package de.ph87.homeautomation.schedule;

import com.luckycatlabs.sunrisesunset.Zenith;
import com.luckycatlabs.sunrisesunset.calculator.SolarEventCalculator;
import com.luckycatlabs.sunrisesunset.dto.Location;
import de.ph87.homeautomation.Config;
import de.ph87.homeautomation.schedule.entry.ScheduleEntry;
import de.ph87.homeautomation.schedule.entry.ScheduleEntryType;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.context.event.ApplicationStartedEvent;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.Instant;
import java.time.ZonedDateTime;
import java.util.Calendar;
import java.util.Comparator;
import java.util.GregorianCalendar;
import java.util.Optional;

@Slf4j
@Service
@Transactional
@RequiredArgsConstructor
public class ScheduleCalculationService {

  private final Config config;

  private final ScheduleReadService scheduleReadService;

  private final ApplicationEventPublisher eventPublisher;

  @EventListener(ApplicationStartedEvent.class)
  public void calculateAllNext() {
    final ZonedDateTime now = ZonedDateTime.now();
    scheduleReadService.findAll().forEach(schedule -> calculateSchedule(schedule, now));
  }

  public void calculateSchedule(final Schedule schedule, final ZonedDateTime now) {
    schedule.getEntries().forEach(scheduleEntry -> calculateEntry(schedule, scheduleEntry, now));
    final Optional<ScheduleEntry> nextEntry = schedule.getEntries().stream()
      .filter(entry -> entry.getNextFuzzyTimestamp() != null && entry.getNextFuzzyTimestamp().isAfter(now))
      .min(Comparator.comparing(ScheduleEntry::getNextFuzzyTimestamp));
    if (nextEntry.isEmpty()) {
      log.info("No next schedule for \"{}\"", schedule.getTitle());
    } else {
      log.info("Next schedule for \"{}\": {}", schedule.getTitle(), nextEntry.get().getNextFuzzyTimestamp());
    }
    eventPublisher.publishEvent(new ScheduleThreadWakeUpEvent());
  }

  private void calculateEntry(final Schedule schedule, final ScheduleEntry entry, final ZonedDateTime now) {
    log.debug("calculateNext \"{}\", {}:", schedule.getTitle(), entry);
    if (!schedule.isEnabled() || !entry.isEnabled() || !isAnyWeekdayEnabled(entry)) {
      entry.setNextClearTimestamp(null);
      return;
    }
    ZonedDateTime midnight = now.withHour(0).withMinute(0).withSecond(0).withNano(0);
    ZonedDateTime next = calculateEntryForDay(entry, midnight);
    while (next != null && (!next.isAfter(now) || !isAfterLast(entry, next) || !isWeekdayEnabled(entry, next))) {
      log.debug("  -- skipping: next={}", next);
      midnight = midnight.plusDays(1);
      next = calculateEntryForDay(entry, midnight);
    }
    log.debug("  => {}", next);
    entry.setNextClearTimestamp(next);
  }

  private boolean isAfterLast(final ScheduleEntry entry, final ZonedDateTime next) {
    return entry.getLastClearTimestamp() == null || next.isAfter(entry.getLastClearTimestamp());
  }

  private ZonedDateTime calculateEntryForDay(final ScheduleEntry entry, final ZonedDateTime midnight) {
    switch (entry.getType()) {
      case TIME:
        return midnight.withHour(entry.getHour()).withMinute(entry.getMinute()).withSecond(entry.getSecond());
      case SUNRISE:
      case SUNSET:
        return astroNext(entry, midnight);
      default:
        log.error("AstroEvent not implemented: {}", entry.getType());
        break;
    }
    return null;
  }

  private ZonedDateTime astroNext(final ScheduleEntry entry, ZonedDateTime midnight) {
    final Location location = new Location(config.getLatitude(), config.getLongitude());
    final SolarEventCalculator calculator = new SolarEventCalculator(location, config.getTimezone());
    final Calendar calendar = GregorianCalendar.from(midnight);
    final Calendar nextCalendar = astroNext(calculator, entry.getType(), new Zenith(entry.getZenith()), calendar);
    if (nextCalendar == null) {
      return null;
    }
    return ZonedDateTime.ofInstant(Instant.ofEpochMilli(nextCalendar.getTimeInMillis()), midnight.getZone());
  }

  private Calendar astroNext(final SolarEventCalculator calculator, final ScheduleEntryType type, final Zenith solarZenith, final Calendar calendar) {
    switch (type) {
      case SUNRISE:
        return calculator.computeSunriseCalendar(solarZenith, calendar);
      case SUNSET:
        return calculator.computeSunsetCalendar(solarZenith, calendar);
    }
    return null;
  }

  private boolean isAnyWeekdayEnabled(final ScheduleEntry entry) {
    return entry.isMonday() || entry.isTuesday() || entry.isWednesday() || entry.isThursday() || entry.isFriday() || entry.isSaturday() || entry.isSunday();
  }

  private boolean isWeekdayEnabled(final ScheduleEntry entry, final ZonedDateTime value) {
    switch (value.getDayOfWeek()) {
      case MONDAY:
        return entry.isMonday();
      case TUESDAY:
        return entry.isTuesday();
      case WEDNESDAY:
        return entry.isWednesday();
      case THURSDAY:
        return entry.isThursday();
      case FRIDAY:
        return entry.isFriday();
      case SATURDAY:
        return entry.isSaturday();
      case SUNDAY:
        return entry.isSunday();
    }
    return false;
  }

}