/* -*-comment-start: "//";comment-end:""-*-
 * GNU Mes --- Maxwell Equations of Software
 * Copyright © 2016,2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 * Copyright © 2021 W. J. van der Laan <laanwj@protonmail.com>
 *
 * This file is part of GNU Mes.
 *
 * GNU Mes 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 Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "mes/lib.h"
#include "mes/mes.h"

#include <stdlib.h>

SCM
type_ (SCM x)
{
  return make_number (TYPE (x));
}

SCM
car_ (SCM x)
{
  SCM a = CAR (x);
  if (TYPE (x) == TPAIR)
    return a;
  return make_number (a);
}

SCM
cdr_ (SCM x)
{
  SCM d = CDR (x);
  if (TYPE (x) == TPAIR || TYPE (x) == TCLOSURE)
    return d;
  return make_number (d);
}

SCM
exit_ (SCM x)                   /*:((name . "exit")) */
{
  assert_msg (TYPE (x) == TNUMBER, "TYPE (x) == TNUMBER");
  exit (VALUE (x));
}

SCM
frame_printer (SCM frame)
{
  fdputs ("#<", __stdout);
  display_ (struct_ref_ (frame, 2));
  fdputc (' ', __stdout);
  fdputs ("procedure: ", __stdout);
  display_ (struct_ref_ (frame, 3));
  fdputc ('>', __stdout);
}

SCM
make_frame_type ()              /*:((internal)) */
{
  SCM record_type = cell_symbol_record_type;    // FIXME
  SCM fields = cell_nil;
  fields = cons (cell_symbol_procedure, fields);
  fields = cons (fields, cell_nil);
  fields = cons (cell_symbol_frame, fields);
  return make_struct (record_type, fields, cell_unspecified);
}

SCM
make_frame (SCM stack, long index)
{
  SCM frame_type = make_frame_type ();
  long array_index = 0;
  SCM procedure = 0;
  if (index != 0)
    {
      array_index = (STACK_SIZE - (index * FRAME_SIZE));
      procedure = g_stack_array[array_index + FRAME_PROCEDURE];
    }
  if (procedure == 0)
    procedure = cell_f;
  SCM values = cell_nil;
  values = cons (procedure, values);
  values = cons (cell_symbol_frame, values);
  return make_struct (frame_type, values, cstring_to_symbol ("frame-printer"));
}

SCM
make_stack_type ()              /*:((internal)) */
{
  SCM record_type = cell_symbol_record_type;    // FIXME
  SCM fields = cell_nil;
  fields = cons (cstring_to_symbol ("frames"), fields);
  fields = cons (fields, cell_nil);
  fields = cons (cell_symbol_stack, fields);
  return make_struct (record_type, fields, cell_unspecified);
}

SCM
make_stack (SCM stack)          /*:((arity . n)) */
{
  SCM stack_type = make_stack_type ();
  long size = (STACK_SIZE - g_stack) / FRAME_SIZE;
  SCM frames = make_vector__ (size);
  long i;
  for (i = 0; i < size; i = i + 1)
    {
      SCM frame = make_frame (stack, i);
      vector_set_x_ (frames, i, frame);
    }
  SCM values = cell_nil;
  values = cons (frames, values);
  values = cons (cell_symbol_stack, values);
  return make_struct (stack_type, values, cell_unspecified);
}

SCM
stack_length (SCM stack)
{
  SCM frames = struct_ref_ (stack, 3);
  return vector_length (frames);
}

SCM
stack_ref (SCM stack, SCM index)
{
  SCM frames = struct_ref_ (stack, 3);
  return vector_ref (frames, index);
}

SCM
xassq (SCM x, SCM a)            /* For speed in core. */
{
  while (a != cell_nil)
    {
      if (x == CDAR (a))
        return CAR (a);
      a = CDR (a);
    }
  return cell_f;
}

SCM
memq (SCM x, SCM a)
{
  int t = TYPE (x);
  if (t == TCHAR || t == TNUMBER)
    {
      long v = VALUE (x);
      while (a != cell_nil)
        {
          if (v == VALUE (CAR (a)))
            return a;
          a = CDR (a);
        }
      return cell_f;
    }
  if (t == TKEYWORD)
    {
      while (a != cell_nil)
        {
          if (TYPE (CAR (a)) == TKEYWORD)
            if (string_equal_p (x, CAR (a)) == cell_t)
              return a;
          a = CDR (a);
        }
      return cell_f;
    }
  while (a != cell_nil)
    {
      if (x == CAR (a))
        return a;
      a = CDR (a);
    }
  return cell_f;
}

SCM
equal2_p (SCM a, SCM b)
{
equal2:
  if (a == b)
    return cell_t;
  if (TYPE (a) == TPAIR && TYPE (b) == TPAIR)
    {
      if (equal2_p (CAR (a), CAR (b)) == cell_t)
        {
          a = CDR (a);
          b = CDR (b);
          goto equal2;
        }
      return cell_f;
    }
  if (TYPE (a) == TSTRING && TYPE (b) == TSTRING)
    return string_equal_p (a, b);
  if (TYPE (a) == TVECTOR && TYPE (b) == TVECTOR)
    {
      if (LENGTH (a) != LENGTH (b))
        return cell_f;
      long i;
      for (i = 0; i < LENGTH (a); i = i + 1)
        {
          SCM ai = VECTOR (a) + i;
          SCM bi = VECTOR (b) + i;
          if (TYPE (ai) == TREF)
            ai = REF (ai);
          if (TYPE (bi) == TREF)
            bi = REF (bi);
          if (equal2_p (ai, bi) == cell_f)
            return cell_f;
        }
      return cell_t;
    }
  return eq_p (a, b);
}

SCM
last_pair (SCM x)
{
  while (x != cell_nil)
    {
      if (CDR (x) == cell_nil)
        return x;
      x = CDR (x);
    }
  return x;
}

SCM
pair_p (SCM x)
{
  if (TYPE (x) == TPAIR)
    return cell_t;
  return cell_f;
}

SCM
char_to_integer (SCM x)
{
  return make_number (VALUE (x));
}

SCM
integer_to_char (SCM x)
{
  return make_char (VALUE (x));
}