using YLErp.BLL;
using YLErp.Configuration;
using YLErp.DBModels;
using YLErp.DBModels.Consts;
using YLErp.DBModels.Enums;

namespace YLErp.Modules.TradeModule.DocGenerateModule
{
    /// <summary>
    /// 国联交易确认书编号生成器
    /// 规则：
    /// - 代客交易（簿记分类为"代客"）：GLMS-{对手方代码}-{成交日期(yyyyMMdd)}-FICC-{当日第N笔代客交易(数字递增)}-{标的代码}，从01开始
    ///   例：GLMS-IS-20260424-01-250210IB
    /// - 融券交易（簿记分类为"融券"）：GLMS-{对手方代码}-{成交日期(yyyyMMdd)}-FICC-{当日第N笔融券交易使用字母递增}-{标的代码}，从A开始
    ///   例：GLMS-IS-20260424-A-250210IB
    /// </summary>
    public class GuolianContractNoGenerator
    {
        private static readonly object _syncLock = new object();

        public static bool IsGuolianSwapTrade(trade trade)
        {
            return IsGuolianSwapTrade(trade, PS.Config.Company);
        }

        public static bool IsGuolianSwapTrade(trade trade, CompanyEnum company)
        {
            return company == CompanyEnum.国联
                && trade?.TradeType == "收益互换";
        }

        public static bool ShouldGenerateTradeNumberAfterSave(trade trade, CompanyEnum company)
        {
            return IsGuolianSwapTrade(trade, company)
                && string.IsNullOrWhiteSpace(trade.TradeNumber);
        }

        public static bool CanReuseRejectedTradeNumber(trade trade, CompanyEnum company)
        {
            return IsGuolianSwapTrade(trade, company);
        }

        /// <summary>
        /// 交易首次入库后按国联交易确认书编号规则回写交易编号。
        /// </summary>
        /// <returns>是否生成了交易编号</returns>
        public static bool TryGenerateTradeNumberAfterSave(YLContext dbContext, trade trade)
        {
            if (!IsGuolianSwapTrade(trade) || !string.IsNullOrWhiteSpace(trade.TradeNumber))
            {
                return false;
            }

            if (trade.id <= 0)
            {
                throw new InvalidOperationException("国联收益互换交易编号必须在交易入库后生成");
            }

            var clientCode = DataCacheProvider.GetClientDataSource().GetData(trade.ClientId)?.Code;
            if (string.IsNullOrWhiteSpace(clientCode))
            {
                throw new ServiceException("对手方代码缩写缺失，请联系运营组同事维护");
            }

            trade.TradeNumber = NormalizeTradeNumberCase(
                Generate(dbContext, trade, clientCode),
                PS.Config.ErpElement.UpperTradeNumber);
            return true;
        }

        public static string NormalizeTradeNumberCase(string tradeNumber, bool upperTradeNumber)
        {
            return upperTradeNumber && !string.IsNullOrEmpty(tradeNumber)
                ? tradeNumber.ToUpperInvariant()
                : tradeNumber;
        }

        /// <summary>
        /// 按国联确认书编号规则拼装编号（纯函数，不依赖数据库，便于单测）。
        /// 格式：GLMS-{clientCode}-{成交日期(yyyyMMdd)}-FICC-{序号}-{标的代码(去点)}
        /// - 代客交易：序号用两位数字，从 01 开始
        /// - 融券交易：序号用字母递增，从 A 开始
        /// </summary>
        public static string BuildTradeNumber(trade trade, string clientCode, string bookCategory, int sequenceNo)
        {
            var isAgencyTrade = bookCategory == AssetUnit.BookCategoryAgency;
            var underlyingCode = (trade.UnderlyingCode ?? "").Replace(".", ""); // 去掉标的代码中的点号
            var tradeDateStr = (trade.TradeDate ?? DateTime.MinValue).ToString("yyyyMMdd");
            var seq = isAgencyTrade ? sequenceNo.ToString("D2") : NumberToLetter(sequenceNo);
            return $"GLMS-{clientCode}-{tradeDateStr}-FICC-{seq}-{underlyingCode}";
        }

        public static int GetNextSequenceNo(
            IEnumerable<string> tradeNumbers,
            string clientCode,
            DateTime tradeDate,
            string bookCategory)
        {
            if (bookCategory != AssetUnit.BookCategoryAgency &&
                bookCategory != AssetUnit.BookCategorySecuritiesLending)
            {
                throw new ArgumentException("簿记分类无效", nameof(bookCategory));
            }

            var prefix = $"GLMS-{clientCode}-{tradeDate:yyyyMMdd}-FICC-";
            var isAgencyTrade = bookCategory == AssetUnit.BookCategoryAgency;
            var maxSequenceNo = 0;

