package com.wasu.cs.utils;

import java.util.Date;

/**
 * Created by chenming on 2016/9/27.
 *
 * @Description: 用于计算相对时间，输出几秒前、几分钟前，几小时前，几天前...
 * @email chenming@wasu.com
 */

public class RelativeDateUtils {
	private static final long ONE_MINUTE = 60000L;
	private static final long ONE_HOUR = 3600000L;
	private static final long ONE_DAY = 86400000L;
	private static final long ONE_WEEK = 604800000L;

	private static final String ONE_SECOND_AGO = "秒前";
	private static final String ONE_MINUTE_AGO = "分钟前";
	private static final String ONE_HOUR_AGO = "小时前";
	private static final String ONE_DAY_AGO = "天前";
	private static final String ONE_MONTH_AGO = "月前";
	private static final String ONE_YEAR_AGO = "年前";

	public static String format(Date date, Date curTime) {
		long delta = curTime.getTime() - date.getTime();
		if (delta < 1L * ONE_MINUTE) {
			long seconds = toSeconds(delta);
			return (seconds <= 0 ? 1 : seconds) + ONE_SECOND_AGO;
		}
		if (delta < 45L * ONE_MINUTE) {
			long minutes = toMinutes(delta);
			return (minutes <= 0 ? 1 : minutes) + ONE_MINUTE_AGO;
		}
		if (delta < 24L * ONE_HOUR) {
			long hours = toHours(delta);
			return (hours <= 0 ? 1 : hours) + ONE_HOUR_AGO;
		}
		if (delta < 48L * ONE_HOUR) {
			return "昨天";
		}
		if (delta < 30L * ONE_DAY) {
			long days = toDays(delta);
			return (days <= 0 ? 1 : days) + ONE_DAY_AGO;
		}
		if (delta < 12L * 4L * ONE_WEEK) {
			long months = toMonths(delta);
			return (months <= 0 ? 1 : months) + ONE_MONTH_AGO;
		} else {
			long years = toYears(delta);
			return (years <= 0 ? 1 : years) + ONE_YEAR_AGO;
		}
	}

	private static long toSeconds(long date) {
		return date / 1000L;
	}

	private static long toMinutes(long date) {
		return toSeconds(date) / 60L;
	}

	private static long toHours(long date) {
		return toMinutes(date) / 60L;
	}

	private static long toDays(long date) {
		return toHours(date) / 24L;
	}

	private static long toMonths(long date) {
		return toDays(date) / 30L;
	}

	private static long toYears(long date) {
		return toMonths(date) / 365L;
	}
}
