////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2013-2021 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_hook_fcn_h)
#define octave_hook_fcn_h 1

#include "octave-config.h"

#include <string>

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

class
base_hook_function
{
public:

  friend class hook_function;

  base_hook_function (void) : count (1) { }

  base_hook_function (const base_hook_function&) : count (1) { }

  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&) { }

protected:

  size_t count;
};

class
hook_function
{
public:

  hook_function (void)
  {
    static base_hook_function nil_rep;
    rep = &nil_rep;
    rep->count++;
  }

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

  ~hook_function (void)
  {
    if (--rep->count == 0)
      delete rep;
  }

  hook_function (const hook_function& hf)
    : rep (hf.rep)
  {
    rep->count++;
  }

  hook_function& operator = (const hook_function& hf)
  {
    if (rep != hf.rep)
      {
        if (--rep->count == 0)
          delete rep;

        rep = hf.rep;
        rep->count++;
      }

    return *this;
  }

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

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

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

private:

  base_hook_function *rep;
};

class
named_hook_function : public base_hook_function
{
public:

  named_hook_function (const std::string& n, const octave_value& d)
    : name (n), data (d)
  { }

  void eval (const octave_value_list& initial_args);

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

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

private:

  std::string name;

  octave_value data;
};

class
fcn_handle_hook_function : public base_hook_function
{
public:

  fcn_handle_hook_function (const octave_value& fh_arg, const octave_value& d)
    : ident (), valid (false), fcn_handle (fh_arg), data (d)
  {
    octave_fcn_handle *fh = fcn_handle.fcn_handle_value (true);

    if (fh)
      {
        valid = true;

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

  void eval (const octave_value_list& initial_args);

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

  bool is_valid (void) const { return valid; }

private:

  std::string ident;

  bool valid;

  octave_value fcn_handle;

  octave_value 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) : fcn_map () { }

  ~hook_function_list (void) = default;

  hook_function_list (const hook_function_list& lst)
    : fcn_map (lst.fcn_map)
  { }

  hook_function_list& operator = (const hook_function_list& lst)
  {
    if (&lst != this)
      fcn_map = lst.fcn_map;

    return *this;
  }

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

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

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

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

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

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

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

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

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

    while (p != 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
          fcn_map.erase (q);
      }
  }

private:

  map_type fcn_map;
};

#endif
