using System;
using System.Threading.Tasks;
using System.Text;
using Compliance.Domain.Models;
using Compliance.DTOs;
using Compliance.Infrastructure.Repositories;

namespace Compliance.Services.ValidationRules
{
    public class ReactiveEnergyValidationRule(IDistributorRepository distributorRepository) : IValidationRule
    {
        private readonly IDistributorRepository _distributorRepository = distributorRepository;
        private const string RULE_NAME = "Reactive Energy Validation";
        private const string PEAK_ERROR = "Peak reactive energy charge doesn't match the expected value";
        private const string OFF_PEAK_ERROR = "Off-peak reactive energy charge doesn't match the expected value";
        private const string POWER_FACTOR_ERROR = "Power factor is below minimum allowed";
        private const decimal TOLERANCE = 0.01m;
        public int Priority => 3;  // Run after demand validation

        public async Task<ValidationResult> ValidateAsync(
            BillComplianceRequest request,
            DistributorInformation distributorInfo,
            Client clientInfo)
        {
            if (!ShouldValidateReactiveEnergy(request.ConsumerGroup, request.Subgroup))
            {
                return new ValidationResult
                {
                    IsValid = true,
                    RuleName = RULE_NAME,
                    Message = string.Empty
                };
            }

            var reactiveInfo = await _distributorRepository.GetReactiveEnergyInformationAsync(
                request.DistributorName,
                request.ConsumerGroup,
                request.Month) ?? throw new InvalidOperationException("Reactive energy information not found");

            var isValid = true;
            var message = new StringBuilder();

            // Validate power factor
            if (request.PowerFactor < reactiveInfo.MinimumPowerFactor)
            {
                isValid = false;
                message.AppendLine($"{POWER_FACTOR_ERROR}. Minimum: {reactiveInfo.MinimumPowerFactor:F2}, Found: {request.PowerFactor:F2}");
            }

            // Calculate and validate peak period charges
            var expectedPeakCharge = CalculateReactiveCharge(
                request.PeakActiveEnergy,
                request.PeakReactiveEnergy,
                request.PeakDemandTariff,
                reactiveInfo.ReferenceRate,
                reactiveInfo.PeakAdjustmentFactor);

            if (Math.Abs(request.PeakReactiveCharge - expectedPeakCharge) > TOLERANCE)
            {
                isValid = false;
                message.AppendLine($"{PEAK_ERROR}. Expected: {expectedPeakCharge:F2}, Found: {request.PeakReactiveCharge:F2}");
            }

            // Calculate and validate off-peak period charges
            var expectedOffPeakCharge = CalculateReactiveCharge(
                request.OffPeakActiveEnergy,
                request.OffPeakReactiveEnergy,
                request.OffPeakDemandTariff,
                reactiveInfo.ReferenceRate,
                reactiveInfo.OffPeakAdjustmentFactor);

            if (Math.Abs(request.OffPeakReactiveCharge - expectedOffPeakCharge) > TOLERANCE)
            {
                isValid = false;
                message.AppendLine($"{OFF_PEAK_ERROR}. Expected: {expectedOffPeakCharge:F2}, Found: {request.OffPeakReactiveCharge:F2}");
            }

            return new ValidationResult
            {
                IsValid = isValid,
                RuleName = RULE_NAME,
                Message = message.ToString().TrimEnd()
            };
        }

        private static bool ShouldValidateReactiveEnergy(string consumerGroup, string subgroup)
        {
            // According to ANEEL, reactive energy charges apply to these groups
            return consumerGroup.ToUpper() switch
            {
                "A" => true,  // All A group consumers
                "B" when subgroup == "B3" => true,  // Commercial/industrial B3 consumers
                _ => false
            };
        }

        private static decimal CalculateReactiveCharge(
            decimal activeEnergy,
            decimal reactiveEnergy,
            decimal tariff,
            decimal referenceRate,
            decimal adjustmentFactor)
        {
            if (activeEnergy == 0) return 0;

            var powerFactor = activeEnergy / (decimal)Math.Sqrt((double)(activeEnergy * activeEnergy + reactiveEnergy * reactiveEnergy));
            if (powerFactor >= 0.92m) return 0;

            var excessReactive = reactiveEnergy - (activeEnergy * 0.426m); // tan(arcos(0.92))
            return excessReactive * tariff * referenceRate * adjustmentFactor;
        }
    }
}