package com.yunzhi.demo.common;

import java.time.*;
import java.time.format.DateTimeFormatter;

public class DateUtils {
    public static LocalDateTime from(String str, String formater) {
        DateTimeFormatter fmt = DateTimeFormatter.ofPattern(formater);
        return LocalDateTime.parse(str, fmt);
    }

    public static long daysBetween(LocalDateTime dt1, LocalDateTime dt2) {
        Duration duration = Duration.between(dt1, dt2);
        return duration.toDays();
    }

    public static String toString(LocalDateTime dt, String formater) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(formater);
        return dt.format(formatter);
    }

    public static String weekDay(LocalDateTime dt) {
        String[] week = new String[]{"一", "二", "三", "四", "五", "六", "日"};
        DayOfWeek dayOfWeek = dt.getDayOfWeek();
        int inx = dayOfWeek.getValue() - 1;
        return String.format("星期%s", week[inx]);
    }

    /**
     * 毫秒转 UTC 时间
     * @param milliseconds
     * @return
     */
    public static LocalDateTime getDateTime(long milliseconds) {
        return LocalDateTime.ofInstant(Instant.ofEpochMilli(milliseconds), ZoneOffset.UTC);
    }
}