#include <iostream>
#include <cstdlib>
#include <time.h>

using namespace std;

struct Element
{
    int value;
    Element *next = 0;
};

struct List
{
    Element *head = 0;
    Element *tail = 0;
    int elementAmount;
};

bool isEmpty(List *list)
{
    return list->head == 0;
}

int randomValue()
{
    srand(time(NULL));
    return rand()%10+1;
}

void addFirstElement(List **list, Element *element)
{
    (*list)->head = element;
    (*list)->tail = element;
    (*list)->elementAmount++;
}

void addElementTop(List **list)
{
    Element *element = new Element();
    element->value = randomValue();
    if(isEmpty(*list)) {
        addFirstElement(list, element);
    }
    else {
        element->next = (*list)->head;
        (*list)->head = element;
        (*list)->elementAmount++;
    }
}

void addElementEnd(List **list)
{
    Element *element = new Element();
    element->value = randomValue();

    if(isEmpty(*list)) {
        addFirstElement(list, element);
    }
    else {
        (*list)->tail->next = element;
        (*list)->tail = element;
        (*list)->elementAmount++;
    }
}

void addElement(List **list)
{
    Element *element = new Element();
    element->value = randomValue();
    int index;

    cout << "Please specific index to add element before : " ;
    cin >> index;

    if(isEmpty(*list)) {
        addElementTop(list);
    }
    else if(index > ((*list)->elementAmount)) {
        addElementEnd(list);
    }
    else {
        Element *tmpl = new Element();
        tmpl = (*list)->head;

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

        element->next = tmpl->next;
        tmpl->next = element;
        (*list)->elementAmount++;

        delete tmpl;
    }

}

void showFirst(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else {
        cout << "Top value of list is : " << (*list)->head->value << endl;
    }
}

void showLast(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else {
        cout << "Last value of list is : " << (*list)->tail->value << endl;
    }
}

void showList(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else {
        Element *temporaryElement = (*list)->head;

        while (temporaryElement != 0) {
            cout << temporaryElement->value << endl;
            temporaryElement = temporaryElement->next;
        }
        delete temporaryElement;
    }
}

void avarage(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else {
        Element *temporaryElement = (*list)->head;
        int sum = 0;

        for(int i = 0; i < (*list)->elementAmount; i++) {
            sum = sum + temporaryElement->value;
            temporaryElement = temporaryElement->next;
        }

        delete temporaryElement;

        double average = (double)sum/(double)(*list)->elementAmount;

        cout << "Average of list elements is " << average;
    }
}

void removeElementTop(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else if((*list)->elementAmount > 1) {
        Element *temporaryElement = (*list)->head;
        (*list)->head = (*list)->head->next;
        (*list)->elementAmount--;
        delete temporaryElement;
    }
    else {
        Element *temporaryElement = (*list)->head;
        (*list)->head = 0;
        (*list)->tail = 0;
        (*list)->elementAmount = 0;
        delete temporaryElement;
    }
}

void removeElementEnd(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else if((*list)->elementAmount > 1) {
        Element *temporaryElement = (*list)->head;

        while(temporaryElement->next != 0) {
            if(temporaryElement->next->next == 0) {
                temporaryElement->value = 0;
                (*list)->elementAmount--;
            }
            else {
                temporaryElement = temporaryElement->next;
            }
        }
    }
    else {
        Element *temporaryElement = (*list)->head;
        (*list)->head = 0;
        (*list)->tail = 0;
        (*list)->elementAmount = 0;
        delete temporaryElement;
    }
}

void removeElement(List **list)
{
    if(isEmpty(*list)) {
        cout << "Sorry, list is empty." << endl;
    }
    else {
        int index;

        cout << "Please specific index to add element before : " ;
        cin >> index;

        if(index <= 1) {
            removeElementTop(list);
        }
        else if(index >= (*list)->elementAmount) {
            removeElementEnd(list);
        }
        else {
            Element *tmpl = (*list)->head;

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

            Element *element = tmpl->next;
            tmpl->next = element->next;
            (*list)->elementAmount--;
            delete element;
            delete tmpl;
        }
    }
}

void removeList(List **list)
{
    while(!isEmpty(*list)) {
        removeElementTop(list);
    }
}

void printMenu()
{
    cout << "*** MENU ***" << endl;
    cout << "1. Check if list is empty" << endl;
    cout << "2. Add element to end of list" << endl;
    cout << "3. Add element to beginning of list" << endl;
    cout << "4. Add element before specific index" << endl;
    cout << "5. Remove element from end of list" << endl;
    cout << "6. Remove element from beginning of list" << endl;
    cout << "7. Remove element from specific index" << endl;
    cout << "8. Get top element from list" << endl;
    cout << "9. Get lase element from list" << endl;
    cout << "10. Count arithmetic average" << endl;
    cout << "11. Show list" << endl;
    cout << "12. Remove list" << endl;
    cout << "13. Exit" << endl;
}

int main()
{
    List *list = new List;
    int choice;
    while(true)
    {
        printMenu();

        cout<<"Your choice : ";
        cin>>choice;

        switch(choice)
        {
            case 1:
                if(isEmpty(list)) {
                    cout << "List is empty." << endl;
                }
                break;

            case 2:
                addElementEnd(&list);
                break;

            case 3:
                addElementTop(&list);
                break;

            case 4:
                addElement(&list);
                break;

            case 5:
                removeElementTop(&list);
                break;

            case 6:
                removeElementEnd(&list);
                break;

            case 7:
                removeElement(&list);
                break;

            case 8:
                showFirst(&list);
                break;

            case 9:
                showLast(&list);
                break;

            case 10:
                avarage(&list);
                break;

            case 11:
                showList(&list);
                break;

            case 12:
                removeList(&list);
                break;

            case 13:
                removeList(&list);
                delete list;
                return 0;
                break;

            default:
                cout << "Error something wrong" << endl;
        }
    }
    return 0;
}