#include <stdbool.h>
#include <stddef.h>

#include "hydroforth/number.h"

bool hydroforth__number__is_digit(char c)
{
  return '0' <= c && c <= '9';
}

bool hydroforth__number__convert_hex_digit(char c, unsigned char *const val)
{
  if (hydroforth__number__is_digit(c))
  {
    *val = c - '0';
  }
  else
  {
    switch (c)
    {
    case 'A':
    case 'a':
      *val = 0xa;
      break;

    case 'B':
    case 'b':
      *val = 0xb;
      break;

    case 'C':
    case 'c':
      *val = 0xc;
      break;

    case 'D':
    case 'd':
      *val = 0xd;
      break;

    case 'E':
    case 'e':
      *val = 0xe;
      break;

    case 'F':
    case 'f':
      *val = 0xf;
      break;

    default:
      return false;
    }
  }

  return true;
}

bool hydroforth__number__parse_number_hex(const char *const start, unsigned char len, int *const val)
{
  int n;
  for (unsigned char i = 0; i < len; i++)
  {
    unsigned char m;
    if (!hydroforth__number__convert_hex_digit(start[i], &m))
    {
      return false;
    }
    n *= 16;
    n += m;
  }

  return true;
}

bool hydroforth__number__parse_number(const char *const start, unsigned char len, int *const val)
{
  if (start[0] == '0')
  {
    if (len > 1)
    {
      switch (start[1])
      {
      case 'X':
      case 'x':
        return hydroforth__number__parse_number_hex(start + 2, len - 2, val);

      default:
        return hydroforth__number__parse_number(start + 1, len - 1, val);
      }
    }
    else
    {
      *val = 0;
      return true;
    }
  }
  else
  {
    int n = start[0] - '0';
    for (unsigned char i = 1; i < len; i++)
    {
      n *= 10;
      n += start[i] - '0';
    }
    *val = n;
    return true;
  }
}