/* -*-comment-start: "//";comment-end:""-*-
 * GNU Mes --- Maxwell Equations of Software
 * Copyright © 2016,2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 * Copyright © 2019 Jeremiah Orians <jeremiah@pdp10.guru>
 *
 * 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 <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>

void
assert_number (char *name, struct scm *x)
{
  struct scm *y = x;
  if (y->type != TNUMBER)
    {
      eputs (name);
      error (cell_symbol_not_a_number, x);
    }
}

struct scm *
greater_p (struct scm *x)       /* ((name . ">") (arity . n)) */
{
  struct scm *y = x;
  if (y == cell_nil)
    {
      return cell_t;
    }

  assert_number ("greater_p", y->car);
  SCM n = y->car->value;
  y = y->cdr;

  while (y != cell_nil)
    {
      assert_number ("greater_p", y->car);

      if (y->car->value >= n)
        {
          return cell_f;
        }

      n = y->car->value;
      y = y->cdr;
    }

  return cell_t;
}

struct scm *
less_p (struct scm *x)          /* ((name . "<") (arity . n)) */
{
  struct scm *y = x;
  if (y == cell_nil)
    {
      return cell_t;
    }

  assert_number ("less_p", y->car);
  SCM n = y->car->value;
  y = y->cdr;

  while (y != cell_nil)
    {
      assert_number ("less_p", y->car);

      if (y->car->value <= n)
        {
          return cell_f;
        }

      n = y->car->value;
      y = y->cdr;
    }

  return cell_t;
}

struct scm *
is_p (struct scm *x)            /* ((name . "=") (arity . n)) */
{
  struct scm *y = x;
  if (y == cell_nil)
    {
      return cell_t;
    }

  assert_number ("is_p", y->car);
  SCM n = y->car->value;
  y = y->cdr;

  while (y != cell_nil)
    {
      if (y->car->value != n)
        {
          return cell_f;
        }

      y = y->cdr;
    }

  return cell_t;
}

struct scm *
minus (struct scm *x)           /* ((name . "-") (arity . n)) */
{
  struct scm *y = x;
  assert_number ("minus", y->car);
  SCM n = y->car->value;
  y = y->cdr;

  if (y == cell_nil)
    {
      n = -n;
    }

  while (y != cell_nil)
    {
      assert_number ("minus", y->car);
      n = n - y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
plus (struct scm *x)            /* ((name . "+") (arity . n)) */
{
  struct scm *y = x;
  SCM n = 0;

  while (y != cell_nil)
    {
      assert_number ("plus", y->car);
      n = n + y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
divide (struct scm *x)          /* ((name . "/") (arity . n)) */
{
  struct scm *y = x;
  SCM n = 1;

  if (y != cell_nil)
    {
      assert_number ("divide", y->car);
      n = y->car->value;
      y = y->cdr;
    }

  while (y != cell_nil)
    {
      assert_number ("divide", y->car);

      if (!n)
        {
          break;
        }

      n = n / y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
modulo (struct scm *a, struct scm *b)
{
  struct scm *a2 = a;
  struct scm *b2 = b;
  assert_number ("modulo", a);
  assert_number ("modulo", b);
  SCM x = a2->value;

  x = x % b2->value;
  if (b2->value < 0)
    x = x + b2->value;

  return make_number (x);
}

struct scm *
multiply (struct scm *x)        /* ((name . "*") (arity . n)) */
{
  struct scm *y = x;
  SCM n = 1;

  while (y != cell_nil)
    {
      assert_number ("multiply", y->car);
      n = n * y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
logand (struct scm *x)          /* ((arity . n)) */
{
  struct scm *y = x;
  SCM n = -1;

  while (y != cell_nil)
    {
      assert_number ("multiply", y->car);
      n = n & y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
logior (struct scm *x)          /* ((arity . n)) */
{
  struct scm *y = x;
  SCM n = 0;

  while (y != cell_nil)
    {
      assert_number ("logior", y->car);
      n = n | y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
lognot (struct scm *x)
{
  struct scm *y = x;
  assert_number ("lognot", x);
  SCM n = ~y->value;
  return make_number (n);
}

struct scm *
logxor (struct scm *x)          /* ((arity . n)) */
{
  struct scm *y = x;
  SCM n = 0;

  while (y != cell_nil)
    {
      assert_number ("logxor", y->car);
      n = n ^ y->car->value;
      y = y->cdr;
    }

  return make_number (n);
}

struct scm *
ash (struct scm *n, struct scm *count)
{
  struct scm *n2 = n;
  struct scm *count2 = count;
  assert_number ("ash", n);
  assert_number ("ash", count);
  SCM cn = n2->value;
  SCM ccount = count2->value;

  SCM r;
  if (ccount < 0)
    r = cn >> -ccount;
  else
    r = cn << ccount;

  return make_number (r);
}