package solarsim.common;

import java.io.BufferedReader;
import solarsim.io.MyInputStreamReader;
import solarsim.*;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.*;

/**
 * Clasa care descrie starea sistemului la un moment dat. Contine o lista de obiecte {@link Particle}
 * care specifica masele, pozitiile si vitezele elementelor sistemului.
 * @author Marius Ion
 */
public class State {

    private enum FP_Precision {
        FLOAT, DOUBLE;
    };

    private List<Particle> particles;
    private static final FP_Precision precision = FP_Precision.FLOAT;

    private State(){}

    public State(List<Particle> particles) {
        this.particles = particles;
    }

    /**
     * Metoda statica ce permite citirea starii dintr-un buffer. Starea a fost
     * scrisa in buffer de catre programul C.
     * @param inputStream   streamul din care se citeste
     * @return  starea sistemului
     * @throws IOException cand s-a produs o eroare la citirea din InputStream
     */
    public static State readStateFromBuffer(byte[] data, int offset, int length)
    throws IOException {
        ByteArrayInputStream ins = new ByteArrayInputStream(data, offset, length);
        return readStateFromInputStream(ins);
    }

    /**
     * Metoda statica ce permite citirea starii dintr-un InputStream. Starea a fost
     * scrisa in stream de catre programul C.
     * @param inputStream   streamul din care se citeste
     * @return  starea sistemului
     * @throws IOException cand s-a produs o eroare la citirea din InputStream
     */
    public static State readStateFromInputStream(InputStream inputStream)
    throws IOException {
        State state = new State();
        MyInputStreamReader in = new MyInputStreamReader(inputStream);

        int n = in.readInt();
        if( n == 0 )
            return null;
        state.particles = new ArrayList<Particle>(n);
        for( int i = 0; i < n; i++ ) {
            state.particles.add(new Particle());
        }

        for( int i = 0; i < n; i++ ) {
            double mass;
            if( precision == FP_Precision.DOUBLE )
                mass = in.readDouble();
            else
                mass = (double)in.readFloat();
            state.particles.get(i).mass = mass;
        }
        
        for( int i = 0; i < n; i++ ) {
            Vector position;
            if( precision == FP_Precision.DOUBLE )
                position = in.readVector();
            else
                position = in.readFloatVector();
            state.particles.get(i).position = position;
        }

        for( int i = 0; i < n; i++ ) {
            Vector velocity;
            if( precision == FP_Precision.DOUBLE )
                velocity = in.readVector();
            else
                velocity = in.readFloatVector();
            state.particles.get(i).velocity = velocity;
        }

        return state;
    }

    /**
     * Getter pentru particule.
     * @return lista particulelor din sistem.
     */
    public List<Particle> getParticles() {
        return particles;
    }

    @Override
    public String toString() {
        StringBuffer buf = new StringBuffer();

        for( int i = 0; i < particles.size(); i++ ) {
            buf.append("Particle " + i + ":\n");
            buf.append("\tmass:" + particles.get(i).mass + "\n");
            buf.append("\tposition:" + particles.get(i).position + "\n");
            buf.append("\tvelocity:" + particles.get(i).velocity + "\n");
            buf.append("\n");
        }

        return buf.toString();
    }

}