#include <stdio.h>
#include <io.h>
#include <conio.h>
#include <iostream>
#include <fstream>
using namespace std;


struct Students {
    char FIO[30];
    int year_birthday;
    int num_group;
    int balls[4];
    double s_ball;
};
Students student;
FILE *Fs, *Ft;
char fs_name[] = "students.dat";
char ft_name[] = "result.txt";
int size_of_type = sizeof(Students);

void create();
void add();
bool view();
void out(Students, int);
void edit(int);
void save(Students *, int);
void zadanie();

void main() {
    int kod, kod_edit, edit_number;
    Ft = _fsopen(ft_name, "w", _SH_DENYWR);
    //fopen_s(&Ft, ft_name, "w");
    while (1) {
        puts("\n1 - Create\t2 - View\t3 - Edit\t4 - Zadanie\t0 - Exit\n");
        puts("Input the code here: ");
        scanf_s("%d", &kod);
        switch (kod) {
        case 0:
            fclose(Ft);
            return;
        case 1: // Create File
            create();
            if (!Fs) {
                puts("\nCreate Error!");
                return;
            }
            break;
        case 2: // View
            if (!view()) {
                puts("\n\nError View!\n");
                return;
            }
            break;
        case 3: // Edit
            puts("\n1 - Add\t2 - Edit\n");
            scanf_s("%d", &kod_edit);
            switch (kod_edit) {
            case 1: // Add new record
                add();
                puts("Add a new line");
                break;
            case 2:
                // Edit record
                view();
                printf("\n\nVvedite nomer izmenyaemoj zapisi:\t");
                scanf_s("%d", &edit_number);
                edit(edit_number);
                break;
            }
            break;
        case 4:
            zadanie();
            break;
        }
    }
    _getch();
}
void create() {
    fopen_s(&Fs, fs_name, "wb");
    puts("\nFile Created!\n");
    fclose(Fs);
}
void add() {
    Students student1;
    double fiz, mat, inf, khi, sball;
    fflush(stdin);
    cout << "Please, enter your FIO - ";
    cin.getline(student.FIO, 30);
    printf("\nBirthday Year, Number Group - ");
    scanf_s("%d %d", &student.year_birthday, &student.num_group);
    printf("\nInput Balls: fizik, matem, informatic, khimya - ");
    scanf_s("%d %d %d %d", &student.balls[0], &student.balls[1],
        &student.balls[2], &student.balls[3]);
    fiz = student.balls[0];
    mat = student.balls[1];
    inf = student.balls[2];
    khi = student.balls[3];
    sball = (fiz + mat + inf + khi) / 4;
    printf("%6.2lf", sball);
    student.s_ball = sball;
    Fs = _fsopen(fs_name, "ab", _SH_DENYWR);
    //fopen_s(&Fs, fs_name, "ab");
    fwrite(&student, size_of_type, 1, Fs);
    fclose(Fs);
}

bool view() {
    int i = 1;
    fopen_s(&Fs, fs_name, "rb");
    if (!Fs)
        return false;
    printf("\n\t--------------- Informations ---------------\n");
    fprintf(Ft, "\n\n\n\t--------------- Informations ---------------\n");
    while (1) {
        if (!fread(&student, size_of_type, 1, Fs)) break;
        out(student, i);
        i++;
    }
    puts("\n\n\n");
    fclose(Fs);
    return true;
}

void out(Students s, int i = 0) {
    printf("\n%d. %s - %d, group: %d; Fizik: %d, Matem: %d, Informatic: %d, Khimiya: %d, Sredni ball: %1.2lf", i, s.FIO, s.year_birthday, s.num_group, s.balls[0], s.balls[1], s.balls[2], s.balls[3], s.s_ball);
    fprintf(Ft, "\n%s - %d, group: %d; Fizik: %d, Matem: %d, Informatic: %d, Khimiya: %d, Sredni ball: %1.2lf", s.FIO, s.year_birthday, s.num_group, s.balls[0], s.balls[1], s.balls[2], s.balls[3], s.s_ball);
}

void edit(int edit_number) {
    Students *st, newStudent;
    int descriptor, i, kol;
    long len;
    printf("\nEdit student:\nFIO - ");
    fflush(stdin);
    cin.getline(newStudent.FIO, 30);
    printf("\nBirthday Year, Number Group - ");
    scanf_s("%d %d", &newStudent.year_birthday, &newStudent.num_group);
    printf("\nInput Balls: fizik, matem, informatic, khimya - ");
    scanf_s("%d %d %d %d", &newStudent.balls[0], &newStudent.balls[1], &newStudent.balls[2], &newStudent.balls[3]);
    newStudent.s_ball = (newStudent.balls[0] + newStudent.balls[1] + newStudent.balls[2] + newStudent.balls[3]) / 4;
    Fs = _fsopen(fs_name, "rb", _SH_DENYWR);
    //fopen_s(&Fs, fs_name, "rb");
    descriptor = _fileno(Fs);
    len = _filelength(descriptor);
    kol = len / size_of_type;
    st = new Students[kol];
    for (i = 0; i<kol; i++) {
        fread((st + i), size_of_type, 1, Fs);
    }
    fclose(Fs);
    st[edit_number - 1] = newStudent;
    for (i = 0; i<kol; i++)
        out(st[i], i + 1);
    save(st, kol);
    delete[]st;
}

void save(Students *st, int num) {
    int i;
    Fs = _fsopen(fs_name, "wb", _SH_DENYWR);
    //fopen_s(&Fs, fs_name, "wb");
    for (i = 0; i<num; i++)
        fwrite(&st[i], size_of_type, 1, Fs);
    fclose(Fs);
}


void zadanie() {
    Students *st;
    int descriptor, i, j = 0, kol;
    long len;
    printf("\n ------- Studenti sdavwie sesiyu na fizic 4 or 5 and other > 8 ------- ");
    fprintf(Ft, "\n ------- Studenti sdavwie sesiyu na fizic 4 or 5  and other > 8------- ");
    Fs = _fsopen(fs_name, "rb", _SH_DENYWR);
    //fopen_s(&Fs, fs_name, "rb");
    descriptor = _fileno(Fs);
    len = _filelength(descriptor);
    kol = len / size_of_type;
    st = new Students[kol];
    for (i = 0; i<kol; i++) {
        fread((st + i), size_of_type, 1, Fs);
    }
    fclose(Fs);
    for (i = 0; i<kol; i++) {
        if ((st[i].balls[0] == 4 || st[i].balls[0] == 5) && st[i].balls[1] > 8 && st[i].balls[2] > 8 && st[i].balls[3] > 8)
            out(st[i], 0);
    }
    delete[]st;
}