using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using Xceed.Wpf.Toolkit;

namespace Muchinfo.MTPClient.Infrastructure.Helpers
{
    public static class DateTimeHelper
    {
        /// <summary>
        /// Builds the quarter.
        /// </summary>
        /// <param name="yearList">The year list.</param>
        /// <returns>System.Collections.Generic.List{System.String}.</returns>
        public static Dictionary<string, string> BuildQuarter(List<string> yearList)
        {
            if (yearList == null) return null;
            var list = new Dictionary<string, string>();

            var curYear = DateTime.Now.Year.ToString();
            var curMonth = DateTime.Now.Month;
            var curQuarter = 4;
            if (curMonth < 4)
            {
                curQuarter = 1;
            }
            else if (curQuarter < 7)
            {
                curQuarter = 2;
            }
            else if (curQuarter < 10)
            {
                curQuarter = 3;
            }
            else if (curQuarter < 13)
            {
                curQuarter = 4;
            }

            foreach (var year in yearList)
            {
                for (int i = 1; i < 5; i++)
                {
                    if (curYear == year && i > curQuarter) break;
                    list.Add(year + i.ToString().PadLeft(2, '0'), year + i.ToString().PadLeft(2, '0'));
                }
            }
            return list;
        }

        /// <summary>
        /// Builds the month.
        /// </summary>
        /// <param name="yearList">The year list.</param>
        /// <returns>List{System.String}.</returns>
        public static Dictionary<string, string> BuildMonth(List<string> yearList)
        {
            if (yearList == null) return null;
            var list = new Dictionary<string, string>();

            var curYear = DateTime.Now.Year.ToString();
            var curMonth = DateTime.Now.Month;
            foreach (var year in yearList)
            {
                for (int i = 1; i <= 12; i++)
                {
                    if (curYear == year && i > curMonth) break;
                    list.Add(year + i.ToString().PadLeft(2, '0'), year + i.ToString().PadLeft(2, '0'));
                }
            }
            return list;
        }

        /// <summary>
        /// Builds the week.
        /// </summary>
        /// <param name="yearList">The year list.</param>
        /// <returns>List{System.String}.</returns>
        public static Dictionary<string, string> BuildWeek(List<string> yearList)
        {
            if (yearList == null) return null;
            var list = new Dictionary<string, string>();

            var curYear = DateTime.Now.Year.ToString();
            var gc = new GregorianCalendar();
            var curWeek = gc.GetWeekOfYear(DateTime.Now, CalendarWeekRule.FirstDay, DayOfWeek.Sunday);
            foreach (var year in yearList)
            {
                for (int i = 1; i < 53; i++)
                {
                    if (curYear == year && i > curWeek) break;
                    list.Add(year + i.ToString().PadLeft(2, '0'), year + i.ToString().PadLeft(2, '0'));
                }
            }
            return list;
        }

        /// <summary>
        /// 获取某一季的开始\结束日期
        /// </summary>
        /// <param name="year">The year.</param>
        /// <param name="quarter">The quarter.</param>
        /// <returns>KeyValuePair{System.StringSystem.String}.</returns>
        public static KeyValuePair<string, string> GetQuarterStartEnd(int year, int quarter)
        {
            switch (quarter)
            {
                case 1:
                    return new KeyValuePair<string, string>(year + "-01-31", year + "-03-31");
                case 2:
                    return new KeyValuePair<string, string>(year + "-04-30", year + "-06-30");
                case 3:
                    return new KeyValuePair<string, string>(year + "-07-31", year + "-09-30");
                case 4:
                    return new KeyValuePair<string, string>(year + "-10-31", year + "-12-31");
                default:
                    return new KeyValuePair<string, string>(year + "-01-31", year + "-03-31");
            }
        }

        /// <summary>
        /// 获取某一周的开始\结束日期--网上抄的
        /// </summary>
        /// <param name="year">The year.</param>
        /// <param name="weeks">The weeks.</param>
        /// <param name="weekrule">The weekrule.</param>
        /// <param name="firstDayIsSunday">if set to <c>true</c> [first day is sunday].</param>
        /// <param name="first">The first.</param>
        /// <param name="last">The last.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
        public static bool GetDaysOfWeeks(int year, int weeks, CalendarWeekRule weekrule, bool firstDayIsSunday, out DateTime first, out DateTime last)
        {
            //初始化 out 参数
            first = DateTime.MinValue;
            last = DateTime.MinValue;

            //不用解释了吧...
            if (year < 1 | year > 9999)
                return false;

            //一年最多53周地球人都知道...
            if (weeks < 1 | weeks > 53)
                return false;

            //取当年首日为基准...为什么？容易得呗...
            DateTime firstCurr = new DateTime(year, 1, 1);
            //取下一年首日用于计算...
            DateTime firstNext = new DateTime(year + 1, 1, 1);

            //将当年首日星期几转换为数字...星期日特别处理...ISO 8601 标准...
            int dayOfWeekFirst = (int)firstCurr.DayOfWeek;
            if (dayOfWeekFirst == 0) dayOfWeekFirst = 7;

            //得到未经验证的周首日...
            first = firstCurr.AddDays((weeks - 1) * 7 - dayOfWeekFirst + (firstDayIsSunday ? 0 : 1));

            //周首日是上一年日期的情况...
            if (first.Year < year)
            {
                switch (weekrule)
                {
                    case CalendarWeekRule.FirstDay:
                        //不用解释了吧...
                        first = firstCurr;
                        break;
                    case CalendarWeekRule.FirstFullWeek:
                        //顺延一周...
                        first = first.AddDays(7);
                        break;
                    case CalendarWeekRule.FirstFourDayWeek:
                        //周首日距年首日不足4天则顺延一周...
                        if (firstCurr.Subtract(first).Days > 3)
                        {
                            first = first.AddDays(7);
                        }
                        break;
                    default:
                        break;
                }
            }

            //得到未经验证的周末日...
            last = first.AddDays(7).AddSeconds(-1);

            //周末日是下一年日期的情况...
            if (last.Year > year)
            {
                switch (weekrule)
                {
                    case CalendarWeekRule.FirstDay:
                        last = firstNext.AddSeconds(-1);
                        break;
                    case CalendarWeekRule.FirstFullWeek:
                        //不用处理
                        break;
                    case CalendarWeekRule.FirstFourDayWeek:
                        //周末日距下一年首日不足4天则提前一周...
                        if (firstNext.Subtract(first).Days < 4)
                        {
                            first = first.AddDays(-7);
                            last = last.AddDays(-7);
                        }
                        break;
                    default:
                        break;
                }
            }
            return true;
        }
    }
}