/*******************************************************
 * COMP2012 - 2014/15 Fall
 * Programming Assignment 2
 * File: List.cpp
 *******************************************************/

#include <iostream>
#include "List.h"

using namespace std;

/******************* member functions *******************/
PolyList::PolyList()
{
    head=NULL;
    tail=NULL;
}

bool PolyList::empty() const
{
    if (head!=NULL) return false;
    else return true;
}

//////////////////////////////////////////////////////////
// add your implementation for the member functions below
// ...
// copy constructor
PolyList::PolyList(const PolyList& a){
    PolyNode * a_head = new PolyNode;
    a_head = a.head;
    PolyNode * curr = new PolyNode;
    curr = head;

    curr->coef = a_head->coef;
    curr->expx = a_head->expx;
    curr->expy = a_head->expy;
    a_head = a_head->next;

    while (a_head != NULL)
    {
        curr->next = new PolyNode;
        curr->next->prev = curr;
        curr = curr->next;
        curr->coef = head->coef;
        curr->expx = head->expx;
        curr->expy = head->expy;
        a_head = a_head ->next;
    }

    tail = curr;






}
// destructor
PolyList::~PolyList(){
    while ( head!= NULL){
        PolyNode * new_head = head;
        head = head->next;
        head->prev = NULL;
        delete new_head;
    }
}

// returns the number of node in the linked list
int PolyList::length() const{
    PolyNode * count = head;
    int node_num = 0;
    while(count != NULL)
    {
        node_num++;
        count = count->next;
    }
    return node_num;
}

// add a node to the end of the linked list
void PolyList::attachNode(PolyNode* new_node){

    if((*this).empty()){
        (*this).setHead(new_node);
        (*this).setTail(new_node);
    }else{
        (*this).getTail()->next = new_node;
        new_node->prev = (*this).getTail();
        (*this).setTail(new_node);
    }

}

// delete the first node in the linked list
void PolyList::deleteHead(){
    PolyNode * new_head = head;
    head = head->next;
    head->prev = NULL;
    delete new_head;
}

// Assignment operator
PolyList& PolyList::operator=(const PolyList& a){

    PolyNode* head = this->head;
    while(head != NULL) {
        PolyNode* temp = head->next;
        delete head;
        head = temp;
    }

    PolyNode * a_head = new PolyNode;
    a_head = a.head;
    PolyNode * curr = new PolyNode;
    curr = head;

    curr->coef = a_head->coef;
    curr->expx = a_head->expx;
    curr->expy = a_head->expy;
    a_head = a_head->next;

    while (a_head != NULL)
    {
        curr->next = new PolyNode;
        curr->next->prev = curr;
        curr = curr->next;
        curr->coef = head->coef;
        curr->expx = head->expx;
        curr->expy = head->expy;
        a_head = a_head ->next;
    }

    tail = curr;

    return (*this);


}

// Equal-to operator
bool PolyList::operator==(const PolyList& a) const{
    PolyNode * a_head = a.head;
    PolyNode * curr = head;

    while(a_head!= NULL && curr!= NULL)
    {

        if((a_head->coef == curr->coef)&&(a_head->expx == curr->expx)&&(a_head->expy == curr->expy))
        {
            curr = curr->next;
            a_head = a_head->next;
        }
        else
            return false;
    }
    return true;
}

// find and return the n-th node in the linked list
PolyNode* PolyList::operator[](int n) const{
    /*
        PolyNode * find = new PolyNode;
        find = head;
        int i = 1;
        while (i != n){
            find = find->next;
            i++;
        }
        return find;
     */

    if( n > (*this).length())
    {
        return NULL;
    }

    PolyNode * find = new PolyNode;
    for (int i = 0;i < (*this).length();i++)
    {
        if( i == n )
            break;
        else
            find = find ->next;

    }
    return find;

}

//Get Head
PolyNode* PolyList::getHead()const{
    return head;
}

void PolyList::setHead(PolyNode* NewHead){
    head = NewHead;
}

void PolyList::setTail(PolyNode* NewTail){
    tail = NewTail;
}

PolyNode* PolyList::getTail()const{
    return tail;


}