/**
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */

/**
 * @file to_number.c
 * @brief Implements the OP_TO_NUMBER opcode for converting values to integers in the VM.
 *
 * This file handles the OP_TO_NUMBER instruction, which converts a value to an integer.
 * The value is popped from the stack, and the result is pushed back.
 *
 * Behavior:
 * - Pops the value from the stack.
 * - Converts the value to an integer.
 * - Pushes the result onto the stack.
 *
 * Error Handling:
 * - Exits with an error if the conversion fails.
 *
 * Example:
 * // Bytecode: OP_TO_NUMBER
 * // Stack before: ["42"]
 * // Stack after: [42]
 *
 * @author Johannes Findeisen
 * @date 2025-10-16
 */

case OP_TO_NUMBER: {
  Value v = pop_value(vm);
  if (v.type == VAL_INT) {
    push_value(vm, make_int(v.i));
    free_value(v);
  } else if (v.type == VAL_FLOAT) {
    double d = v.d;
    if (d >= (double)INT64_MIN && d <= (double)INT64_MAX) {
      int64_t ii = (int64_t)d;
      if ((double)ii == d) {
        push_value(vm, make_int(ii));
      } else {
        push_value(vm, make_float(d));
      }
    } else {
      push_value(vm, make_float(d));
    }
    free_value(v);
  } else if (v.type == VAL_STRING) {
    const char *s = v.s ? v.s : "";
    const char *p = s;
    while (*p == ' ' || *p == '\t' || *p == '\r' || *p == '\n')
      p++;
    char *endp = NULL;
    /* Try float first to support decimals and scientific notation */
    double dval = strtod(p, &endp);
    while (endp && (*endp == ' ' || *endp == '\t' || *endp == '\r' || *endp == '\n'))
      endp++;
    if (!endp || *endp != '\0') {
      /* Fallback to integer-only parse */
      endp = NULL;
      long long parsed = strtoll(p, &endp, 10);
      while (endp && (*endp == ' ' || *endp == '\t' || *endp == '\r' || *endp == '\n'))
        endp++;
      if (endp && *endp == '\0') {
        push_value(vm, make_int((int64_t)parsed));
      } else {
        push_value(vm, make_int(0));
      }
    } else {
      /* Preserve int when exact; else float */
      if (dval >= (double)INT64_MIN && dval <= (double)INT64_MAX) {
        int64_t ii = (int64_t)dval;
        if ((double)ii == dval) {
          push_value(vm, make_int(ii));
        } else {
          push_value(vm, make_float(dval));
        }
      } else {
        push_value(vm, make_float(dval));
      }
    }
    free_value(v);
  } else if (v.type == VAL_BOOL) {
    push_value(vm, make_int(v.i ? 1 : 0));
    free_value(v);
  } else {
    free_value(v);
    push_value(vm, make_int(0));
  }
  break;
}