MrZaiko/Polysmee

package io.github.polysmee.calendar;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
import java.util.Set;

/**
 * This class will be used to show the user his daily appointments on
 * the base of all his appointments through static methods
 */
public class DailyCalendar {


    private static long midnightEpochTimeMyAppointments;
    private static long midnightEpochTimePublicAppointments;

    private DailyCalendar() {
        //private constructor to prevent creating instances of this class
    }


    /**
     * Gets the chosen's date time at midnight in milliseconds, and sets the
     * midnightEpochTime attribute to that; this function is used when the user
     * changes the day he wants to see his appointments on
     *
     * @param year  the chosen's date year
     * @param month the chosen's date month
     * @param day   the chosen's date day of the week
     */
    public static void setDayEpochTimeAtMidnight(int year, int month, int day, boolean publicAppointments) {
        Calendar date = Calendar.getInstance();
        date.set(year, month, day);
        date.set(Calendar.HOUR_OF_DAY, 0);
        date.set(Calendar.MINUTE, 0);
        date.set(Calendar.SECOND, 0);
        date.set(Calendar.MILLISECOND, 0);
        if (publicAppointments) {
            midnightEpochTimePublicAppointments = date.getTimeInMillis();
        } else
            midnightEpochTimeMyAppointments = date.getTimeInMillis();
    }

    /**
     * Gets the date's time at midnight in milliseconds epoch as chosen by the user
     *
     * @return the time at midnight in milliseconds
     */
    public static long getDayEpochTimeAtMidnight(boolean publicAppointments) {
        if (publicAppointments)
            return midnightEpochTimePublicAppointments;
        return midnightEpochTimeMyAppointments;
    }

    /**
     * For a given set of user appointments, gets the ones that are programmed to happen
     * on the day the user chose on the calendar. The appointments are ordered according
     * to the chosen sorting metric (either the number of participants, or the start time)
     *
     * @param userAppointments set of appointments of the user.
     * @return the list of ordered appointments of the user for the chosen day
     * @throws IllegalArgumentException if the set given as argument is null
     */
    public static List<CalendarAppointmentInfo> getAppointmentsForTheDay(Set<CalendarAppointmentInfo> userAppointments, boolean publicAppointments, boolean sortChronologically) {
        if (userAppointments == null)
            throw new IllegalArgumentException();
        long todayMidnightTime = getDayEpochTimeAtMidnight(publicAppointments);
        long nextDayMidnightTime = todayMidnightTime + 24 * 3600 * 1000; //get the epoch time in milliseconds of next day at midnight
        List<CalendarAppointmentInfo> todayAppointments = new ArrayList<>();
        for (CalendarAppointmentInfo appointment : userAppointments) {
            if (appointment.getStartTime() >= todayMidnightTime && appointment.getStartTime() < nextDayMidnightTime) {
                todayAppointments.add(appointment);
            }
        }
        if(sortChronologically) {
            Collections.sort(todayAppointments, (calendarAppointmentInfo, t1) -> Long.compare(calendarAppointmentInfo.getStartTime(), t1.getStartTime()));
        } else {
            Collections.sort(todayAppointments, (calendarAppointmentInfo, t1) -> Integer.compare(calendarAppointmentInfo.getNumberOfParticipants(), t1.getNumberOfParticipants()));
        }


        return Collections.unmodifiableList(todayAppointments);
    }


}