/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2026 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */

/**
 * @file sqrt.c
 * @brief Implements the OP_SQRT opcode using C99 math.h sqrt().
 *
 * Behavior:
 * - Pops one numeric operand (int or float).
 * - If x < 0, pushes NaN; else pushes sqrt(x).
 * - Returns VAL_INT when the result fits exactly in int64, otherwise VAL_FLOAT.
 *
 * Stack effect:
 * - Pop: x
 * - Push: sqrt(x) | NaN
 */

#include <math.h>

case OP_SQRT: {
  Value v = pop_value(vm);
  if (v.type == VAL_INT || v.type == VAL_FLOAT) {
    double x = (v.type == VAL_FLOAT) ? v.d : (double)v.i;
    if (x < 0.0) {
      push_value(vm, make_float(NAN));
    } else {
      double r = sqrt(x);
      /* preserve int if exactly integral */
      if (r >= (double)INT64_MIN && r <= (double)INT64_MAX) {
        int64_t ii = (int64_t)r;
        if ((double)ii == r) {
          push_value(vm, make_int(ii));
        } else {
          push_value(vm, make_float(r));
        }
      } else {
        push_value(vm, make_float(r));
      }
    }
    free_value(v);
  } else {
    fprintf(stderr, "Runtime type error: SQRT expects number, got %s\n", value_type_name(v.type));
    exit(1);
  }
  break;
}