            foreach (var tradeNumber in tradeNumbers ?? Enumerable.Empty<string>())
            {
                if (string.IsNullOrWhiteSpace(tradeNumber) ||
                    !tradeNumber.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                var sequenceEndIndex = tradeNumber.IndexOf('-', prefix.Length);
                if (sequenceEndIndex <= prefix.Length)
                {
                    continue;
                }

                var sequenceText = tradeNumber.Substring(
                    prefix.Length,
                    sequenceEndIndex - prefix.Length);
                var sequenceNo = isAgencyTrade
                    ? ParseNumericSequence(sequenceText)
                    : LetterToNumber(sequenceText);

                if (sequenceNo.HasValue && sequenceNo.Value > maxSequenceNo)
                {
                    maxSequenceNo = sequenceNo.Value;
                }
            }

            if (maxSequenceNo == int.MaxValue)
            {
                throw new InvalidOperationException("国联收益互换交易编号序号已超出支持范围");
            }

            return maxSequenceNo + 1;
        }

        /// <summary>
        /// 生成国贸交易确认书编号
        /// </summary>
        /// <param name="dbContext">数据库上下文</param>
        /// <param name="trade">交易记录</param>
        /// <param name="clientCode">客户代码</param>
        /// <returns>确认书编号</returns>
        public static string Generate(
            YLContext dbContext,
            trade trade,
            string clientCode)
        {
            var tradeDate = trade.TradeDate ?? DateTime.MinValue;
            var bookCategory = dbContext.assetunit
                .Where(a => a.id == trade.AssetId)
                .Select(a => a.BookCategory)
                .FirstOrDefault();

            if (bookCategory != AssetUnit.BookCategoryAgency &&
                bookCategory != AssetUnit.BookCategorySecuritiesLending)
            {
                throw new ServiceException("簿记账户未维护有效的簿记分类");
            }

            lock (_syncLock)
            {
                // 幂等：如果已生成过确认书编号，直接返回
                var existingForTrade = dbContext.trade_contract_r
                    .Where(r => r.TradeId == trade.id && r.Type == ContractTypeEnum.Trade && r.IsValid)
                    .Select(r => r.ContractCode)
                    .FirstOrDefault();

                if (!string.IsNullOrWhiteSpace(existingForTrade))
                {
                    return existingForTrade;
                }

                // 编号中的数字/字母序列记录生成时的分类，不受簿记账户后续分类调整影响。
                var tradeDateStart = tradeDate.Date;
                var sameDayTradeNumbers = dbContext.trade
                    .Where(t => t.TradeDate >= tradeDateStart
                        && t.TradeDate < tradeDateStart.AddDays(1)
                        && t.ClientId == trade.ClientId
                        && t.id != trade.id
                        && t.TradeNumber != null
                        && t.TradeNumber != "")
                    .Select(t => t.TradeNumber)
                    .ToArray();
                var sequenceNo = GetNextSequenceNo(
                    sameDayTradeNumbers,
                    clientCode,
                    tradeDate,
                    bookCategory);

                while (true)
                {
                    var candidate = BuildTradeNumber(trade, clientCode, bookCategory, sequenceNo);
                    var isExists = dbContext.trade.Any(t => t.id != trade.id && t.TradeNumber == candidate);
                    if (!isExists)
                    {
                        return candidate;
                    }

                    if (sequenceNo == int.MaxValue)
                    {
                        throw new InvalidOperationException("国联收益互换交易编号序号已超出支持范围");
                    }

                    sequenceNo++;
                }
            }
        }

        private static int? ParseNumericSequence(string sequence)
        {
            return sequence.All(char.IsDigit) && int.TryParse(sequence, out var number) && number > 0
                ? number
                : null;
        }

        private static int? LetterToNumber(string sequence)
        {
            if (string.IsNullOrWhiteSpace(sequence))
            {
                return null;
            }

            var number = 0;
            foreach (var value in sequence)
            {
                var letter = char.ToUpperInvariant(value);
                if (letter < 'A' || letter > 'Z')
                {
                    return null;
                }

                var letterValue = letter - 'A' + 1;
                if (number > (int.MaxValue - letterValue) / 26)
                {
                    return null;
                }

                number = number * 26 + letterValue;
            }

            return number;
        }

        /// <summary>
        /// 将数字转换为字母序列（1=A, 2=B, 26=Z, 27=AA, 28=AB...）
        /// </summary>
        private static string NumberToLetter(int number)
        {
            if (number <= 0)
            {
                return "A";
            }

            string result = "";
            while (number > 0)
            {
                number--; // 调整为从0开始
                result = (char)('A' + (number % 26)) + result;
                number /= 26;
            }
            return result;
        }
    }
}