43 lines
1.3 KiB
C#
43 lines
1.3 KiB
C#
namespace TaxCalculator.Api.Services
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{
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using DAL;
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public class TaxCalculatorService : ITaxCalculatorService
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{
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private readonly ITaxBandRepository _taxBandRepository;
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public TaxCalculatorService(ITaxBandRepository taxBandRepository)
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{
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_taxBandRepository = taxBandRepository ?? throw new ArgumentNullException(nameof(taxBandRepository));
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}
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public async Task<decimal> CalculateTax(int annualSalary)
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{
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if (annualSalary < 0)
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{
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throw new ArgumentException("Gross annual salary must be non-negative.");
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}
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decimal taxPaid = 0;
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foreach (var band in await _taxBandRepository.GetTaxBands())
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{
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if (annualSalary <= band.LowerLimit)
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continue;
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decimal taxableAmountInBand = band.UpperLimit.HasValue
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? Math.Min(annualSalary, band.UpperLimit.Value) - band.LowerLimit
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: annualSalary - band.LowerLimit;
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decimal taxInBand = taxableAmountInBand * (band.TaxRate / 100m);
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taxPaid += taxInBand;
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if (!band.UpperLimit.HasValue || annualSalary <= band.UpperLimit.Value)
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break;
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}
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return taxPaid;
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}
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}
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}
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