////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1996-2020 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <cstdlib>
#include <cstring>

#include <complex>
#include <istream>
#include <limits>
#include <ostream>
#include <string>

#include "quit.h"

#include "intprops-wrappers.h"
#include "lo-error.h"
#include "lo-ieee.h"
#include "lo-mappers.h"
#include "lo-utils.h"

bool xis_int_or_inf_or_nan (double x)
{ return octave::math::isnan (x) || octave::math::x_nint (x) == x; }

bool xtoo_large_for_float (double x)
{
  return (octave::math::isfinite (x)
          && fabs (x) > std::numeric_limits<float>::max ());
}

bool xtoo_large_for_float (const Complex& x)
{
  return (xtoo_large_for_float (x.real ())
          || xtoo_large_for_float (x.imag ()));
}

bool xis_int_or_inf_or_nan (float x)
{ return octave::math::isnan (x) || octave::math::x_nint (x) == x; }

// Save a string.

char *
strsave (const char *s)
{
  if (! s)
    return nullptr;

  int len = strlen (s);
  char *tmp = new char [len+1];
  tmp = strcpy (tmp, s);
  return tmp;
}

std::string
octave_fgets (FILE *f)
{
  bool eof;
  return octave_fgets (f, eof);
}

std::string
octave_fgets (FILE *f, bool& eof)
{
  eof = false;

  std::string retval;

  int grow_size = 1024;
  int max_size = grow_size;

  char *buf = static_cast<char *> (std::malloc (max_size));
  if (! buf)
    (*current_liboctave_error_handler) ("octave_fgets: unable to malloc %d bytes", max_size);

  char *bufptr = buf;
  int len = 0;

  do
    {
      if (std::fgets (bufptr, grow_size, f))
        {
          len = strlen (bufptr);

          if (len == grow_size - 1)
            {
              int tmp = bufptr - buf + grow_size - 1;
              grow_size *= 2;
              max_size += grow_size;
              auto tmpbuf = static_cast<char *> (std::realloc (buf, max_size));
              if (! tmpbuf)
                {
                  free (buf);
                  (*current_liboctave_error_handler) ("octave_fgets: unable to realloc %d bytes", max_size);
                }
              buf = tmpbuf;
              bufptr = buf + tmp;

              if (*(bufptr-1) == '\n')
                {
                  *bufptr = '\0';
                  retval = buf;
                }
            }
          else if (bufptr[len-1] != '\n')
            {
              bufptr[len++] = '\n';
              bufptr[len] = '\0';
              retval = buf;
            }
          else
            retval = buf;
        }
      else
        {
          if (len == 0)
            {
              eof = true;

              free (buf);

              buf = nullptr;
            }

          break;
        }
    }
  while (retval.empty ());

  free (buf);

  octave_quit ();

  return retval;
}

std::string
octave_fgetl (FILE *f)
{
  bool eof;
  return octave_fgetl (f, eof);
}

std::string
octave_fgetl (FILE *f, bool& eof)
{
  std::string retval = octave_fgets (f, eof);

  if (! retval.empty () && retval.back () == '\n')
    retval.pop_back ();

  return retval;
}

namespace octave
{
  // Note that the caller is responsible for repositioning the stream on
  // failure.

  template <typename T>
  T
  read_inf_nan_na (std::istream& is, char c0)
  {
    T val = 0.0;

    switch (c0)
      {
      case 'i': case 'I':
        {
          char c1 = is.get ();
          if (c1 == 'n' || c1 == 'N')
            {
              char c2 = is.get ();
              if (c2 == 'f' || c2 == 'F')
                val = std::numeric_limits<T>::infinity ();
              else
                is.setstate (std::ios::failbit);
            }
          else
            is.setstate (std::ios::failbit);
        }
        break;

      case 'n': case 'N':
        {
          char c1 = is.get ();
          if (c1 == 'a' || c1 == 'A')
            {
              char c2 = is.get ();
              if (c2 == 'n' || c2 == 'N')
                val = std::numeric_limits<T>::quiet_NaN ();
              else
                {
                  val = numeric_limits<T>::NA ();
                  if (c2 != std::istream::traits_type::eof ())
                    is.putback (c2);
                  else
                    is.clear (is.rdstate () & ~std::ios::failbit);
                }
            }
          else
            is.setstate (std::ios::failbit);
        }
        break;

      default:
        (*current_liboctave_error_handler)
          ("read_inf_nan_na: invalid character '%c'", c0);
      }

    return val;
  }

  // Read a double value.  Discard any sign on NaN and NA.

  template <typename T>
  double
  read_fp_value (std::istream& is)
  {
    T val = 0.0;

