/* Copyright (c) 2015, 2021, Oracle and/or its affiliates.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License, version 2.0,
 as published by the Free Software Foundation.

 This program is also distributed with certain software (including
 but not limited to OpenSSL) that is licensed under separate terms,
 as designated in a particular file or component or in included license
 documentation.  The authors of MySQL hereby grant you an additional
 permission to link the program and your derivative works with the
 separately licensed software that they have included with MySQL.

 This program 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, version 2.0, for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */


#ifndef _MYSQLX_DECIMAL_H_
#define _MYSQLX_DECIMAL_H_

#include <string>
#include <stdint.h>
#include <stdexcept>

namespace mysqlx
{
  class invalid_value : public std::runtime_error
  {
  public:
    invalid_value(const std::string &w) : std::runtime_error(w) {}
    virtual ~invalid_value() throw() {}
  };


  class Decimal
  {
  public:
    Decimal() {}

    Decimal(const std::string &s)
    {
      std::size_t scale = 0;
      std::size_t dot_pos = s.find('.');
      bool dot_skipped = false;
      if (dot_pos != std::string::npos)
      {
        scale = s.length() - dot_pos - 1;
      }
      m_buffer.push_back(static_cast<char>(scale));

      std::string::const_iterator c = s.begin();
      if (c != s.end())
      {
        int sign = (*c == '-') ? 0xd : (*c == '+' ? 0xc : 0);
        if (sign == 0)
          sign = 0xc;
        else
          ++c;

        while (c != s.end())
        {
          int c1 = *(c++);
          if (c1 == '.')
          {
            if (dot_skipped)
            {
              /*more than one dot*/
              throw invalid_value("Invalid decimal value " + s);
            }
            dot_skipped = true;
            continue;
          }
          if (c1 < '0' || c1 > '9')
            throw invalid_value("Invalid decimal value "+s);
          if (c == s.end())
          {
            m_buffer.push_back((c1 - '0') << 4 | sign);
            sign = 0;
            break;
          }
          int c2 = *(c++);
          if (c2 == '.')
          {
            if (dot_skipped)
            {
              /*more than one dot*/
              throw invalid_value("Invalid decimal value " + s);
            }
            dot_skipped = true;
            if (c == s.end())
            {
              m_buffer.push_back((c1 - '0') << 4 | sign);
              sign = 0;
              break;
            }
            else
            {
              c2 = *(c++);
            }
          }
          if (c2 < '0' || c2 > '9')
            throw invalid_value("Invalid decimal value "+s);

          m_buffer.push_back((c1 - '0') << 4 | (c2 - '0'));
        }
        if (m_buffer.length() <= 1) /* only scale */
          throw invalid_value("Invalid decimal value "+s);
        if (sign)
          m_buffer.push_back(sign << 4);
      }
    }

    std::string str() const
    {
      std::string r;

      if (m_buffer.length() < 1)
      {
        throw invalid_value("Invalid decimal value " + m_buffer);
      }
      size_t scale = m_buffer[0];

      for (std::string::const_iterator d = m_buffer.begin()+1; d != m_buffer.end(); ++d)
      {
        uint32_t n1 = ((uint32_t)*d & 0xf0) >> 4;
        uint32_t n2 = (uint32_t)*d & 0xf;

        if (n1 > 9)
        {
          if (n1 == 0xb || n1 == 0xd)
            r = "-" + r;
          break;
        }
        else
          r.push_back('0' + n1);
        if (n2 > 9)
        {
          if (n2 == 0xb || n2 == 0xd)
            r = "-" + r;
          break;
        }
        else
          r.push_back('0' + n2);
      }

      if (scale > r.length())
      {
        throw invalid_value("Invalid decimal value " + m_buffer);
      }

      if (scale > 0)
      {
        r.insert(r.length()-scale, 1, '.');
      }

      return r;
    }

    std::string to_bytes() const
    {
      return m_buffer;
    }


    static Decimal from_str(const std::string &s)
    {
      return Decimal(s);
    }

    operator std::string () const
    {
      return str();
    }

    static Decimal from_bytes(const std::string &buffer)
    {
      Decimal dec;
      dec.m_buffer = buffer;
      return dec;
    }

  private:
    /* first byte stores the scale (number of digits after '.') */
    /* then all digits in BCD */
    std::string m_buffer;
  };

}


#endif
