#include <gtest/gtest.h>
#include <cmath>
#include "../../../src/utils/RandomGenerator.h"

class RandomGeneratorTest: public testing::Test
{
protected:
	void generateRandoms();
	void checkStats();

private:
	void checkMinMeanMax(double min, double mean, double max);
	void minMeanMax(double& min, double& mean, double& max);
	double stddev(double mean);

protected:
	static const int Num = 10000;

protected:
	RandomGenerator random;
	double x[Num];
};

TEST_F(RandomGeneratorTest, Stats)
{
	generateRandoms();
	checkStats();
}

TEST_F(RandomGeneratorTest, getArray)
{
    QByteArray ba = random.getArray();
}

void RandomGeneratorTest::generateRandoms()
{
	for(int i = 0; i < Num; i++)
		x[i] = random.getInRange_11();
}

void RandomGeneratorTest::checkStats()
{
	double min;
	double mean;
	double max;
	minMeanMax(min, mean, max);

	checkMinMeanMax(min, mean, max);
	ASSERT_GT(stddev(mean), 0.55);
}

void RandomGeneratorTest::checkMinMeanMax(double min, double mean, double max)
{
	ASSERT_NEAR(-1, min, 0.01);
	ASSERT_NEAR(0, mean, 0.2);
	ASSERT_NEAR(1, max, 0.01);
}

void RandomGeneratorTest::minMeanMax(double& min, double& mean, double& max)
{
	double sum = 0;
	min = 1000;
	max = -1000;
	for(int i = 0; i < Num; i++)
	{
		min = fmin(x[i], min);
		max = fmax(x[i], max);
		sum += x[i];
	}
	mean = sum / Num;
}

double RandomGeneratorTest::stddev(double mean)
{
	double varSum = 0;
	for(int i = 0; i < Num; i++)
		varSum += pow((mean - x[i]), 2);
	return sqrt(varSum / Num);
}