import mpi.MPI;

import java.util.concurrent.ThreadLocalRandom;

public class HelloWorld {
    public static void main(String[] args) throws Exception{
        MPI.Init(args);
        double starttime, endtime;
        int rank = MPI.COMM_WORLD.Rank();
        int numranks = MPI.COMM_WORLD.Size();
        final int N = 10;
        int[] randomNumbers = new int[N];

        if(rank == 0){
            randomNumbers = generateRandomUnsortedIntArray(N, 9);
            System.out.println("unsorted array on rank 0 before bcast..");
            for (int i = 0; i <= N-1; i++) {
                System.out.print(randomNumbers[i] + " ");
            }
            System.out.println("");
            }

        MPI.COMM_WORLD.Bcast(randomNumbers, 0, N, MPI.INT, 0);

        //if (rank != 0) {
        //    System.out.println("Broadcast complete on rank " + rank);
        //}
        MPI.COMM_WORLD.Barrier();
        if (rank == 0) {
            System.out.println("Rank 0 Sorted array:");
            starttime = System.nanoTime();
            insertionSort(randomNumbers);
            for (int i = 0; i <= N-1; i++) {
                System.out.print(randomNumbers[i] + " ");
            }
            endtime = System.nanoTime();
            System.out.println("");
            System.out.println("Execution time (rank 0):" + (endtime - starttime));

        }
        MPI.COMM_WORLD.Barrier();

        if(rank != 0){
            starttime = System.nanoTime();
            insertionSort(randomNumbers);
            //for (int i = 0; i <= N-1; i++) {
            //    System.out.print(randomNumbers[i] + " ");
            //}
            endtime = System.nanoTime();
            System.out.println("");
            System.out.println("Execution time (rank "+ rank + "):" + (endtime - starttime));
        }

        if (rank == (numranks-1)) {
            for (int i = 0; i <= N-1; i++) {
                System.out.print(randomNumbers[i] + " ");
            }
        }


        MPI.Finalize();
    }

    private static int[] generateRandomUnsortedIntArray(int length, int maxInt){
        /*
        Generates an array of length length and fills it with random
        integers with a max value of maxInt then returns the array
         */

        // Create array variable
        int[] randArray = new int[length];

        // Iterate over 0..length
        for(int i = 0; i < length; i++){
            // Get next random number, then store it in array at current iteration point
            randArray[i] = ThreadLocalRandom.current().nextInt(maxInt);
        }

        // Return array
        return randArray;

    }

    public static void insertionSort(int[] array) {
        int N = array.length;
        for (int i = 1; i < N; i++) {
            int temp = array[i];
            int j = i-1;
            while (j >= 0 && array[j] > temp) {
                array[j+1] = array[j];
                j = j - 1;
            }
            array[j+1] = temp;
        }
    }
}