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

struct Student {
    char *imie;
    char *nazwisko;
    int nr_in;
};

struct Node {
    struct Node* next;
    struct Student student;
};

int show_menu() {
    int choice;
    printf("\n\n\t*] -------------------------------- [*");
    printf("\n\n\t1. Wyswietl wszystkich studentow.\n");
    printf("\t2. Dodanie nowego studenta.\n");
    printf("\t3. Usuniecie studenta o podanym nr indeksu\n");
    printf("\t4. Zakonczenie programu\n");
    printf("\n\t*] -------------------------------- [*\n\n");
    printf("\tTwoj wybor: ");
    scanf("%d", &choice);
    return choice;
}

void remove_student() {
    FILE *file = fopen("studenci.bin", "rb");
    struct Node *head = NULL;

    int index;
    printf("\n\tPodaj index: ");
    scanf("%d", &index);

    struct Student student;
    while(fread(&student, sizeof(struct Student), 1, file)) {
        if (index == student.nr_in) {
            continue;
        }

        do_listy(&head, student);

    }

    fclose(file);

    FILE *wrFile = fopen("studenci.bin", "wb");

    while (head != NULL) {
     fwrite(&(head->student), sizeof(struct Student), 1, wrFile);
     head = head->next;
    }

    fclose(wrFile);

}

void add_student() {
    FILE *file = fopen("studenci.bin", "ab");
    struct Student student;
    student.imie = (char *) malloc(sizeof(char));
    student.nazwisko = (char *) malloc(sizeof(char));
    printf("\n\tPodaj imie: ");
    scanf("%s", student.imie);
    printf("\n\tPodaj Nazwisko: ");
    scanf("%s", student.nazwisko);
    printf("\n\tPodaj index: ");
    scanf("%d", &(student.nr_in));

    fwrite(&student, sizeof(struct Student), 1, file);
    fclose(file);
}

void print_students() {
    FILE *file = fopen("studenci.bin", "rb");
    struct Student student;


    while(fread(&student, sizeof(struct Student), 1, file)) {
        printf("\n\tImie: %s, Nazwisko: %s, Numer Indeksu: %d \n", student.imie, student.nazwisko, student.nr_in);
    }

    fclose(file);
}

void do_listy(struct Node** head_ref, struct Student student)
{
    struct Node* new_node = (struct Node*) malloc(sizeof(struct Node));

    struct Node *last = *head_ref;

    new_node->student  = student;

    new_node->next = NULL;

    if (*head_ref == NULL)
    {
       *head_ref = new_node;
       return;
    }

    while (last->next != NULL)
        last = last->next;

    last->next = new_node;
    return;
}

int main(void) {

    int choice = show_menu();

    while (choice != 4) {
        switch(choice) {
            case 1:
                print_students();
                break;
            case 2:
                add_student();
                break;
            case 3:
                remove_student();
                break;
            default:
                break;
        }

        printf("\n");

        choice = show_menu();
    }

    return 0;
}