using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SellmeierEquation
{
    public class Coefficients {
        public float[] B { get; private set; }
        public float[] C { get; private set; }

        public Coefficients(float[] b, float[] c) {
            B = b; 
            C = c;

            if (b == null || c == null) {
                throw new System.Exception("Invalid args");
            }

            if (b.Length == 0 || c.Length == 0) {
                throw new System.Exception("Invalid args");
            }

            if (b.Length != c.Length) {
                throw new System.Exception("Invalid args");
            }
        }
    }


    private Coefficients _coeffs;

    public SellmeierEquation(Coefficients coeffs) {
        _coeffs = coeffs;
    }

    public float Calc(float wavelength) {
        return Calc(_coeffs, wavelength);
    }

    public static float Calc(Coefficients coeffs, float wavelength) {
        float lSquare = wavelength * wavelength;
        float resultSquared = 1.0f;

        for (int i = 0; i < coeffs.B.Length; i++) {
            float bi = coeffs.B[i];
            float ci = coeffs.C[i];
            resultSquared += (bi * lSquare) / (lSquare - ci);
        }

        return Mathf.Sqrt(resultSquared);
    }
}