#include <assert.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdlib.h>
#include <math.h>

#include "gc.h"
#include "builtin.h"
#include "interp.h"

static gc_root_t builtin_list;
static gc_root_t template_type_root;
static gc_root_t lambda_type_root;

static void register_structure(void);
static void register_template(void);
static void register_lambda(void);

static void bi_string_to_number(interp_state_t *state);
static void bi_freeze(interp_state_t *state);
static void bi_immutable_p(interp_state_t *state);

void builtin_init(void)
{
  register_gc_root(&builtin_list,        NIL);
  register_gc_root(&template_type_root,  UNDEFINED);
  register_gc_root(&lambda_type_root,    UNDEFINED);

  register_builtin(BI_UNDEFINED,         UNDEFINED);
  register_builtin(BI_STRING_TO_NUMBER,  make_builtin_fn(bi_string_to_number));
  register_builtin(BI_FREEZE,            make_builtin_fn(bi_freeze));
  register_builtin(BI_IMMUTABLE_P,       make_builtin_fn(bi_immutable_p));

#ifdef NAN
  register_builtin(BI_POS_NAN, make_float(NAN));
  register_builtin(BI_NEG_NAN, make_float(-NAN));
#endif

#ifdef INFINITY
  register_builtin(BI_POS_INFINITY, make_float(INFINITY));
  register_builtin(BI_NEG_INFINITY, make_float(-INFINITY));
#endif

  register_structure();
  register_template();
  register_lambda();
}

void register_builtin(const char *name, value_t value)
{
  gc_root_t name_root;

  register_gc_root(&name_root, string_to_value(name));
  builtin_list.value = cons(value, builtin_list.value);
  builtin_list.value = cons(name_root.value, builtin_list.value);
  unregister_gc_root(&name_root);
}

value_t lookup_builtin(const char *name)
{
  value_t name_val = string_to_value(name);

  for (value_t list = builtin_list.value; !is_nil(list);
       list = _CDDR(list))
  {
    if (byte_strcmp(_CAR(list), name_val) == 0)
    {
      return _CADR(list);
    }
  }

  return FALSE_VALUE;
}

value_t get_template_type(void)
{
  return template_type_root.value;
}

value_t get_lambda_type(void)
{
  return lambda_type_root.value;
}

#define SS(x) STRUCTURE_SLOT_ ## x

static void register_structure(void)
{
  register_builtin(BI_STRUCTURE, get_structure_type());
}

static void register_template(void)
{
  /* Template: Instances of this structure describe what a LAMBDA
   * will look like when instanciated with the 'lambda' bytecode. */
  template_type_root.value = make_struct(get_structure_type());

  /* Slot 1: List of superclasses, most to least specific */
  _get_struct(template_type_root.value)->slots[SS(SUPERS)] = NIL;
  /* Slot 2: Total number of slots (excl. type) */
  _get_struct(template_type_root.value)->slots[SS(NSLOTS)] = fixnum_value(TEMPLATE_SLOTS);
  /* Slot 3: Callable object used as proxy when structure is APPLY'd. */
  _get_struct(template_type_root.value)->slots[SS(CALLABLE)] = FALSE_VALUE;

  _get_struct(template_type_root.value)->immutable = true;

  register_builtin(BI_TEMPLATE, template_type_root.value);
}

static void register_lambda(void)
{
  /* Lambda: Instances of this structure are fundamental callable objects. */
  lambda_type_root.value = make_struct(get_structure_type());

  /* Slot 1: List of superclasses, most to least specific */
  _get_struct(lambda_type_root.value)->slots[SS(SUPERS)] = NIL;
  /* Slot 2: Total number of slots (excl. type) */
  _get_struct(lambda_type_root.value)->slots[SS(NSLOTS)] = fixnum_value(LAMBDA_SLOTS);
  /* Slot 3: Callable object used as proxy when structure is APPLY'd. */
  _get_struct(lambda_type_root.value)->slots[SS(CALLABLE)] = FALSE_VALUE;

  _get_struct(lambda_type_root.value)->immutable = true;

  register_builtin(BI_LAMBDA, lambda_type_root.value);
}

#undef SS

static void bi_string_to_number(interp_state_t *state)
{
  char *str;
  char *end;
  fixnum_t num;
  value_t rval;

  str = value_to_string(CAR(state->argv.value));
  num = strtol(str, &end, 0);
  free(str);

  if ((*end == '\0') && (_get_fixnum(fixnum_value(num)) == num))
    rval = fixnum_value(num);
  else
    rval = FALSE_VALUE;

  interp_return_values(state, cons(rval, NIL));
}

static void bi_freeze(interp_state_t *state)
{
  value_t val = CAR(state->argv.value);

  if (is_vector(val))
  {
    _get_vector(val)->immutable = true;
  }
  else if (is_byte_string(val))
  {
    _get_byte_string(val)->immutable = true;
  }
  else if (is_struct(val))
  {
    _get_struct(val)->immutable = true;
  }

  interp_return_values(state, cons(val, NIL));
}

static void bi_immutable_p(interp_state_t *state)
{
  value_t val;
  bool frozen;

  val = CAR(state->argv.value);

  if (is_vector(val))
  {
    frozen = _get_vector(val)->immutable;
  }
  else if (is_byte_string(val))
  {
    frozen = _get_byte_string(val)->immutable;
  }
  else if (is_struct(val))
  {
    frozen = _get_struct(val)->immutable;
  }
  else
  {
    /* These values can't be changed, and thus can be considered frozen: */
    frozen = !is_object(val) || is_float(val) || is_builtin_fn(val);
  }

  interp_return_values(state, cons(boolean_value(frozen), NIL));
}

/* vim:set sw=2 expandtab: */