#include <stdio.h>
#include <stdlib.h>
#include "spn.h"

void read_array(const char* filename, unsigned char* array, int size) {
    FILE* f = fopen(filename, "r");
    for (int i = 0; i < size; i++) {
        fscanf(f, "%hhu", &array[i]);
    }
    fclose(f);
}

int main(int argc, char* argv[]) {
    if (argc != 6) {
        printf("%s <key_file> <subst_file> <perm_file> <input> <output>\n", argv[0]);
        return 1;
    }

    FILE* fkey = fopen(argv[1], "r");
    unsigned int key;
    fscanf(fkey, "%u", &key);
    fclose(fkey);

    unsigned char subst[16], perm[16];
    read_array(argv[2], subst, 16);
    read_array(argv[3], perm, 16);

    FILE* fin = fopen(argv[4], "rb");
    FILE* fout = fopen(argv[5], "wb");

    unsigned short block;
    while (fread(&block, 2, 1, fin)) {
        unsigned short dec = decrypt(block, key, perm, subst);
        fputc(dec >> 8, fout);
        fputc(dec & 0xFF, fout);
    }

    fclose(fin);
    fclose(fout);
    return 0;
}