/*
 * Experiment.cpp
 *
 *  Created on: 16 maj 2016
 *      Author: oramus
 */

#include <stdlib.h>
#include <iostream>
#include <omp.h>

#include "Experiment.h"
#include "Distribution.h"

#define DEBUG_ON_

using namespace std;

Experiment::Experiment(int balls, int drawsNumber) {
  this->balls = balls;
  this->drawsNumber = drawsNumber;

  hmax = 0;  // wyznaczamy maksymalna sume
  hmin = 0;  // i najmniejsza sume
  for (int i = 0; i < drawsNumber; i++) {
    hmax += balls - i;
    hmin += i + 1;  // 1 + 2 + 3 + ... liczba losowan
  }

  cout << "Histogram min: " << hmin << " max: " << hmax << endl;

  histogram = new long[hmax + 1];

  for (long i = 0; i < hmax + 1; i++) histogram[i] = 0;
}

void Experiment::clearUsed(bool* used) {
  for (int i = 0; i < balls; i++) {
    used[i] = false;
  }
}

long Experiment::singleExperimentResult(drand48_data* drandBuf, bool* used) {
  long sum = 0;
  int ball;
  double p, randomBall, randomProbability;

  clearUsed(used);
  for (int i = 0; i < drawsNumber;) {
    drand48_r(drandBuf, &randomBall);
    ball = 1 + (int)((double)balls * randomBall);

    if (used[ball - 1]) continue;

    p = Distribution::getProbability(
        i + 1, ball);  // pobieramy prawdopodobienstwo wylosowania tej kuli

    drand48_r(drandBuf, &randomProbability);
    if (randomProbability < p)  // akceptacja wyboru kuli z zadanym prawdopodobienstwem
    {
#ifdef DEBUG_ON
      cout << "Dodano kule o numerze " << ball << endl;
#endif
      used[ball - 1] = true;
      sum += ball;  // kule maja numery od 1 do balls wlacznie
      i++;
    }
  }

  ///   cout << "Suma = " << sum << endl;

  return sum;
}

Result* Experiment::calc(long experiments) {
#pragma omp parallel
  {
    long* privateHistogram = new long[hmax + 1];
    bool* used = new bool[balls];

    int threadId = omp_get_thread_num();
    int totalThreads = omp_get_num_threads();

    int chunkSize = (int)(experiments / totalThreads);
    int startIdx = threadId * chunkSize;
    int endIdx;
    if (threadId == totalThreads - 1) {
      endIdx = experiments;
    } else {
      endIdx = (threadId + 1) * chunkSize;
    }

    struct drand48_data drandBuf;
    int seed = 1202107158 + threadId * 1999;
    srand48_r(seed, &drandBuf);

#pragma omp for
    for (long l = startIdx; l < endIdx; l++) {
      privateHistogram[singleExperimentResult(&drandBuf, used)]++;
    }

#pragma omp critical
    {
      for (int i = 0; i < hmax + 1; i++) {
        histogram[i] += privateHistogram[i];
      }
    }
  }

  long maxID = 0;
  long minID = 0;
  long maxN = 0;
  long minN = experiments;
  double sum = 0.0;
  long values = 0;

  for (long idx = hmin; idx <= hmax; idx++) {
    if (maxN < histogram[idx]) {
      maxN = histogram[idx];
      maxID = idx;
    }
    sum += idx * histogram[idx];
    values += histogram[idx];
  }
  // indeks to wartosc, histogram -> liczba wystapien
  return new Result(maxID, maxN, sum / values, values);
}

Experiment::~Experiment() { delete[] histogram; }