// disfluid, implementation of the Solid specification
// Copyright (C) 2020, 2021  Vivien Kraus

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.

// This program 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 Affero General Public License for more details.

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

#include <Disfluid-0.h>
#include <libguile.h>
#include <string.h>

struct DisfluidApi
{
  SCM scm_make_client;
  SCM scm_get_client_id;
  SCM scm_get_key_pair;
  SCM scm_get_redirect_uri;
};

struct user_code
{
  DisfluidUser func;
  void *data;
};

static void *
inner_guile (void *data)
{
  struct user_code *user = data;
  struct DisfluidApi api;
  api.scm_make_client =
    scm_c_public_ref ("webid-oidc client reverse-stubs", "make-client");
  api.scm_get_client_id =
    scm_c_public_ref ("webid-oidc client reverse-stubs", "get-client-id");
  api.scm_get_key_pair =
    scm_c_public_ref ("webid-oidc client reverse-stubs", "get-key-pair");
  api.scm_get_redirect_uri =
    scm_c_public_ref ("webid-oidc client reverse-stubs", "get-redirect-uri");
  return user->func (&api, user->data);
}

void *
disfluid_api_init (DisfluidUser func, void *data)
{
  struct user_code code;
  code.func = func;
  code.data = data;
  return scm_with_guile (inner_guile, &code);
}

struct DisfluidClient
{
  SCM object;
};

struct DisfluidClient *
disfluid_client_make (const struct DisfluidApi *api,
		      const char *client_id,
		      const char *redirect_uri, const char *jwk)
{
  SCM scm_client_id = scm_from_utf8_string (client_id);
  SCM scm_redirect_uri = scm_from_utf8_string (redirect_uri);
  SCM scm_jwk = SCM_BOOL_F;
  if (jwk)
    {
      scm_jwk = scm_from_utf8_string (jwk);
    }
  SCM object =
    scm_call_3 (api->scm_make_client, scm_client_id, scm_redirect_uri,
		scm_jwk);
  scm_dynwind_begin (0);
  struct DisfluidClient *ret = scm_malloc (sizeof (struct DisfluidClient));
  scm_dynwind_unwind_handler (free, ret, 0);
  ret->object = scm_gc_protect_object (object);
  scm_dynwind_end ();
  return ret;
}

void
disfluid_client_free (struct DisfluidClient *client)
{
  scm_gc_unprotect_object (client->object);
  free (client);
}

static size_t
copy_scm_string (SCM string, size_t start, size_t max, char *dest)
{
  size_t total_length = 0;
  scm_dynwind_begin (0);
  char *all_bytes = scm_to_utf8_stringn (string, &total_length);
  scm_dynwind_free (all_bytes);
  const size_t requested_length = max;
  const size_t available_length = total_length - start;
  size_t copied_length = requested_length;
  if (available_length < copied_length)
    {
      copied_length = available_length;
    }
  memcpy (dest, all_bytes + start, copied_length);
  if (copied_length < max)
    {
      dest[copied_length] = '\0';
    }
  scm_dynwind_end ();
  return total_length;
}

size_t
disfluid_client_get_id (const struct DisfluidApi *api,
			const struct DisfluidClient *client,
			size_t start, size_t max, char *id)
{
  SCM scm_id = scm_call_1 (api->scm_get_client_id, client->object);
  return copy_scm_string (scm_id, start, max, id);
}

size_t
disfluid_client_get_key_pair (const struct DisfluidApi *api,
			      const struct DisfluidClient *client,
			      size_t start, size_t max, char *jwk)
{
  SCM scm_jwk = scm_call_1 (api->scm_get_key_pair, client->object);
  return copy_scm_string (scm_jwk, start, max, jwk);
}

size_t
disfluid_client_get_redirect_uri (const struct DisfluidApi *api,
				  const struct DisfluidClient *client,
				  size_t start, size_t max,
				  char *redirect_uri)
{
  SCM scm_uri = scm_call_1 (api->scm_get_redirect_uri, client->object);
  return copy_scm_string (scm_uri, start, max, redirect_uri);
}