优惠券设计

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace CouponsMg.Coupons
{
    public enum Period
    {
        /// <summary>
        /// 1小时
        /// </summary>
        [Description("1小时")]
        OneHour = 1,

        /// <summary>
        /// 2小时
        /// </summary>
        [Description("2小时")]
        TwoHours = 2,

        /// <summary>
        /// 3小时
        /// </summary>
        [Description("3小时")]
        ThreeHours = 3,

        /// <summary>
        /// 4小时
        /// </summary>
        [Description("4小时")]
        FourHours = 4,

        /// <summary>
        ///5小时
        /// </summary>
        [Description("5小时")]
        FiveHours = 5,

        /// <summary>
        /// 6小时
        /// </summary>
        [Description("6小时")]
        SixHours = 6,

        /// <summary>
        /// 8小时
        /// </summary>
        [Description("8小时")]
        EightHours = 8,

        /// <summary>
        /// 9小时
        /// </summary>
        [Description("9小时")]
        TenHours = 9,

        /// <summary>
        /// 12小时
        /// </summary>
        [Description("12小时")]
        TwelveHours = 12,

        /// <summary>
        /// 1天
        /// </summary>
        [Description("1天")]
        OneDay = 24,

        /// <summary>
        /// 2天
        /// </summary>
        [Description("2天")]
        TwoDays = OneDay * 2,

        /// <summary>
        ///3天
        /// </summary>
        [Description("3天")]
        ThreeDays = OneDay * 3,

        /// <summary>
        /// 5天
        /// </summary>
        [Description("5天")]
        FiveDays = OneDay * 5,

        /// <summary>
        /// 7天
        /// </summary>
        [Description("7天")]
        SevenDays = OneDay * 7,

        /// <summary>
        /// 14天
        /// </summary>
        [Description("14天")]
        FourteenDays = OneDay * 14,

        /// <summary>
        /// 1个月
        /// </summary>
        [Description("1个月")]
        OneMonth = OneDay * 30,

        /// <summary>
        /// 3个月
        /// </summary>
        [Description("3个月")]
        ThreeMonths = OneMonth *3,

        /// <summary>
        /// 6个月
        /// </summary>
        [Description("6个月")]
        SixMounths = OneMonth *6,

        /// <summary>
        /// 1年
        /// </summary>
        [Description("1年")]
        OneYear = OneMonth *12,
    }

    public abstract class CouponsBaseModel : INotifyPropertyChanged
    {

        #region Property Changed

        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        #endregion

        #region 属性

        #region 领取时间段

        /// <summary>
        /// 可领取优惠券期限范围类型。默认为7天
        /// </summary>
        public Period CanPickupPeriodType { get; set; } = Period.SevenDays;

        private DateTime canPickUpStartTime = DateTime.Now;
        /// <summary>
        /// 优惠券可领取开始日期 默认为 当前日期
        /// </summary>
        public DateTime CanPickUpStartTime
        {
            get { return canPickUpStartTime; }
            set
            {
                if (value == null)
                {
                    return;
                }

                canPickUpStartTime = value;
                CanPickUpEndTime = canPickUpStartTime.AddHours((int)CanPickupPeriodType);

                OnPropertyChanged(nameof(CanPickUpStartTime));
            }
        }

        private DateTime canPickUpEndTime = DateTime.Now.AddDays(7);
        /// <summary>
        /// 优惠券可领取的截止日期 默认为当前日期后7天
        /// </summary>
        public DateTime CanPickUpEndTime
        {
            get { return canPickUpEndTime; }
            set
            {
                if (value == null)
                {
                    return;
                }

                if (CanPickUpStartTime > value)
                {
                    throw new ArgumentOutOfRangeException("优惠券可领取开始日期不能大于截止日期");
                }

                canPickUpEndTime = value;
                OnPropertyChanged(nameof(CanPickUpEndTime));
            }
        }

        #endregion

        #region 有效期时间段

        /// <summary>
        /// 优惠券有效期时间段类型，默认为7天
        /// </summary>
        public Period EffectivePeriodType { get; set; } = Period.SevenDays;

        private DateTime effectiveDate = DateTime.Now;
        /// <summary>
        /// 优惠券生效日期. 默认为当前日期
        /// </summary>
        public DateTime EffectiveDate
        {
            get { return effectiveDate; }
            set
            {
                if (value == null)
                {
                    return;
                }

                effectiveDate = value;
                ExpireDate = effectiveDate.AddHours((int)EffectivePeriodType);
                OnPropertyChanged(nameof(EffectiveDate));
            }
        }

        private DateTime expireDate = DateTime.Now.AddDays(7);
        /// <summary>
        /// 优惠券失效日期 默认为当前日期后7天
        /// </summary>
        public DateTime ExpireDate
        {
            get { return expireDate; }
            set
            {
                if (value == null)
                {
                    return;
                }

                if (effectiveDate > expireDate)
                {
                    throw new ArgumentOutOfRangeException("优惠券生效日期不能大于失效日期");
                }

                expireDate = value;
                OnPropertyChanged(nameof(ExpireDate));
            }
        }

