#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <ctype.h>
#include <cilk/cilk.h>

int* filter(int* arr, int* size, int (*fcn)(int));
int isOdd(int a){
	return a%2;
}
void setValues(int* arr, int size, int max){
	time_t t;
	srand ((unsigned) time(&t));
	for(int i = 0; i < size; i++)
		arr[i] = rand()%max;
}
void print1DimArray(int* arr, int size){
	if(size == 0){
		printf("empty\n");
		return;
	}
	for (int i = 0; i < size-1; i++)
		printf("%d, ", arr[i]);
	printf("%d\n", arr[size-1]);
}

int main(){
	int size = 10;
	int* array = (int*) malloc(sizeof(int) * size);

	setValues(array,size,10); //sets values of array to random values with max of 10

	print1DimArray(array,size);
	int newSize = size;
	int* filteredArray = filter(array, &newSize, isOdd);
	print1DimArray(filteredArray,newSize);

	free(filteredArray);
	free(array);
	return 0;
}

void fill(int* dest, int* source, int offset, int size){
	cilk_for(int i = 0; i < size; i++){
		dest[offset+i] = source[i];
	}
}

void filterHelper(int* arr, int *size, int (*fcn)(int), int* returnArray){
	if(*size == 1){
		if((*fcn)(*arr) == 1)
			returnArray[0] = *arr;
		else
			*size = 0;
		return;
	}

	int sizeOne = *size/2;
	int sizeTwo = *size/2 + (*size)%2;

	int* a1 = malloc(sizeof(int*)*sizeOne);
	int* a2 = malloc(sizeof(int*)*sizeTwo);

	cilk_spawn 	filterHelper(arr, &sizeOne, fcn, a1);
				filterHelper(&arr[*size/2], &sizeTwo, fcn, a2);

	*size = sizeOne + sizeTwo;

	cilk_spawn 	fill(returnArray, a1, 0, sizeOne);
				fill(returnArray, a2, sizeOne, sizeTwo);

	free(a1); free(a2);
}


int* filter(int* arr, int *size, int (*fcn)(int)){
	int* newArr = (int*) malloc((*size)*sizeof(int));
	filterHelper(arr, size, fcn, newArr);
	newArr = (int*) realloc(newArr, sizeof(int)*(*size));
	return newArr;
}