////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2022 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 (octave_help_h)
#define octave_help_h 1

#include "octave-config.h"

#include <iosfwd>
#include <string>

class string_vector;

class octave_value;
class octave_value_list;

OCTAVE_NAMESPACE_BEGIN

  class interpreter;

  class help_system
  {
  public:

    help_system (interpreter& interp)
      : m_interpreter (interp),
        m_built_in_docstrings_file (init_built_in_docstrings_file ()),
        m_doc_cache_file (init_doc_cache_file ()),
        m_info_file (init_info_file ()),
        m_info_program (init_info_program ()),
        m_makeinfo_program ("makeinfo"),
        m_suppress_verbose_help_message (false),
        m_texi_macros_file (init_texi_macros_file ())
    { }

    octave_value
    built_in_docstrings_file (const octave_value_list& args, int nargout);

    std::string
    built_in_docstrings_file (void) const { return m_built_in_docstrings_file; }

    std::string built_in_docstrings_file (const std::string& file)
    {
      return set (m_built_in_docstrings_file, file);
    }

    octave_value doc_cache_file (const octave_value_list& args, int nargout);

    std::string doc_cache_file (void) const { return m_doc_cache_file; }

    std::string doc_cache_file (const std::string& file)
    {
      return set (m_doc_cache_file, file);
    }

    octave_value info_file (const octave_value_list& args, int nargout);

    std::string info_file (void) const { return m_info_file; }

    std::string info_file (const std::string& file)
    {
      return set (m_info_file, file);
    }

    octave_value info_program (const octave_value_list& args, int nargout);

    std::string info_program (void) const { return m_info_program; }

    std::string info_program (const std::string& file)
    {
      return set (m_info_program, file);
    }

    octave_value makeinfo_program (const octave_value_list& args, int nargout);

    std::string makeinfo_program (void) const { return m_makeinfo_program; }

    std::string makeinfo_program (const std::string& file)
    {
      return set (m_makeinfo_program, file);
    }

    octave_value
    suppress_verbose_help_message (const octave_value_list& args, int nargout);

    bool suppress_verbose_help_message (void) const
    {
      return m_suppress_verbose_help_message;
    }

    bool suppress_verbose_help_message (bool flag)
    {
      return set (m_suppress_verbose_help_message, flag);
    }

    octave_value texi_macros_file (const octave_value_list& args, int nargout);

    std::string texi_macros_file (void) const { return m_texi_macros_file; }

    std::string texi_macros_file (const std::string& file)
    {
      return set (m_texi_macros_file, file);
    }

    std::string raw_help (const std::string&, bool&) const;

    std::string which (const std::string& name) const;
    std::string which (const std::string& name, std::string& type) const;

    string_vector make_name_list (void) const;

    void get_help_text (const std::string& name, std::string& text,
                        std::string& format) const;

    void get_help_text_from_file (const std::string& fname, std::string& text,
                                  std::string& format) const;

  private:

    interpreter& m_interpreter;

    // Name of the file containing doc strings for built-in functions.
    // (--built-in-docstrings-file file)
    std::string m_built_in_docstrings_file;

    // Name of the doc cache file specified on the command line.
    // (--doc-cache-file file)
    std::string m_doc_cache_file;

    // Name of the info file specified on command line.
    // (--info-file file)
    std::string m_info_file;

    // Name of the info reader we'd like to use.
    // (--info-program program)
    std::string m_info_program;

    // Name of the makeinfo program to run.
    std::string m_makeinfo_program;

    // If TRUE, don't print additional help message in help and usage
    // functions.
    bool m_suppress_verbose_help_message;

    // Name of the file containing local Texinfo macros that are prepended
    // to doc strings before processing.
    // (--texi-macros-file)
    std::string m_texi_macros_file;

    static std::string init_built_in_docstrings_file (void);

    static std::string init_doc_cache_file (void);

    static std::string init_info_file (void);

    static std::string init_info_program (void);

    static std::string init_texi_macros_file (void);

    template <typename T>
    T set (T& var, const T& new_val)
    {
      T old_val = var;
      var = new_val;
      return old_val;
    }

    string_vector local_functions (void) const;

    bool raw_help_from_symbol_table (const std::string& nm,
                                     std::string& h, std::string& w,
                                     bool& symbol_found) const;

    bool raw_help_from_file (const std::string& nm,
                             std::string& h, std::string& file,
                             bool& symbol_found) const;

    bool raw_help_from_docstrings_file (const std::string& nm, std::string& h,
                                        bool& symbol_found) const;
  };

  extern string_vector make_name_list (void);

OCTAVE_NAMESPACE_END

#endif