#include <iostream>
#include <cmath>
#include <ctime>
#include <fstream>
#include "mersenne.h"

using namespace std;

#define ARRAYELEMCOUNT(x) sizeof(x) / sizeof(x[0])
#define TAB "\t"

typedef unsigned int uint;

class CRandu
//==========
{
public:
	CRandu() : m_Rnd(time(0)) {}
	inline void Seed(uint seed) {m_Rnd = seed;}
	inline uint RandInt31Bit()
	//------------------------
	{
		m_Rnd = (65539 * m_Rnd) % 2147483648; //2147483648 == 2^31
		return m_Rnd;
	}
	//Return 'random' number from ]0,1]
	inline double Rand()
	//--------------------
	{
		return RandInt31Bit() / 2147483647.0;
	}
private:
	uint m_Rnd;
};

int main()
//--------
{
	bool runPartA = true;
	bool runPartB = true;

	if(runPartA)
	{
		const uint seeds[] = {1, 4, 32, 58804, 32768, 65536, 574042, 5444066, 268435456, 1846665012};
		cout << "#Seed\tCycle length " << endl;
		for(uint i = 0; i<ARRAYELEMCOUNT(seeds); i++)
		{
			CRandu randu;
			randu.Seed(seeds[i]);
			uint counter = 1;
			while(randu.RandInt31Bit() != seeds[i]) {counter++;}
			//Note: If seed is >=2^31, this conditions is always true -> infinite loop.
			//So here simply expecting seed to be < 2^31.

			cout.width(12);
			cout << seeds[i] << TAB << counter << endl;
		}
	}

	if(runPartB)
	{
		cout << "Starting part b" << endl;
		ofstream randudatastrm("randudata.txt", ios::trunc);
		const uint seeds[] = {1, 4, 32};
		const uint hitlimit = 1000;
		for(uint i = 0; i<ARRAYELEMCOUNT(seeds); i++)
		{
			cout << "Seed " << i+1 << "/" << ARRAYELEMCOUNT(seeds) << endl;
			randudatastrm << "#Seed = " << seeds[i] << endl;
			uint hitcounter = 0;
			CRandu randu;
			randu.Seed(seeds[i]);
			double x, y;
			while(hitcounter < hitlimit)
			{
				x = randu.Rand();
				y = randu.Rand();
				if(x <= 0.005 && y <= 0.005)
				{
					hitcounter++;
					randudatastrm << x << TAB << y << endl;
				}
			}
			randudatastrm << endl;
		}
	}

	return 0;
}