package parallel;

import util.Prime;
import util.PrimeCounter;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;

public class ForkJoinPoolPrimeCounter implements PrimeCounter {

	private static final int SEQUENTIAL_THRESHOLD = 1000;
	private final int numThreads;

	public ForkJoinPoolPrimeCounter(int numThreads) {
		this.numThreads = numThreads;
	}

	public int countPrimes(int[] nums) {
		int count = 0;
		// TODO: Complete method countPrimes

		return count;
	}

	private static class CountPrimes extends RecursiveTask<Integer> {

		private final int low, high;
		private final int[] nums;

		public CountPrimes(int[] nums, int low, int high) {
			this.nums = nums;
			this.low = low;
			this.high = high;
		}

		@Override
		protected Integer compute() {
			if (low > high) {
				return 0;
			}
			if ((high - low) <= SEQUENTIAL_THRESHOLD) {
				int count = 0;
				for (int i = low; i <= high; i++) {
					if (Prime.isPrime(nums[i])) {
						count++;
					}
				}
				return count;
			} 
			else {
				int right, left, rightAns, leftAns;
				right = left = rightAns = leftAns = 0;
				right = low + ((int) Math.floor((high - low) / 2 ) - 1);
				left = low + ((int) Math.ceil((high - low) / 2 ));
				// TODO: Complete method compute


				
				return leftAns + rightAns;
			}
		}
	}
}