    // FIXME: resetting stream position is likely to fail unless we are
    // reading from a file.
    std::streampos pos = is.tellg ();

    char c1 = ' ';

    while (isspace (c1))
      c1 = is.get ();

    bool neg = false;

    switch (c1)
      {
      case '-':
        neg = true;
        OCTAVE_FALLTHROUGH;

      case '+':
        {
          char c2 = 0;
          c2 = is.get ();
          if (c2 == 'i' || c2 == 'I' || c2 == 'n' || c2 == 'N')
            val = read_inf_nan_na<T> (is, c2);
          else
            {
              is.putback (c2);
              is >> val;
            }

          if (neg && ! is.fail ())
            val = -val;
        }
        break;

      case 'i': case 'I':
      case 'n': case 'N':
        val = read_inf_nan_na<T> (is, c1);
        break;

      default:
        is.putback (c1);
        is >> val;
        break;
      }

    std::ios::iostate status = is.rdstate ();
    if (status & std::ios::failbit)
      {
        // Convert MAX_VAL returned by C++ streams for very large numbers to Inf
        if (val == std::numeric_limits<T>::max ())
          {
            if (neg)
              val = -std::numeric_limits<T>::infinity ();
            else
              val = std::numeric_limits<T>::infinity ();
            is.clear (status & ~std::ios::failbit);
          }
        else
          {
            // True error.  Reset stream to original position and pass status on.
            is.clear ();
            is.seekg (pos);
            is.setstate (status);
          }
      }

    return val;
  }

  template <typename T>
  std::complex<T>
  read_cx_fp_value (std::istream& is)
  {
    T re = 0.0;
    T im = 0.0;

    std::complex<T> cx = 0.0;

    char ch = ' ';

    while (isspace (ch))
      ch = is.get ();

    if (ch == '(')
      {
        re = read_value<T> (is);
        ch = is.get ();

        if (ch == ',')
          {
            im = read_value<T> (is);
            ch = is.get ();

            if (ch == ')')
              cx = std::complex<T> (re, im);
            else
              is.setstate (std::ios::failbit);
          }
        else if (ch == ')')
          cx = re;
        else
          is.setstate (std::ios::failbit);
      }
    else
      {
        is.putback (ch);
        cx = read_value<T> (is);
      }

    return cx;
  }

  // FIXME: Could we use traits and enable_if to avoid duplication in the
  // following specializations?

  template <> double read_value (std::istream& is)
  {
    return read_fp_value<double> (is);
  }

  template <> Complex read_value (std::istream& is)
  {
    return read_cx_fp_value<double> (is);
  }

  template <> float read_value (std::istream& is)
  {
    return read_fp_value<float> (is);
  }

  template <> FloatComplex read_value (std::istream& is)
  {
    return read_cx_fp_value<float> (is);
  }

  // Note: precision is supposed to be managed outside of this function by
  // setting stream parameters.

  template <> void write_value (std::ostream& os, const double& value)
  {
    if (lo_ieee_is_NA (value))
      os << "NA";
    else if (lo_ieee_isnan (value))
      os << "NaN";
    else if (lo_ieee_isinf (value))
      os << (value < 0 ? "-Inf" : "Inf");
    else
      os << value;
  }

  template <> void write_value (std::ostream& os, const Complex& value)
  {
    os << '(';
    write_value<double> (os, real (value));
    os << ',';
    write_value<double> (os, imag (value));
    os << ')';
  }

  // Note: precision is supposed to be managed outside of this function by
  // setting stream parameters.

  template <> void write_value (std::ostream& os, const float& value)
  {
    if (lo_ieee_is_NA (value))
      os << "NA";
    else if (lo_ieee_isnan (value))
      os << "NaN";
    else if (lo_ieee_isinf (value))
      os << (value < 0 ? "-Inf" : "Inf");
    else
      os << value;
  }

  template <> void write_value (std::ostream& os, const FloatComplex& value)
  {
    os << '(';
    write_value<float> (os, real (value));
    os << ',';
    write_value<float> (os, imag (value));
    os << ')';
  }

  namespace math
  {
    bool int_multiply_overflow (int a, int b)
    {
      return octave_i_multiply_overflow_wrapper (a, b);
    }

    bool int_multiply_overflow (long int a, long int b)
    {
      return octave_li_multiply_overflow_wrapper (a, b);
    }

#if defined (OCTAVE_HAVE_LONG_LONG_INT)
    bool int_multiply_overflow (long long int a, long long int b)
    {
      return octave_lli_multiply_overflow_wrapper (a, b);
    }
#endif

    bool int_multiply_overflow (unsigned int a, unsigned int b)
    {
      return octave_ui_multiply_overflow_wrapper (a, b);
    }

    bool int_multiply_overflow (unsigned long int a, unsigned long int b)
    {
      return octave_uli_multiply_overflow_wrapper (a, b);
    }

#if defined (OCTAVE_HAVE_UNSIGNED_LONG_LONG_INT)
    bool int_multiply_overflow (unsigned long long int a,
                                unsigned long long int b)
    {
      return octave_ulli_multiply_overflow_wrapper (a, b);
    }
#endif

  }
}