#include <errno.h>
#include <float.h>

static double xstrtod(const char *p, char **q, char decimal, char sci,
                      int skip_trailing, int *maybe_int);

int to_double(char *item, double *p_value, char sci, char decimal, int *maybe_int)
{
    char *p_end = NULL;

    *p_value = xstrtod(item, &p_end, decimal, sci, 1, maybe_int);

    return (errno == 0) && (!*p_end);
}

#if PY_VERSION_HEX < 0x02060000
  #define PyBytes_Check                PyString_Check
  #define PyBytes_AS_STRING            PyString_AS_STRING
#endif

int floatify(PyObject* str, double *result, int *maybe_int) {
    int status;
    char *data;
    PyObject* tmp = NULL;
    const char sci = 'E';
    const char dec = '.';

    if (PyBytes_Check(str)) {
        data = PyBytes_AS_STRING(str);
    } else if (PyUnicode_Check(str)) {
        tmp = PyUnicode_AsUTF8String(str);
        data = PyBytes_AS_STRING(tmp);
    } else {
        PyErr_SetString(PyExc_TypeError, "Invalid object type");
        return -1;
    }

    status = to_double(data, result, sci, dec, maybe_int);

    if (!status) {
        /* handle inf/-inf */
        if (0 == strcmp(data, "-inf")) {
            *result = -HUGE_VAL;
            *maybe_int = 0;
        } else if (0 == strcmp(data, "inf")) {
            *result = HUGE_VAL;
            *maybe_int = 0;
        } else {
            PyErr_SetString(PyExc_ValueError, "Unable to parse string");
            Py_XDECREF(tmp);
            return -1;
        }
    }

    Py_XDECREF(tmp);
    return 0;

/*
#if PY_VERSION_HEX >= 0x03000000
  return PyFloat_FromString(str);
#else
  return PyFloat_FromString(str, NULL);
#endif
*/

}


// ---------------------------------------------------------------------------
// Implementation of xstrtod

//
// strtod.c
//
// Convert string to double
//
// Copyright (C) 2002 Michael Ringgaard. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. Neither the name of the project nor the names of its contributors
//    may be used to endorse or promote products derived from this software
//    without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// -----------------------------------------------------------------------
// Modifications by Warren Weckesser, March 2011:
// * Rename strtod() to xstrtod().
// * Added decimal and sci arguments.
// * Skip trailing spaces.
// * Commented out the other functions.
//

PANDAS_INLINE void lowercase(char *p) {
    for ( ; *p; ++p) *p = tolower(*p);
}

PANDAS_INLINE void uppercase(char *p) {
    for ( ; *p; ++p) *p = toupper(*p);
}


static double xstrtod(const char *str, char **endptr, char decimal,
                      char sci, int skip_trailing, int *maybe_int)
{
  double number;
  int exponent;
  int negative;
  char *p = (char *) str;
  double p10;
  int n;
  int num_digits;
  int num_decimals;

  errno = 0;
  *maybe_int = 1;

  // Skip leading whitespace
  while (isspace(*p)) p++;

  // Handle optional sign
  negative = 0;
  switch (*p)
  {
    case '-': negative = 1; // Fall through to increment position
    case '+': p++;
  }

  number = 0.;
  exponent = 0;
  num_digits = 0;
  num_decimals = 0;

  // Process string of digits
  while (isdigit(*p))
  {
    number = number * 10. + (*p - '0');
    p++;
    num_digits++;
  }

  // Process decimal part
  if (*p == decimal)
  {
    *maybe_int = 0;
    p++;

    while (isdigit(*p))
    {
      number = number * 10. + (*p - '0');
      p++;
      num_digits++;
      num_decimals++;
    }

    exponent -= num_decimals;
  }

  if (num_digits == 0)
  {
    errno = ERANGE;
    return 0.0;
  }

  // Correct for sign
  if (negative) number = -number;

  // Process an exponent string
  if (toupper(*p) == toupper(sci))
  {
    *maybe_int = 0;

    // Handle optional sign
    negative = 0;
    switch (*++p)
    {
      case '-': negative = 1;   // Fall through to increment pos
      case '+': p++;
    }

    // Process string of digits
    num_digits = 0;
    n = 0;
    while (isdigit(*p))
    {
      n = n * 10 + (*p - '0');
      num_digits++;
      p++;
    }

    if (negative)
      exponent -= n;
    else
      exponent += n;

    // If no digits, after the 'e'/'E', un-consume it
    if (num_digits == 0)
        p--;
  }


  if (exponent < DBL_MIN_EXP  || exponent > DBL_MAX_EXP)
  {

    errno = ERANGE;
    return HUGE_VAL;
  }

  // Scale the result
  p10 = 10.;
  n = exponent;
  if (n < 0) n = -n;
  while (n)
  {
    if (n & 1)
    {
      if (exponent < 0)
        number /= p10;
      else
        number *= p10;
    }
    n >>= 1;
    p10 *= p10;
  }


  if (number == HUGE_VAL) {
	  errno = ERANGE;
  }

  if (skip_trailing) {
      // Skip trailing whitespace
      while (isspace(*p)) p++;
  }

  if (endptr) *endptr = p;


  return number;
}
