#include <stdio.h>
#include <stdlib.h>
#include <complex.h>
#include <pthread.h>
#include <math.h>

int P;
int numbers;
double *inputNumbers;
double complex *outputNumbers;

void* threadFunction(void* arg){
	int thread_id = *(int*)arg;
	int start = thread_id * (numbers / P);
	int end = (thread_id + 1) * (numbers /P);
	if(end > numbers){
		end = numbers;
	}

	double complex sum;
	double complex power;

	for(int k = start; k < end; k++){
		sum = 0;
		for(int i = 0; i < numbers; i++){
			power = 0;
			power = (((- 2) * M_PI * I) / numbers) * k * i;
			sum = sum + inputNumbers[i] * cexp(power);
		}
		outputNumbers[k] = sum;
	}
}

int main(int argc, char * argv[]) {

	//citire din fisier
	FILE *fp, *op;
	fp = fopen(argv[1], "r");
	op = fopen(argv[2], "w");
	P = atoi(argv[3]);

	fscanf(fp, "%d", &numbers);

	inputNumbers = calloc(numbers, sizeof(double));
	outputNumbers = calloc(numbers, sizeof(double complex));

	int i = 0;
	while(!feof(fp)){
		fscanf(fp, "%lf", &(inputNumbers[i]));
		i++;
	}

	fprintf(op, "%d\n", numbers);

	//inceput paralelizare
	pthread_t tid[P];
	int thread_id[P];
	for(i = 0; i < P; i++){
		thread_id[i] = i;
	}
	for(i = 0; i < P; i++){
		pthread_create(&(tid[i]), NULL, threadFunction, &(thread_id[i]));
	}
	for(i = 0; i < P; i++){
		pthread_join(tid[i], NULL);
	}

	//scriere in fisier
	for(int k = 0; k < numbers; k ++){
		fprintf(op, "%f ", creal(outputNumbers[k]));
		fprintf(op, "%f\n", cimag(outputNumbers[k]));
	}

	free(inputNumbers);
	free(outputNumbers);

	fclose(fp);

	return 0;

}