package edu.rice.hj.example.primers;

import edu.rice.hj.api.HjDataDrivenFuture;

import static edu.rice.hj.Module1.*;

/**
 * <p>FibWithDdfs class.</p>
 *
 * @author <a href="http://shams.web.rice.edu/">Shams Imam</a> (shams@rice.edu)
 */
public class FibWithDdfs {

    /**
     * <p>fib.</p>
     *
     * @param n   a int.
     * @param res a {@link edu.rice.hj.api.HjDataDrivenFuture} object.
     */
    public static void fib(final int n, HjDataDrivenFuture<Integer> res) {

        if (n <= 0) {
            res.put(0);
            return;
        } else if (n == 1) {
            res.put(1);
            return;
        }

        // compute f1 asynchronously
        final HjDataDrivenFuture<Integer> f1 = newDDF();
        asyncNb(() -> fib(n - 1, f1));

        // compute f2 serially (f1 is done asynchronously).
        final HjDataDrivenFuture<Integer> f2 = newDDF();
        fib(n - 2, f2);

        // wait for dependences, before updating the result
        asyncNbAwait(f1, f2, () -> res.put(f1.safeGet() + f2.safeGet()));
    }

    /**
     * <p>main.</p>
     *
     * @param args an array of {@link String} objects.
     */
    public static void main(final String[] args) {

        final int N = 10;
        final int[] result = new int[N];

        launchHabaneroApp(() -> {
            for (int i = 0; i < N; i++) {
                final int index = i;

                final HjDataDrivenFuture<Integer> f1 = newDDF();
                fib(index, f1);
                asyncNbAwait(f1, () -> result[index] = f1.safeGet());
            }
        });

        for (int i = 0; i < N; i++) {
            System.out.printf("fib(%2d) = %2d \n", i, result[i]);
        }
    }
}