/* Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.

 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 PLUGIN_X_CLIENT_MYSQLXCLIENT_XDECIMAL_H_
#define PLUGIN_X_CLIENT_MYSQLXCLIENT_XDECIMAL_H_

#include <cstdint>
#include <stdexcept>
#include <string>

#include "errmsg.h"
#include "xerror.h"

namespace xcl {

class Decimal {
 public:
  Decimal() = default;

  explicit 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*/
            m_buffer = "";
            return;
          }
          dot_skipped = true;
          continue;
        }
        if (c1 < '0' || c1 > '9') {
          m_buffer = "";
          return;
        }
        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*/
            m_buffer = "";
            return;
          }
          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') {
          m_buffer = "";
          return;
        }

        m_buffer.push_back((c1 - '0') << 4 | (c2 - '0'));
      }
      if (m_buffer.length() <= 1) {
        m_buffer = "";
        return;
      }
      if (sign) m_buffer.push_back(sign << 4);
    }
  }

  std::string to_string() const {
    std::string result;
    str(&result);

    return result;
  }

  XError str(std::string *value_str) const {
    if (m_buffer.length() < 1) {
      return XError{CR_MALFORMED_PACKET, "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) (*value_str) = "-" + (*value_str);
        break;
      } else {
        (*value_str).push_back('0' + n1);
      }
      if (n2 > 9) {
        if (n2 == 0xb || n2 == 0xd) (*value_str) = "-" + (*value_str);
        break;
      } else {
        (*value_str).push_back('0' + n2);
      }
    }

    if (scale > (*value_str).length()) {
      return XError{CR_MALFORMED_PACKET, "Invalid decimal value " + m_buffer};
    }

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

    return {};
  }

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

  bool is_valid() const { return 0 != m_buffer.size(); }

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

  explicit operator std::string() const {
    std::string result;
    auto error = str(&result);

    if (error) return "";

    return result;
  }

  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;
};
}  // namespace xcl

#endif  // PLUGIN_X_CLIENT_MYSQLXCLIENT_XDECIMAL_H_