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

struct car* add_car(struct car* first, const char* target) {
    struct car* new_car = (struct car*)calloc(1, sizeof(struct car));
    if (new_car == NULL) {
        return first;
    }
    
    strcpy(new_car->value, target);
    new_car->next = NULL;
    
    if (first == NULL) {
        return new_car;  
    } else {
        struct car* current = first;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = new_car;  
        return first;
    }
}

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

void cancel_train(struct car* first) {
    while (first != NULL) {
        struct car* current = first;
        first = first->next;
        free(current);
    }
}

struct car* clear_train(struct car* first, const char* target) {
    struct car* new_first = first;
    struct car* prev = NULL;
    struct car* current = first;

    while (current != NULL) {
        if (strcmp(current->value, target) == 0) {
            if (prev == NULL) {
                new_first = current->next;
                free(current);
                current = new_first;
            } else {
                prev->next = current->next;
                free(current);
                current = prev->next;
            }
        
        } else {
            prev = current;
            current = current->next;
        }
    }
    
    return new_first;
}