package edu.rice.hj.example.comp322;

import edu.rice.hj.api.HjSuspendable;
import edu.rice.hj.api.HjSuspendingProcedure;
import edu.rice.hj.api.SuspendableException;

import java.util.Random;

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

/**
 * ParallelMap --- Cubes the elements of an array
 * <p>
 * The purpose of this example is to illustrate abstract metrics and Amdahl's Law
 * using a simple map function.
 *
 * @author Vivek Sarkar (vsarkar@rice.edu)
 */
public class ParallelMap {

    /**
     * Constant <code>DEFAULT_N=100</code>
     */
    public static final int DEFAULT_N = 100;

    // Store the cubes of corresponding elements from X into Y

    /**
     * <p>mapFuncForCubes.</p>
     *
     * @param X an array of double.
     * @param Y an array of double.
     */
    public static void mapFuncForCubes(final double[] X, final double[] Y) throws SuspendableException {
        forall(0, X.length - 1, new HjSuspendingProcedure<Integer>() {
            @Override
            public void apply(final Integer i) throws SuspendableException {
                doWork(1);
                Y[i] = Math.pow(X[i], 3);
            }
        });
    }

    /**
     * <p>main.</p>
     *
     * @param argv an array of {@link String} objects.
     */
    public static void main(final String[] argv) {
        // Initialization
        final int n;
        if (argv.length > 0) {
            n = Integer.parseInt(argv[0]);
        } else {
            n = DEFAULT_N;
        }

        final double[] X = new double[n];
        final double[] Y = new double[n];
        final Random myRand = new Random(n);
        for (int i = 0; i < n; i++) {
            X[i] = myRand.nextInt(n);
        }

        launchHabaneroApp(new HjSuspendable() {
            @Override
            public void run() throws SuspendableException {
                mapFuncForCubes(X, Y);
            }
        });
        System.out.println("Done cubing elements of X into Y");

        final int numElementsToPrint = Math.min(n - 1, 8);
        printSomeElements(X, numElementsToPrint, "Elements of X: ");
        printSomeElements(Y, numElementsToPrint, "Elements of Y: ");
    }

    private static void printSomeElements(final double[] anArray, final int numElems, final String prefixMsg) {

        System.out.print(prefixMsg);
        for (int i = 0; i < numElems; i++) {
            System.out.printf("%10.1f ", anArray[i]);
        }
        System.out.println("...");
    }
}