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 VSOP87 {

    public static enum Planet {
        MERCURY("mercury"), VENUS("venus"), EARTH("earth"),
        JUPITER("jupiter"), SATURN("saturn"),
        URANUS("uranus"), NEPTUNE("neptune");
        final String name;
        Planet(String name) { this.name = name; }
    }

    public static enum Variable {
	LAT("lat"), LONG("long"), DIST("dist");
	final String name;
	Variable(String name) { this.name = name; }
    }

    // The argument is in Julian millennia (value is in radians).
    public static Comput.Polynomial[] lambdas = new Comput.Polynomial[] {
	new Comput.Polynomial(4.40260884240, 26087.9031415742),  // Mercury
	new Comput.Polynomial(3.17614669689, 10213.2855462110),  // Venus
	new Comput.Polynomial(1.75347045953,  6283.0758499914),  // Earth
	new Comput.Polynomial(6.20347611291,  3340.6124266998),  // Mars
	new Comput.Polynomial(0.59954649739,   529.6909650946),  // Jupiter
	new Comput.Polynomial(0.87401675650,   213.2990954380),  // Saturn
	new Comput.Polynomial(5.48129387159,    74.7815985673),  // Uranus
	new Comput.Polynomial(5.31188628676,    38.1330356378),  // Neptune
	new Comput.Polynomial(5.19846674103, 77713.7714681205),  // Moon D
	new Comput.Polynomial(1.62790523337, 84334.6615813083),  // Moon F
	new Comput.Polynomial(2.35555589827, 83286.9142695536),  // Moon l
	new Comput.Polynomial(3.81034454697, 83997.0911355954)   // Moon Lm
    };

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

    public static Comput.SumPoisson2Terms getFunc(Planet pl, Variable v) {
	if ( ! data.containsKey(pl) ) {
	    data.put(pl, new EnumMap<Variable, Comput.SumPoisson2Terms>(Variable.class));
	}
	if ( ! data.get(pl).containsKey(v) ) {
	    List<Comput.Poisson2Term> series = new ArrayList<Comput.Poisson2Term>();
	    try {
		InputStream str = VSOP87.class.getResourceAsStream("vsop87-simp.dat");
		BufferedReader in = new BufferedReader(new InputStreamReader(str, "utf-8"));
		String s;
		while ( ( s = in.readLine() ) != null ) {
		    String[] fields = s.split("\t");
		    if ( ! fields[0].equals(pl.name) || ! fields[1].equals(v.name) )
			continue;
		    int deg = Integer.parseInt(fields[2]);
		    String[] subfields = fields[3].split(",");
		    double[] om = new double[12];
		    for ( int j=0 ; j<12 ; 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.get(pl).put(v, new Comput.SumPoisson2Terms(series));
	}
	return data.get(pl).get(v);
    }

    public static double getVal(Planet pl, Variable v, double tdbJd) {
	return getFunc(pl, v).v(Ephem.fromJd(tdbJd)/10);
    }

}