/*
 *  Feynman -- Wayland compositor for GNU Emacs
 *
 * Copyright (c) 2022 Sameer Rahmani <lxsameer@gnu.org>
 *
 * This program 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, version 2.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "export.h"
#include <emacs-module.h>

/* Declare mandatory GPL symbol.  */
FEYNMAN_EXPORT int plugin_is_GPL_compatible = 0;

/* New emacs lisp function. All function exposed to Emacs must have this
 * prototype. */
static emacs_value feynman_init(emacs_env *env, ptrdiff_t nargs,
                                emacs_value args[], void *data) {
  (void)nargs;
  (void)args;
  (void)data;
  return env->make_integer(env, 42);
}

/* Bind NAME to FUN.  */
static void bind_function(emacs_env *env, const char *name, emacs_value Sfun) {
  /* Set the function cell of the symbol named NAME to SFUN using
     the 'fset' function.  */

  /* Convert the strings to symbols by interning them */
  emacs_value Qfset = env->intern(env, "fset");
  emacs_value Qsym = env->intern(env, name);

  /* Prepare the arguments array */
  emacs_value args[] = {Qsym, Sfun};

  /* Make the call (2 == nb of arguments) */
  env->funcall(env, Qfset, 2, args);
}

/* Provide FEATURE to Emacs.  */
static void provide(emacs_env *env, const char *feature) {
  /* call 'provide' with FEATURE converted to a symbol */

  emacs_value Qfeat = env->intern(env, feature);
  emacs_value Qprovide = env->intern(env, "provide");
  emacs_value args[] = {Qfeat};

  env->funcall(env, Qprovide, 1, args);
}

FEYNMAN_EXPORT int emacs_module_init(struct emacs_runtime *ert) {
  emacs_env *env = ert->get_environment(ert);
  /* create a lambda (returns an emacs_value) */
  emacs_value fun = env->make_function(
      env, 0,                      /* min. number of arguments */
      0,                           /* max. number of arguments */
      feynman_init,                /* actual function pointer */
      "Initialize the compositor", /* docstring */
      NULL /* user pointer of your choice (data param in feynman_init) */
  );

  bind_function(env, "feynman/init", fun);
  provide(env, "feynman");
  return 0;
}