#include <cs50.h>
#include <stdio.h>
#include <string.h>

int key;
int convert(string x);
void digit(string y);

int main(int argc, string argv[])
{
    printf("argv: %s\n", argv[1]);

    //checks if positive digits
    digit(argv[1]);

    if (argc != 2)
    {
        printf("Usage: ./caesar key");
    }
    else
    {
        key = convert(argv[1]);
        printf("Key: %i\n", key);
        string plain = get_string("Gimme plaintext: ");
        printf("plaintext: %s\n", plain);
        printf("ciphertext: ");
        for (int i = 0, len = strlen(plain) ; i < len; i++)
        {
            //QUESTION HERE!!!
            char cypher = (plain[i] + key) % 26;
            printf("%c", cypher);
        }
        printf("\n");
    }

}


//is digit?
void digit(string y)
{
    int len = strlen(y);
    printf("Usage: ");
    for (int i = 0; i < len; i++)
        if (y[i] >= 48 && y[i] <= 57)
        {
            printf("%c", y[i]);
        }
        else
        {
            printf("./caesar key\n");
            exit(0);
        }
    printf("\n");
}


// convert string into digits, or my atoi
int convert(string x)
{
    int res = 0;
    int len = strlen(x);

    printf("String: %s\n", x);
    printf("Len: %i\n", len);

    for (int j = 0 ; j < len ; j++)
    {
        res = res * 10 + x[j] - '0';
    }
    return res;
}