#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include <stdexcept>
using namespace std;

template <typename T>
class Node
{
public:
  T element; // Element contained in the node
  Node < T > * next; // Pointer to the next node

  Node() // No-arg constructor
  {
    next = NULL;
  }

  Node(T element) // Constructor
  {
    this->element = element;
    next = NULL;
  }
};

template <typename T>
class Iterator : public std::iterator<std::forward_iterator_tag, T>
{
public:
  Iterator(Node<T> * p)
  {
    current = p;
  };

  Iterator operator++()
  {
    current = current->next;
    return * this;
  }

  T & operator * ()
  {
    return current->element;
  }

  bool operator == (const Iterator<T> & iterator)
  {
    return current == iterator.current;
  }

  bool operator != (const Iterator<T> & iterator)
  {
    return current != iterator.current;
  }

private:
  Node < T > * current;
};

template <typename T>
class LinkedList
{
public:
  LinkedList();
  LinkedList(LinkedList<T> &list);
  ~LinkedList();
  void addFirst(T element);
  void addLast(T element);
  T getFirst();
  T getLast();
  T removeFirst() throw(runtime_error);
  T removeLast();
  void add(T element);
  void add(int index, T element);
  void clear();
  bool contains(T element);
  T get(int index);
  int indexOf(T element);
  bool isEmpty();
  int lastIndexOf(T element);
  bool remove(T element);
  int getSize();
  T removeAt(int index);
  T set(int index, T element);

  Iterator < T > begin()
  {
    return Iterator < T > (head);
  };

  Iterator < T > end()
  {
    return Iterator < T > (tail->next);
  };

private:
  Node < T > * head, *tail;
  int size;
};

template <typename T>
LinkedList <T>::LinkedList()
{
  head = tail = NULL;
  size = 0;
}

template<typename T>
LinkedList<T>::LinkedList(LinkedList<T> &list)
{
  head = tail = NULL;
  size = 0;

  Node<T> *current = list.head;
  while (current != NULL) {
  this->add(current->element);
  current = current->next;
  }
}

template<typename T>
LinkedList<T>::~LinkedList()
{
  clear();
}

template < typename T >
void LinkedList < T >::addFirst(T element)
{
  Node < T > * newNode = new Node < T > (element);
  newNode->next = head;
  head = newNode;
  size++;

  if (tail == NULL)
    tail = head;
}

template < typename T >
void LinkedList < T >::addLast(T element)
{
  if (tail == NULL)
  {
    head = tail = new Node < T > (element);
  }
  else
  {
    tail->next = new Node < T > (element);
    tail = tail->next;
  }

  size++;
}

template < typename T >
T LinkedList < T >::getFirst()
{
  if (size == 0)
    throw runtime_error("Index out of range");
  else
    return head->element;
}

template < typename T >
T LinkedList < T >::getLast()
{
  if (size == 0)
    throw runtime_error("Index out of range");
  else
    return tail->element;
}

template < typename T >
T LinkedList < T >::removeFirst() throw(runtime_error)
{
  if (size == 0)
    throw runtime_error("No elements in the list");
  else
  {
    Node < T > * temp = head;
    head = head->next;
    size--;
    if (head == NULL) tail = NULL;
    T element = temp->element;
    delete temp;
    return element;
  }
}

template < typename T >
T LinkedList < T >::removeLast()
{
  if (size == 0)
    throw runtime_error("No elements in the list");
  else if (size == 1)
  {
    Node < T > * temp = head;
    head = tail = NULL;
    size = 0;
    T element = temp->element;
    delete temp;
    return element;
  }
  else
  {
    Node < T > * current = head;

    for (int i = 0; i < size - 2; i++)
      current = current->next;

    Node < T > * temp = tail;
    tail = current;
    tail->next = NULL;
    size--;
    T element = temp->element;
    delete temp;
    return element;
  }
}

template < typename T >
void LinkedList < T >::add(T element)
{
  addLast(element);
}

template < typename T >
void LinkedList < T >::add(int index, T element)
{
  if (index == 0)
    addFirst(element);
  else if (index >= size)
    addLast(element);
  else
  {
    Node < T > * current = head;
    for (int i = 1; i < index; i++)
      current = current->next;
    Node < T > * temp = current->next;
    current->next = new Node < T > (element);
    (current->next)->next = temp;
    size++;
  }
}

template < typename T >
void LinkedList < T >::clear()
{
  while (head != NULL)
  {
    Node < T > * temp = head;
    delete temp;
    head = head->next;
  }

  tail = NULL;
}

template < typename T >
T LinkedList < T >::get(int index)
{
  if (index < 0 || index > size - 1)
    throw runtime_error("Index out of range");

  Node < T > * current = head;
  for (int i = 0; i < index; i++)
    current = current->next;

  return current->element;
}

template < typename T >
int LinkedList < T >::indexOf(T element)
{
  // Implement it in this exercise
  Node < T > * current = head;
  for (int i = 0; i < size; i++)
  {
    if (current->element == element)
      return i;
    current = current->next;
  }

  return -1;
}

template < typename T >
bool LinkedList < T >::isEmpty()
{
  return head == NULL;
}

template < typename T >
int LinkedList < T >::getSize()
{
  return size;
}

template < typename T >
T LinkedList < T >::removeAt(int index)
{
  if (index < 0 || index >= size)
    throw runtime_error("Index out of range");
  else if (index == 0)
    return removeFirst();
  else if (index == size - 1)
    return removeLast();
  else
  {
    Node < T > * previous = head;

    for (int i = 1; i < index; i++)
    {
      previous = previous->next;
    }

    Node < T > * current = previous->next;
    previous->next = current->next;
    size--;
    T element = current->element;
    delete current;
    return element;
  }
}

// The functions remove(T element), lastIndexOf(T element),
// contains(T element), and set(int index, T element) are
// left as an exercise

#endif