#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include <nfc/nfc.h>
#include <freefare.h>

int main(int argc, char **argv) {
  int error = EXIT_SUCCESS;

  nfc_device *device = NULL;
  FreefareTag *tags  = NULL;

  nfc_connstring devices[8];
  size_t device_count;

  nfc_context *context;
  nfc_init(&context);
  if (context == NULL) {
    errx(EXIT_FAILURE, "Unable to init libnfc (malloc)");
  }

  uint8_t const key_data_null[8]  = {0, 0, 0, 0, 0, 0, 0, 0};
  MifareDESFireKey key_null = mifare_desfire_des_key_new_with_version(key_data_null);

  uint8_t key_data_real[16] = {0};
  {
    char const *name = (argc > 1) ? argv[1] : "key";
    FILE *f = fopen(name, "rb");
    if (!f) {
      errx(EXIT_FAILURE, "error opening key file: %s", name);
    }
    if (fread(key_data_real, 1, sizeof key_data_real, f) < sizeof key_data_real) {
      errx(EXIT_FAILURE, "key file too small.");
    }
    fclose(f);
  }
  MifareDESFireKey key_real = mifare_desfire_aes_key_new(key_data_real);

  FILE *out = argc > 2 ? fopen(argv[2], "w") : stdout;

  device_count = nfc_list_devices(context, devices, sizeof(devices) / sizeof(devices[0]));
  if (device_count <= 0) {
    errx(EXIT_FAILURE, "No NFC device found.");
  }

  if (device_count > 1) {
    printf("More than 1 device available. Using %s\n", devices[0]);
  }

  device = nfc_open(context, devices[0]);
  if (!device) {
    errx(EXIT_FAILURE, "nfc_open() failed.");
  }

  if (nfc_initiator_init(device) < 0) {
    errx(EXIT_FAILURE, "Initiator failed.");
  }

  while (true) {
    /* Poll for targets */
    const nfc_modulation nmModulations = {.nmt = NMT_ISO14443A, .nbr = NBR_106};
    nfc_target target;
    nfc_initiator_poll_target(device, &nmModulations, 1, 10, 1, &target);

    /* Got at least one, read tag list */
    tags = freefare_get_tags(device);
    if (!tags) {
      nfc_close(device);
      errx(EXIT_FAILURE, "Error listing tags.");
    }

    if (!tags[0]) {
      goto free_tags;
    }

    FreefareTag tag = tags[0];
    if (MIFARE_DESFIRE != freefare_get_tag_type(tag))
      goto free_tags;

    char *tag_uid = freefare_get_tag_uid(tag);

    /* Result of various operations */
    int res;

    res = mifare_desfire_connect(tag);
    if (res < 0) {
      warnx("Can't connect to Mifare DESFire target.");
      goto free_tag;
    }

    res = mifare_desfire_authenticate(tag, 0, key_null);
    if (res >= 0) {
      // Default key still active, create new key
      res = mifare_desfire_change_key(tag, 0, key_real, key_null);

      if (res < 0) {
        warnx("Error changing key");
        goto free_tag;
      }
    }

    res = mifare_desfire_authenticate_aes(tag, 0, key_real);
    if (res < 0) {
      warnx("Authentication on master application failed");
      goto free_tag;
    } else {
      fprintf(out, "%s\n", tag_uid);
      fflush(out);
    }

  wait_disconnect:
    while (0 == nfc_initiator_target_is_present(device, 0))
      ;
    mifare_desfire_disconnect(tag);

  free_tag:
    free(tag_uid);
  free_tags:
    freefare_free_tags(tags);
    fflush(stdout);
    fflush(stderr);
  }

  mifare_desfire_key_free(key_null);
  mifare_desfire_key_free(key_real);

  nfc_close(device);
  nfc_exit(context);

  exit(error);
}