using System.Collections.Generic;
using FluidSim.Components;
using FluidSim.Interfaces;

namespace FluidSim.Core
{
    public class Solver
    {
        private readonly List<Volume0D> _volumes = new();
        private readonly List<Pipe1D> _pipes = new();
        private readonly List<Connection> _connections = new();

        public void AddVolume(Volume0D v) => _volumes.Add(v);
        public void AddPipe(Pipe1D p) => _pipes.Add(p);
        public void AddConnection(Connection c) => _connections.Add(c);

        public void Step()
        {
            // 1. Volumes publish state to their ports
            foreach (var v in _volumes)
                v.PushStateToPort();

            // 2. Set volume states as boundary conditions on pipes
            foreach (var conn in _connections)
            {
                if (IsPipePort(conn.PortA) && IsVolumePort(conn.PortB))
                    SetVolumeBC(conn.PortA, conn.PortB);
                else if (IsVolumePort(conn.PortA) && IsPipePort(conn.PortB))
                    SetVolumeBC(conn.PortB, conn.PortA);
            }

            // 3. Run pipe simulations
            foreach (var p in _pipes)
                p.Simulate();

            // 4. Transfer pipe‑port flows to volume ports
            foreach (var conn in _connections)
            {
                if (IsPipePort(conn.PortA) && IsVolumePort(conn.PortB))
                    TransferPipeToVolume(conn.PortA, conn.PortB);
                else if (IsVolumePort(conn.PortA) && IsPipePort(conn.PortB))
                    TransferPipeToVolume(conn.PortB, conn.PortA);
            }

            // 5. Integrate volumes
            foreach (var v in _volumes)
                v.Integrate();
        }

        bool IsVolumePort(Port p) => _volumes.Exists(v => v.Port == p);
        bool IsPipePort(Port p) => _pipes.Exists(pp => pp.PortA == p || pp.PortB == p);
        Pipe1D GetPipe(Port p) => _pipes.Find(pp => pp.PortA == p || pp.PortB == p);

        void SetVolumeBC(Port pipePort, Port volPort)
        {
            Pipe1D pipe = GetPipe(pipePort);
            if (pipe == null) return;
            bool isLeft = pipe.PortA == pipePort;

            if (isLeft)
                pipe.SetLeftVolumeState(volPort.Density, volPort.Pressure);
            else
                pipe.SetRightVolumeState(volPort.Density, volPort.Pressure);
        }

        void TransferPipeToVolume(Port pipePort, Port volPort)
        {
            double mdot = pipePort.MassFlowRate;
            volPort.MassFlowRate = -mdot;

            if (mdot < 0)  // pipe → volume
            {
                // pipePort.SpecificEnthalpy is already total (h + ½u²)
                volPort.SpecificEnthalpy = pipePort.SpecificEnthalpy;
            }
            // else: volume → pipe, volume’s own static enthalpy is used (already set)
        }
    }
}