using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CallCenter.Utility.Time
{
    public class DateTools
    {
        /// <summary>  
        /// 得到本周第一天(以星期天为第一天)  
        /// </summary>  
        /// <param name="datetime"></param>  
        /// <returns></returns>  
        public static DateTime GetWeekFirstDaySun(DateTime datetime)
        {
            //星期天为第一天  
            int weeknow = Convert.ToInt32(datetime.DayOfWeek);
            int daydiff = (-1) * weeknow;

            //本周第一天  
            string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
            return Convert.ToDateTime(FirstDay);
        }

        /// <summary>  
        /// 得到本周第一天(以星期一为第一天)  
        /// </summary>  
        /// <param name="datetime"></param>  
        /// <returns></returns>  
        public static DateTime GetWeekFirstDayMon(DateTime datetime)
        {
            //星期一为第一天  
            int weeknow = Convert.ToInt32(datetime.DayOfWeek);

            //因为是以星期一为第一天，所以要判断weeknow等于0时，要向前推6天。  
            weeknow = (weeknow == 0 ? (7 - 1) : (weeknow - 1));
            int daydiff = (-1) * weeknow;

            //本周第一天  
            string FirstDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
            return Convert.ToDateTime(FirstDay);
        }

        /// <summary>  
        /// 得到本周最后一天(以星期六为最后一天)  
        /// </summary>  
        /// <param name="datetime"></param>  
        /// <returns></returns>  
        public static DateTime GetWeekLastDaySat(DateTime datetime)
        {
            //星期六为最后一天  
            int weeknow = Convert.ToInt32(datetime.DayOfWeek);
            int daydiff = (7 - weeknow) - 1;

            //本周最后一天  
            string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
            return Convert.ToDateTime(LastDay);
        }

        /// <summary>  
        /// 得到本周最后一天(以星期天为最后一天)  
        /// </summary>  
        /// <param name="datetime"></param>  
        /// <returns></returns>  
        public static DateTime GetWeekLastDaySun(DateTime datetime)
        {
            //星期天为最后一天  
            int weeknow = Convert.ToInt32(datetime.DayOfWeek);
            weeknow = (weeknow == 0 ? 7 : weeknow);
            int daydiff = (7 - weeknow);

            //本周最后一天  
            string LastDay = datetime.AddDays(daydiff).ToString("yyyy-MM-dd");
            return Convert.ToDateTime(LastDay);
        }

        /// <summary>
        /// 取得某月的第一天
        /// </summary>
        /// <param name="datetime">要取得月份第一天的时间</param>
        /// <returns></returns>
        public static DateTime FirstDayOfMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day);
        }
        /// <summary>
            /// 取得某月的最后一天
            /// </summary>
            /// <param name="datetime">要取得月份最后一天的时间</param>
            /// <returns></returns>
        public static DateTime LastDayOfMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddMonths(1).AddDays(-1);
        }

        /// <summary>
        /// 取得上个月第一天
        /// </summary>
        /// <param name="datetime">要取得上个月第一天的当前时间</param>
        /// <returns></returns>
        public static DateTime FirstDayOfPreviousMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddMonths(-1);
        }

        
        /// <summary>
        /// 取得上个月的最后一天
        /// </summary>
        /// <param name="datetime">要取得上个月最后一天的当前时间</param>
        /// <returns></returns>
        public static DateTime LastDayOfPrdviousMonth(DateTime datetime)
        {
            return datetime.AddDays(1 - datetime.Day).AddDays(-1);
        }

        /// <summary>
        /// 获取当天、本周、本月、本年、累计时间
        /// </summary>
        /// <param name="datetype"></param>
        /// <param name="date">指定日期</param>
        /// <param name="outtype">输出格式，1带时间，0不带时间</param>
        /// <param name="start"></param>
        /// <param name="end"></param>
        public static void GetStartEndTime(int datetype,string date,int outtype, out string start, out string end)
        {
            start = string.Empty;
            end = string.Empty;

            var datenow = DateTime.Parse(date);
            var datestart = datenow;
            var dateend = datenow;
            switch (datetype)
            {
                case 0://当天
                    break;
                case 1://本周
                    int n = (int)datenow.DayOfWeek == 0 ? 7 : (int)datenow.DayOfWeek;
                    datestart = datenow.AddDays(1 - n);//本周周一
                    dateend = datestart.AddDays(6);//本周周日
                    break;
                case 2://本月

                    datestart = datenow.AddDays(1 - datenow.Day);  //本月月初  
                    dateend = datestart.AddMonths(1).AddDays(-1);  //本月月末  
                    break;
                case 3://本年
                    datestart = new DateTime(datenow.Year, 1, 1);  //本年年初  
                    dateend = new DateTime(datenow.Year, 12, 31);  //本年年末  
                    break;
                case 4://全部
                    break;
                default:
                    break;
            }
            if (datetype != 4)
            {
                if (outtype == 1)
                {
                    start = datestart.ToString("yyyy-MM-dd") + " 00:00:00";
                    end = dateend.ToString("yyyy-MM-dd") + " 23:59:59";
                }
                else
                {
                    start = datestart.ToString("yyyy-MM-dd");
                    end = dateend.ToString("yyyy-MM-dd");
                }
            }
        }

    }
}