/******************************************************************************
 * This program implements the ACORN pseudo-random number generator.
 * 
 * Copyright © 2021 Richard Lesh.  All rights reserved.
 *****************************************************************************/

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.pureprogrammer.Utils;

public class ACORN_PRNG_Test {

    static class ACORN_PRNG {
        private long modulus;
        private int order;
        private List<Long> seeds = new ArrayList<>();

        public ACORN_PRNG(int order) {
            this.modulus = 4294967295L;
            this.order = order;
            for (int m = 0; m <= order; ++m) {
                long s = (long)(modulus * Math.random());
                if (s % 2 == 0) {
                    ++s;
                }
                seeds.add(s);
            }
        }

        public long nextInt() {
            for (int m = 1; m <= order; ++m) {
                seeds.set(m, (m == 1 ? seeds.get(0) : seeds.get(m - 1)) + seeds.get(m));
                seeds.set(m, seeds.get(m) & modulus);
            }
            return seeds.get(order);
        }

        public double nextFloat() {
            return nextInt() / (modulus + 1.0);
        }
    }

    public static void main(String[] args) {
        if (args.length == 1 && args[0].equals("-h") ) {
            System.out.println("Syntax: " + "ACORN_PRNG_Test" + " [num_random] [int|float]");
            System.out.println("If no arguments are provided a random stream of bytes");
            System.out.println("are output.");
            System.exit(1);
        }
        int num = args.length >= 1 ? Utils.stoiWithDefault(args[0], 10) : -1;
        String type = args.length == 2 ? args[1] : "int";

        System.out.println("type: " + (type.equals("int")  ? "d" : "f"));
        System.out.println("count: " + num);
        System.out.println("numbit: 32");
        ACORN_PRNG generator = new ACORN_PRNG(10);
        if (type.equals("int") ) {
            if (num < 1) {
                while (true) {
                    int randint = (int)(generator.nextInt());
                    byte b = (byte)(randint & 0xFF);
                    System.out.write(b);
                    randint >>= 8;
                    b = (byte)(randint & 0xFF);
                    System.out.write(b);
                    randint >>= 8;
                    b = (byte)(randint & 0xFF);
                    System.out.write(b);
                    randint >>= 8;
                    b = (byte)(randint & 0xFF);
                    System.out.write(b);
                }
            } else {
                for (int i = 0; i < num; ++i) {
                    System.out.println(generator.nextInt());
                }
            }
        } else {
            for (int i = 0; i < num; ++i) {
                System.out.println(Utils.format("{0:.10f}", generator.nextFloat()));
            }
        }
    }
}