#include <stdio.h>

#define MAX_ALLOWED_BYTES 256 * 256
#define RANGE(x, y, z) ((x) >= (y) && (x) <= (z))

static int letter_count[256];

int main(int argc, char **argv)
{
        char curr_letter;
        FILE *fp;
        int i, j;

        puts("                -= SSCAT =-");
        puts("-= Serious Substition Cipher Analysis Tool =-\n");

        if (argc < 2) {
                fprintf(stderr, "Please provide valid file(s) for Analysis!\n"
                                "Usage: %s <File 1> <File 2> ... <File n>\n", argv[0]);
                return -1;
        }

        memset(letter_count, 0x00, 256);

        for (j = 1; j < argc; j++) {
                fp = fopen(argv[j], "rb");

                if (fp == NULL) {
                        fprintf(stderr, "Provided file %s is not valid!\n\n", argv[j]);
                        continue;
                }

                printf("Processing file %s now!\n", argv[j]);

                for (i = 0; i < MAX_ALLOWED_BYTES && !feof(fp); i++) {
                        curr_letter = getc(fp);
                        letter_count[curr_letter]++;

                        if (i == MAX_ALLOWED_BYTES - 1)
                                fprintf(stderr, "File %s is too big! Will not continue reading\n", argv[j]);

                }

                fclose(fp);

                for (i = 0; i < 256; i++) {
                        if (letter_count[i] != 0x00)
                                if (RANGE(i, 'A', 'Z') || RANGE(i, 'a', 'z'))
                                        printf("Letter %c was found %d time(s)!\n", i, letter_count[i]);
                }
        }

        sleep(1);
        puts("Analysis finished!");
        puts("Thanks for using SSCAT!");
        return 0;
}