package com.quietor.calendar.week;

import com.quietor.calendar.constants.CalendarMonth;
import com.quietor.calendar.constants.YearDays;
import com.quietor.calendar.tool.CalendarTool;
import com.quietor.calendar.exception.CalendarException;

/**
 * @author Quietor
 * @create 2018-06-17 17:47
 * @desc 根据已知星期的日期计算指定日志的星期
 * 该方法需要具体的分析每个年份是否是闰年，在此基础上计算两个日期之间的天数差值
 **/
public class CaclulateWeekdayWithGregorian {

    public static int calculateDays(int startYear, CalendarMonth startMonth, int startDay, int endYear, CalendarMonth endMonth, int endDay) throws CalendarException {

        CalendarTool.checkParam(startYear, startMonth, startDay);
        CalendarTool.checkParam(endYear, endMonth, endDay);

        int startPassedDays = calculatePassedDays(startYear, startMonth, startDay);
        int endPassedDays = calculatePassedDays(endYear, endMonth, endDay);

        int daysOfWholeYear = calculateDaysOfYears(startYear, endYear);
        int days = calculateDays(startYear, endYear);

        int totalDays = daysOfWholeYear + endPassedDays - startPassedDays;
        int total = days + endPassedDays - startPassedDays;

        return totalDays;
    }

    /**
     * @param startYear 起始年份
     * @param endYear 截止年份
     * @return 从起止年份到截止年份前一年的天数
     * 常量 YearDays.LEAP_YEAR_DAYS = 366
     * 常量 YearDays.NONLEAP_YEAR_DAYS = 365
     * @throws CalendarException
     */
    public static int calculateDays(int startYear, int endYear) throws CalendarException {

        startYear -= 1;
        endYear -= 1;
        int startLeaps = Integer.valueOf(startYear / 4) - Integer.valueOf(startYear / 100) + Integer.valueOf(startYear / 400);
        int endLeaps = Integer.valueOf(endYear / 4) - Integer.valueOf(endYear / 100) + Integer.valueOf(endYear / 400);

        int totalDays = endLeaps * YearDays.LEAP_YEAR_DAYS + (endYear - endLeaps) * YearDays.NONLEAP_YEAR_DAYS -(startLeaps * YearDays.LEAP_YEAR_DAYS + (startYear - startLeaps) * YearDays.NONLEAP_YEAR_DAYS);

        return totalDays;
    }

    /**
     * @param startYear 起始年份
     * @param endYear 截止年份
     * @return 从起止年份到截止年份前一年的天数
     * 常量 YearDays.LEAP_YEAR_DAYS = 366
     * 常量 YearDays.NONLEAP_YEAR_DAYS = 365
     * @throws CalendarException
     */
    public static int calculateDaysOfYears(int startYear, int endYear) throws CalendarException {
        if(startYear > endYear) {
            throw new CalendarException(String.format("illegal parameter year, startYear=%s endYear=%s", startYear, endYear));
        }

        int difference = endYear - startYear;

        int totalDays = 0;
        //从起始年的1月1号开始加和，一直到截止年的前一年所有的天数，这样的计算需要减去起始年已经过过去的天数
        for(int i= startYear; i < endYear; i++) {
            boolean isLeap = CalendarTool.isLeapyear(i);
            if (isLeap) {
                totalDays += YearDays.LEAP_YEAR_DAYS;
            } else {
                totalDays += YearDays.NONLEAP_YEAR_DAYS;
            }
        }

        return totalDays;
    }

    /**
     * 计算一年中到指定日期时已经度过的天数
     * @param year
     * @param month
     * @param day
     * @return
     */
    public static int calculatePassedDays(int year, CalendarMonth month, int day) throws CalendarException {
        CalendarTool.checkParam(year, month, day);

        int monthValue = month.getSort();

        int passedTotal = 0;
        for(int i = 1; i < monthValue; i++) {
            CalendarMonth passedMonth = CalendarMonth.getMonthBySort(i);
            if(passedMonth.equals(CalendarMonth.FEBRUARY)) {
                boolean isLeap = CalendarTool.isLeapyear(year);
                if(isLeap) {
                    passedTotal += 29;
                    continue;
                }
            }
            passedTotal += passedMonth.getDays();
        }

        return passedTotal + day;
    }


    public static void main(String[] args) throws CalendarException {
        int totalDays = calculateDays(1977, CalendarMonth.MARCH, 27, 2005, CalendarMonth.MAY, 31);
        System.out.println(totalDays);
    }

}