package com.company;
import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        euler();
    }

    private static void euler() throws IOException {
        double coelhos;
        double raposas;
        double a11 = 5;
        double a12 = 0.05;
        double a21 = 0.0004;
        double a22 = 0.2;
        double[] steps = {1, 0.5, 0.25, 0.1};
        String[] filePaths = {"..\\eulerStep1.csv", "..\\eulerStep0.5.csv", "..\\eulerStep0.25.csv", "..\\eulerStep0.1.csv"};

        double step;
        String filePath;
        String valuesC;
        String valuesR;
        for (int s=0; s<4; s++){
            step = steps[s];
            filePath = filePaths[s];
            valuesC = "";
            valuesR = "";
            coelhos = 520;
            raposas = 85;

            System.out.println("------>STEP: " + step + "<------");
            for(int i=0; i<20/step; i++){ //qual destes primeiro? Coelhos ou raposas?
                coelhos = coelhos + step * (a11*coelhos - a12*coelhos*raposas);
                raposas = raposas + step * (a21*coelhos*raposas - a22*raposas);

                if (coelhos<=0){
                    coelhos = 0;
                    raposas = (raposas + step * a21*coelhos*raposas - a22*raposas);

                }
                if (raposas<=0){
                    raposas = 0;
                    coelhos = (coelhos + step * a11*coelhos - a12*coelhos*raposas);
                }
                //Serem os dois zero

                //Vai deixar "," no final
                valuesC += (int)coelhos + ",";
                valuesR += (int)raposas + ",";
                System.out.println("Coelhos: " + (int)coelhos + " Raposas: " + (int)raposas);
            }
            writeCSV(valuesC, valuesR, filePath);
        }
    }

    //values: String with "," -> CSV file
    public static void writeCSV(String valuesC, String valuesR, String filePath) throws IOException {
        FileWriter fileWriter = new FileWriter(filePath);
        PrintWriter printWriter = new PrintWriter(fileWriter);
        printWriter.println(valuesC);
        printWriter.println(valuesR);
        printWriter.close();
    }
}