/*
 * Copyright (C) 2003,2004,2010 Tommi Maekitalo
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * As a special exception, you may use this file as part of a free
 * software library without restriction. Specifically, if other files
 * instantiate templates or use macros or inline functions from this
 * file, or you compile this file and link it with other files to
 * produce an executable, this file does not by itself cause the
 * resulting executable to be covered by the GNU General Public
 * License. This exception does not however invalidate any other
 * reasons why the executable file might be covered by the GNU Library
 * General Public License.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef CXXTOOLS_ARG_H
#define CXXTOOLS_ARG_H

#include <sstream>
#include <string.h>

namespace cxxtools
{

/// @cond internal
class ArgBase
{
  protected:
    bool m_isset;

    static void removeArg(int& argc, char* argv[], int pos, int n)
    {
      for ( ; pos < argc - n; ++pos)
        argv[pos] = argv[pos + n];
      argc -= n;
      argv[argc] = 0;
    }

  public:
    ArgBase()
      : m_isset(false)
    { }

    /**
     * returns true if the option was found and the default value was not used
     */
    bool isSet() const   { return m_isset; }
};

template <typename T>
class ArgBaseT : public ArgBase
{
    T m_value;

  protected:
    explicit ArgBaseT(const T& def)
      : m_value(def)
    { }

    bool extract(const char* str, int& argc, char* argv[], int i, int n)
    {
      std::istringstream s(str);
      s >> m_value;
      if (!s.fail())
      {
        m_isset = true;
        removeArg(argc, argv, i, n);
        return true;
      }
      return false;
    }

  public:
    /**
     returns the value.
     */
    const T& getValue() const   { return m_value; }

    /** @brief Read and extract commandline parameters from argc/argv.

        Programs usually need some parameters. Usually they start with a '-'
        followed by a single character and optionally a value.
        Arg<T> extracts these and other parameters.

        This default class processes paramters with a value, which defines
        a input-extractor-operator operator>> (istream&, T&).

        Options are removed from the option-list, so programs can easily check
        after all options are extracted, if there are parameters left.

        example:
        \code
          int main(int argc, char* argv[])
          {
            cxxtools::Arg<int> option_n(argc, argv, 'n', 0);
            std::cout << "value for -n: " << option_n << endl;
          }
        \endcode

     */
    operator T() const   { return m_value; }

    /// dereference operator returns value
    T operator *() const   { return m_value; }

    ArgBaseT<T>& operator= (const T& value)
    {
      m_value = value;
      return *this;
    }
};

template <>
class ArgBaseT<const char*> : public ArgBase
{
    const char* m_value;

  protected:
    explicit ArgBaseT(const char* def)
      : m_value(def)
    { }

    bool extract(const char* str, int& argc, char* argv[], int i, int n)
    {
      m_value = str;
      m_isset = true;
      removeArg(argc, argv, i, n);
      return true;
    }

  public:
    /// returns the extracted value.
    const char* getValue() const   { return m_value; }

    /// class is convertible to "const char*"
    operator const char*() const   { return m_value; }

    /// dereference operator returns value
    const char* operator *() const   { return m_value; }

    ArgBaseT<const char*>& operator= (const char* value)
    {
      m_value = value;
      return *this;
    }
};

template <>
class ArgBaseT<std::string> : public ArgBase
{
    std::string m_value;

  protected:
    explicit ArgBaseT(const std::string& def)
      : m_value(def)
    { }

    bool extract(const char* str, int& argc, char* argv[], int i, int n)
    {
      m_value = str;
      m_isset = true;
      removeArg(argc, argv, i, n);
      return true;
    }

  public:
    /// returns the extracted value.
    const std::string& getValue() const   { return m_value; }

    /// class is convertible to "const std::string&"
    operator const std::string&() const   { return m_value; }

    /// dereference operator returns value
    std::string operator *() const   { return m_value; }

    ArgBaseT<std::string>& operator= (const std::string& value)
    {
      m_value = value;
      return *this;
    }
};

template <>
class ArgBaseT<char> : public ArgBase
{
    char m_value;

  protected:
    explicit ArgBaseT(char def)
      : m_value(def)
    { }

    bool extract(const char* str, int& argc, char* argv[], int i, int n)
    {
      m_value = str[0];
      m_isset = str[0] != '\0';
      removeArg(argc, argv, i, n);
      return true;
    }

  public:
    /// returns the extracted value.
    char getValue() const   { return m_value; }

    /// class is convertible to "char"
    operator char() const   { return m_value; }

    /// dereference operator returns value
    char operator *() const   { return m_value; }

    ArgBaseT<char>& operator= (char value)
    {
      m_value = value;
      return *this;
    }
};

/// @endcond internal

/** @brief Read and extract commandline parameters from argc/argv.

