using static DecimalMath.DecimalEx;

namespace InnovEnergy.Lib.Units.Composite;


public record AcPhase : Phase
{
    public AcPhase(Voltage voltage, Current current, Angle phi) : base(voltage, current)
    {
        if (voltage < 0) throw new ArgumentException("RMS value cannot be negative", nameof(voltage));
        if (current < 0) throw new ArgumentException("RMS value cannot be negative", nameof(current));
        
        Phi = phi;
    }

    public Angle Phi { get; }
    
    public ApparentPower ApparentPower => Voltage.Value * Current.Value ;
    public Power         ActivePower   => ApparentPower.Value * PowerFactor;
    public ReactivePower ReactivePower => ApparentPower.Value * Sin(Phi);
    public Decimal       PowerFactor   => Cos(Phi);
    
    
    public static AcPhase operator +(AcPhase left, AcPhase right)
    {
        // the Voltages of two phases are expected to be in phase and equal

        var v = (left.Voltage + right.Voltage) / 2m;  // TODO: check that l & r approximately equal
        
        // currents (RMS) can be different and out of phase 
        // https://www.johndcook.com/blog/2020/08/17/adding-phase-shifted-sine-waves/
        
        // IF
        // left(t) = ILeft sin(ωt)
        // right(t) = IRight sin(ωt + φ).
        // sum(t) = left(t) + right(t) = ISum sin(ωt + ψ).
        // THEN
        
        // ψ = arctan( IRight * sin(φ) / (ILeft + IRight cos(φ)) ).
        // C = IRight * sin(φ) / sin(ψ).
                
        // in this calc left(t) has zero phase shift.
        // we can shift both waves by -left.Phi, so
        // φ := right.phi - left.phi


        var phi = right.Phi - left.Phi;

        var phiSum = ATan2(right.Current * Sin(phi), left.Current + right.Current * Cos(phi));
        var iSum   = right.Current * Sin(phi) / Sin(phiSum);

        return new AcPhase(v, iSum, phiSum);
    }
}