using GB5Shared.DTO.Framework.Login;
using GoodBooks.PAY.PAYDAL.CustomCode.Loyalty;
using GoodBooks.PAY.PAYDAL.DTO.Loyalty;
using Microsoft.Extensions.Logging;

namespace GoodBooks.PAY.PAYBLL.Loyalty
{
    // ─────────────────────────────────────────────────────────────────────────
    //  LoyaltyEarnCfgBLL
    //
    //  Earn rule priority engine:
    //    RuleType 5 = ByProduct   — matches on ReferenceId = productId
    //    RuleType 4 = ByCategory  — matches on ReferenceId = categoryId
    //    RuleType 3 = ByGateway   — matches on ReferenceId = gatewayId
    //    RuleType 2 = ByTier      — matches on ReferenceId = tierId
    //    RuleType 1 = Global      — always matches (no ReferenceId check)
    //
    //  Earliest match after ordering by RuleType DESC wins.
    //  DAL returns rules ordered by RULETYPE DESC — first match is highest priority.
    // ─────────────────────────────────────────────────────────────────────────
    public class LoyaltyEarnCfgBLL : ILoyaltyEarnCfgBLL
    {
        private readonly ILoyaltyEarnCfgDAL          _earnCfgDal;
        private readonly ILogger<LoyaltyEarnCfgBLL>  _logger;

        public LoyaltyEarnCfgBLL(ILoyaltyEarnCfgDAL earnCfgDal, ILogger<LoyaltyEarnCfgBLL> logger)
        {
            _earnCfgDal = earnCfgDal;
            _logger     = logger;
        }

        public async Task<IEnumerable<LoyaltyEarnCfgDTO>> GetEarnCfgsByProgram(
            int programId, LoginDTO login, CancellationToken ct)
        {
            try
            {
                return await _earnCfgDal.GetEarnCfgsByProgram(programId, login).ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "GetEarnCfgsByProgram failed for ProgramId {ProgramId}", programId);
                throw;
            }
        }

        /// <summary>
        /// Pure in-memory priority resolution — no I/O.
        /// Caller must supply rules already filtered by date range (GetEarnCfgsByProgram handles this).
        /// Rules must be ordered by RuleType DESC (DAL guarantee).
        /// </summary>
        public LoyaltyEarnCfgDTO? ResolveEarnRule(
            IEnumerable<LoyaltyEarnCfgDTO> rules,
            int? productId,
            int? categoryId,
            int? gatewayId,
            int? tierId)
        {
            if (rules is null) return null;

            foreach (var rule in rules) // already ordered by RuleType DESC
            {
                bool match = rule.RuleType switch
                {
                    5 => productId.HasValue  && rule.ReferenceId == productId,  // ByProduct
                    4 => categoryId.HasValue && rule.ReferenceId == categoryId, // ByCategory
                    3 => gatewayId.HasValue  && rule.ReferenceId == gatewayId,  // ByGateway
                    2 => tierId.HasValue     && rule.ReferenceId == tierId,     // ByTier
                    1 => true,                                                  // Global
                    _ => false
                };

                if (match) return rule;
            }

            return null;
        }

        /// <summary>
        /// Points = Floor(netPayableAmt × rule.EarnPoints × tierMultiplier).
        /// tierMultiplier = tier.EarnMultiplier when tiering is active; 1.0 otherwise.
        /// </summary>
        public decimal CalculateEarnPoints(decimal netPayableAmt, LoyaltyEarnCfgDTO earnRule, LoyaltyTierDTO? tier)
        {
            decimal multiplier = tier?.EarnMultiplier > 0m ? tier.EarnMultiplier : 1.0m;
            return Math.Floor(netPayableAmt * earnRule.EarnPoints * multiplier);
        }
    }
}