////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1999-2021 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_oct_shlib_h)
#define octave_oct_shlib_h 1

#include "octave-config.h"

#include <functional>
#include <list>
#include <map>
#include <string>

#include "oct-time.h"
#include "oct-refcount.h"

namespace octave
{
  class
  OCTAVE_API
  dynamic_library
  {
  public: // FIXME: make this class private?

    typedef std::function<std::string (const std::string&)> name_mangler;

    class dynlib_rep
    {
    public:

      dynlib_rep (void)
        : m_count (1), m_fcn_names (), m_file (), m_time_loaded (time_t ()),
          m_search_all_loaded (false)
      { }

    protected:

      dynlib_rep (const std::string& f);

    public:

      virtual ~dynlib_rep (void)
      {
        s_instances.erase (m_file);
      }

      virtual bool is_open (void) const
      { return false; }

      virtual void * search (const std::string&,
                             const name_mangler& = name_mangler ())
      { return nullptr; }

      bool is_out_of_date (void) const;

      // This method will be overridden conditionally.
      static dynlib_rep * new_instance (const std::string& f);

      static dynlib_rep * get_instance (const std::string& f, bool fake);

      sys::time time_loaded (void) const
      { return m_time_loaded; }

      std::string file_name (void) const
      { return m_file; }

      std::size_t num_fcn_names (void) const { return m_fcn_names.size (); }

      std::list<std::string> function_names (void) const;

      void add_fcn_name (const std::string&);

      bool remove_fcn_name (const std::string&);

      void clear_fcn_names (void) { m_fcn_names.clear (); }

    public:

      refcount<octave_idx_type> m_count;

    protected:

      void fake_reload (void);

      static std::map<std::string, dynlib_rep *> s_instances;

      // Set of hooked function names.
      typedef std::map<std::string, std::size_t>::iterator fcn_names_iterator;
      typedef std::map<std::string, std::size_t>::const_iterator fcn_names_const_iterator;

      std::map<std::string, std::size_t> m_fcn_names;
      std::string m_file;
      sys::time m_time_loaded;
      bool m_search_all_loaded;
    };

  private:

    static dynlib_rep s_nil_rep;

  public:

    dynamic_library (void) : m_rep (&s_nil_rep) { m_rep->m_count++; }

    dynamic_library (const std::string& f, bool fake = true)
      : m_rep (dynlib_rep::get_instance (f, fake)) { }

    ~dynamic_library (void)
    {
      if (--m_rep->m_count == 0 && m_rep != &s_nil_rep)
        delete m_rep;
    }

    dynamic_library (const dynamic_library& sl)
      : m_rep (sl.m_rep)
    {
      m_rep->m_count++;
    }

    dynamic_library& operator = (const dynamic_library& sl)
    {
      if (m_rep != sl.m_rep)
        {
          if (--m_rep->m_count == 0 && m_rep != &s_nil_rep)
            delete m_rep;

          m_rep = sl.m_rep;
          m_rep->m_count++;
        }

      return *this;
    }

    bool operator == (const dynamic_library& sl) const
    { return (m_rep == sl.m_rep); }

    operator bool () const { return m_rep->is_open (); }

    void open (const std::string& f)
    { *this = dynamic_library (f); }

    std::list<std::string> close (void)
    {
      std::list<std::string> removed_fcns = m_rep->function_names ();

      m_rep->clear_fcn_names ();

      *this = dynamic_library ();

      return removed_fcns;
    }

    void * search (const std::string& nm,
                   const name_mangler& mangler = name_mangler ()) const
    {
      void *f = m_rep->search (nm, mangler);
      if (f)
        m_rep->add_fcn_name (nm);

      return f;
    }

    void add (const std::string& name)
    { m_rep->add_fcn_name (name); }

    bool remove (const std::string& name)
    { return m_rep->remove_fcn_name (name); }

    std::size_t number_of_functions_loaded (void) const
    { return m_rep->num_fcn_names (); }

    bool is_out_of_date (void) const
    { return m_rep->is_out_of_date (); }

    std::string file_name (void) const
    { return m_rep->file_name (); }

    sys::time time_loaded (void) const
    { return m_rep->time_loaded (); }

  private:

    dynlib_rep *m_rep;
  };
}

#endif