    Programs usually need some parameters. Usually they start with a '-'
    followed by a single character and optionally a value.
    Arg<T> extracts these and other parameters.

    This default class processes paramters with a value, which defines
    a input-extractor-operator operator>> (istream&, T&).

    Options are removed from the option-list, so programs can easily check
    after all options are extracted, if there are parameters left.

    example:
    \code
      int main(int argc, char* argv[])
      {
        cxxtools::Arg<int> option_n(argc, argv, 'n', 0);
        std::cout << "value for -n: " << option_n << endl;
      }
    \endcode

 */
template <typename T>
class Arg : public ArgBaseT<T>
{
  public:
    /**
     default constructor. Initializes value.

     \param def    initial value
     */
    explicit Arg(const T& def = T())
      : ArgBaseT<T>(def)
      { }

    /**
     extract parameter.

     \param argc      1. parameter of main
     \param argv      2. of main
     \param ch        optioncharacter
     \param def       default-value

     example:
     \code
      cxxtools::Arg<unsigned> offset(argc, argv, 'o', 0);
      unsigned value = offset.getValue();
     \endcode
     */
    Arg(int& argc, char* argv[], char ch, const T& def = T())
      : ArgBaseT<T>(def)
    {
      set(argc, argv, ch);
    }

    /**
     GNU defines long options starting with `--`. This (and more) is
     supported here. Instead of giving a single option-character, you
     specify a string.

     example:
     \code
       cxxtools::Arg<int> option_number(argc, argv, "--number", 0);
       std::cout << "number =" << option_number.getValue() << std::endl;
     \endcode
     */
    Arg(int& argc, char* argv[], const char* str, const T& def = T())
      : ArgBaseT<T>(def)
    {
      this->m_isset = set(argc, argv, str);
    }

    Arg(int& argc, char* argv[])
      : ArgBaseT<T>(T())
    {
      this->m_isset = set(argc, argv);
    }

    /**
     extract parameter.

     \param argc      1. parameter of main
     \param argv      2. of main
     \param ch        optioncharacter

     example:
     \code
      cxxtools::Arg<unsigned> offset;
      offset.set(argc, argv, 'o');
      unsigned value = offset.getValue();
     \endcode
     */
    bool set(int& argc, char* argv[], char ch)
    {
      // don't extract value, when already found
      if (this->m_isset)
        return false;

      for (int i = 1; i < argc; ++i)
      {
        if (argv[i][0] == '-' && argv[i][1] == ch)
        {
          if (argv[i][2] == '\0' && i < argc - 1)
          {
            // -O foo
            if (this->extract(argv[i + 1], argc, argv, i, 2))
              return true;
          }

          // -Ofoo
          if (this->extract(argv[i] + 2, argc, argv, i, 1))
            return true;
        }
      }

      return false;
    }

    /**
     GNU defines long options starting with "--". This (and more) is
     supported here. Instead of giving a single option-character, you
     specify a string.

     example:
     \code
       cxxtools::Arg<int> option_number;
       number.set(argc, argv, "--number");
       std::cout << "number =" << option_number.getValue() << std::endl;
     \endcode
     */
    bool set(int& argc, char* argv[], const char* str)
    {
      // don't extract value, when already found
      if (this->m_isset)
        return false;

      unsigned n = strlen(str);
      for (int i = 1; i < argc; ++i)
      {
        if (strncmp(argv[i], str, n) == 0)
        {
          if (i < argc - 1 && argv[i][n] == '\0')
          {
            // --option value
            if (this->extract(argv[i + 1], argc, argv, i, 2))
              return true;
          }

          if (argv[i][n] == '=')
          {
            // --option=vlaue
            if (this->extract(argv[i] + n + 1, argc, argv, i, 1))
              return true;
          }
        }
      }

      return false;
    }

    /**
     Reads next parameter and removes it.
     */
    bool set(int& argc, char* argv[])
    {
      // don't extract value, when already found
      if (this->m_isset)
        return false;

      if (argc > 1)
        this->extract(argv[1], argc, argv, 1, 1);

      return this->m_isset;
    }
};

////////////////////////////////////////////////////////////////////////
/**
 specialization for bool.

