////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2013-2022 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_hook_fcn_h)
#define octave_hook_fcn_h 1

#include "octave-config.h"

#include <memory>
#include <string>

#include "ovl.h"
#include "ov.h"
#include "ov-fcn-handle.h"
#include "variables.h"

OCTAVE_BEGIN_NAMESPACE(octave)

  class base_hook_function
  {
  public:

    base_hook_function (void) = default;

    base_hook_function (const base_hook_function&) = default;

    virtual ~base_hook_function (void) = default;

    virtual std::string id (void) const { return ""; }

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

    virtual void eval (const octave_value_list&) { }
  };

  class hook_function
  {
  public:

    hook_function (void)
    {
      static std::shared_ptr<base_hook_function>
        nil_rep (new base_hook_function ());

      m_rep = nil_rep;
    }

    hook_function (const octave_value& f,
                   const octave_value& d = octave_value ());

    ~hook_function (void) = default;

    hook_function (const hook_function& hf) = default;

    hook_function& operator = (const hook_function& hf) = default;

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

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

    void eval (const octave_value_list& initial_args)
    {
      m_rep->eval (initial_args);
    }

  private:

    std::shared_ptr<base_hook_function> m_rep;
  };

  class named_hook_function : public base_hook_function
  {
  public:

    named_hook_function (const std::string& n, const octave_value& d)
      : m_name (n), m_data (d)
    { }

    void eval (const octave_value_list& initial_args);

    std::string id (void) const { return m_name; }

    bool is_valid (void) const { return is_valid_function (m_name); }

  private:

    std::string m_name;

    octave_value m_data;
  };

  class fcn_handle_hook_function : public base_hook_function
  {
  public:

    fcn_handle_hook_function (const octave_value& fh_arg, const octave_value& d)
      : m_ident (), m_valid (false), m_fcn_handle (fh_arg), m_data (d)
    {
      octave_fcn_handle *fh = m_fcn_handle.fcn_handle_value (true);

      if (fh)
        {
          m_valid = true;

          std::ostringstream buf;
          buf << fh;
          m_ident = fh->fcn_name () + ':' + buf.str ();
        }
    }

    void eval (const octave_value_list& initial_args);

    std::string id (void) const { return m_ident; }

    bool is_valid (void) const { return m_valid; }

  private:

    std::string m_ident;

    bool m_valid;

    octave_value m_fcn_handle;

    octave_value m_data;
  };

  class hook_function_list
  {
  public:

    typedef std::map<std::string, hook_function> map_type;

    typedef map_type::iterator iterator;
    typedef map_type::const_iterator const_iterator;

    hook_function_list (void) = default;

    ~hook_function_list (void) = default;

    hook_function_list (const hook_function_list& lst) = default;

    hook_function_list& operator = (const hook_function_list& lst) = default;

    bool empty (void) const { return m_fcn_map.empty (); }

    void clear (void) { m_fcn_map.clear (); }

    void insert (const std::string& id, const hook_function& f)
    {
      m_fcn_map[id] = f;
    }

    iterator find (const std::string& id)
    {
      return m_fcn_map.find (id);
    }

    const_iterator find (const std::string& id) const
    {
      return m_fcn_map.find (id);
    }

    iterator end (void) { return m_fcn_map.end (); }

    const_iterator end (void) const { return m_fcn_map.end (); }

    void erase (iterator p) { m_fcn_map.erase (p); }

    void run (const octave_value_list& initial_args = octave_value_list ())
    {
      auto p = m_fcn_map.begin ();

      while (p != m_fcn_map.end ())
        {
          std::string hook_fcn_id = p->first;
          hook_function hook_fcn = p->second;

          auto q = p++;

          if (hook_fcn.is_valid ())
            hook_fcn.eval (initial_args);
          else
            m_fcn_map.erase (q);
        }
    }

  private:

    map_type m_fcn_map;
  };

OCTAVE_END_NAMESPACE(octave)

#endif