/* run-decrypt.c  - Helper to perform a verify operation
   Copyright (C) 2009 g10 Code GmbH
                 2016 by Bundesamt für Sicherheit in der Informationstechnik
                 Software engineering by Intevation GmbH

   This file is part of GPGME.

   GPGME is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of
   the License, or (at your option) any later version.

   GPGME 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this program; if not, see <https://www.gnu.org/licenses/>.
*/

/* We need to include config.h so that we know whether we are building
   with large file system (LFS) support. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

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

#include <gpgme.h>

#define PGM "run-decrypt"

#include "run-support.h"


static int verbose;

static gpg_error_t
status_cb (void *opaque, const char *keyword, const char *value)
{
  (void)opaque;
  fprintf (stderr, "status_cb: %s %s\n", keyword, value);
  return 0;
}


static void
print_result (gpgme_decrypt_result_t result)
{
  gpgme_recipient_t recp;
  int count = 0;

  printf ("Original file name: %s\n", nonnull(result->file_name));
  printf ("Wrong key usage: %i\n", result->wrong_key_usage);
  printf ("Unsupported algorithm: %s\n",
          nonnull(result->unsupported_algorithm));
  if (result->session_key)
    printf ("Session key: %s\n", result->session_key);

  for (recp = result->recipients; recp->next; recp = recp->next)
    {
      printf ("recipient %d\n", count++);
      printf ("  status ....: %s\n", gpgme_strerror (recp->status));
      printf ("  keyid: %s\n", nonnull (recp->keyid));
      printf ("  algo ...: %s\n", gpgme_pubkey_algo_name (recp->pubkey_algo));
    }
}


static int
show_usage (int ex)
{
  fputs ("usage: " PGM " [options] FILE\n\n"
         "Options:\n"
         "  --verbose        run in verbose mode\n"
         "  --status         print status lines from the backend\n"
         "  --openpgp        use the OpenPGP protocol (default)\n"
         "  --cms            use the CMS protocol\n"
         "  --export-session-key            show the session key\n"
         "  --override-session-key STRING   use STRING as session key\n"
         "  --unwrap         remove only the encryption layer\n"
         , stderr);
  exit (ex);
}


int
main (int argc, char **argv)
{
  int last_argc = -1;
  gpgme_error_t err;
  gpgme_ctx_t ctx;
  gpgme_protocol_t protocol = GPGME_PROTOCOL_OpenPGP;
  gpgme_decrypt_flags_t flags = 0;
  FILE *fp_in = NULL;
  gpgme_data_t in = NULL;
  gpgme_data_t out = NULL;
  gpgme_decrypt_result_t result;
  int print_status = 0;
  int export_session_key = 0;
  const char *override_session_key = NULL;
  int raw_output = 0;

  if (argc)
    { argc--; argv++; }

  while (argc && last_argc != argc )
    {
      last_argc = argc;
      if (!strcmp (*argv, "--"))
        {
          argc--; argv++;
          break;
        }
      else if (!strcmp (*argv, "--help"))
        show_usage (0);
      else if (!strcmp (*argv, "--verbose"))
        {
          verbose = 1;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--status"))
        {
          print_status = 1;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--openpgp"))
        {
          protocol = GPGME_PROTOCOL_OpenPGP;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--cms"))
        {
          protocol = GPGME_PROTOCOL_CMS;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--export-session-key"))
        {
          export_session_key = 1;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--override-session-key"))
        {
          argc--; argv++;
          if (!argc)
            show_usage (1);
          override_session_key = *argv;
          argc--; argv++;
        }
      else if (!strcmp (*argv, "--unwrap"))
        {
          flags |= GPGME_DECRYPT_UNWRAP;
          raw_output = 1;
          argc--; argv++;
        }
      else if (!strncmp (*argv, "--", 2))
        show_usage (1);

    }

  if (argc < 1 || argc > 2)
    show_usage (1);

  fp_in = fopen (argv[0], "rb");
  if (!fp_in)
    {
      err = gpgme_error_from_syserror ();
      fprintf (stderr, PGM ": can't open `%s': %s\n",
               argv[0], gpgme_strerror (err));
      exit (1);
    }

  init_gpgme (protocol);

  err = gpgme_new (&ctx);
  fail_if_err (err);
  gpgme_set_protocol (ctx, protocol);
  if (print_status)
    {
      gpgme_set_status_cb (ctx, status_cb, NULL);
      gpgme_set_ctx_flag (ctx, "full-status", "1");
    }
  if (export_session_key)
    {
      err = gpgme_set_ctx_flag (ctx, "export-session-key", "1");
      if (err)
        {
          fprintf (stderr, PGM ": error requesting exported session key: %s\n",
                   gpgme_strerror (err));
          exit (1);
        }
    }
  if (override_session_key)
    {
      err = gpgme_set_ctx_flag (ctx, "override-session-key",
                                override_session_key);
      if (err)
        {
          fprintf (stderr, PGM ": error overriding session key: %s\n",
                   gpgme_strerror (err));
          exit (1);
        }
    }

  err = gpgme_data_new_from_stream (&in, fp_in);
  if (err)
    {
      fprintf (stderr, PGM ": error allocating data object: %s\n",
               gpgme_strerror (err));
      exit (1);
    }

  err = gpgme_data_new (&out);
  if (err)
    {
      fprintf (stderr, PGM ": error allocating data object: %s\n",
               gpgme_strerror (err));
      exit (1);
    }

  err = gpgme_op_decrypt_ext (ctx, flags, in, out);
  result = gpgme_op_decrypt_result (ctx);
  if (err)
    {
      fprintf (stderr, PGM ": decrypt failed: %s\n", gpgme_strerror (err));
      exit (1);
    }
  if (result)
    {
      if (!raw_output)
        print_result (result);
      if (!raw_output)
        fputs ("Begin Output:\n", stdout);
      print_data (out);
      if (!raw_output)
        fputs ("End Output.\n", stdout);
    }

  gpgme_data_release (out);
  gpgme_data_release (in);

  gpgme_release (ctx);
  return 0;
}
