namespace YLErp.Modules.VolatilityModule
{
    /// <summary>
    /// 曲面波动率提供(适用于渤海因为没有考虑UserGroup)
    /// </summary>
    public class UnderlyingVolitalityProvider
    {
        protected readonly DateTime _valueDate;
        protected readonly string[] _volTypes;

        Dictionary<string, volatility> _dicData;

        public UnderlyingVolitalityProvider(DateTime valueDate, IEnumerable<string> volTypes)
        {
            if (volTypes == null || !volTypes.Any(n => !string.IsNullOrEmpty(n)))
            {
                _volTypes = new[] { "交易" };
            }
            else
            {
                _volTypes = volTypes.Where(n => !string.IsNullOrEmpty(n)).ToArray();
            }
            _valueDate = valueDate.Date;
        }

        private void Initialize()
        {
            if (_dicData != null)
            {
                return;
            }

            lock (this)
            {
                if (_dicData != null)
                {
                    return;
                }

                //只取1个月以内的
                var startDate = _valueDate.AddMonths(-3);

                var predicate = PredicateBuilder.Create<volatility>(
                    v => v.QuotationDate >= startDate && v.QuotationDate <= _valueDate && _volTypes.Contains(v.VolType));

                using (var db = DbContextFactory.GetYLDbContext())
                {
                    //数据量小的表尽量靠前
                    var groupQuery = from v in db.volatility.Where(predicate)
                                     group v by new { v.UserGroup, v.ContractCode, v.VolType } into vg
                                     select new
                                     {
                                         vg.Key.UserGroup,
                                         vg.Key.ContractCode,
                                         vg.Key.VolType,
                                         QuotationDate = vg.Max(n => n.QuotationDate)
                                     };

                    var volQuery = from vg in groupQuery
                                   join v in db.volatility.AsNoTracking()
                                   on vg equals new { v.UserGroup, v.ContractCode, v.VolType, v.QuotationDate }
                                   select v;

                    _dicData = volQuery.ToDictionary(n =>
                    {
                        var index = Array.IndexOf(_volTypes, n.VolType);
                        return $"{index}^{n.UserGroup}^{n.ContractCode}";
                    });
                }
            }
        }

        public volatility GetVol(string volType, string userGroup, string underlyingCode)
        {
            if (string.IsNullOrWhiteSpace(volType) || string.IsNullOrWhiteSpace(underlyingCode))
            {
                return null;
            }

            if (userGroup is null)
            {
                userGroup = string.Empty;
            }

            var index = Array.IndexOf(_volTypes, volType);

            if (index < 0)
            {
                return null;
            }

            Initialize();

            var key = $"{index}^{userGroup}^{underlyingCode}";

            if (!_dicData.TryGetValue(key, out var unVol))
            {
                using (var db = DbContextFactory.GetYLDbContext())
                {
                    var volQuery = from v in db.volatility.AsNoTracking()
                                   where v.ContractCode == underlyingCode && v.UserGroup == userGroup
                                   && v.QuotationDate <= _valueDate && _volTypes.Contains(v.VolType)
                                   orderby v.QuotationDate descending
                                   select v;

                    _dicData[key] = unVol = volQuery.FirstOrDefault();
                }
            }

            return unVol;
        }
    }
}