/***********************
Name:		Mary Soy
Date:		10/26/09
Class:		CSCI 3333
Professor:	Schweller
File:		LinkedList.h
************************/
#ifndef H_LinkedList
#define H_LinkedList

#include <iostream>
#include <cassert>
#include <iomanip>
using namespace std;

struct StudentNode
{
	int id;
	double GPA;
	StudentNode * next;

	//Constructor with 2 parameters.
	StudentNode(int i = 0, double d = 0.0)
	{
		id  = i;
		GPA = d;
		next = NULL;
	}
};

class LinkedList
{
public:
	//insert student with data into linkedlist
	void insertStudent(StudentNode s);
	//returns the gpa of a studen with a given id.
	//return -1 if the student is not in the data structure.
	double getGPA(StudentNode s);
	//change the gpa of the student with the given id to newGPA
	void updateGPA(StudentNode s);
	//destroys all nodes in a list
	void destroyList();
	//displays the content of a list
	void printLL();
	//return true if list is empty
	bool isEmpty();

	//default constructor initialized head to NULL
	LinkedList();
	//destructor deletes all nodes from the list
	~LinkedList();

private:
	//he head & tail of a list
	StudentNode *head;
	StudentNode *tail;
	int numStudent;
};

LinkedList::LinkedList()
{
	head = NULL;
	tail = NULL;
    numStudent = 0;
}

LinkedList::~LinkedList()
{
	destroyList();
}

void LinkedList::destroyList()
{
	StudentNode * temp;

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

	tail = NULL;
	numStudent = 0;
}

void LinkedList::insertStudent(StudentNode s)
{
	StudentNode * newNode;
	newNode = new StudentNode(s);

	assert(newNode != NULL);

	if( head == NULL)
	{
		head = newNode;
		tail = newNode;
		numStudent++;
	}
	else
	{
		tail->next = newNode;
		tail = newNode;
		numStudent++;
	}
}

void LinkedList::printLL()
{
	StudentNode * traverse;
	traverse = new StudentNode();
	traverse = head;

	while( traverse != NULL )
	{
		cout << "Student with id# " << traverse->id
			<< " and a GPA of: " << fixed << showpoint << setprecision(1) << traverse->GPA << ".\n";
		traverse = traverse->next;
	}
}

bool LinkedList::isEmpty()
{
	if (head == NULL)
	{
	return false;
	}
	else
	{
		return true;
	}
}

double LinkedList::getGPA(StudentNode s)
{
	StudentNode * traverse = head;
	while(traverse != NULL)
	{
		if(traverse->id == s.id)
		{
			cout << "The GPA of student id # " << traverse->id << " is: ";
			return traverse->GPA;
		}
		traverse = traverse->next;
	}

	return -1;
}

void LinkedList::updateGPA(StudentNode s)
{
	StudentNode * traverse = head;
	bool found = false;
	while(traverse != NULL)
	{
		if(traverse->id == s.id)
		{
			traverse->GPA = s.GPA;
			found = true;
		}
		traverse = traverse->next;
	}
	if(found == false)
	{
		cout << "Student with id: " << s.id << " could not be found.\n";
	}
}

#endif