package nl.np.util;

import static junit.framework.Assert.assertEquals;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

import org.junit.Ignore;
import org.junit.Test;

public class DateUtilTest {
    private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

    @Ignore
    @Test
    public void testCalculateWeekNumber() {
        Calendar dec282015 = initDate(28, Calendar.DECEMBER, 2015);
        int dec282015WeekNumber = DateUtil.calculateWeekNumber(dec282015);
        // assertEquals(53, dec282015WeekNumber);

        Calendar firstJan2016 = initDate(1, Calendar.JANUARY, 2016);

        int firstJan2016WeekNumber = DateUtil.calculateWeekNumber(firstJan2016);
        assertEquals(53, firstJan2016WeekNumber);

        Date now = new Date();
        int todaysWeekNumber = DateUtil.calculateWeekNumber(now);
    }

    private Calendar initDate(int date, int month, int year) {
        Calendar dec282015 = Calendar.getInstance();
        dec282015.set(Calendar.DATE, date);
        dec282015.set(Calendar.MONTH, month);
        dec282015.set(Calendar.YEAR, year);
        return dec282015;
    }

    @Ignore
    @Test
    public void testCalculateFirstThursdayOfYear() {
        for(int year = 2000; year < 2026; year++) {
            Date firstThursday = DateUtil.calculateFirstThursdayOfYear(year);
            System.out.println(sdf.format(firstThursday));
        }
    }

    @Ignore
    @Test
    public void testFirstDayOfWeek() {
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
        for(int year = 2016; year < 2020; year++) {
            for(int i = 0; i < 52; i++) {
                int week = i + 1;
                Date date = DateUtil.calculateFirstDayOfWeek(week, year);
                System.out.println(String.format("%d - %s", week, sdf.format(date)));
            }
            System.out.println("===");
        }
    }

    @Ignore
    @Test
    public void findPerfectNumber() {
        int max = 25000000;
        findPerfectNumbers(max);
    }

    private void findPerfectNumbers(int max) {
        for(int i = 2; i <= max; i++) {
            if(isPerfect(i)) {
                System.out.println(i);
            }
        }
    }

    private boolean isPerfect(int i) {
        List<Integer> dividers = findDividers(i);
        int sumDividers = calculateSum(dividers);
        return sumDividers == i;
    }

    private List<Integer> findDividers(int number) {
        List<Integer> dividers = new ArrayList<Integer>();
        for(int i = 1; i <= number / 2; i++) {
            if(number % i == 0) {
                dividers.add(i);
            }
        }
        return dividers;
    }

    private int calculateSum(List<Integer> dividers) {
        int sum = 0;
        for(int div : dividers) {
            sum += div;
        }
        return sum;
    }

    @Ignore
    @Test
    public void twoToTheEleventh() {
        int[] numbers = { 4, 8, 32, 128, 2048, 8192 };
        for(int number : numbers) {
            int product = (number / 2) * (number - 1);
            System.out.println(product);
            System.out.println("Perfect? " + isPerfect(product));
        }
    }

    @Test
    public void highestComposite() {
        int oldFactorsLength = 0;
        for(int number = 1; number <= 32768; number++) {
            // int number = 5040;
            List<Integer> factors = findFactors(number);
            if(factors.size() > oldFactorsLength) {
                logFactors(number, factors);
                oldFactorsLength = factors.size();
            }
        }
    }

    private List<Integer> findFactors(int number) {
        List<Integer> factors = new ArrayList<Integer>();
        for(int i = 1; i <= number / 2; i++) {
            if(number % i == 0) {
                factors.add(i);
            }
        }
        return factors;
    }

    private void logFactors(int number, List<Integer> factors) {
        StringBuilder sb = new StringBuilder();
        sb.append("Factors (").append(number).append(") [").append(factors.size()).append("] =");
        for(int factor : factors) {
            sb.append(" ").append(factor);
        }
        System.out.println(sb.toString());
    }

}