#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* newcar=calloc(1, sizeof(struct car));
    strcpy(newcar->value, target);
    newcar->next=NULL;
    if (first==NULL) 
    {
        return newcar;
    }
    struct car* this=first;
    while (this->next!=NULL) 
    {
        this=this->next;
    }
    this->next=newcar;
    return first;
    return NULL;
}

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


struct car* clear_train(struct car* first, const char* target) 
{
    while (first!=NULL && strcmp(first->value, target)==0) 
    {
        struct car* temp=first;
        first=first->next;
        free(temp);
    }
    if (first==NULL) 
    {
        return NULL;
    }
    struct car* current=first;
    while (current->next!=NULL) 
    {
        if (strcmp(current->next->value, target)==0) 
        {
            struct car* temp=current->next;
            current->next=current->next->next;
            free(temp);
        }
        else 
        {
            current=current->next;
        }
    }
    return first;
}