// first version of a linked list class with add, size, and to_string and it
// passes valgrind

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

struct list_node {
    list_node(int init_data = 0, list_node * link = nullptr) {
        data = init_data;
        next = link;
    }

    int data;
    list_node * next;
};

class linked_list {
public:
    linked_list() {
        front = nullptr;
        back = nullptr;
        count = 0;
    }

    ~linked_list() {
        delete_nodes(front);
    }

    void delete_nodes(list_node * current) {
        while (current != nullptr) {
            list_node * temp = current;
            current = current->next;
            delete temp;
        }
    }

    int size() const {
        return count;
    }

    void add(int value) {
        if (count == 0) {
            front = new list_node(value);
            back = front;
            count = 1;
        } else {
            back->next = new list_node(value);
            count++;
            back = back->next;
        }
    }

    string to_string() const {
        ostringstream out;
        out << "[";
        if (count > 0) {
            out << front->data;
            list_node * current = front->next;
            while (current != nullptr) {
                out << ", " << current->data;
                current = current->next;
            }
        }
        out << "]";
        return out.str();
    }

private:
    list_node * front;
    list_node * back;
    int count;
};

int main() {
    linked_list list;
    list.add(3);
    list.add(5);
    list.add(2);
    list.add(17);
    cout << "list size = " << list.size() << endl;
    cout << list.to_string() << endl;
    cout << endl;

    linked_list list1;
    for (int n : {3, 18, 12, 7, 13, 20, 0, 7}) {
        cout << "list1 = " << list1.to_string() << ", adding " << n << endl;
        list1.add(n);
    }
    cout << "final list1 = " << list1.to_string() << endl;
    cout << "final list1 size = " << list1.size() << endl;
    cout << endl;
        
    return 0;
}