#include <iostream>
#include <memory>

#include "functions.h"

using namespace std;

int main()
{
	// general
	int* pNumber = nullptr; // pointer definition, always initialize a pointer (at least with nullptr)
	pNumber = new int(0); // creates a new integer value on the heap

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

	*pNumber = 789;

	//pNumber = new int(0); // BAD BAD - memory leak, because we override an existin g pointer address with a new one without saving or deleting the old one

	// here are 100s lines of code

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

	safeDelete(pNumber);

	// pointer as references outside local scope
	int number = 10;
	changeInteger(number);
	number = changeIntegerPerReturn(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 a loose connection to a shared pointer

	unique_ptr<int> pNumber2 = make_unique<int>(10);
	*pNumber2 = 100;
	//unique_ptr<int> pNumber3 = pNumber2; // compiler error- you can't create a copy of an unique pointer
	unique_ptr<int> pNumber4 = make_unique<int>(*pNumber2);

	shared_ptr<int> pNumber5 = make_shared<int>(10);
	shared_ptr<int> pNumber6 = pNumber5;

	*pNumber6 = 100;

	pNumber5.reset();

	weak_ptr<int> pNumber7 = pNumber6;
	//*pNumber7 = 1000; // compiler error, weak pointer has no direct access to a shared pointer, you have to create a new shared pointer

	if (!pNumber7.expired())
	{
		shared_ptr<int> tmpSharedNumber = pNumber7.lock();
		*tmpSharedNumber = 10000;
	}

	pNumber6.reset();
	shared_ptr<int> tmpSharedNumber2 = pNumber7.lock();
	if (tmpSharedNumber2 != nullptr) *tmpSharedNumber2 = 100000;

	// pointer-pointer
	createInteger(pNumber);
	createIntegerWithPointerPointer(&pNumber);

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

	// const example
	const int constNumber = 10;
	//constNumber = 20; // a const value can not be changed
	
	const int* constNumberPointer = new int(10);
	//*constNumberPointer = 20; // this is a const value
	constNumberPointer = new int(20); // but not a const pointer

	int const* numberConstPointer = new int(10);
	//*numberConstPointer = 20; // this is a const value
	numberConstPointer = new int(20); // but not a const pointer

	int* const numberPointerConst = new int(10);
	*numberPointerConst = 20; // the value is not const
	//numberPointerConst = new int(20); // but the pointer is const

	const int* const constNumberPointerConst = new int(10);
	//*constNumberPointerConst = 20; // this is a const value
	//constNumberPointerConst = new int(20); // and the pointer as well

	int const* const numberConstPointerConst = new int(10);
	//*numberConstPointerConst = 20; // this is a const value
	//numberConstPointerConst = new int(20); // and the pointer as well

	const int const* const constNumberConstPointerConst = new int(10);
	//*constNumberConstPointerConst = 20; // this is a const value
	//constNumberConstPointerConst = new int(20); // and the pointer as well

	return 0;
}