using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Runtime.CompilerServices;
using YLErp.BLL;

namespace YLErp.Modules.RiskEngine
{
    /// <summary>
    /// 风控规则专用日历辅助类。
    /// 用于按规则对应的市场日历确认“上一收盘日”，避免简单按行情表倒序取最近日期导致口径偏差。
    /// </summary>
    public static class RiskCalendarHelper
    {
        private const string CalendarDateFormat = "yyyy,MM,dd";

        /// <summary>
        /// 日历数据异常直接影响平仓日期校验和上一交易日取数，单独使用固定 logger 名称便于线上按模块检索。
        /// </summary>
        private static readonly IYcLogger Logger = LogFactory.GetLogger("RiskCalendarHelper");

        /// <summary>
        /// calendar.HolidayJson 历史主格式是 yyyy,MM,dd；这里额外兼容常见日期格式，避免历史数据被静默当作交易日。
        /// 解析后统一转成 DateTime.Date，后续交易日判断不再依赖原始字符串格式。
        /// </summary>
        private static readonly string[] SupportedCalendarDateFormats =
        {
            CalendarDateFormat,
            "yyyy/MM/dd",
            "yyyy-MM-dd",
            "yyyyMMdd",
            "yyyy-MM-ddTHH:mm:ss",
            "yyyy-MM-ddTHH:mm:ssK",
            "yyyy-MM-ddTHH:mm:ss.fffK"
        };

        /// <summary>
        /// 按当前风控执行使用的数据库上下文保存日历缓存，同一次风控检查内复用，数据库上下文释放后不阻止缓存被回收。
        /// </summary>
        private static readonly ConditionalWeakTable<YLContext, Dictionary<string, HashSet<DateTime>>> HolidayCaches =
            new ConditionalWeakTable<YLContext, Dictionary<string, HashSet<DateTime>>>();

        /// <summary>
        /// 获取指定日期的上一银行间交易日。
        /// </summary>
        /// <param name="dbContext">当前风控执行使用的数据库上下文。</param>
        /// <param name="date">当前交易日或业务基准日。</param>
        /// <returns>严格早于入参日期的上一银行间交易日。</returns>
        /// <exception cref="ArgumentNullException">数据库上下文为空。</exception>
        /// <exception cref="Exception">缺少银行间日历、日历内容异常或在保护范围内找不到上一交易日。</exception>
        public static DateTime GetPreviousInterbankTradingDay(YLContext dbContext, DateTime date)
        {
            return GetPreviousTradingDay(dbContext, date, "IB", "银行间");
        }

        /// <summary>
        /// 判断指定日期是否为银行间交易日。
        /// </summary>
        /// <param name="dbContext">当前风控执行使用的数据库上下文。</param>
        /// <param name="date">待判断的平仓日期。</param>
        /// <returns>日期不在银行间非交易日集合中时返回 true。</returns>
        /// <exception cref="ArgumentNullException">数据库上下文为空。</exception>
        /// <exception cref="Exception">缺少银行间日历或日历内容异常。</exception>
        public static bool IsInterbankTradingDay(YLContext dbContext, DateTime date)
        {
            if (dbContext == null)
                throw new ArgumentNullException(nameof(dbContext));

            var holidayCache = HolidayCaches.GetOrCreateValue(dbContext);
            var holidays = GetHolidays(dbContext, date.Year, "IB", "银行间", holidayCache);
            return !holidays.Contains(date.Date);
        }

        public static DateTime GetPreviousExchangeTradingDay(YLContext dbContext, DateTime date)
        {
            return GetPreviousTradingDay(dbContext, date, "CHN", "交易所");
        }

        private static DateTime GetPreviousTradingDay(YLContext dbContext, DateTime date, string country, string calendarName)
        {
            if (dbContext == null)
                throw new ArgumentNullException(nameof(dbContext));

            // 以本次风控检查的数据库上下文为缓存边界，避免不同规则重复读取和解析相同市场日历。
            var holidayCache = HolidayCaches.GetOrCreateValue(dbContext);
            var currentDate = date.Date.AddDays(-1);

            // 最多向前查 370 天，既覆盖跨年和长假场景，也避免日历配置异常时出现无限循环。
            for (var i = 0; i < 370; i++)
            {
                var holidays = GetHolidays(dbContext, currentDate.Year, country, calendarName, holidayCache);

                // calendar.HolidayJson 存的是非交易日；不在非交易日集合内，即认为是对应市场的交易日。
                if (!holidays.Contains(currentDate))
                    return currentDate;

                currentDate = currentDate.AddDays(-1);
            }

            throw new Exception($"未找到{date:yyyy-MM-dd}的上一{calendarName}交易日");
        }

        /// <summary>
        /// 获取指定年份的非交易日集合。
        /// </summary>
        /// <param name="dbContext">当前风控执行使用的数据库上下文。</param>
        /// <param name="year">日历年份。</param>
        /// <param name="holidayCache">单次风控检查内按市场和年份共享的非交易日缓存。</param>
        /// <returns>按 Date 归一化后的非交易日集合。</returns>
        private static HashSet<DateTime> GetHolidays(YLContext dbContext, int year, string country, string calendarName, Dictionary<string, HashSet<DateTime>> holidayCache)
        {
            var normalizedCountry = NormalizeCountry(country);
            var cacheKey = $"{normalizedCountry}:{year}";
            if (holidayCache.TryGetValue(cacheKey, out var holidays))
                return holidays;

