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

char * createlogin(char filename[50]);
char * checkusername(char filename[50]);
char * checkpin(char filename[50]);

int main(void){

    int     done = 0;
    char    loginorcreate[7], filename[50];

    while(!done){
    printf("'login' or 'create' new user?:   ");
    scanf("%s", &loginorcreate);

    if (strcmp(loginorcreate, "login") == 0){
        checkusername(filename);
    }
    else if (strcmp(loginorcreate, "create") == 0){
        createlogin(filename);
    }
    else{
        printf("exiting...\n");
        return(0);
        done = 1;
    }
    }

}

char * createlogin(char filename[50]){
    FILE *userfile;
    char username[20],  pin[20];

    printf("Create a username:   ");
    scanf("%s", &username);

    sprintf(filename, "C:/programming/users/%s.txt", username);

    if (access (filename, F_OK) != -1){
        printf("Username already exist\n");
        return(0);
    }
    else{

    printf("Create a password:   ");
    scanf("%s", &pin);

    userfile = fopen(filename, "w+");

    fprintf(userfile, "%s\n%s\n", username, pin);
    fclose(userfile);

    for(int i = 0; i < 3; i++){
        printf(".");
        Sleep(250);
    }

    printf("\nUser created\n");
    Sleep(500);
    }

    return filename;
}

char * checkusername(char filename[50]){
    FILE    *userfile;
    char    readusername[20], loginusername[20];
    int     found_username = 0;

    printf("Username:   ");
    scanf("%s", &loginusername);

    sprintf(filename, "C:/programming/users/%s.txt", loginusername);
    userfile = fopen(filename, "r");

    while(fgets(readusername, 20, userfile) != 0){
        if((strstr(readusername, loginusername)) != 0){
            printf("Username found\n");
            checkpin(filename);
            found_username++;
        }
    }
    if (found_username == 0){
        printf("Wrong username\n");
        fclose(userfile);
        return(0);
    }

    }

char * checkpin(char filename[50]){
    FILE    *userfile;
    char    pin[20], pininfile[20];
    int     found_pin = 0;

    printf("Enter your password:   ");
    scanf("%s", &pin);

    userfile = fopen(filename, "r");

    while(fgets(pininfile, 20, userfile) != 0){
        if((strstr(pininfile, pin)) != 0){
            printf("Login succesful\n");
            found_pin++;
            fclose(userfile);
        }
    }
    if (found_pin == 0){
        printf("Wrong password\n");
        fclose(userfile);
        return(0);
    }


}