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

#define MAX_NAME 20
#define NOTEN_ANZAHL 5

typedef struct Student
{
    char name[MAX_NAME];
    int matrikelnummer;
    int *noten;
    float mittelnote;
} Student;

void mittelnote_berechnen(Student* s)
{
    float sume = 0;
    for(int i = 0; i < NOTEN_ANZAHL; i++)
        sume += s->noten[i];

    s->mittelnote = sume / NOTEN_ANZAHL ;
}

void print_student(Student s) {
    printf("%s ", s.name);
    for(int i = 0; i < NOTEN_ANZAHL; i++) {
        printf("%d ", s.noten[i]);
    }
    printf("%d ", s.matrikelnummer);
    printf("%f\n", s.mittelnote);
}

void print_student_infile(Student s, FILE* file) {
    if(file == NULL) {
        puts("bad file pointer");
        return;
    }
    fprintf(file, "%s ", s.name);
    for(int i = 0; i < NOTEN_ANZAHL; i++) {
        fprintf(file, "%d ", s.noten[i]);
    }
    fprintf(file, "%d ", s.matrikelnummer);
    fprintf(file, "%f\n", s.mittelnote);
}

int cmp_by_avg(const void* p1, const void* p2) {
    Student* studentA = (Student*) p1;
    Student* studnetB = (Student*) p2;

    return studentA->mittelnote >= studnetB->mittelnote ? 1 : -1;
}

void solve_3(Student* studenten, int studenten_anzahl) {
    qsort(studenten, studenten_anzahl, sizeof(Student), cmp_by_avg);

    FILE* new_file = fopen("sorted_by_avg.txt", "w+");
    for(int i = 0; i < studenten_anzahl; i++) {
        print_student_infile(studenten[i], new_file);
    }
}

int cmp_by_name(const void* p1, const void* p2) {
    Student* studentA = (Student*) p1;
    Student* studnetB = (Student*) p2;

    return strcmp(studentA->name, studnetB->name);
}

void solve_4(Student* studenten, int studenten_anzahl) {
    qsort(studenten, studenten_anzahl, sizeof(Student), cmp_by_name);

    FILE* new_file = fopen("sorted_by_name.txt", "w+");
    for(int i = 0; i < studenten_anzahl; i++) {
        print_student_infile(studenten[i], new_file);
    }
    // b
    fseek(new_file, 0, SEEK_END);
    int bytes = ftell(new_file);
    printf("Number of bytes of sorted_by_name.txt is: %d\n", bytes);
}

int main()
{
    int i,n;
    FILE *f;
    f = fopen("dat_Student.txt", "r");
    if(f == NULL) {
        printf("Man kann nicht aus dat_student.txt lesen\n");
        return -1;
    }

    int studenten_anzahl;
    fscanf(f, "%d", &studenten_anzahl);
    Student* studenten = (Student*) malloc(sizeof(Student) * n);

    // citim toti studentii
    for(int i = 0; i < studenten_anzahl; i++) {
        studenten[i].noten = (int*) malloc(sizeof(int) * NOTEN_ANZAHL);
        fscanf(f, "%s", studenten[i].name);
        for(int j = 0; j < NOTEN_ANZAHL; j++) {
            fscanf(f, "%d", &studenten[i].noten[j]);
        }
        fscanf(f, "%d", &studenten[i].matrikelnummer);
        mittelnote_berechnen(&studenten[i]);
    }

    //task 2
    for(int i = 0; i < studenten_anzahl; i++) {
        print_student(studenten[i]);
    }

    //task 3
    solve_3(studenten, studenten_anzahl);

    //task 4
    // a
    solve_4(studenten, studenten_anzahl);

    // delocam memoria folosita
    for(int i = 0; i < studenten_anzahl; i++) {
        free(studenten[i].noten);
    }
    free(studenten);
}