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

#include <read_rand.h>

#define MTK_SIP_KERNEL_GET_RND 0x8200026A

// Function to print a single line of the hexdump
static void print_hexdump_line(const unsigned char *buffer, int bytes_read, int offset)
{
    // Print the offset
    printf("%08x  ", offset);

    // Print the hex representation
    for (int i = 0; i < 16; i++) {
        if (i < bytes_read) {
            printf("%02x ", buffer[i]);
        } else {
            printf("   ");
        }

        // Print an extra space between groups of 8 bytes
        if (i == 7) {
            printf(" ");
        }
    }

    printf(" |");

    // Print the ASCII representation
    for (int i = 0; i < bytes_read; i++) {
        if (buffer[i] >= 32 && buffer[i] <= 126) {
            printf("%c", buffer[i]);
        } else {
            printf(".");
        }
    }

    printf("|\n");
}

// Function to perform hexdump on a given buffer
static void hexdump(const unsigned char *buffer, size_t size)
{
    int offset = 0;

    while (size > 0) {
        int bytes_to_print = size > 16 ? 16 : size;
        print_hexdump_line(buffer, bytes_to_print, offset);
        buffer += bytes_to_print;
        offset += bytes_to_print;
        size -= bytes_to_print;
    }
}

int main(int argc, char *argv[])
{
    int rc;
    uint8_t buf[1024] = { };
    int rand_len;

    if (argc < 2) {
        fprintf(stderr, "USAGE: %s <rand length>\n", argv[0]);
        return 1;
    }

    rand_len = atoi(argv[1]);
    if (rand_len < 0 || rand_len > (int) sizeof(buf)) {
        fprintf(stderr, "rand length must be between 0 and 1024\n");
        return 1;
    }

    rc = read_hwrandom(buf, (size_t) rand_len);
    if (rc != 0) {
        fprintf(stderr, "read hwrandom failed with %d\n", rc);
        return 1;
    }

    hexdump(buf, (size_t) rand_len);
    return 0;
}