#include <iostream>
#include <memory> // smart pointer header

using namespace std;

void changeInteger(int n);
void changeIntegerPerPointer(int* pN);
int changeIntegerPerReturn(int n);
void changeIntegerPerReference(int& n);

bool createInteger(int* pN);
bool createIntegerWithPointerPointer(int** ppN);

int main()
{
	// general
	int* pNumber = nullptr;
	pNumber = new int(0);

	cout << "size of pNumber: " << sizeof(pNumber) << endl;
	cout << "size of pNumber data: " << sizeof(*pNumber) << endl;

	*pNumber = 567;

	// pNumber = new int(0); // BAD BAD - Memory Leak, because we override an existing pointer address with a new one without saving the old one
	
	// here are 100s of lines of code
	
	if (pNumber != nullptr)
	{
		delete pNumber;
		pNumber = nullptr;
	}

	// pointer as references
	//int number = 0;
	//changeInteger(number);
	//changeIntegerPerPointer(&number);
	//changeIntegerPerPointer(pNumber);
	//changeIntegerPerReference(number);

	// smart pointer
	// unique_ptr -> only one owner exist for the object
	// shared_ptr -> can have multiple owners
	// weak_ptr -> is loose connection to a shared_ptr

	unique_ptr<int> number = make_unique<int>(10);
	*number = 100;
	//unique_ptr<int> number2 = number; // compiler error - you can create a copy of an unique pointer
	unique_ptr<int> number2 = make_unique<int>(*number);

	shared_ptr<int> number3 = make_shared<int>(20);
	shared_ptr<int> number4 = number3;
	*number3 = 200;
	*number4 = 2000;

	number3.reset();

	weak_ptr<int> weakNumber = number4;
	//*weakNumber = 20000; // compiler error, weak pointer have no direct access to a shared pointer, you have to create one

	if (!weakNumber.expired())
	{
		shared_ptr<int> tmpSharedNumber = weakNumber.lock();
		*tmpSharedNumber = 20000;
	}

	number4.reset();
	shared_ptr<int> tmpSharedNumber = weakNumber.lock();

	// pointer-pointer
	if (createInteger(pNumber))
	{
		cout << "Create integer was succesful" << endl;
	}

	if (createIntegerWithPointerPointer(&pNumber))
	{
		cout << "Create integer was succesful" << endl;
	}

	if (pNumber != nullptr)
	{
		delete pNumber;
		pNumber = nullptr;
	}

	return 0;
}

void changeInteger(int n)
{
	n = 100;
}

void changeIntegerPerPointer(int* pN)
{
	cout << "address of pN: " << &pN << endl;

	if (pN == nullptr) return; // BE CAREFUL - if you don't what you get, do a test before

	*pN = 200;
}

void changeIntegerPerReference(int& n)
{
	n = 300;
}

bool createInteger(int* pN)
{
	pN = new int(0); // CAUTION - creates a MEMORY LEAK

	return false;
}

bool createIntegerWithPointerPointer(int** ppN)
{
	*ppN = new int(0);

	return true;
}