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

typedef struct {
    char *name, *date, *group;
    int fis, math, inf, phis;
    float ball;
} users;

users *user_struct(char *text, int *len)
{
    int i;
    users *udata = (users *)malloc(sizeof(users) * 1);
    char *tok = strtok(text, "\n"), **strarr = (char **)malloc(sizeof(char *) * 1);
    size_t ln = 1, type = 0;

    while (tok != NULL)
    {
        if (strlen(tok) > 5)
        {
            strarr = (char **)realloc(strarr, sizeof(char *) * ln);
            memcpy((strarr[ln - 1] = (char *)malloc(strlen(tok) + 1)), tok, strlen(tok) + 1);
        }
        tok = strtok(NULL, "\n"); ln++;
    }

    for (i = 0; i < ln - 1; i++) {
        udata = (users *)realloc(udata, sizeof(users) * (i + 1));
        udata[i].name = (char *)malloc(50); udata[i].date = (char *)malloc(11);
        udata[i].group = (char *)malloc(50);

        char *stok = strtok(strarr[i], "|");
        while (stok != NULL)
        {
            if (type == 0 && strlen(stok) < 49)
                strcpy(udata[i].name, stok);

            if (type == 1 && strlen(stok) < 11)
                strcpy(udata[i].date, stok);

            if (type == 2 && strlen(stok) < 49)
                strcpy(udata[i].group, stok);

            if (type == 3 && strlen(stok) == 1)
                udata[i].fis = atoi(stok);

            if (type == 4 && strlen(stok) == 1)
                udata[i].math = atoi(stok);

            if (type == 5 && strlen(stok) == 1)
                udata[i].inf = atoi(stok);

            if (type == 6 && strlen(stok) == 1)
                udata[i].phis = atoi(stok);

            stok = strtok(NULL, "|"); type++;
        }
        udata[i].ball = (udata[i].fis + udata[i].math +
                         udata[i].inf + udata[i].phis) / 4;
        type = 0;
    }
    free(strarr);
    *len = ln - 1;
    return udata;
}

void add_record(users *udata, int *ln)
{
    int len = *ln;

    udata = (users *)realloc(udata, sizeof(users) * (len + 1));
    udata[len].name = (char *)malloc(50); udata[len].date = (char *)malloc(11);
    udata[len].group = (char *)malloc(50);

    printf("Enter name of student: "); scanf("%s", udata[len].name);
    printf("Enter group of student: "); scanf("%s", udata[len].group);
    printf("Enter date of student: "); scanf("%s", udata[len].date);
    printf("Enter a physics score: "); scanf("%d", &udata[len].fis);
    printf("Enter a math score: "); scanf("%d", &udata[len].math);
    printf("Enter a inf. score: "); scanf("%d", &udata[len].inf);
    printf("Enter a chemistry score: "); scanf("%d", &udata[len].phis);

    udata[len].ball = (udata[len].fis + udata[len].math +
                           udata[len].inf + udata[len].phis) / 4;

    FILE *fs = fopen("users.txt", "a+");
    fprintf(fs, "%s|%s|%s|%d|%d|%d|%d|\n",
            udata[len].name, udata[len].date,
            udata[len].group, udata[len].math,
            udata[len].inf, udata[len].phis);
    fclose(fs); (*ln)++;
}

void view_record(users *udata, int len)
{
    int i;
    for (i = 0; i < len; i++)
    {
        printf("Student #%d\n", i + 1);
        printf("Name: %s\n", udata[i].name);
        printf("Group: %s\n", udata[i].group);
        printf("Date: %s\n", udata[i].date);
        printf("Physics score: %d\n", udata[i].fis);
        printf("Math score: %d\n", udata[i].math);
        printf("Inf. score: %d\n", udata[i].inf);
        printf("Chemistry score: %d\n", udata[i].phis);
        printf("Result: %.2f\n\n", udata[i].ball);
    }
    getchar(); getchar();
}

void save_records(users *udata, int len)
{
    int i;
    FILE *fa = fopen("users.txt", "w");

    for (i = 0; i < len; i++)
        fprintf(fa, "%s|%s|%s|%d|%d|%d|%d|\n",
                    udata[i].name, udata[i].date,
                    udata[i].group, udata[i].math,
                    udata[i].inf, udata[i].phis);

    fclose(fa);
}

void edit_record(users *udata, int len)
{
    int i;
    char name[50]; int id = -1;
    printf("Enter name of student: ");
    scanf("%s", name);

    for (i = 0; i < len; i++)
        if (strncmp(udata[i].name, name, strlen(name)))
        {
            id = i; break;
        }

    printf("Student number %d\n", id);
    if (id == -1) return;

    printf("Enter new group name: "); scanf("%s", udata[id].group);
    printf("Enter new date: "); scanf("%s", udata[id].date);
    printf("Enter new physics score: "); scanf("%d", &udata[id].fis);
    printf("Enter new math score: "); scanf("%d", &udata[id].math);
    printf("Enter new inf. score: "); scanf("%d", &udata[id].inf);
    printf("Enter new chemistry score: "); scanf("%d", &udata[id].phis);
    udata[id].ball = (udata[id].fis + udata[id].math +
                      udata[id].inf + udata[id].phis) / 4;

    save_records(udata, len);
}

void search_record(users *udata, int len)
{
    int i;

    for (i = 0; i < len; i++)
        if (udata[i].math >= 8 || udata[i].inf >= 8 || udata[i].phis >= 8|| udata[i].fis >= 8)
        {
            printf("Student #%d\n", i + 1);
            printf("Name: %s\n", udata[i].name);
            printf("Group: %s\n", udata[i].group);
            printf("Date: %s\n", udata[i].date);
            printf("Physics score: %d\n", udata[i].fis);
            printf("Math score: %d\n", udata[i].math);
            printf("Inf. score: %d\n", udata[i].inf);
            printf("Chemistry score: %d\n", udata[i].phis);
            printf("Result: %.2f\n\n", udata[i].ball);
        }
    getchar(); getchar();
}

void menu(users *udata, int len)
{
    int id = 0;
    while (id != 5)
    {
        system("cls");
        printf(
            "==Kutuzov Matvey: Database of students==\n"
            "Full list of options:\n"
            "  1) - Add new record to database.\n"
            "  2) - View a data of students.\n"
            "  3) - Edit exist record.\n"
            "  4) - Search a student by scores.\n"
            "  5) - Exit.\n"
            "Enter a number of option: "
        ); scanf("%d", &id);

        if (id == 1)
            add_record(udata, &len);

        if (id == 2)
            view_record(udata, len);

        if (id == 3)
            edit_record(udata, len);

        if (id == 4)
            search_record(udata, len);

        if (id == 5) break;
    }
}

int main()
{
    FILE *fp = fopen("users.txt", "a+");
    if (!fp) return 1;

    char *text = (char *)malloc(1), c;
    int i, len = 2, st_len = 0; text[0] = '\0';

    while ((c = fgetc(fp)) != EOF)
        if (len < 300) strncat((text = (char *)realloc(text, len++ + 1)), &c, 1);
    fclose(fp);

    users *udata = user_struct(text, &st_len);
    if (st_len == 0) return 1;

    menu(udata, st_len);


    free(text);

    for (i = 0; i < st_len; i++)
    {
        free(udata[i].name); free(udata[i].group);
        free(udata[i].date);
    }

    free(udata);

    return 0;
}