            // 先按年份和有效状态缩小范围，再在内存里做 Trim + ToUpperInvariant 匹配，兼容历史 Country 存在大小写或前后空格的情况。
            // 这里没有在数据库查询里直接 Trim，是为了避免不同 EF/数据库提供方对字符串函数翻译不一致。
            var validCalendars = dbContext.calendar
                .Where(c => c.Year == year
                    && (c.ValidState == null || c.ValidState != ConsGlobal.InValid)
                    && c.Country != null)
                .ToList();
            var matchedCalendars = validCalendars.Where(c => NormalizeCountry(c.Country) == normalizedCountry).ToList();
            var calendar = matchedCalendars.FirstOrDefault();

            if (calendar == null)
            {
                var availableCountries = string.Join(",", validCalendars.Select(c => c.Country?.Trim()).Where(c => !string.IsNullOrWhiteSpace(c)).Distinct());
                Logger.Error($"[风控日历] 未找到目标市场日历 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, AvailableCountries:{availableCountries}");
                throw new Exception($"未找到{year}年{calendarName}日历，Country={normalizedCountry}，当前可用日历：{availableCountries}");
            }
            if (matchedCalendars.Count > 1)
            {
                // 多条匹配不改变原有“取第一条”的行为，只记录数据质量问题，避免线上突然因历史重复配置中断风控。
                Logger.Info($"[风控日历] 同一年存在多个匹配市场日历，使用第一条 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, MatchedIds:{string.Join(",", matchedCalendars.Select(c => c.id))}");
            }
            if (!string.Equals(calendar.Country, normalizedCountry, StringComparison.Ordinal))
            {
                // Country 能通过归一化匹配说明历史数据存在大小写或空格差异，只在日历首次加载时记录一次，便于后续清洗数据。
                Logger.Info($"[风控日历] 日历Country已归一化匹配 - Year:{year}, CalendarName:{calendarName}, RawCountry:{calendar.Country}, NormalizedCountry:{normalizedCountry}, CalendarId:{calendar.id}");
            }

            if (string.IsNullOrWhiteSpace(calendar.HolidayJson))
            {
                Logger.Error($"[风控日历] HolidayJson为空 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, CalendarId:{calendar.id}");
                throw new Exception($"{year}年{calendarName}日历HolidayJson为空");
            }

            List<string> holidayList;
            try
            {
                holidayList = JsonConvert.DeserializeObject<List<string>>(calendar.HolidayJson);
            }
            catch (Exception ex)
            {
                Logger.Error($"[风控日历] HolidayJson解析失败 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, CalendarId:{calendar.id}, Error:{ex.Message}");
                throw new Exception($"{year}年{calendarName}日历HolidayJson解析失败", ex);
            }

            // 日历解析和日志统计只在缓存未命中时执行；同一次风控检查内重复判断交易日不会重复解析 HolidayJson。
            holidays = NormalizeHolidays(holidayList, year, calendarName, normalizedCountry, calendar.id);
            holidayCache[cacheKey] = holidays;
            return holidays;
        }

        private static string NormalizeCountry(string country)
        {
            return (country ?? string.Empty).Trim().ToUpperInvariant();
        }

        private static HashSet<DateTime> NormalizeHolidays(IEnumerable<string> holidayList, int year, string calendarName, string normalizedCountry, int calendarId)
        {
            var holidays = new HashSet<DateTime>();
            var formatCounts = new Dictionary<string, int>();
            var rawCount = 0;
            var blankCount = 0;
            var duplicateCount = 0;
            foreach (var holidayText in holidayList ?? Enumerable.Empty<string>())
            {
                rawCount++;
                if (string.IsNullOrWhiteSpace(holidayText))
                {
                    blankCount++;
                    continue;
                }

                // 每条原始日期只在缓存加载阶段解析一次；正常数据只累计格式分布，避免大量节假日逐条写日志。
                var holidayDate = ParseHolidayDate(holidayText, year, calendarName, normalizedCountry, calendarId, out var matchedFormat);
                if (!holidays.Add(holidayDate))
                {
                    duplicateCount++;
                }
                formatCounts[matchedFormat] = formatCounts.TryGetValue(matchedFormat, out var count) ? count + 1 : 1;
            }
            Logger.Info($"[风控日历] HolidayJson日期归一化完成 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, CalendarId:{calendarId}, RawCount:{rawCount}, HolidayCount:{holidays.Count}, BlankCount:{blankCount}, DuplicateCount:{duplicateCount}, Formats:{string.Join(",", formatCounts.Select(item => item.Key + ":" + item.Value))}");
            return holidays;
        }

        private static DateTime ParseHolidayDate(string holidayText, int year, string calendarName, string normalizedCountry, int calendarId, out string matchedFormat)
        {
            var normalizedHolidayText = holidayText.Trim();
            foreach (var format in SupportedCalendarDateFormats)
            {
                if (DateTime.TryParseExact(normalizedHolidayText, format, CultureInfo.InvariantCulture, DateTimeStyles.AllowWhiteSpaces, out var holidayDate))
                {
                    matchedFormat = format;
                    return holidayDate.Date;
                }
            }

            // 支持带时区的历史数据；最终取日期部分用于非交易日集合匹配，避免字符串格式差异导致静默漏判。
            if (DateTimeOffset.TryParse(normalizedHolidayText, CultureInfo.InvariantCulture, DateTimeStyles.AllowWhiteSpaces, out var holidayDateOffset))
            {
                matchedFormat = "DateTimeOffset.TryParse";
                return holidayDateOffset.Date;
            }

            Logger.Error($"[风控日历] HolidayJson日期格式无法识别 - Year:{year}, CalendarName:{calendarName}, Country:{normalizedCountry}, CalendarId:{calendarId}, RawValue:{holidayText}");
            throw new Exception($"{year}年{calendarName}日历HolidayJson存在无法识别的日期格式：{holidayText}");
        }
    }
}