package org.madore.ephem;

import java.util.List;
import java.util.ArrayList;
import java.util.EnumMap;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;

public final class ZonalTides {

    public static enum Variable {
	DUT1("dut1"), DLOD("dlod"), DOMEGA("domega");
	final String name;
	Variable(String name) { this.name = name; }
    }

    // The argument is in Julian centuries (value is in radians).
    public static Comput.Polynomial[] lambdas = new Comput.Polynomial[] {
	new Comput.Polynomial(134.96340251*Comput.degree, 1717915923.2178*Comput.arcsecond, 31.8792*Comput.arcsecond +0.051635*Comput.arcsecond, -0.00024470*Comput.arcsecond), // Delaunay l
	new Comput.Polynomial(357.52910918*Comput.degree, 129596581.0481*Comput.arcsecond, -0.5532*Comput.arcsecond +0.000136*Comput.arcsecond, -0.00001149*Comput.arcsecond), // Delaunay l′
	new Comput.Polynomial(93.27209062*Comput.degree, 1739527262.8478*Comput.arcsecond, -12.7512*Comput.arcsecond -0.001037*Comput.arcsecond, 0.00000417*Comput.arcsecond), // Delaunay F
	new Comput.Polynomial(297.85019547*Comput.degree, 1602961601.2090*Comput.arcsecond, -6.3706*Comput.arcsecond +0.006593*Comput.arcsecond, -0.00003169*Comput.arcsecond), // Delaunay D
	new Comput.Polynomial(125.04455501*Comput.degree, -6962890.5431*Comput.arcsecond, 7.4722*Comput.arcsecond +0.007702*Comput.arcsecond, -0.00005939*Comput.arcsecond) // Delaunay Ω
    };

    private static EnumMap<Variable, Comput.SumPoisson2Terms> data = new EnumMap<Variable, Comput.SumPoisson2Terms>(Variable.class);

    public static Comput.SumPoisson2Terms getFunc(Variable v) {
	if ( ! data.containsKey(v) ) {
	    List<Comput.Poisson2Term> series = new ArrayList<Comput.Poisson2Term>();
	    try {
		InputStream str = ZonalTides.class.getResourceAsStream("zonal-tides.dat");
		BufferedReader in = new BufferedReader(new InputStreamReader(str, "utf-8"));
		String s;
		while ( ( s = in.readLine() ) != null ) {
		    String[] fields = s.split("\t");
		    if ( ! fields[1].equals(v.name) )
			continue;
		    int deg = Integer.parseInt(fields[2]);
		    String[] subfields = fields[3].split(",");
		    double[] om = new double[5];
		    for ( int j=0 ; j<5 ; j++ )
			om[j] = Double.parseDouble(subfields[j]);
		    double b = Double.parseDouble(fields[4]);
		    double a = Double.parseDouble(fields[5]);
		    series.add(Comput.Poisson2Term.ab(deg, a, b, om, lambdas));
		}
	    } catch ( Exception e ) {
		throw new RuntimeException(e);
	    }
	    data.put(v, new Comput.SumPoisson2Terms(series));
	}
	return data.get(v);
    }

}