/****************************************************************
*  Engineering 4892 Data Structures
*  Assignment: 3  Date Due: June 14th/2001
*  Name: Daryl Martin
*  Student #: 9713520
*  Username: darylm
*****************************************************************/

#include "dlist.h"

/*****************************************************************
* insert - insert a node into a list at the ith position
*	Pre: 0 <= i <= |L|
*	Post: L' = L with x inserted at the ith position. 
*		  If i == |L| then x is appended
*****************************************************************/

template <class T>
List<T>::Status 
List<T>::insert(const T& x, int i) {
	int length = size();	//get the length of the linked list
	Node *current = head;	//declare a pointer to follow the list
	Node* toAdd;	//declare new node

	if (i < 0 || i > length){	//If fails the pre conditions
		err = NoSuchElement;
		}
	
	else {
		if (i == 0){push_front(x);}	//if at the beginning of the list
		else if (i == length){push_back(x);}	//if at the end of the list
		
		else{
			for (int k=0;k < i;k++){			//loop to go to the ith element
					current = current->next;	//in the list
			}
			toAdd = new(std::nothrow) Node;
			if(toAdd != 0){	//check for memory
				
					toAdd->prev = current->prev;	//These commands configure
					toAdd->next = current;			//the inserted node properly
					current->prev->next = toAdd;
					current->prev = toAdd;
					toAdd->data = x;
			}
			else{		//if there isn't enough memory available
				err=NewFail;
		
			}
		}
	}
	
	return err;
}

/****************************************************************
* remove - remove the ith element of the list
*	Pre: 0 <= i < |L|
*	Post: L' = L with i'th element removed.
*****************************************************************/

template <class T>
List<T>::Status 
List<T>::remove(int i){
	
	Node *current = head;	//create a pointer to follow list
	int length = size();	//find the lenght of the list

	if (i < 0 || i > length - 1){
		err = NoSuchElement;
		}	//fails preconditions

	else {
		if (i == 0){pop_front();}	//if the value is at the head
		else if ( (length - 1) == i){pop_back();}	//if the value is at the tail
		
		else{
			for (int j=0;j < i;j++){
				current = current->next;		//jump to the end of the linked list
			}	
			current->prev->next = current->next;	//"Jump" over the node we want
			current->next->prev = current->prev;	//to delete with pointers
			delete current;	//delete the current node
			}
	}

	return err;

}

/****************************************************************
* operator[] - find the data in the ith node
*	Pre: 0 <= i < |L|
*	Post: Result = L[i] (i'th element of L)
*****************************************************************/

template <class T>
const T&
List<T>::operator[] (int i) const {

	int length = size();	//find the lenght of the list
	Node *current = head;	//create a pointer to follow the list
	static T data = 0;	//create a null piece of data
	

	if (i < 0 || i > (length -1)){	//fail the preconditions
		err = NoSuchElement;
		}
	else{
		for(int a=0;a<i;a++){
			current = current->next;	//find the node we want to extract info from
		}
		data = current->data;	
	}
return data;
}