        #endregion

        private double thresholdAmount = 0;
        /// <summary>
        /// 优惠券使用门槛。<=0 为无门槛. 默认为无门槛
        /// </summary>
        public double ThresholdAmount
        {
            get { return thresholdAmount; }
            set
            {
                if (value <= 0)
                {
                    thresholdAmount = 0;
                }
                else
                {
                    thresholdAmount = value;
                }

                OnPropertyChanged(nameof(ThresholdAmount));
            }
        }


        private bool isStackable = false;
        /// <summary>
        /// 优惠券是否可叠加使用. 默认为不可叠加使用
        /// </summary>
        public bool IsStackable
        {
            get { return isStackable; }
            set
            {
                isStackable = value;
                OnPropertyChanged(nameof(IsStackable));
            }
        }


        private bool isAutoPickUp = false;
        /// <summary>
        /// 是否可自动领取. 默认为不可自动领取
        /// </summary>
        public bool IsAutoPickUp
        {
            get { return isAutoPickUp; }
            set
            {
                isAutoPickUp = value;
                if (isAutoPickUp)
                {
                    IsPickedUp = true;
                }

                OnPropertyChanged(nameof(IsAutoPickUp));
            }
        }


        private bool isPickedUp = false;
        /// <summary>
        /// 是否已领取
        /// </summary>
        public bool IsPickedUp
        {
            get { return isPickedUp; }
            set
            {
                isAutoPickUp = value;
                OnPropertyChanged(nameof(IsPickedUp));
            }
        }

        //是否过期
        public bool IsExpired => IsPickedUp && ExpireDate < EffectiveDate;


        private bool isAvailable = true;
        /// <summary>
        /// 是否可用。 如为否，则不可领取，不可使用
        /// </summary>
        public bool IsAvailable
        {
            get { return isAvailable; }
            set
            {
                isAvailable = value;
                OnPropertyChanged(nameof(IsAvailable));
            }
        }

        /// <summary>
        /// 是否可领取
        /// </summary>
        public bool CanPickUp { get; set; }

        #endregion

        public void PickUp()
        {
            bool canPickup = CheckCouponsIsInAvailablePickupPeriod();
            if (canPickup)
            {
                IsPickedUp = true;
                EffectiveDate = DateTime.Now;

            }

        }

        /// <summary>
        /// 检查优惠券是否在可领取日期范围内
        /// </summary>
        /// <returns></returns>
        private bool CheckCouponsIsInAvailablePickupPeriod()
        {
            if (CanPickUpStartTime == null || CanPickUpEndTime == null)
            {
                return false;
            }

            DateTime now = DateTime.Now;

            //还未到可领取事件，不可领取
            if (now < CanPickUpStartTime)
            {
                return false;
            }

            //已过领取事件，不可领取
            if (now >= CanPickUpEndTime)
            {
                return false;
            }

            return true;
        }

        /// <summary>
        /// 检查优惠券可领取状态
        /// </summary>
        /// <returns></returns>
        private bool CheckCouponsCanPickableState()
        {
            if (IsPickedUp)
            {
                return false;
            }

            //是否在可领取日期范围内
            bool isInAvailablePickupPeriod = CheckCouponsIsInAvailablePickupPeriod();
            return isInAvailablePickupPeriod;
        }

        private bool CheckCouponsAvailableState()
        {
            //优惠券已领取
            if (IsPickedUp)
            {
                if (EffectiveDate == null || ExpireDate == null)
                {
                    return false;
                }

                DateTime now = DateTime.Now;

                //已过有效期
                if (now >= CanPickUpEndTime)
                {
                    return false;
                }

                return true;
            }
            else
            {
                //是否在可领取日期范围内
                bool isInAvailablePickupPeriod = CheckCouponsIsInAvailablePickupPeriod();
                //已过可领取日期
                if (!isInAvailablePickupPeriod)
                {
                    return false;
                }
            }

            return true;
        }
    }
}