/* GNU Guile interface for GNU Make.
Copyright (C) 2011-2013 Free Software Foundation, Inc.
This file is part of GNU Make.

GNU Make 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; either version 3 of the License, or (at your option) any later
version.

GNU Make 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 "makeint.h"
#include "gnumake.h"

#include "debug.h"
#include "filedef.h"
#include "dep.h"
#include "variable.h"

#include <libguile.h>

/* Pre-2.0 versions of Guile don't have a typedef for gsubr function types.  */
#if SCM_MAJOR_VERSION < 2
# define GSUBR_TYPE         SCM (*) ()
/* Guile 1.x doesn't really support i18n.  */
# define EVAL_STRING(_s)    scm_c_eval_string (_s)
#else
# define GSUBR_TYPE         scm_t_subr
# define EVAL_STRING(_s)    scm_eval_string (scm_from_utf8_string (_s))
#endif

static SCM make_mod = SCM_EOL;
static SCM obj_to_str = SCM_EOL;

/* Convert an SCM object into a string.  */
static char *
cvt_scm_to_str (SCM obj)
{
  return scm_to_locale_string (scm_call_1 (obj_to_str, obj));
}

/* Perform the GNU make expansion function.  */
static SCM
guile_expand_wrapper (SCM obj)
{
  char *str = cvt_scm_to_str (obj);
  SCM ret;
  char *res;

  DB (DB_BASIC, (_("guile: Expanding '%s'\n"), str));
  res = gmk_expand (str);
  ret = scm_from_locale_string (res);

  free (str);
  free (res);

  return ret;
}

/* Perform the GNU make eval function.  */
static SCM
guile_eval_wrapper (SCM obj)
{
  char *str = cvt_scm_to_str (obj);

  DB (DB_BASIC, (_("guile: Evaluating '%s'\n"), str));
  gmk_eval (str, 0);

  return SCM_BOOL_F;
}

/* Invoked by scm_c_define_module(), in the context of the GNU make module.  */
static void
guile_define_module (void *data UNUSED)
{
/* Ingest the predefined Guile module for GNU make.  */
#include "gmk-default.h"

  /* Register a subr for GNU make's eval capability.  */
  scm_c_define_gsubr ("gmk-expand", 1, 0, 0, (GSUBR_TYPE) guile_expand_wrapper);

  /* Register a subr for GNU make's eval capability.  */
  scm_c_define_gsubr ("gmk-eval", 1, 0, 0, (GSUBR_TYPE) guile_eval_wrapper);

  /* Define the rest of the module.  */
  scm_c_eval_string (GUILE_module_defn);
}

/* Initialize the GNU make Guile module.  */
static void *
guile_init (void *arg UNUSED)
{
  /* Define the module.  */
  make_mod = scm_c_define_module ("gnu make", guile_define_module, NULL);

  /* Get a reference to the object-to-string translator, for later.  */
  obj_to_str = scm_variable_ref (scm_c_module_lookup (make_mod, "obj-to-str"));

  /* Import the GNU make module exports into the generic space.  */
  scm_c_eval_string ("(use-modules (gnu make))");

  return NULL;
}

static void *
internal_guile_eval (void *arg)
{
  return cvt_scm_to_str (EVAL_STRING (arg));
}

/* This is the function registered with make  */
static char *
func_guile (const char *funcname UNUSED, unsigned int argc UNUSED, char **argv)
{
  static int init = 0;

  if (! init)
    {
      /* Initialize the Guile interpreter.  */
      scm_with_guile (guile_init, NULL);
      init = 1;
    }

  if (argv[0] && argv[0][0] != '\0')
    return scm_with_guile (internal_guile_eval, argv[0]);

  return NULL;
}

/* ----- Public interface ----- */

/* We could send the flocp to define_new_function(), but since guile is
   "kind of" built-in, that didn't seem so useful.  */
int
guile_gmake_setup (const gmk_floc *flocp UNUSED)
{
  /* Create a make function "guile".  */
  gmk_add_function ("guile", func_guile, 0, 1, GMK_FUNC_DEFAULT);

  return 1;
}