#include "lista.h"

typedef struct Node{
    void* dato;
    struct Node* prev;
    struct Node* next;
} Node;

typedef struct List{
    Node* first;
    Node* last;
    Node* current;
} List;


List* createList(){
    List* L = (List*) malloc(sizeof(List));
    L->first = NULL;
    L->last = NULL;
    L->current = NULL;
    return L;
}

void pushFront(List* L, void* data){
    Node* nodo = (Node*) malloc(sizeof(Node));
    nodo->dato = data;
    if(!L->first){
        L->first = nodo;
        L->last = nodo;
        nodo->next = nodo;
        nodo->prev = nodo;
    }
    else{
        nodo->next = L->first;
        nodo->prev = L->last;

        L->last->next = nodo;
        L->first->prev = nodo;

        L->first = nodo;
    }
}

void pushBack(List* L, void* data){
    Node* nodo = (Node*) malloc(sizeof(Node));
    nodo->dato = data;
    if(L->first == NULL){
        L->first = nodo;
        L->last = nodo;
        nodo->next = nodo;
        nodo->prev = nodo;
    }
    else{
        nodo->next = L->first;
        nodo->prev = L->last;

        L->last->next = nodo;
        L->first->prev = nodo;

        L->last = L->first->prev;
    }
}

void popFront(List* L){
    if(L->first){
        Node* aux=NULL;
        aux = L->first;
        L->first->next->prev = L->last;
        L->last->next = L->first->next;
        L->first = L->first->next;
        free(aux);
    }
}

void popBack(List* L){
    if(L->first){
        Node* aux = (Node*) malloc(sizeof(Node));
        aux = L->last;
        L->last->prev->next = L->first;
        L->first->prev = L->last->prev;
        L->last = L->last->prev;
        free(aux);
    }
}

void popCurrent(List* L){
    if(L->first){
       Node* aux = (Node*) malloc(sizeof(Node));
       aux = L->current;
       L->current->next->prev = L->current->prev;
       L->current->prev->next = L->current->next;
       if(L->first == L->current){
            L->first=L->first->next;
       }
       L->current = L->current->next;
       free(aux);
    }
}

void* First(List* L){
    if(L->first == NULL){
        return NULL;
    }
    else{
        L->current = L->first;
        return L->first->dato;
    }
}

void* Last(List* L){
    if(L->last == NULL){
        return NULL;
    }
    else{
        L->current = L->last;
        return L->last->dato;
    }
}

void* Next(List* L){
    if(L->first == NULL){
        return NULL;
    }
    else{
        L->current = L->current->next;
        return L->current->dato;
    }
}

void* Current(List* L){
    if(L->current == NULL){
        return NULL;
    }
    else{
        return L->current->dato;
    }
}