#include <stdexcept>
#include <utility>

#include "stack.h"

Stack::Stack() : first(nullptr)
{
}

Stack::~Stack()
{
  delete first;
}

Stack::Stack(Stack const& s)
  : first{(s.first ? new Element{*s.first} : nullptr)}
{
}

Stack::Stack(Stack&& s)
  : first{s.first}
{
  s.first = nullptr;
}

Stack& Stack::operator=(Stack const& rhs)
{
  Stack copy{rhs};
  std::swap(copy.first, first);
  return *this;
}

Stack& Stack::operator=(Stack&& rhs)
{
  std::swap(rhs.first, first);
  return *this;
}

bool Stack::empty() const
{
  return first == nullptr;
}

void Stack::push(int const& i)
{
  first = new Element(i, first);
}

void Stack::pop()
{
  if ( empty() )
  {
    throw Empty_Stack("empty stack");
  }
  Element* victim{ first };
  first = victim->next;
  victim->next = nullptr;
  delete victim;
}

int Stack::top() const
{
  if ( empty() )
  {
    throw Empty_Stack("empty stack");
  }
  return first->data;
}

Stack::Element::Element(int const& i, Element* n)
  : data{i}, next{n}
{
}

Stack::Element::~Element()
{
  delete next;
}

Stack::Element::Element(Element const& e)
  : data{e.data}, next{e.next ? new Element{*e.next} : nullptr}
{
}