/*
 *  spreadspace avr utils
 *
 *
 *  Copyright (C) 2013-2016 Christian Pointner <equinox@spreadspace.org>
 *
 *  This file is part of spreadspace avr utils.
 *
 *  spreadspace avr utils is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  any later version.
 *
 *  spreadspace avr utils is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
 */

#include <avr/io.h>
#include <avr/wdt.h>
#include <avr/interrupt.h>
#include <avr/power.h>
#include <stdio.h>
#include <string.h>

#include "util.h"
#include "led.h"
#include "usbio.h"

#include <Crypto.h>
#include <ChaChaPoly.h>

ChaChaPoly cipher;

void print_hex_dump(const uint8_t* data, size_t len) {
  for(size_t i=0; i<len; ++i) {
    printf(" 0x%02X", data[i]);
    if((i+1)%8 == 0) printf("\r\n");
  }
  printf("\r\n");
}

void encrypt() {

  uint8_t hdr[] = "hello world!";
  size_t hdr_len = sizeof(hdr)-1;
  uint8_t body[] = "this is a secret message.";
  size_t body_len = sizeof(body)-1;

  uint8_t key[] = {0x70, 0x43, 0xb6, 0x9b, 0xde, 0x20, 0x44, 0x66,
                   0x61, 0xba, 0x57, 0x9e, 0x83, 0xfd, 0xa0, 0x83,
                   0x0e, 0x3e, 0x61, 0xc9, 0x5b, 0x5a, 0xc8, 0xde,
                   0xeb, 0x79, 0x97, 0x3b, 0xa0, 0xdf, 0x02, 0xd8};

  uint8_t iv[] = {0x6f, 0xac, 0x1c, 0x6a, 0x94, 0xa5, 0x78, 0x87,
                  0x61, 0xcf, 0x9e, 0xcd};

  cipher.clear();
  if(!cipher.setKey(key, sizeof(key))) {
    printf("failed to set key\r\n");
    return;
  }
  if(!cipher.setIV(iv, sizeof(iv))) {
    printf("failed to set iv\r\n");
    return;
  }

  uint8_t buf[256];
  uint8_t tag[16];
  memset(buf, 0, sizeof(buf));
  memset(tag, 0, sizeof(tag));

  cipher.addAuthData(hdr, hdr_len);
  cipher.encrypt(buf, body, body_len);
  cipher.computeTag(tag, sizeof(tag));

  printf("encrypted data (%d bytes):\r\n", body_len);
  print_hex_dump(buf, body_len);
  printf("\r\n");
  printf("auth tag (%d bytes):\r\n", sizeof(tag));
  print_hex_dump(tag, sizeof(tag));
}

void handle_cmd(uint8_t cmd)
{
  switch(cmd) {
  case 'e': encrypt(); return;
  case '0': led_off(); break;
  case '1': led_on(); break;
  case 't': led_toggle(); break;
  case 'r': reset2bootloader(); break;
  default: printf("error\r\n"); return;
  }
  printf("ok\r\n");
}

int main(void)
{
  MCUSR &= ~(1 << WDRF);
  wdt_disable();

  cpu_init();
  led_init();
  usbio_init();
  sei();

  for(;;) {
    int16_t BytesReceived = usbio_bytes_received();
    while(BytesReceived > 0) {
      int ReceivedByte = fgetc(stdin);
      if(ReceivedByte != EOF) {
        handle_cmd(ReceivedByte);
      }
      BytesReceived--;
    }

    usbio_task();
  }
}