 Often programs need some switches, which are switched on or off.
 Users just enter a option without parameter.

 example:
 \code
   cxxtools::Arg<bool> debug(argc, argv, 'd');
   if (debug)
     std::cout << "debug-mode is set" << std::endl;
 \endcode
 */
template <>
class Arg<bool> : public ArgBase
{
  public:
    /**
     default constructor. Initializes value.

     \param def    initial value
     */
    Arg(bool def = false)
      : m_value(def)
    { }

    /**
     Use this constructor to extract a bool-parameter.

     As a special case options can be grouped. The parameter is
     recognized also in a argument, which starts with a '-' and contains
     somewhere the given character.

     example:
     \code
      cxxtools::Arg<bool> debug(argc, argv, 'd');
      cxxtools::Arg<bool> ignore(argc, argv, 'i');
     \endcode

     Arguments debug and ignore are both set when the program is called
     with:
     \code
      prog -id

      prog -i -d
     \endcode

     Options can also switched off with a following '-' like this:
     \code
      prog -d-
     \endcode

     In the program use:
     \code
      Arg<bool> debug(argc, argv, 'd');
      if (debug.isSet())
      {
        if (debug)
          std::cout << "you entered -d" << std::endl;
        else
          std::cout << "you entered -d-" << std::endl;
      }
      else
        std::cout << "no -d option given" << std::endl;
     \endcode

     This is useful, if a program defaults to some enabled feature,
     which can be disabled.
     */
    Arg(int& argc, char* argv[], char ch, bool def = false)
      : m_value(def)
    {
      m_isset = set(argc, argv, ch);
    }

    Arg(int& argc, char* argv[], const char* str, bool def = false)
      : m_value(def)
    {
      m_isset = set(argc, argv, str);
    }

    bool set(int& argc, char* argv[], char ch)
    {
      // don't extract value, when already found
      if (m_isset)
        return false;

      for (int i = 1; i < argc; ++i)
      {
        if (argv[i][0] == '-' && argv[i][1] != '-')
        {
          // starts with a '-', but not with "--"
          if (argv[i][1] == ch && argv[i][2] == '\0')
          {
            // single option found
            m_value = true;
            m_isset = true;
            removeArg(argc, argv, i, 1);
            return true;
          }
          else if (argv[i][1] == ch && argv[i][2] == '-' && argv[i][3] == '\0')
          {
            // Option was explicitly disabled with -x-
            m_value = false;
            m_isset = true;
            removeArg(argc, argv, i, 1);
            return true;
          }
          else
          {
            // look, if we find the option in an optiongroup
            for (char* p = argv[i] + 1; *p != '\0'; ++p)
              if (*p == ch)
              {
                // here it is - extract it
                m_value = true;
                m_isset = true;
                do
                {
                  *p = *(p + 1);
                } while (*p++ != '\0');

                return true;
              }
          }
        }
      }

      return false;
    }

    /**
     Setter for long-options.

     The option-parameter is defined with a string. This can extract
     long-options like:
     \code
       prog --debug
     \endcode

     with
     \code
       Arg<bool> debug(argc, argv, "--debug");
     \endcode

     */
    bool set(int& argc, char* argv[], const char* str)
    {
      // don't extract value, when already found
      if (m_isset)
        return false;

      for (int i = 1; i < argc; ++i)
      {
        if (strcmp(argv[i], str) == 0)
        {
          m_value = true;
          m_isset = true;
          removeArg(argc, argv, i, 1);
          return true;
        }
      }

      return false;
    }

    /**
     returns true, if options is set.
     */
    bool isTrue() const   { return m_value; }

    /**
     returns true, if options is not set.
     */
    bool isFalse() const  { return !m_value; }

    /**
     convertable to bool.
     */
    operator bool() const  { return m_value; }

  private:
    bool m_value;
};

/// Output operator for a argument.
template <typename T>
std::ostream& operator<< (std::ostream& out, const ArgBaseT<T>& arg)
{
  return out << arg.getValue();
}

}

#endif // CXXTOOLS_ARG_H
