup().getCourseId() != null
                        ? exchange.getOwnedAssignment().getGroup().getCourseId().getName()
                        : "Nieznane zajęcie";

                response += (" - " + courseFrom + " za " + courseTo.toLowerCase());
            }

            SimpleMailMessage mailMessage = new SimpleMailMessage();
            mailMessage.setFrom(appEmail);
            mailMessage.setTo(user.getEmail());
            mailMessage.setSubject("[PlanNaPlan] Zamiana przedmiotów");
            mailMessage.setText(response);
            emailSender.send(mailMessage);

        }
    }
}