using System;
using System.Linq;
using EvoCalculator.Core.Models.Calculation.Interfaces;
using EvoCalculator.Core.Models.Calculation.Models;

namespace EvoCalculator.Core.FinanceFormulas
{
    public class XNPV : IFinanceFormula<double>
    {
        private readonly Flow[] _flows;
        private readonly double _rate;

        public XNPV(Flow[] flows, double rate)
        {
            _flows = flows;
            _rate = rate;
        }

        public double GetResult()
        {
            var firstDate = _flows[0].Date;
            return _flows.Sum(flow =>
                flow.Value / Math.Pow(1 + _rate, (flow.Date - firstDate).TotalDays / 365));
        }
    }
}