using System;
using FluidSim.Interfaces;
using FluidSim.Utils;

namespace FluidSim.Components
{
    public class Volume0D
    {
        public Port Port { get; private set; }

        public double Mass { get; private set; }
        public double InternalEnergy { get; private set; }

        public double Gamma { get; set; } = 1.4;
        public double GasConstant { get; set; } = 287.0;

        public double Volume { get; set; }
        public double dVdt { get; set; }

        private double _dt;

        public double Density => Mass / Volume;
        public double Pressure => (Gamma - 1.0) * InternalEnergy / Volume;
        public double Temperature => Pressure / (Density * GasConstant);
        public double SpecificEnthalpy => Gamma / (Gamma - 1.0) * Pressure / Density;

        public Volume0D(double initialVolume, double initialPressure,
                        double initialTemperature, int sampleRate,
                        double gasConstant = 287.0, double gamma = 1.4)
        {
            GasConstant = gasConstant;
            Gamma = gamma;
            Volume = initialVolume;
            dVdt = 0.0;
            _dt = 1.0 / sampleRate;

            double rho0 = initialPressure / (GasConstant * initialTemperature);
            Mass = rho0 * Volume;
            InternalEnergy = (initialPressure * Volume) / (Gamma - 1.0);

            Port = new Port();
            PushStateToPort();
        }

        public void PushStateToPort()
        {
            Port.Pressure = Pressure;
            Port.Density = Density;
            Port.Temperature = Temperature;
            Port.SpecificEnthalpy = SpecificEnthalpy;
        }

        public void Integrate()
        {
            double mdot = Port.MassFlowRate;
            double h_in = Port.SpecificEnthalpy;

            double dm = mdot * _dt;
            double dE = (mdot * h_in) * _dt - Pressure * dVdt * _dt;

            Mass += dm;
            InternalEnergy += dE;

            // Hard physical bounds – prevent NaN and unphysical states
            if (Mass < 1e-12) Mass = 1e-12;
            if (InternalEnergy < 1e-12) InternalEnergy = 1e-12;

            PushStateToPort();
        }
    }
}