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

using namespace std;

struct QueueNodeT {
   QueueDataT data;
   QueueNodeT * next;
};

QueueT::QueueT(){
   size = 0;
   front = nullptr;
   rear = nullptr;
}

void DeleteList(QueueNodeT * &  head) {
    QueueNodeT * tmp{head};

    while (head != nullptr) {
       head = head->next;
       delete tmp;
       tmp = head;
    }
    return;
}

QueueT::~QueueT() {
   size = 0;
   rear = nullptr;
   DeleteList(front);

   return;
}

void QueueT::Enqueue(QueueDataT data){
    QueueNodeT * tmp;

    tmp = new QueueNodeT;
    tmp->next = nullptr;
    tmp->data = data;

    if (rear != nullptr) {
        rear->next = tmp;
    } else {
        front = tmp;
    }
    ++size;
    rear = tmp;

    
}

void QueueT::Dequeue(){
    QueueNodeT * tmp;
    tmp = front;

    if (front == nullptr) {
        cerr << "Error: Attempt to do Dequeue on an empty queue" << endl;
    } else {
        front = front->next;
        delete tmp;
        size --;
        if (front == nullptr) {
           rear = nullptr;
        }
    }
}

QueueDataT QueueT::Front() const{
    QueueDataT value{-1};

    if (front != nullptr) {
        value = front->data;
    } else {
        cerr << "Error: Attempt to do Front on an empty queue" << endl;
    }

    return value;
}

size_t QueueT::Size() const{
    return size;
}