#include "a_train.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

//pridaj vozen na koniec spojkového zoznamu
struct car* add_car(struct car* first, const char* target) {
    // alokacia noveho prvku
    struct car* newcar = calloc(1, sizeof(struct car));
    if (newcar == NULL) {
        fprintf(stderr, "Chyba: nepodarilo sa alokovať pamäť pre nový vozeň.\n");
        return first;
    }

    // kopirujeme cielovu stanicu
    strcpy(newcar->value, target);
    newcar->next = NULL;

    // vlak prazdny -> novy vozen je prvy
    if (first == NULL) {
        return newcar;
    }

    // inak pridame na koniec
    struct car* this = first;
    while (this->next != NULL) {
        this = this->next;
    }
    this->next = newcar;

    return first;
}

// vypis voznov
void print_train(struct car* first) {
    struct car* this = first;
    while (this != NULL) {
        printf("%s\n", this->value);
        this = this->next;
    }
}

// zrusit vlak a uvolnit pamat
void cancel_train(struct car* first) {
    if (first == NULL) return;

    // Rekurzívne uvoľnenie
    cancel_train(first->next);
    free(first);
}

// odstranit vozne s target stanicou
struct car* clear_train(struct car* first, const char* target) {
    struct car* current = first;
    struct car* prev = NULL;

    while (current != NULL) {
        if (strcmp(current->value, target) == 0) {
            // vymazat zaznam
            struct car* to_delete = current;
            current = current->next;

            if (prev == NULL) {
                // vymazat prvy prvok
                first = current;
            } else {
                prev->next = current;
            }

            free(to_delete);
        } else {
            // Pokračujeme ďalej
            prev = current;
            current = current->next;
        }
    }

    return first;
}