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 MunicipalTaxValidationRule(IDistributorRepository distributorRepository) : IValidationRule
    {
        private readonly IDistributorRepository _distributorRepository = distributorRepository;
        private const string RULE_NAME = "Municipal Tax Validation";
        private const string AMOUNT_ERROR = "Municipal tax amount doesn't match the expected value";
        private const string BASE_ERROR = "Municipal tax base calculation is incorrect";
        private const string EXEMPT_ERROR = "Municipal tax charged to exempt consumer";
        private const decimal TOLERANCE = 0.01m;
        public int Priority => 7;  // Run after ICMS validation

        public async Task<ValidationResult> ValidateAsync(
            BillComplianceRequest request,
            DistributorInformation distributorInfo,
            Client clientInfo)
        {
            var taxInfo = await _distributorRepository.GetMunicipalTaxInformationAsync(
                request.DistributorName,
                request.Municipality,
                request.Month) ?? throw new InvalidOperationException("Municipal tax information not found");

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

            // Check if consumer is exempt
            if (taxInfo.ExemptGroups.Contains(request.ConsumerGroup.ToLower()))
            {
                if (request.MunicipalTaxAmount != 0)
                {
                    isValid = false;
                    message.AppendLine(EXEMPT_ERROR);
                }
                return new ValidationResult
                {
                    IsValid = isValid,
                    RuleName = RULE_NAME,
                    Message = message.ToString().TrimEnd()
                };
            }

            // Get applicable rate
            var rate = taxInfo.SpecialRates.TryGetValue(request.ConsumerGroup.ToLower(), out var specialRate)
                ? specialRate
                : taxInfo.BaseRate;

            // Calculate base and expected tax
            var baseAmount = CalculateTaxBase(request, taxInfo);
            var expectedTax = baseAmount * (rate / 100m);

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

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

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

        private static decimal CalculateTaxBase(BillComplianceRequest request, MunicipalTaxInformation taxInfo)
        {
            var baseAmount = request.TUSDAmount + 
                           request.TEAmount + 
                           request.PowerFactorAdjustment + 
                           request.FlagAmount;

            if (taxInfo.ApplyToICMS)
            {
                baseAmount += request.ICMSAmount;
            }

            if (taxInfo.ApplyToPublicLighting)
            {
                baseAmount += request.PublicLightingAmount;
            }

            return baseAmount;
        }
    }
}