#include <string.h>
#include <tree_sitter/parser.h>
#include "emacs-module.h"

int plugin_is_GPL_compatible;

extern TSLanguage *tree_sitter_LANG_C(void);

/* REF: http://diobla.info/blog-archive/modules-tut.html  */

/* Return a USER_PTR to the language definition.  */
static emacs_value
Ftree_sitter_language
(emacs_env *env, ptrdiff_t nargs, emacs_value args[], void *data)
{
  TSLanguage *language = tree_sitter_LANG_C();
  return env->make_user_ptr (env, NULL, language);
}

/* Use this command to "dump" the file:
   xxd -i < grammar.js > parser.c.dump
 */
static emacs_value
Ftree_sitter_grammar
(emacs_env *env, ptrdiff_t nargs, emacs_value args[], void *data)
{
  char grammar[] = {
#include "grammar.js.dump"
    , '\0' };
  return env->make_string (env, grammar, strlen(grammar));
}

/* 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);

  emacs_value args[] = { Qsym, Sfun };
  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);
}

int
emacs_module_init (struct emacs_runtime *ert)
{
  emacs_env *env = ert->get_environment (ert);

  emacs_value lang = env->make_function
    (env, 0, 0, &Ftree_sitter_language,
     "Return a language object.", NULL);

    emacs_value grammar = env->make_function
      (env, 0, 0, &Ftree_sitter_grammar,
       "Return a language definition.", NULL);

  bind_function (env, "tree-sitter-LANG", lang);
  bind_function (env, "tree-sitter-LANG-grammar", grammar);
  provide (env, "tree-sitter-LANG");

  /* Return 0 to indicate module loaded successfully.  */
  return 0;
}