def date_check(date_str):
    now = datetime.date.today()
    zf_list = {
        '一': 1,
        '二': 2,
        '两': 2,
        '三': 3,
        '四': 4,
        '五': 5,
        '六': 6,
        '七': 7,
        '八': 8,
        '九': 9,
        '1': 1,
        '2': 2,
        '3': 3,
        '4': 4,
        '5': 5,
        '6': 6,
        '7': 7,
        '8': 8,
        '9': 9
    }
    t = None
    if date_str.find('今天') >= 0:
        delta = datetime.timedelta(days=0)
        t = now - delta
    elif date_str.find('昨天') >= 0:
        delta = datetime.timedelta(days=1)
        t = now - delta
    elif date_str.find('前天') >= 0:
        delta = datetime.timedelta(days=2)
        t = now - delta
    elif date_str.find('天前') >= 0:
        day = re.findall(r'(?P<day>.*?)天前', date_str)
        if len(day) > 0 and day[0] in zf_list.keys():
            delta = datetime.timedelta(days=zf_list[day[0]])
            t = now - delta
        else:
            t = now
    elif date_str.find('周前') >= 0:
        week = re.findall(r'(?P<week>.*?)周前', date_str)
        if len(week) > 0 and week[0] in zf_list.keys():
            delta = datetime.timedelta(weeks=zf_list[week[0]])
            t = now - delta
        else:
            t = now
    else:
        r = re.findall(r'(?P<year>\d*?)年', date_str)
        if len(r) > 0:
            year = int(r[0])
        else:
            year = now.year
        r = re.findall(r'(?P<m>.)月(?P<d>.)日', date_str)
        if len(r) > 0:
            month = int(r[0][0])
            day = int(r[0][1])
        else:
            month = now.month
            day = now.day
        t = datetime.date(year, month, day)
    return t.strftime('%Y-%m-%d %H:%M:%S')